MC908LK24CFUE [NXP]
8 BIT MCU;
| 型号： | MC908LK24CFUE |
| 厂家： | 
NXP |
| 描述： | 8 BIT MCU |
| 文件： | 总464页 (文件大小：2347K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MC68HC908LJ24
MC68HC908LK24
Data Sheet
M68HC08
Microcontrollers
Rev. 2.1
MC68HC908LJ24/D
August 16, 2005
freescale.com
MC68HC908LJ24
MC68HC908LK24
Data Sheet
To provide the most up-to-date information, the revision of our
documents on the World Wide Web will be the most current. Your printed
copy may be an earlier revision. To verify you have the latest information
available, refer to:
http://freescale.com
The following revision history table summarizes changes contained in
this document. For your convenience, the page number designators
have been linked to the appropriate location.
This product incorporates SuperFlash® technology licensed from SST.
© Freescale, Inc., 2005
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
3
Revision History
Revision History
Revision
Level
Page
Number(s)
Date
Description
8/2003
2
First general release.
—
Data Sheet
4
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
List of Sections
Section 1. General Description . . . . . . . . . . . . . . . . . . . .37
Section 2. Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . .49
Section 3. Random-Access Memory (RAM) . . . . . . . . . .67
Section 4. FLASH Memory (FLASH) . . . . . . . . . . . . . . . .69
Section 5. Configuration Registers (CONFIG) . . . . . . . .79
Section 6. Central Processor Unit (CPU) . . . . . . . . . . . .85
Section 7. Oscillator (OSC) . . . . . . . . . . . . . . . . . . . . . .103
Section 8. Clock Generator Module (CGM). . . . . . . . . .109
Section 9. System Integration Module (SIM) . . . . . . . .139
Section 10. Monitor ROM (MON) . . . . . . . . . . . . . . . . . .163
Section 11. Timer Interface Module (TIM) . . . . . . . . . . .193
Section 12. Real Time Clock (RTC) . . . . . . . . . . . . . . . .217
Section 13. Infrared Serial Communications
Interface Module (IRSCI) . . . . . . . . . . . .245
Section 14. Serial Peripheral Interface Module (SPI). .287
Section 15. Multi-Master IIC Interface (MMIIC) . . . . . . .319
Section 16. Analog-to-Digital Converter (ADC) . . . . . .333
Section 17. Liquid Crystal Display (LCD) Driver . . . . .349
Section 18. Input/Output (I/O) Ports . . . . . . . . . . . . . . .375
Section 19. External Interrupt (IRQ) . . . . . . . . . . . . . . .401
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List of Sections
List of Sections
Section 20. Keyboard Interrupt Module (KBI). . . . . . . .407
Section 21. Computer Operating Properly (COP) . . . .415
Section 22. Low-Voltage Inhibit (LVI) . . . . . . . . . . . . . .421
Section 23. Break Module (BRK) . . . . . . . . . . . . . . . . . .427
Section 24. Electrical Specifications. . . . . . . . . . . . . . .435
Section 25. Mechanical Specifications . . . . . . . . . . . . .451
Section 26. Ordering Information . . . . . . . . . . . . . . . . .457
Appendix A. MC68HC908LK24. . . . . . . . . . . . . . . . . . . .459
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MC68HC908LJ24/LK24 — Rev. 2.1
List of Sections
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Table of Contents
Section 1. General Description
1.1
1.2
1.3
1.4
1.5
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Pin Assignments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
1.6
1.6.1
1.6.2
1.6.3
1.6.4
1.6.5
1.6.6
1.6.7
1.6.8
1.6.9
Power Supply Pins (V and V ). . . . . . . . . . . . . . . . . . . .44
DD SS
Analog Power Supply Pin (V
). . . . . . . . . . . . . . . . . . . . .44
DDA
LCD Bias Voltage (V
) . . . . . . . . . . . . . . . . . . . . . . . . . . .45
LCD
Oscillator Pins (OSC1 and OSC2) . . . . . . . . . . . . . . . . . . . .45
External Reset Pin (RST). . . . . . . . . . . . . . . . . . . . . . . . . . .45
External Interrupt Pin (IRQ) . . . . . . . . . . . . . . . . . . . . . . . . .45
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . .45
ADC Voltage High Reference Pin (V
). . . . . . . . . . . . . .45
REFH
ADC Voltage Low Reference Pin (V
) . . . . . . . . . . . . . .46
REFL
1.6.10 Port A Input/Output (I/O) Pins (PTA7–PTA0). . . . . . . . . . . .46
1.6.11 Port B I/O Pins (PTB7–PTB0) . . . . . . . . . . . . . . . . . . . . . . .46
1.6.12 Port C I/O Pins (PTC7–PTC0) . . . . . . . . . . . . . . . . . . . . . . .46
1.6.13 Port D I/O Pins (PTD7–PTD0) . . . . . . . . . . . . . . . . . . . . . . .46
1.6.14 Port E I/O Pins (PTE7–PTE0) . . . . . . . . . . . . . . . . . . . . . . .47
1.6.15 Port F I/O Pins (PTF7–PTF0). . . . . . . . . . . . . . . . . . . . . . . .47
1.6.16 LCD Backplane and Frontplane
(BP0-BP2, BP3/FP0, FP1–FP10, FP27–FP32) . . . . . . .47
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Table of Contents
Table of Contents
Section 2. Memory Map
2.1
2.2
2.3
2.4
2.5
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Unimplemented Memory Locations . . . . . . . . . . . . . . . . . . . . .49
Reserved Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . .50
Input/Output (I/O) Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
Section 3. Random-Access Memory (RAM)
3.1
3.2
3.3
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
Section 4. FLASH Memory (FLASH)
4.1
4.2
4.3
4.4
4.5
4.6
4.7
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70
FLASH Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
FLASH Page Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . .72
FLASH Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . .73
FLASH Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . .74
4.8
4.8.1
FLASH Block Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76
FLASH Block Protect Register . . . . . . . . . . . . . . . . . . . . . . .77
Section 5. Configuration Registers (CONFIG)
5.1
5.2
5.3
5.4
5.5
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80
Configuration Register 1 (CONFIG1) . . . . . . . . . . . . . . . . . . . .81
Configuration Register 2 (CONFIG2) . . . . . . . . . . . . . . . . . . . .82
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Section 6. Central Processor Unit (CPU)
6.1
6.2
6.3
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
6.4
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . .90
6.4.1
6.4.2
6.4.3
6.4.4
6.4.5
6.5
Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . .92
6.6
6.6.1
6.6.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
6.7
6.8
6.9
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . .93
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
Section 7. Oscillator (OSC)
7.1
7.2
7.3
7.4
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
Internal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105
X-tal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105
7.5
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105
Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . .106
Crystal Amplifier Output Pin (OSC2) . . . . . . . . . . . . . . . . .106
Oscillator Enable Signal (SIMOSCEN). . . . . . . . . . . . . . . .106
Internal RC Clock (ICLK) . . . . . . . . . . . . . . . . . . . . . . . . . .106
CGM Oscillator Clock (CGMXCLK) . . . . . . . . . . . . . . . . . .106
CGM Reference Clock (CGMRCLK) . . . . . . . . . . . . . . . . .106
7.5.1
7.5.2
7.5.3
7.5.4
7.5.5
7.5.6
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7.6
7.6.1
7.6.2
Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107
7.7
Oscillator During Break Mode. . . . . . . . . . . . . . . . . . . . . . . . .107
Section 8. Clock Generator Module (CGM)
8.1
8.2
8.3
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
8.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
Oscillator Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114
Phase-Locked Loop Circuit (PLL) . . . . . . . . . . . . . . . . . . .114
PLL Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114
Acquisition and Tracking Modes . . . . . . . . . . . . . . . . . . . .116
Manual and Automatic PLL Bandwidth Modes. . . . . . . . . .116
Programming the PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . .118
Special Programming Exceptions . . . . . . . . . . . . . . . . . . .122
Base Clock Selector Circuit . . . . . . . . . . . . . . . . . . . . . . . .122
CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . .123
8.4.1
8.4.2
8.4.3
8.4.4
8.4.5
8.4.6
8.4.7
8.4.8
8.4.9
8.5
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . .124
8.5.1
8.5.2
8.5.3
8.5.4
8.5.5
8.5.6
8.5.7
8.5.8
PLL Analog Power Pin (V
) . . . . . . . . . . . . . . . . . . . . . .124
DDA
PLL Analog Ground Pin (V
) . . . . . . . . . . . . . . . . . . . . .124
SSA
Oscillator Output Frequency Signal (CGMXCLK) . . . . . . .124
CGM Reference Clock (CGMRCLK) . . . . . . . . . . . . . . . . .124
CGM VCO Clock Output (CGMVCLK) . . . . . . . . . . . . . . . .125
CGM Base Clock Output (CGMOUT). . . . . . . . . . . . . . . . .125
CGM CPU Interrupt (CGMINT) . . . . . . . . . . . . . . . . . . . . .125
8.6
CGM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125
PLL Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
PLL Bandwidth Control Register . . . . . . . . . . . . . . . . . . . .128
PLL Multiplier Select Registers . . . . . . . . . . . . . . . . . . . . .130
PLL VCO Range Select Register . . . . . . . . . . . . . . . . . . . .131
PLL Reference Divider Select Register . . . . . . . . . . . . . . .132
8.6.1
8.6.2
8.6.3
8.6.4
8.6.5
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8.7
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
8.8
Special Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134
CGM During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . .134
8.8.1
8.8.2
8.8.3
8.9
Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . .135
Acquisition/Lock Time Definitions. . . . . . . . . . . . . . . . . . . .135
Parametric Influences on Reaction Time . . . . . . . . . . . . . .135
Choosing a Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
8.9.1
8.9.2
8.9.3
Section 9. System Integration Module (SIM)
9.1
9.2
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .140
9.3
SIM Bus Clock Control and Generation . . . . . . . . . . . . . . . . .142
Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143
Clock Start-up from POR or LVI Reset. . . . . . . . . . . . . . . .143
Clocks in Stop Mode and Wait Mode . . . . . . . . . . . . . . . . .144
9.3.1
9.3.2
9.3.3
9.4
9.4.1
9.4.2
9.4.2.1
9.4.2.2
9.4.2.3
9.4.2.4
9.4.2.5
9.4.2.6
Reset and System Initialization. . . . . . . . . . . . . . . . . . . . . . . .144
External Pin Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145
Active Resets from Internal Sources . . . . . . . . . . . . . . . . .145
Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146
Computer Operating Properly (COP) Reset. . . . . . . . . .147
Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . .148
Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . .148
Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . .148
Monitor Mode Entry Module Reset (MODRST) . . . . . . .148
9.5
SIM Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149
SIM Counter During Power-On Reset . . . . . . . . . . . . . . . .149
SIM Counter During Stop Mode Recovery. . . . . . . . . . . . .149
SIM Counter and Reset States. . . . . . . . . . . . . . . . . . . . . .149
9.5.1
9.5.2
9.5.3
9.6
Exception Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . .152
SWI Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153
9.6.1
9.6.1.1
9.6.1.2
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9.6.1.3
9.6.1.4
9.6.1.5
9.6.1.6
9.6.2
Interrupt Status Registers . . . . . . . . . . . . . . . . . . . . . . .153
Interrupt Status Register 1. . . . . . . . . . . . . . . . . . . . . . .153
Interrupt Status Register 2. . . . . . . . . . . . . . . . . . . . . . .155
Interrupt Status Register 3. . . . . . . . . . . . . . . . . . . . . . .155
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156
Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156
Status Flag Protection in Break Mode . . . . . . . . . . . . . . . .156
9.6.3
9.6.4
9.7
9.7.1
9.7.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158
9.8
SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
SIM Break Status Register. . . . . . . . . . . . . . . . . . . . . . . . .160
SIM Reset Status Register . . . . . . . . . . . . . . . . . . . . . . . .161
SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . .162
9.8.1
9.8.2
9.8.3
Section 10. Monitor ROM (MON)
10.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
10.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164
10.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164
10.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165
10.4.1 Entering Monitor Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . .167
10.4.2 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
10.4.3 Break Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
10.4.4 Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
10.4.5 Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172
10.5 Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177
10.6 ROM-Resident Routines. . . . . . . . . . . . . . . . . . . . . . . . . . . . .179
10.6.1 PRGRNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181
10.6.2 ERARNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183
10.6.3 LDRNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184
10.6.4 MON_PRGRNGE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .185
10.6.5 MON_ERARNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .186
10.6.6 MON_LDRNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187
10.6.7 EE_WRITE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .188
10.6.8 EE_READ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191
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Section 11. Timer Interface Module (TIM)
11.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193
11.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194
11.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194
11.4 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195
11.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195
11.5.1 TIM Counter Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . .199
11.5.2 Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .199
11.5.3 Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200
11.5.3.1
11.5.3.2
Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . .200
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . .201
11.5.4 Pulse Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . .201
11.5.4.1
11.5.4.2
11.5.4.3
Unbuffered PWM Signal Generation . . . . . . . . . . . . . . .202
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . .203
PWM Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . .204
11.6 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .205
11.7 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .205
11.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206
11.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206
11.8 TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . .206
11.9 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .207
11.9.1 TIM Clock Pins (PTD4/KBI4/T1CLK, PTD5/KBI5/T2CLK) .207
11.9.2 TIM Channel I/O Pins (PTB2/T1CH0, PTB3/T1CH1,
PTB4/T2CH0, PTB5/T2CH1) . . . . . . . . . . . . . . . . . . . .207
11.10 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208
11.10.1 TIM Status and Control Register . . . . . . . . . . . . . . . . . . . .208
11.10.2 TIM Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . .210
11.10.3 TIM Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . .211
11.10.4 TIM Channel Status and Control Registers . . . . . . . . . . . .212
11.10.5 TIM Channel Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . .215
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Section 12. Real Time Clock (RTC)
12.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .217
12.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218
12.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218
12.4 I/O Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219
12.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
12.5.1 Time Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223
12.5.2 Calendar Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223
12.5.3 Alarm Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223
12.5.4 Chronograph Functions . . . . . . . . . . . . . . . . . . . . . . . . . . .223
12.5.5 Timebase Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224
12.6 RTC Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224
12.7 RTC Clock Calibration and Compensation. . . . . . . . . . . . . . .225
12.7.1 Calibration Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .226
12.8 RTC Register and Bit Write Protection . . . . . . . . . . . . . . . . . .227
12.9 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229
12.9.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229
12.9.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230
12.10 RTC Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230
12.10.1 RTC Calibration Control Register (RTCCOMR). . . . . . . . .231
12.10.2 RTC Calibration Data Register (RTCCDAT) . . . . . . . . . . .233
12.10.3 RTC Control Register 1 (RTCCR1) . . . . . . . . . . . . . . . . . .234
12.10.4 RTC Control Register 2 (RTCCR2) . . . . . . . . . . . . . . . . . .235
12.10.5 RTC Status Register (RTCSR). . . . . . . . . . . . . . . . . . . . . .237
12.10.6 Alarm Minute and Hour Registers (ALMR and ALHR) . . . .240
12.10.7 Second Register (SECR) . . . . . . . . . . . . . . . . . . . . . . . . . .241
12.10.8 Minute Register (MINR) . . . . . . . . . . . . . . . . . . . . . . . . . . .241
12.10.9 Hour Register (HRR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242
12.10.10 Day Register (DAYR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242
12.10.11 Month Register (MTHR) . . . . . . . . . . . . . . . . . . . . . . . . . . .243
12.10.12 Year Register (YRR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243
12.10.13 Day-Of-Week Register (DOWR) . . . . . . . . . . . . . . . . . . . .244
12.10.14 Chronograph Data Register (CHRR) . . . . . . . . . . . . . . . . .244
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Section 13. Infrared Serial Communications
Interface Module (IRSCI)
13.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .245
13.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .246
13.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .247
13.4 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
13.5 IRSCI Module Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
13.6 Infrared Functional Description. . . . . . . . . . . . . . . . . . . . . . . .250
13.6.1 Infrared Transmit Encoder . . . . . . . . . . . . . . . . . . . . . . . . .251
13.6.2 Infrared Receive Decoder . . . . . . . . . . . . . . . . . . . . . . . . .251
13.7 SCI Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . .252
13.7.1 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253
13.7.2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254
13.7.2.1
13.7.2.2
13.7.2.3
13.7.2.4
13.7.2.5
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .255
Character Transmission. . . . . . . . . . . . . . . . . . . . . . . . .255
Break Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .256
Idle Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .256
Transmitter Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . .257
13.7.3 Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .257
13.7.3.1
13.7.3.2
13.7.3.3
13.7.3.4
13.7.3.5
13.7.3.6
13.7.3.7
13.7.3.8
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .257
Character Reception . . . . . . . . . . . . . . . . . . . . . . . . . . .259
Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .259
Framing Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
Baud Rate Tolerance. . . . . . . . . . . . . . . . . . . . . . . . . . .261
Receiver Wakeup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .264
Receiver Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . .265
Error Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .265
13.8 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266
13.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266
13.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266
13.9 SCI During Break Module Interrupts. . . . . . . . . . . . . . . . . . . .267
13.10 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .267
13.10.1 PTB0/TxD (Transmit Data). . . . . . . . . . . . . . . . . . . . . . . . .267
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13.10.2 PTB1/RxD (Receive Data) . . . . . . . . . . . . . . . . . . . . . . . . .267
13.11 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .268
13.11.1 SCI Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .269
13.11.2 SCI Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . .271
13.11.3 SCI Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . .274
13.11.4 SCI Status Register 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .276
13.11.5 SCI Status Register 2 (SCS2) . . . . . . . . . . . . . . . . . . . . . .280
13.11.6 SCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281
13.11.7 SCI Baud Rate Register. . . . . . . . . . . . . . . . . . . . . . . . . . .282
13.11.8 SCI Infrared Control Register. . . . . . . . . . . . . . . . . . . . . . .285
Section 14. Serial Peripheral Interface Module (SPI)
14.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .287
14.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .288
14.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .288
14.4 Pin Name Conventions and I/O Register Addresses . . . . . . .289
14.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .290
14.5.1 Master Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .291
14.5.2 Slave Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .292
14.6 Transmission Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .293
14.6.1 Clock Phase and Polarity Controls. . . . . . . . . . . . . . . . . . .293
14.6.2 Transmission Format When CPHA = 0 . . . . . . . . . . . . . . .294
14.6.3 Transmission Format When CPHA = 1 . . . . . . . . . . . . . . .296
14.6.4 Transmission Initiation Latency . . . . . . . . . . . . . . . . . . . . .297
14.7 Queuing Transmission Data . . . . . . . . . . . . . . . . . . . . . . . . . .299
14.8 Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300
14.8.1 Overflow Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300
14.8.2 Mode Fault Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302
14.9 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .304
14.10 Resetting the SPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306
14.11 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307
14.11.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307
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14.11.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307
14.12 SPI During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . .308
14.13 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308
14.13.1 MISO (Master In/Slave Out). . . . . . . . . . . . . . . . . . . . . . . .309
14.13.2 MOSI (Master Out/Slave In). . . . . . . . . . . . . . . . . . . . . . . .309
14.13.3 SPSCK (Serial Clock). . . . . . . . . . . . . . . . . . . . . . . . . . . . .310
14.13.4 SS (Slave Select) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310
14.13.5 CGND (Clock Ground) . . . . . . . . . . . . . . . . . . . . . . . . . . . .311
14.14 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312
14.14.1 SPI Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312
14.14.2 SPI Status and Control Register . . . . . . . . . . . . . . . . . . . .314
14.14.3 SPI Data Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .317
Section 15. Multi-Master IIC Interface (MMIIC)
15.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .319
15.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .319
15.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320
15.4 I/O Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320
15.5 Multi-Master IIC Registers . . . . . . . . . . . . . . . . . . . . . . . . . . .321
15.5.1 Multi-Master IIC Address Register (MMADR) . . . . . . . . . .321
15.5.2 Multi-Master IIC Control Register (MMCR) . . . . . . . . . . . .323
15.5.3 Multi-Master IIC Master Control Register (MIMCR) . . . . . .324
15.5.4 Multi-Master IIC Status Register (MMSR) . . . . . . . . . . . . .326
15.5.5 Multi-Master IIC Data Transmit Register (MMDTR) . . . . . .328
15.5.6 Multi-Master IIC Data Receive Register (MMDRR) . . . . . .329
15.6 Programming Considerations . . . . . . . . . . . . . . . . . . . . . . . . .330
Section 16. Analog-to-Digital Converter (ADC)
16.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .333
16.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .334
16.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .334
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16.4 Functional Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .335
16.4.1 ADC Port I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .335
16.4.2 Voltage Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .337
16.4.3 Conversion Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .337
16.4.4 Continuous Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . .338
16.4.5 Result Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .338
16.4.6 Monotonicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .339
16.5 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.7 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.7.1 ADC Voltage In (V
) . . . . . . . . . . . . . . . . . . . . . . . . . . .341
ADIN
16.7.2 ADC Analog Power Pin (V
) . . . . . . . . . . . . . . . . . . . . .341
DDA
16.7.3 ADC Analog Ground Pin (V
). . . . . . . . . . . . . . . . . . . . .341
SSA
16.7.4 ADC Voltage Reference High Pin (V
). . . . . . . . . . . . .341
REFH
16.7.5 ADC Voltage Reference Low Pin (V
) . . . . . . . . . . . . .341
REFL
16.8 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .342
16.8.1 ADC Status and Control Register. . . . . . . . . . . . . . . . . . . .342
16.8.2 ADC Data Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .344
16.8.3 ADC Clock Control Register. . . . . . . . . . . . . . . . . . . . . . . .346
Section 17. Liquid Crystal Display (LCD) Driver
17.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .349
17.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .350
17.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .350
17.4 Pin Name Conventions and I/O Register Addresses . . . . . . .350
17.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .353
17.5.1 LCD Duty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .355
17.5.2 LCD Voltages (V
, V
, V
, V
) . . . . . . . . . . .355
LCD3
LCD
LCD1
LCD2
17.5.3 LCD Cycle Frame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .355
17.5.4 Fast Charge and Low Current . . . . . . . . . . . . . . . . . . . . . .356
17.5.5 Contrast Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .357
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17.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .357
17.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .358
17.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .358
17.7 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .358
17.7.1 BP0–BP3 (Backplane Drivers) . . . . . . . . . . . . . . . . . . . . . .359
17.7.2 FP0–FP32 (Frontplane Drivers) . . . . . . . . . . . . . . . . . . . . .361
17.8 Seven Segment Display Connection . . . . . . . . . . . . . . . . . . .365
17.9 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .368
17.9.1 LCD Control Register (LCDCR) . . . . . . . . . . . . . . . . . . . . .368
17.9.2 LCD Clock Register (LCDCLK) . . . . . . . . . . . . . . . . . . . . .370
17.9.3 LCD Data Registers (LDAT1–LDAT17) . . . . . . . . . . . . . . .372
Section 18. Input/Output (I/O) Ports
18.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .375
18.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .376
18.3 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .380
18.3.1 Port A Data Register (PTA) . . . . . . . . . . . . . . . . . . . . . . . .380
18.3.2 Data Direction Register A (DDRA) . . . . . . . . . . . . . . . . . . .381
18.4 Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .383
18.4.1 Port B Data Register (PTB) . . . . . . . . . . . . . . . . . . . . . . . .383
18.4.2 Data Direction Register B (DDRB) . . . . . . . . . . . . . . . . . . .385
18.4.3 Port B LED Control Register (LEDB) . . . . . . . . . . . . . . . . .386
18.5 Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .387
18.5.1 Port C Data Register (PTC) . . . . . . . . . . . . . . . . . . . . . . . .387
18.5.2 Data Direction Register C (DDRC). . . . . . . . . . . . . . . . . . .388
18.5.3 Port C LED Control Register (LEDC) . . . . . . . . . . . . . . . . .389
18.6 Port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .390
18.6.1 Port D Data Register (PTD) . . . . . . . . . . . . . . . . . . . . . . . .390
18.6.2 Data Direction Register D (DDRD). . . . . . . . . . . . . . . . . . .392
18.7 Port E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .394
18.7.1 Port E Data Register (PTE) . . . . . . . . . . . . . . . . . . . . . . . .394
18.7.2 Data Direction Register E (DDRE) . . . . . . . . . . . . . . . . . . .395
18.7.3 Port E LED Control Register (LEDE) . . . . . . . . . . . . . . . . .396
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18.8 Port F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .397
18.8.1 Port F Data Register (PTF) . . . . . . . . . . . . . . . . . . . . . . . .397
18.8.2 Data Direction Register F (DDRF) . . . . . . . . . . . . . . . . . . .398
18.8.3 Port F LED Control Register (LEDF) . . . . . . . . . . . . . . . . .399
Section 19. External Interrupt (IRQ)
19.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .401
19.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .401
19.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .401
19.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .402
19.4.1 IRQ Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .404
19.5 IRQ Module During Break Interrupts . . . . . . . . . . . . . . . . . . .405
19.6 IRQ Status and Control Register (INTSCR) . . . . . . . . . . . . . .405
Section 20. Keyboard Interrupt Module (KBI)
20.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .407
20.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .407
20.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .408
20.4 I/O Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .408
20.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .409
20.5.1 Keyboard Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . .411
20.6 Keyboard Interrupt Registers . . . . . . . . . . . . . . . . . . . . . . . . .412
20.6.1 Keyboard Status and Control Register. . . . . . . . . . . . . . . .412
20.6.2 Keyboard Interrupt Enable Register. . . . . . . . . . . . . . . . . .413
20.7 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414
20.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414
20.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414
20.8 Keyboard Module During Break Interrupts . . . . . . . . . . . . . . .414
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Section 21. Computer Operating Properly (COP)
21.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .415
21.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .415
21.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .416
21.4 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.1 ICLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.2 STOP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.3 COPCTL Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.4 Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.5 Internal Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .418
21.4.6 Reset Vector Fetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .418
21.4.7 COPD (COP Disable). . . . . . . . . . . . . . . . . . . . . . . . . . . . .418
21.4.8 COPRS (COP Rate Select) . . . . . . . . . . . . . . . . . . . . . . . .418
21.5 COP Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .419
21.6 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .419
21.7 Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .419
21.8 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .419
21.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .420
21.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .420
21.9 COP Module During Break Mode . . . . . . . . . . . . . . . . . . . . . .420
Section 22. Low-Voltage Inhibit (LVI)
22.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421
22.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421
22.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421
22.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .422
22.4.1 Polled LVI Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .424
22.4.2 Forced Reset Operation. . . . . . . . . . . . . . . . . . . . . . . . . . .424
22.4.3 Voltage Hysteresis Protection . . . . . . . . . . . . . . . . . . . . . .424
22.4.4 LVI Trip Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425
22.5 LVI Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425
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22.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
22.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
22.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
Section 23. Break Module (BRK)
23.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .427
23.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .427
23.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .428
23.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .428
23.4.1 Flag Protection During Break Interrupts. . . . . . . . . . . . . . .430
23.4.2 CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . .430
23.4.3 TIM1 and TIM2 During Break Interrupts. . . . . . . . . . . . . . .430
23.4.4 COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . .430
23.5 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .430
23.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .430
23.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .431
23.6 Break Module Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .431
23.6.1 Break Status and Control Register. . . . . . . . . . . . . . . . . . .431
23.6.2 Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . .432
23.6.3 SIM Break Status Register. . . . . . . . . . . . . . . . . . . . . . . . .432
23.6.4 SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . .434
Section 24. Electrical Specifications
24.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .435
24.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .435
24.3 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . .436
24.4 Functional Operating Range. . . . . . . . . . . . . . . . . . . . . . . . . .437
24.5 Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . .437
24.6 5V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . .438
24.7 3.3V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . .439
24.8 5V Control Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .440
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24.9 3.3V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .441
24.10 5V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . .441
24.11 3.3V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . .442
24.12 5V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . .443
24.13 3.3V ADC Electrical Characteristics. . . . . . . . . . . . . . . . . . . .444
24.14 Timer Interface Module Characteristics . . . . . . . . . . . . . . . . .445
24.15 CGM Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . .445
24.16 5V SPI Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .446
24.17 3.3V SPI Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . .447
24.18 FLASH Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . .450
Section 25. Mechanical Specifications
25.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .451
25.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .451
25.3 64-Pin Low-Profile Quad Flat Pack (LQFP) . . . . . . . . . . . . . .452
25.4 64-Pin Quad Flat Pack (QFP). . . . . . . . . . . . . . . . . . . . . . . . .453
25.5 80-Pin Low-Profile Quad Flat Pack (LQFP) . . . . . . . . . . . . . .454
25.6 80-Pin Quad Flat Pack (QFP). . . . . . . . . . . . . . . . . . . . . . . . .455
Section 26. Ordering Information
26.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457
26.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457
26.3 MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457
Appendix A. MC68HC908LK24
A.1 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .459
A.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .459
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A.3 Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .460
A.4 Low-Voltage Inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .460
A.5 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . .461
A.5.1
A.5.2
A.5.3
A.5.4
5V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . .461
3.3V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . .461
5V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . .462
3.3V Oscillator Characteristics. . . . . . . . . . . . . . . . . . . . . .462
A.6 MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .462
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Figure
Title
Page
1-1
1-2
1-3
1-4
MC68HC908LJ24 Block Diagram. . . . . . . . . . . . . . . . . . . . . . .41
80-Pin QFP and LQFP Pin Assignment . . . . . . . . . . . . . . . . . .42
64-pin QFP and LQFP Pin Assignment . . . . . . . . . . . . . . . . . .43
Power Supply Bypassing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
2-1
2-2
Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
Control, Status, and Data Registers . . . . . . . . . . . . . . . . . . . . .52
4-1
4-2
4-3
4-4
FLASH I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . .70
FLASH Control Register (FLCR) . . . . . . . . . . . . . . . . . . . . . . .71
FLASH Programming Flowchart. . . . . . . . . . . . . . . . . . . . . . . .75
FLASH Block Protect Register (FLBPR). . . . . . . . . . . . . . . . . .77
5-1
5-2
5-3
CONFIG Registers Summary . . . . . . . . . . . . . . . . . . . . . . . . . .80
Configuration Register 1 (CONFIG1) . . . . . . . . . . . . . . . . . . . .81
Configuration Register 2 (CONFIG2) . . . . . . . . . . . . . . . . . . . .82
6-1
6-2
6-3
6-4
6-5
6-6
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Accumulator (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Index Register (H:X) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
Stack Pointer (SP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
Program Counter (PC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
Condition Code Register (CCR) . . . . . . . . . . . . . . . . . . . . . . . .90
7-1
Oscillator Module Block Diagram . . . . . . . . . . . . . . . . . . . . . .104
8-1
8-2
8-3
8-4
CGM Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112
CGM I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . .113
CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . . . .123
PLL Control Register (PCTL) . . . . . . . . . . . . . . . . . . . . . . . . .126
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Figure
Title
Page
8-5
8-6
8-7
8-8
8-9
PLL Bandwidth Control Register (PBWCR) . . . . . . . . . . . . . .129
PLL Multiplier Select Register High (PMSH) . . . . . . . . . . . . .130
PLL Multiplier Select Register Low (PMSL) . . . . . . . . . . . . . .130
PLL VCO Range Select Register (PMRS) . . . . . . . . . . . . . . .131
PLL Reference Divider Select Register (PMDS) . . . . . . . . . .132
8-10 PLL Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
9-1
9-2
9-3
9-4
9-5
9-6
9-7
9-8
9-9
SIM Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141
SIM I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . .142
CGM Clock Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143
External Reset Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145
Internal Reset Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146
Sources of Internal Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . .146
POR Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147
Interrupt Entry Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
Interrupt Recovery Timing . . . . . . . . . . . . . . . . . . . . . . . . . . .150
9-10 Interrupt Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151
9-11 Interrupt Recognition Example . . . . . . . . . . . . . . . . . . . . . . . .152
9-12 Interrupt Status Register 1 (INT1). . . . . . . . . . . . . . . . . . . . . .153
9-13 Interrupt Status Register 2 (INT2). . . . . . . . . . . . . . . . . . . . . .155
9-14 Interrupt Status Register 3 (INT3). . . . . . . . . . . . . . . . . . . . . .155
9-15 Wait Mode Entry Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157
9-16 Wait Recovery from Interrupt or Break . . . . . . . . . . . . . . . . . .158
9-17 Wait Recovery from Internal Reset. . . . . . . . . . . . . . . . . . . . .158
9-18 Stop Mode Entry Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
9-19 Stop Mode Recovery from Interrupt or Break. . . . . . . . . . . . .159
9-20 SIM Break Status Register (SBSR) . . . . . . . . . . . . . . . . . . . .160
9-21 SIM Reset Status Register (SRSR) . . . . . . . . . . . . . . . . . . . .161
9-22 SIM Break Flag Control Register (SBFCR) . . . . . . . . . . . . . .162
10-1 Monitor Mode Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .166
10-2 Low-Voltage Monitor Mode Entry Flowchart. . . . . . . . . . . . . .170
10-3 Monitor Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
10-4 Break Transaction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
10-5 Read Transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173
10-6 Write Transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173
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List of Figures
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List of Figures
Figure
Title
Page
10-7 Stack Pointer at Monitor Mode Entry . . . . . . . . . . . . . . . . . . .176
10-8 Monitor Mode Entry Timing. . . . . . . . . . . . . . . . . . . . . . . . . . .177
10-9 Data Block Format for ROM-Resident Routines. . . . . . . . . . .180
10-10 EE_WRITE FLASH Memory Usage . . . . . . . . . . . . . . . . . . . .189
11-1 TIM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .196
11-2 TIM I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . .197
11-3 PWM Period and Pulse Width . . . . . . . . . . . . . . . . . . . . . . . .202
11-4 TIM Status and Control Register (TSC) . . . . . . . . . . . . . . . . .208
11-5 TIM Counter Registers High (TCNTH) . . . . . . . . . . . . . . . . . .210
11-6 TIM Counter Registers Low (TCNTL). . . . . . . . . . . . . . . . . . .211
11-7 TIM Counter Modulo Register High (TMODH) . . . . . . . . . . . .211
11-8 TIM Counter Modulo Register Low (TMODL). . . . . . . . . . . . .211
11-9 TIM Channel 0 Status and Control Register (TSC0) . . . . . . .212
11-10 TIM Channel 1 Status and Control Register (TSC1) . . . . . . .212
11-11 CHxMAX Latency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215
11-12 TIM Channel 0 Register High (TCH0H) . . . . . . . . . . . . . . . . .216
11-13 TIM Channel 0 Register Low (TCH0L) . . . . . . . . . . . . . . . . . .216
11-14 TIM Channel 1 Register High (TCH1H) . . . . . . . . . . . . . . . . .216
11-15 TIM Channel 1 Register Low (TCH1L) . . . . . . . . . . . . . . . . . .216
12-1 RTC I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . .219
12-2 RTC Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .222
12-3 RTC Clock Calibration and Compensation. . . . . . . . . . . . . . .225
12-4 1-Hz Clock Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . .227
12-5 RTC Write Protect State Diagram. . . . . . . . . . . . . . . . . . . . . .228
12-6 RTC Calibration Control Register (RTCCOMR) . . . . . . . . . . .231
12-7 RTC Calibration Data Register (RTCCDAT). . . . . . . . . . . . . .233
12-8 RTC Control Register 1 (RTCCR1) . . . . . . . . . . . . . . . . . . . .234
12-9 RTC Control Register 2 (RTCCR2) . . . . . . . . . . . . . . . . . . . .235
12-10 RTC Status Register (RTCSR). . . . . . . . . . . . . . . . . . . . . . . .237
12-11 Alarm Minute Register (ALMR). . . . . . . . . . . . . . . . . . . . . . . .240
12-12 Alarm Hour Register (ALHR) . . . . . . . . . . . . . . . . . . . . . . . . .240
12-13 Second Register (SECR) . . . . . . . . . . . . . . . . . . . . . . . . . . . .241
12-14 Minute Register (MINR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .241
12-15 Hour Register (HRR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242
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Figure
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Page
12-16 Day Register (DAYR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242
12-17 Month Register (MTHR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243
12-18 Year Register (YRR). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243
12-19 Day-Of-Week Register (DOWR). . . . . . . . . . . . . . . . . . . . . . .244
12-20 Chronograph Data Register (CHRR) . . . . . . . . . . . . . . . . . . .244
13-1 IRSCI I/O Registers Summary . . . . . . . . . . . . . . . . . . . . . . . .248
13-2 IRSCI Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
13-3 Infrared Sub-Module Diagram . . . . . . . . . . . . . . . . . . . . . . . .250
13-4 Infrared SCI Data Example. . . . . . . . . . . . . . . . . . . . . . . . . . .251
13-5 SCI Module Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . .252
13-6 SCI Data Formats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253
13-7 SCI Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254
13-8 SCI Receiver Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . .258
13-9 Receiver Data Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . .259
13-10 Slow Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262
13-11 Fast Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263
13-12 SCI Control Register 1 (SCC1). . . . . . . . . . . . . . . . . . . . . . . .269
13-13 SCI Control Register 2 (SCC2). . . . . . . . . . . . . . . . . . . . . . . .272
13-14 SCI Control Register 3 (SCC3). . . . . . . . . . . . . . . . . . . . . . . .274
13-15 SCI Status Register 1 (SCS1) . . . . . . . . . . . . . . . . . . . . . . . .276
13-16 Flag Clearing Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . .279
13-17 SCI Status Register 2 (SCS2) . . . . . . . . . . . . . . . . . . . . . . . .280
13-18 SCI Data Register (SCDR) . . . . . . . . . . . . . . . . . . . . . . . . . . .281
13-19 SCI Baud Rate Register (SCBR) . . . . . . . . . . . . . . . . . . . . . .282
13-20 SCI Infrared Control Register (SCIRCR) . . . . . . . . . . . . . . . .285
14-1 SPI I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .289
14-2 SPI Module Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . .290
14-3 Full-Duplex Master-Slave Connections . . . . . . . . . . . . . . . . .291
14-4 Transmission Format (CPHA = 0) . . . . . . . . . . . . . . . . . . . . .295
14-5 CPHA/SS Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295
14-6 Transmission Format (CPHA = 1) . . . . . . . . . . . . . . . . . . . . .296
14-7 Transmission Start Delay (Master) . . . . . . . . . . . . . . . . . . . . .298
14-8 SPRF/SPTE CPU Interrupt Timing. . . . . . . . . . . . . . . . . . . . .299
14-9 Missed Read of Overflow Condition . . . . . . . . . . . . . . . . . . . .301
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14-10 Clearing SPRF When OVRF Interrupt Is Not Enabled . . . . . .302
14-11 SPI Interrupt Request Generation . . . . . . . . . . . . . . . . . . . . .305
14-12 CPHA/SS Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310
14-13 SPI Control Register (SPCR) . . . . . . . . . . . . . . . . . . . . . . . . .312
14-14 SPI Status and Control Register (SPSCR). . . . . . . . . . . . . . .314
14-15 SPI Data Register (SPDR) . . . . . . . . . . . . . . . . . . . . . . . . . . .317
15-1 MMIIC I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . .321
15-2 Multi-Master IIC Address Register (MMADR). . . . . . . . . . . . .321
15-3 Multi-Master IIC Control Register (MMCR). . . . . . . . . . . . . . .323
15-4 Multi-Master IIC Master Control Register (MIMCR) . . . . . . . .324
15-5 Multi-Master IIC Status Register (MMSR) . . . . . . . . . . . . . . .326
15-6 Multi-Master IIC Data Transmit Register (MMDTR) . . . . . . . .328
15-7 Multi-Master IIC Data Receive Register (MMDRR) . . . . . . . .329
15-8 Data Transfer Sequences for Master/Slave
Transmit/Receive Modes. . . . . . . . . . . . . . . . . . . . . . . . . .331
16-1 ADC I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . .335
16-2 ADC Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .336
16-3 8-Bit Truncation Mode Error . . . . . . . . . . . . . . . . . . . . . . . . . .339
16-4 ADC Status and Control Register (ADSCR). . . . . . . . . . . . . .342
16-5 ADRH and ADRL in 8-Bit Truncated Mode. . . . . . . . . . . . . . .344
16-6 ADRH and ADRL in Right Justified Mode. . . . . . . . . . . . . . . .344
16-7 ADRH and ADRL in Left Justified Mode. . . . . . . . . . . . . . . . .345
16-8 ADRH and ADRL in Left Justified Sign Data Mode . . . . . . . .345
16-9 ADC Clock Control Register (ADCLK) . . . . . . . . . . . . . . . . . .346
17-1 LCD I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . .351
17-2 LCD Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .353
17-3 Simplified LCD Schematic (1/3 Duty, 1/3 Bias) . . . . . . . . . . .354
17-4 Fast Charge Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .357
17-5 Static LCD Backplane Driver Waveform. . . . . . . . . . . . . . . . .359
17-6 1/3 Duty LCD Backplane Driver Waveforms. . . . . . . . . . . . . .359
17-7 1/4 Duty LCD Backplane Driver Waveforms. . . . . . . . . . . . . .360
17-8 Static LCD Frontplane Driver Waveforms. . . . . . . . . . . . . . . .361
17-9 1/3 Duty LCD Frontplane Driver Waveforms . . . . . . . . . . . . .362
17-10 1/4 Duty LCD Frontplane Driver Waveforms . . . . . . . . . . . . .363
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17-11 1/4 Duty LCD Frontplane Driver Waveforms (continued) . . . .364
17-12 7-Segment Display Example . . . . . . . . . . . . . . . . . . . . . . . . .365
17-13 BP0–BP2 and FP0–FP2 Output Waveforms for
7-Segment Display Example . . . . . . . . . . . . . . . . . . . . . . .366
17-14 "f" Segment Voltage Waveform . . . . . . . . . . . . . . . . . . . . . . .367
17-15 "e" Segment Voltage Waveform . . . . . . . . . . . . . . . . . . . . . . .367
17-16 LCD Control Register (LCDCR) . . . . . . . . . . . . . . . . . . . . . . .368
17-17 LCD Clock Register (LCDCLK). . . . . . . . . . . . . . . . . . . . . . . .370
17-18 LCD Data Registers 1–17 (LDAT1–LDAT17). . . . . . . . . . . . .372
18-1 I/O Port Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . .376
18-2 Port A Data Register (PTA) . . . . . . . . . . . . . . . . . . . . . . . . . .380
18-3 Data Direction Register A (DDRA) . . . . . . . . . . . . . . . . . . . . .381
18-4 Port A I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .382
18-5 Port B Data Register (PTB) . . . . . . . . . . . . . . . . . . . . . . . . . .383
18-6 Data Direction Register B (DDRB) . . . . . . . . . . . . . . . . . . . . .385
18-7 Port B I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .385
18-8 Port B LED Control Register (LEDB) . . . . . . . . . . . . . . . . . . .386
18-9 Port C Data Register (PTC) . . . . . . . . . . . . . . . . . . . . . . . . . .387
18-10 Data Direction Register C (DDRC) . . . . . . . . . . . . . . . . . . . . .388
18-11 Port C I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .388
18-12 Port C LED Control Register (LEDC) . . . . . . . . . . . . . . . . . . .389
18-13 Port D Data Register (PTD) . . . . . . . . . . . . . . . . . . . . . . . . . .390
18-14 Data Direction Register D (DDRD) . . . . . . . . . . . . . . . . . . . . .392
18-15 Port D I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .392
18-16 Port E Data Register (PTE) . . . . . . . . . . . . . . . . . . . . . . . . . .394
18-17 Data Direction Register E (DDRE) . . . . . . . . . . . . . . . . . . . . .395
18-18 Port E I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .395
18-19 Port E LED Control Register (LEDE) . . . . . . . . . . . . . . . . . . .396
18-20 Port F Data Register (PTF). . . . . . . . . . . . . . . . . . . . . . . . . . .397
18-21 Data Direction Register F (DDRF) . . . . . . . . . . . . . . . . . . . . .398
18-22 Port F I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .398
18-23 Port F LED Control Register (LEDF) . . . . . . . . . . . . . . . . . . .399
19-1 IRQ Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . .403
19-2 IRQ I/O Port Register Summary . . . . . . . . . . . . . . . . . . . . . . .403
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MC68HC908LJ24/LK24 — Rev. 2.1
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Title
Page
19-3 IRQ Status and Control Register (INTSCR) . . . . . . . . . . . . . .406
20-1 KBI I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .408
20-2 Keyboard Interrupt Block Diagram . . . . . . . . . . . . . . . . . . . . .409
20-3 Keyboard Status and Control Register (KBSCR) . . . . . . . . . .412
20-4 Keyboard Interrupt Enable Register (KBIER) . . . . . . . . . . . . .413
21-1 COP Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .416
21-2 Configuration Register 1 (CONFIG1) . . . . . . . . . . . . . . . . . . .418
21-3 COP Control Register (COPCTL). . . . . . . . . . . . . . . . . . . . . .419
22-1 LVI I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .422
22-2 LVI Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . .422
23-1 Break Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . .429
23-2 Break Module I/O Register Summary. . . . . . . . . . . . . . . . . . .429
23-3 Break Status and Control Register (BRKSCR). . . . . . . . . . . .431
23-4 Break Address Register High (BRKH) . . . . . . . . . . . . . . . . . .432
23-5 Break Address Register Low (BRKL) . . . . . . . . . . . . . . . . . . .432
23-6 SIM Break Status Register (SBSR) . . . . . . . . . . . . . . . . . . . .433
23-7 SIM Break Flag Control Register (SBFCR) . . . . . . . . . . . . . .434
24-1 Typical Internal Oscillator Frequency . . . . . . . . . . . . . . . . . . .442
24-2 SPI Master Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .448
24-3 SPI Slave Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .449
25-1 64-Pin Low-Profile Quad Flat Pack (Case No. 840F). . . . . . .452
25-2 64-Pin Quad Flat Pack (Case No. 840B) . . . . . . . . . . . . . . . .453
25-3 80-Pin Low-Profile Quad Flat Pack (Case No. 917) . . . . . . . .454
25-4 80-Pin Quad Flat Pack (Case No. 841B) . . . . . . . . . . . . . . . .455
A-1 MC68HC908LK24 Crystal Oscillator Connection . . . . . . . . . 460
A-2 MC68HC908LK24 Configuration Register 1 (CONFIG1) . . . 460
MC68HC908LJ24/LK24 — Rev. 2.1
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32
MC68HC908LJ24/LK24 — Rev. 2.1
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Data Sheet — MC68HC908LJ24
List of Tables
Table
Title
Page
2-1
4-1
5-1
Vector Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
FLASH Block Protect Register to Physical Address. . . . . . . . .78
LVI Trip Point Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84
6-1
6-2
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102
8-1
8-3
8-2
Numeric Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121
VPR1 and VPR0 Programming . . . . . . . . . . . . . . . . . . . . . . .128
PRE 1 and PRE0 Programming . . . . . . . . . . . . . . . . . . . . . . .128
9-1
9-2
9-3
Signal Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . .141
PIN Bit Set Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145
Vector Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .154
10-1 Monitor Mode Signal Requirements and Options. . . . . . . . . .168
10-2 Mode Differences (Vectors) . . . . . . . . . . . . . . . . . . . . . . . . . .170
10-3 Monitor Baud Rate Selection . . . . . . . . . . . . . . . . . . . . . . . . .172
10-4 READ (Read Memory) Command . . . . . . . . . . . . . . . . . . . . .173
10-5 WRITE (Write Memory) Command. . . . . . . . . . . . . . . . . . . . .174
10-6 IREAD (Indexed Read) Command . . . . . . . . . . . . . . . . . . . . .174
10-7 IWRITE (Indexed Write) Command . . . . . . . . . . . . . . . . . . . .175
10-8 READSP (Read Stack Pointer) Command. . . . . . . . . . . . . . .175
10-9 RUN (Run User Program) Command. . . . . . . . . . . . . . . . . . .176
10-10 Summary of ROM-Resident Routines . . . . . . . . . . . . . . . . . .179
10-11 PRGRNGE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181
10-12 ERARNGE Routine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183
10-13 LDRNGE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184
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10-14 MON_PRGRNGE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . .185
10-15 MON_ERARNGE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . .186
10-16 ICP_LDRNGE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187
10-17 EE_WRITE Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .188
10-18 EE_READ Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191
11-1 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195
11-2 Prescaler Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .210
11-3 Mode, Edge, and Level Selection. . . . . . . . . . . . . . . . . . . . . .214
12-1 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219
12-2 Compensation Algorithm for Different Values of E . . . . . . . . .226
12-3 Write-Protected RTC Registers and Bits . . . . . . . . . . . . . . . .227
12-4 CALOUT Pin Output Option . . . . . . . . . . . . . . . . . . . . . . . . . .232
13-1 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
13-2 Start Bit Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .260
13-3 Data Bit Recovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .260
13-4 Stop Bit Recovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
13-5 SCI Pin Functions (Standard and Infrared). . . . . . . . . . . . . . .268
13-6 Character Format Selection . . . . . . . . . . . . . . . . . . . . . . . . . .271
13-7 SCI Baud Rate Prescaling . . . . . . . . . . . . . . . . . . . . . . . . . . .282
13-8 SCI Baud Rate Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . .283
13-9 SCI Baud Rate Selection Examples . . . . . . . . . . . . . . . . . . . .284
13-10 Infrared Narrow Pulse Selection. . . . . . . . . . . . . . . . . . . . . . .285
14-1 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .289
14-2 SPI Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .304
14-3 SPI Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311
14-4 SPI Master Baud Rate Selection . . . . . . . . . . . . . . . . . . . . . .316
15-1 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320
15-2 Baud Rate Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .326
16-1 MUX Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .343
16-2 ADC Clock Divide Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . .346
16-3 ADC Mode Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .347
Data Sheet
34
MC68HC908LJ24/LK24 — Rev. 2.1
List of Tables
Freescale Semiconductor
List of Tables
Table
Title
Page
17-1 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .350
17-3 LCD Bias Voltage Control. . . . . . . . . . . . . . . . . . . . . . . . . . . .369
17-2 Resistor Ladder Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . .369
17-4 Fast Charge Duty Cycle Selection . . . . . . . . . . . . . . . . . . . . .370
17-5 LCD Duty Cycle Selection . . . . . . . . . . . . . . . . . . . . . . . . . . .371
17-6 LCD Waveform Base Clock Selection . . . . . . . . . . . . . . . . . .371
18-1 Port Control Register Bits Summary. . . . . . . . . . . . . . . . . . . .378
18-2 Port A Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .382
18-3 Port B Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .386
18-4 Port C Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .389
18-5 Port D Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .393
18-6 Port E Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .396
18-7 Port F Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .399
20-1 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .408
22-1 LVI Status Register (LVISR). . . . . . . . . . . . . . . . . . . . . . . . . .425
22-2 LVIOUT Bit Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425
24-1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . .436
24-2 Functional Operating Range. . . . . . . . . . . . . . . . . . . . . . . . . .437
24-3 Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . .437
24-4 5V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . .438
24-5 3.3V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . .439
24-6 5V Control Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .440
24-7 3.3V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .441
24-8 5V Oscillator Specifications . . . . . . . . . . . . . . . . . . . . . . . . . .441
24-9 3.3V Oscillator Specifications. . . . . . . . . . . . . . . . . . . . . . . . .442
24-10 5V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . .443
24-11 3.3V ADC Electrical Characteristics. . . . . . . . . . . . . . . . . . . .444
24-12 Timer Interface Module Characteristics . . . . . . . . . . . . . . . . .445
24-13 CGM Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . .445
24-14 5V SPI Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .446
24-15 3.3V SPI Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . .447
24-16 FLASH Memory Electrical Characteristics . . . . . . . . . . . . . . .450
26-1 MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
35
List of Tables
List of Tables
Table
Title
Page
A-1 5V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . .461
A-2 3.3V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . .461
A-3 5V Oscillator Specifications . . . . . . . . . . . . . . . . . . . . . . . . . .462
A-4 3.3V Oscillator Specifications. . . . . . . . . . . . . . . . . . . . . . . . .462
A-5 MC68HC908LK24 Order Numbers. . . . . . . . . . . . . . . . . . . . .462
Data Sheet
36
MC68HC908LJ24/LK24 — Rev. 2.1
List of Tables
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 1. General Description
1.1 Contents
1.2
1.3
1.4
1.5
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Pin Assignments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
1.6
1.6.1
1.6.2
1.6.3
1.6.4
1.6.5
1.6.6
1.6.7
1.6.8
1.6.9
Power Supply Pins (V and V ). . . . . . . . . . . . . . . . . . . .44
DD SS
Analog Power Supply Pin (V
). . . . . . . . . . . . . . . . . . . . .44
DDA
LCD Bias Voltage (V
) . . . . . . . . . . . . . . . . . . . . . . . . . . .45
LCD
Oscillator Pins (OSC1 and OSC2) . . . . . . . . . . . . . . . . . . . .45
External Reset Pin (RST). . . . . . . . . . . . . . . . . . . . . . . . . . .45
External Interrupt Pin (IRQ) . . . . . . . . . . . . . . . . . . . . . . . . .45
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . .45
ADC Voltage High Reference Pin (V
). . . . . . . . . . . . . .45
REFH
ADC Voltage Low Reference Pin (V
) . . . . . . . . . . . . . .46
REFL
1.6.10 Port A Input/Output (I/O) Pins (PTA7–PTA0). . . . . . . . . . . .46
1.6.11 Port B I/O Pins (PTB7–PTB0) . . . . . . . . . . . . . . . . . . . . . . .46
1.6.12 Port C I/O Pins (PTC7–PTC0) . . . . . . . . . . . . . . . . . . . . . . .46
1.6.13 Port D I/O Pins (PTD7–PTD0) . . . . . . . . . . . . . . . . . . . . . . .46
1.6.14 Port E I/O Pins (PTE7–PTE0) . . . . . . . . . . . . . . . . . . . . . . .47
1.6.15 Port F I/O Pins (PTF7–PTF0). . . . . . . . . . . . . . . . . . . . . . . .47
1.6.16 LCD Backplane and Frontplane
(BP0-BP2, BP3/FP0, FP1–FP10, FP27–FP32) . . . . . . .47
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
37
General Description
General Description
1.2 Introduction
The MC68HC908LJ24 is a member of the low-cost, high-performance
M68HC08 Family of 8-bit microcontroller units (MCUs). The M68HC08
Family is based on the customer-specified integrated circuit (CSIC)
design strategy. All MCUs in the family use the enhanced M68HC08
central processor unit (CPU08) and are available with a variety of
modules, memory sizes and types, and package types.
1.3 Features
Features of the MC68HC908LJ24 include the following:
• High-performance M68HC08 architecture
• Fully upward-compatible object code with M6805, M146805, and
M68HC05 Families
– 8-MHz at 5V operating voltage
– 4-MHz at 3.3V operating voltage
• 32.768kHz crystal oscillator clock input with 32MHz internal PLL
• Optional continuous crystal oscillator operation in stop mode
1
• 24K-bytes user program FLASH memory with security feature
• 768 bytes of on-chip RAM
• Up to 48 general-purpose input/output (I/O) pins:
– High current 15mA sink capability on 30 pins
• Two 16-bit, 2-channel timer interface modules (TIM1 and TIM2)
with selectable input capture, output compare, PWM capability on
each channel, and external clock input option (T1CLK and T2CLK)
• Real time clock (RTC) with:
– Clock, calendar, alarm, and chronograph functions
– Selectable periodic interrupt requests for seconds, minutes,
hours, days, 2-Hz, 4-Hz, 8-Hz, 16-Hz, and 128-Hz
1. No security feature is absolutely secure. However, Freescale strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Data Sheet
38
MC68HC908LJ24/LK24 — Rev. 2.1
General Description
Freescale Semiconductor
General Description
Features
– Temperature drift compensation by user software and external
temperature sensor with temperature drift profile from crystal
vendor
• Serial communications interface module (SCI) with infrared (IR)
encoder/decoder
• Inter-IC Bus interface module (IIC)
• Serial peripheral interface module (SPI)
• IRQ external interrupt pin with integrated pullup
• 8-bit keyboard wakeup port with programmable pullup
• 4/3 backplanes and static with maximum 32/33 frontplanes liquid
crystal display (LCD) driver
• 6-channel, 10-bit successive approximation analog-to-digital
converter (ADC)
• Resident routines for in-circuit programming and EEPROM
emulation
• Low-power design (fully static with stop and wait modes)
• Master reset pin (with integrated pullup) and power-on reset
• Spike filter protection for EMC performance enhancement
• System protection features
– Optional computer operating properly (COP) reset, driven by
internal RC oscillator
– Low-voltage detection with optional reset or interrupt
– Illegal opcode detection with reset
– Illegal address detection with reset
• 80-pin quad flat pack (QFP), 80-pin low-profile quad flat pack
(LQFP), 64-pin quad flat pack (QFP), and 64-pin low-profile quad
flat pack (LQFP)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
39
General Description
General Description
• Specific features of the MC68HC908LJ24 in 64-pin packages are:
– 40 general-purpose I/Os only
– High current 15-mA sink capability on 22 pins
– 4/3 backplanes and static with maximum 26 or 27 frontplanes
LCD driver
Features of the CPU08 include the following:
• Enhanced HC05 programming model
• Extensive loop control functions
• 16 addressing modes (eight more than the HC05)
• 16-bit Index register and stack pointer
• Memory-to-memory data transfers
• Fast 8 × 8 multiply instruction
• Fast 16/8 divide instruction
• Binary-coded decimal (BCD) instructions
• Optimization for controller applications
• Efficient C language support
1.4 MCU Block Diagram
Figure 1-1 shows the structure of the MC68HC908LJ24.
Data Sheet
40
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
General Description
General Description
MCU Block Diagram
INTERNAL BUS
M68HC08 CPU
PTA7/ADC3
PTA6/ADC2
PTA5/ADC1
PTA4/ADC0
PTA3/KBI3**
PTA2/KBI2**
PTA1/KBI1**
PTA0/KBI0**
CPU
ARITHMETIC/LOGIC
UNIT (ALU)
KEYBOARD INTERRUPT
MODULE
REGISTERS
CONTROL AND STATUS REGISTERS — 128 BYTES
USER FLASH — 24,576 BYTES
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
2-CHANNEL TIMER INTERFACE
MODULE 1
PTB7/ADC5
PTB6/ADC4
PTB5/T2CH1†
PTB4/T2CH0†
PTB3/T1CH1†
PTB2/T1CH0†
PTB1/RxD†
USER RAM — 768 BYTES
MONITOR ROM — 959 BYTES
2-CHANNEL TIMER INTERFACE
MODULE 2
USER FLASH VECTOR SPACE — 48 BYTES
CLOCK GENERATOR MODULE
PTB0/TxD†
SERIAL COMMUNICATIONS
INTERFACE MODULE
(WITH INFRARED
OSC1
32.768-kHz OSCILLATOR
OSC2
PTD7/KBI7/SDA
PTD6/KBI6/SCL
PTD5/KBI5/T2CLK**
PTD4/KBI4/T1CLK**
PTD3/SPSCK/CALOUT
PTD2/MOSI
ENCODER/DECODER)
PHASE-LOCKED LOOP
CGMXFC
REAL TIME CLOCK
MODULE
SYSTEM INTEGRATION
MODULE
* RST
* IRQ
PTD1/MISO
PTD0/SS/CALIN
INTER IC BUS
INTERFACE MODULE
EXTERNAL INTERRUPT
MODULE
PTF7†
:
SERIAL PERIPHERAL
INTERFACE MODULE
PTF0†
COMPUTER OPERATING
PROPERLY MODULE
#
FP32
:
FP27
POWER-ON RESET
MODULE
PTC7/FP26†
:
PTC0/FP19†
LOW-VOLTAGE INHIBIT
MODULE
PTE7/FP18†
:
LIQUID CRYSTAL DISPLAY
DRIVER MODULE
# VLCD
PTE0/FP11†
VDDA
FP10
:
FP1
POWER
VDD
VSS
BP2
VREFH
VREFL
:
ADC REFERENCE
BP0
FP0/BP3
* Pin contains integrated pullup device.
** Pin contains integrated pullup device if configured as KBI.
† High current sink pin, 15mA.
# Pins available on 80-pin packages only.
Figure 1-1. MC68HC908LJ24 Block Diagram
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
41
General Description
General Description
1.5 Pin Assignments
1
60
FP0/BP3
VREFL
2
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
PTD5/KBI5/T2CLK
VREFH
3
FP1
PTB7/ADC5
PTB6/ADC4
PTA7/ADC3
PTA6/ADC2
4
FP2
5
FP3
6
FP4
7
FP5
PTA5/ADC1
PTA4/ADC0
8
FP6
9
FP7
FP30
10
FP8
FP29
11
PTF7
PTA3/KBI3
PTA2/KBI2
PTA1/KBI1
PTA0/KBI0
FP28
12
PTF6
13
PTD6/KBI6/SCL
14
PTD7/KBI7/SDA
15
FP9
16
FP10
PTF5
PTF4
FP27
17
18
19
PTC7/FP26
PTC6/FP25
PTC5/FP24
PTD0/SS/CALIN
PTE0/FP11
PTE1/FP12 20
41
Figure 1-2. 80-Pin QFP and LQFP Pin Assignment
Data Sheet
42
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
General Description
General Description
Pin Assignments
1
48
FP0/BP3
VREFL
2
47
46
45
44
43
42
41
40
39
38
37
36
35
34
PTD5/KBI5/T2CLK
VREFH
3
FP1
FP2
PTB7/ADC5
PTB6/ADC4
PTA7/ADC3
PTA6/ADC2
4
Pins not available on 64-LQFP package:
5
PTF7
PTF6
PTF5
PTF4
PTF3
PTF2
PTF1
PTF0
FP32
FP3
FP31
FP30
FP29
FP28
FP27
6
FP4
7
FP5
PTA5/ADC1
PTA4/ADC0
8
FP6
9
FP7
PTA3/KBI3
PTA2/KBI2
PTA1/KBI1
PTA0/KBI0
PTC7/FP26
PTC6/FP25
PTC5/FP24
PTD0/SS/CALIN
FP8
10
11
12
13
14
15
VLCD
PTD6/KBI6/SCL
PTD7/KBI7/SDA
FP9
Internal PTF7–PTF0 pads are connected to VSS.
Internal FP32–FP27 pads are unconnected.
Internal VLCD pad is connected to VDD.
FP10
PTE0/FP11
PTE1/FP12
16
33
Figure 1-3. 64-pin QFP and LQFP Pin Assignment
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
43
General Description
General Description
1.6 Pin Functions
Description of pin functions are provided here.
1.6.1 Power Supply Pins (V and V )
DD
SS
V
and V are the power supply and ground pins. The MCU operates
SS
DD
from a single power supply.
Fast signal transitions on MCU pins place high, short-duration current
demands on the power supply. To prevent noise problems, take special
care to provide power supply bypassing at the MCU as Figure 1-4
shows. Place the C1 bypass capacitor as close to the MCU as possible.
Use a high-frequency-response ceramic capacitor for C1. C2 is an
optional bulk current bypass capacitor for use in applications that require
the port pins to source high current levels. V must be grounded for
SS
proper MCU operation.
1.6.2 Analog Power Supply Pin (V
)
DDA
V
V
is the voltage supply for the analog parts of the MCU. Connect the
DDA
pin to the same voltage potential as V . For maximum noise
DDA
DD
immunity, route V
via a separate trace and place bypass capacitors
DDA
as close as possible to the package (see Figure 1-4).
MCU
VDD
VSS
VDDA
0.1 µF
0.1 µF
C1(a)
C1(b)
+
+
C2(a)
C2(b)
NOTE: Component values shown
represent typical applications.
VDD
VDD
Figure 1-4. Power Supply Bypassing
Data Sheet
44
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
General Description
General Description
Pin Functions
1.6.3 LCD Bias Voltage (V
)
LCD
V
V
is the bias voltage supply for the LCD driver module. Connect the
LCD
pin to the same voltage potential as V . For maximum noise
LCD
DD
immunity, route V
via a separate trace and place bypass capacitors
LCD
as close as possible to the package. See Section 17. Liquid Crystal
Display (LCD) Driver.
1.6.4 Oscillator Pins (OSC1 and OSC2)
The OSC1 and OSC2 pins are the connections for the on-chip oscillator
circuit. The OSC1 pin contains a schmitt-trigger and a spike filter for
improved EMC performance. See Section 7. Oscillator (OSC).
1.6.5 External Reset Pin (RST)
A logic 0 on the RST pin forces the MCU to a known start-up state. RST
is bidirectional, allowing a reset of the entire system. It is driven low when
any internal reset source is asserted. A Schmitt-trigger and a spike filter
is associated with this pin so that the device is more robust to EMC
noise. This pin also contains an internal pullup resistor. See 9.4 Reset
and System Initialization.
1.6.6 External Interrupt Pin (IRQ)
IRQ is an asynchronous external interrupt pin. This pin contains an
internal pullup resistor. See Section 19. External Interrupt (IRQ).
1.6.7 External Filter Capacitor Pin (CGMXFC)
CGMXFC is an external filter capacitor connection for the CGM.
See 8.4.9 CGM External Connections.
1.6.8 ADC Voltage High Reference Pin (V
)
REFH
V
is the voltage input pin for the ADC voltage high reference.
REFH
See 16.7.4 ADC Voltage Reference High Pin (V
).
REFH
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
45
General Description
General Description
1.6.9 ADC Voltage Low Reference Pin (V
)
REFL
V
is the voltage input pin for the ADC voltage low reference.
REFL
See 16.7.5 ADC Voltage Reference Low Pin (V
).
REFL
1.6.10 Port A Input/Output (I/O) Pins (PTA7–PTA0)
PTA7–PTA0 are special function, bidirectional port pins. See 18.3 Port A.
PTA7/ADC3–PTA4/ADC0 are shared with ADC, and
PTA3/KBI3–PTA0/KBI0 are shared with the KBI module.
1.6.11 Port B I/O Pins (PTB7–PTB0)
PTB7–PTB0 are special function, bidirectional port pins, with high
current sink capability on PTB5–PTB0. See 18.4 Port B.
PTB1/RxD–PTB0/TxD are shared with the SCI module,
PTB5/T2CH1–PTB4/T2CH0 are shared with the TIM2,
PTB3/T1CH1–PTB2/T1CH0 are shared with the TIM1,
PTB7/ADC5–PTB6/ADC4 are shared with the ADC.
1.6.12 Port C I/O Pins (PTC7–PTC0)
PTC7–PTC0 are special function, bidirectional port pins, with high
current sink capability. See 18.5 Port C.
PTC7/FP26–PTC0/FP19 are shared with the LCD frontplane drivers.
1.6.13 Port D I/O Pins (PTD7–PTD0)
PTD7–PTD0 are special function, bidirectional port pins.
PTD7/KBI7/SDA–PTD6/KBI6/SCL are shared with the KBI and IIC
modules. See 18.6 Port D.
PTD5/KBI5/T2CLK–PTD4/KBI4/T1CLK are shared with the KBI, TIM1,
and TIM2 modules.
PTD3/SPSCK/CALOUT–PTD0/SS/CALIN are shared with the SPI and
RTC modules.
Data Sheet
46
MC68HC908LJ24/LK24 — Rev. 2.1
General Description
Freescale Semiconductor
General Description
Pin Functions
1.6.14 Port E I/O Pins (PTE7–PTE0)
PTE7–PTE0 are special function, bidirectional port pins, with high
current sink capability. See 18.7 Port E.
PTE7/FP18–PTE0/FP11 are shared with the LCD frontplane drivers.
1.6.15 Port F I/O Pins (PTF7–PTF0)
PTF7–PTF0 are general purpose bidirectional port pins with high current
sink capability. See 18.8 Port F.
1.6.16 LCD Backplane and Frontplane (BP0-BP2, BP3/FP0, FP1–FP10, FP27–FP32)
BP0–BP2 are the LCD backplane driver pins and FP1– FP10 and
FP27–FP32 are the frontplane driver pins. FP0/BP3 is the shared driver
pin between FP0 and BP3.
See Section 17. Liquid Crystal Display (LCD) Driver.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
47
General Description
General Description
Data Sheet
48
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
General Description
Data Sheet — MC68HC908LJ24
Section 2. Memory Map
2.1 Contents
2.2
2.3
2.4
2.5
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Unimplemented Memory Locations . . . . . . . . . . . . . . . . . . . . .49
Reserved Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . .50
Input/Output (I/O) Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
2.2 Introduction
The CPU08 can address 64k-bytes of memory space. The memory
map, shown in Figure 2-1, includes:
• 24,576 bytes of user FLASH memory
• 768 bytes of random-access memory (RAM)
• 48 bytes of user-defined vectors
• 959 bytes of monitor ROM
2.3 Unimplemented Memory Locations
Accessing an unimplemented location can cause an illegal address
reset. In the memory map (Figure 2-1) and in register figures in this
document, unimplemented locations are shaded.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
49
Memory Map
Memory Map
2.4 Reserved Memory Locations
Accessing a reserved location can have unpredictable effects on MCU
operation. In Figure 2-2 and in register figures in this document,
reserved locations are marked with the word Reserved or with the
letter R.
2.5 Input/Output (I/O) Section
Most of the control, status, and data registers are in the zero page
$0000–$007F. Additional I/O registers have the following addresses:
• $FE00; SIM break status register, SBSR
• $FE01; SIM reset status register, SRSR
• $FE03; SIM break flag control register, SBFCR
• $FE04; Interrupt status register 1, INT1
• $FE05; Interrupt status register 2, INT2
• $FE06; Interrupt status register 3, INT3
• $FE07; Reserved
• $FE08; FLASH control register, FLCR
• $FE09; Reserved
• $FE0A; Reserved
• $FE0B; Reserved
• $FE0C; break address register high, BRKH
• $FE0D; break address register low, BRKL
• $FE0E; break status and control register, BRKSCR
• $FE0F; LVI status register, LVISR
• $FFCF; FLASH block protect register, FLBPR (FLASH register)
• $FFFF; COP control register, COPCTL
Data registers are shown in Figure 2-2, Table 2-1 is a list of vector
locations.
Data Sheet
50
MC68HC908LJ24/LK24 — Rev. 2.1
Memory Map
Freescale Semiconductor
Memory Map
Input/Output (I/O) Section
$0000
↓
$007F
I/O Registers
128 Bytes
$0080
↓
$037F
RAM
768 Bytes
$0380
↓
$8FFF
Unimplemented
35,968 Bytes
$9000
↓
$EFFF
User FLASH Memory
24,576 Bytes
$F000
↓
$FBFF
Unimplemented
3,072 Bytes
$FC00
↓
$FDFF
Monitor ROM 1
512 Bytes
$FE00
$FE01
$FE02
$FE03
$FE04
$FE05
$FE06
$FE07
$FE08
$FE09
$FE0A
$FE0B
$FE0C
$FE0D
$FE0E
$FE0F
SIM Break Status Register (SBSR)
SIM Reset Status Register (SRSR)
Reserved
SIM Break Flag Control Register (SBFCR)
Interrupt Status Register 1 (INT1)
Interrupt Status Register 2 (INT2)
Interrupt Status Register 3 (INT3)
Reserved
FLASH Control Register (FLCR)
Reserved
Reserved
Reserved
Break Address Register High (BRKH)
Break Address Register Low (BRKL)
Break Status and Control Register (BRKSCR)
LVI Status Register (LVISR)
$FE10
↓
$FFCE
Monitor ROM 2
447 Bytes
$FFCF
FLASH Block Protect Register (FLBPR)
$FFD0
↓
$FFFF
User Vectors
48 Bytes
Figure 2-1. Memory Map
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
51
Memory Map
Memory Map
Addr.
Register Name
Bit 7
PTA7
U
6
5
4
3
2
1
Bit 0
PTA0
U
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
Port A Data Register
(PTA)
$0000
U
U
U
U
U
U
PTB7
U
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
U
Port B Data Register
(PTB)
$0001
$0002
$0003
$0004
$0005
$0006
$0007
$0008
$0009
U
U
U
U
U
U
PTC7
U
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
U
Port C Data Register
(PTC)
U
U
U
U
U
U
PTD7
U
PTD6
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
U
Port D Data Register
(PTD)
U
U
U
U
U
U
DDRA7
0
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
0
Data Direction Register A
(DDRA)
0
0
0
0
0
0
DDRB7
0
DDRB6
DDRB5
DDRB4
DDRB3
DDRB2
DDRB1
DDRB0
0
Data Direction Register B
(DDRB)
0
0
0
0
0
0
DDRC7
0
DDRC6
DDRC5
DDRC4
DDRC3
DDRC2
DDRC1
DDRC0
0
Data Direction Register C
(DDRC)
0
DDRD6
0
0
DDRD5
0
0
DDRD4
0
0
DDRD3
0
0
DDRD2
0
0
DDRD1
0
DDRD7
0
DDRD0
0
Data Direction Register D
(DDRD)
PTE7
U
PTE6
U
PTE5
U
PTE4
U
PTE3
U
PTE2
U
PTE1
U
PTE0
U
Port E Data Register
(PTE)
DDRE7
0
DDRE6
0
DDRE5
0
DDRE4
0
DDRE3
0
DDRE2
0
DDRE1
0
DDRE0
0
Data Direction Register E
(DDRE)
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 1 of 13)
Data Sheet
52
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Memory Map
Memory Map
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
PTF7
U
6
PTF6
U
5
PTF5
U
4
PTF4
U
3
PTF3
U
2
1
Bit 0
PTF0
U
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
PTF2
PTF1
Port F Data Register
(PTF)
$000A
U
U
DDRF7
DDRF6
DDRF5
0
DDRF4
0
DDRF3
0
DDRF2
DDRF1
DDRF0
0
Data Direction Register F
(DDRF)
$000B
$000C
$000D
$000E
$000F
$0010
$0011
$0012
$0013
0
0
0
0
0
0
Port-B LED Control
LEDB5
0
LEDB4
0
LEDB3
0
LEDB2
LEDB1
LEDB0
0
Register Write:
(LEDB)
Reset:
0
0
0
0
Read:
Port-C LED Control
LEDC7
LEDC6
LEDC5
0
LEDC4
0
LEDC3
0
LEDC2
LEDC1
LEDC0
0
Register Write:
(LEDC)
Reset:
0
LEDE7
0
0
0
0
LEDE1
0
Read:
Port-E LED Control
LEDE6
LEDE5
0
LEDE4
0
LEDE3
0
LEDE2
LEDE0
0
Register Write:
(LEDE)
Reset:
0
0
LEDF2
0
Read:
Port-F LED Control
LEDF7
0
LEDF6
LEDF5
0
LEDF4
0
LEDF3
0
LEDF1
0
LEDF0
0
Register Write:
(LEDF)
Reset:
0
Read:
SPRIE
0
R
0
SPMSTR
CPOL
CPHA
SPWOM
0
SPE
0
SPTIE
0
SPI Control Register
Write:
(SPCR)
Reset:
1
0
1
Read: SPRF
OVRF
MODF
SPTE
SPI Status and Control
ERRIE
MODFEN SPR1
SPR0
Register Write:
(SPSCR)
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
0
R7
T7
U
0
R6
T6
U
0
R5
T5
U
0
R4
T4
U
1
0
0
0
R3
T3
U
R2
T2
U
R1
T1
U
R0
T0
U
SPI Data Register
(SPDR)
0
LOOPS
0
ENSCI
0
M
0
WAKE
0
ILTY
0
PEN
0
PTY
0
SCI Control Register 1
(SCC1)
0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 2 of 13)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
53
Memory Map
Memory Map
Addr.
Register Name
Bit 7
6
TCIE
0
5
SCRIE
0
4
ILIE
0
3
TE
2
RE
0
1
Bit 0
SBK
0
Read:
Write:
Reset:
Read:
Write:
Reset:
SCTIE
RWU
0
SCI Control Register 2
(SCC2)
$0014
0
0
R8
T8
DMARE DMATE
ORIE
NEIE
FEIE
PEIE
SCI Control Register 3
(SCC3)
$0015
$0016
$0017
$0018
$0019
$001A
$001B
$001C
$001D
U
U
0
0
0
0
0
0
Read: SCTE
Write:
TC
SCRF
IDLE
OR
NF
FE
PE
SCI Status Register 1
(SCS1)
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
1
0
1
0
0
0
0
0
0
0
0
0
0
0
BKF
RPF
SCI Status Register 2
(SCS2)
0
R7
T7
U
0
R6
T6
U
0
R5
T5
U
0
0
0
0
0
R4
T4
U
R3
T3
U
R2
T2
U
R1
T1
U
R0
T0
U
SCI Data Register
(SCDR)
0
CKS
0
SCP1
SCP0
R
0
SCR2
0
SCR1
0
SCR0
0
SCI Baud Rate Register
(SCBR)
0
0
0
0
0
0
SCI Infrared Control
R
CKTST
TNP1
TNP0
0
IREN
0
Register Write:
(SCIRCR)
Reset:
0
0
0
0
0
0
0
0
0
0
Keyboard Status and Read:
KEYF
0
ACKK
0
IMASKK MODEK
Control Register
Write:
(KBSCR)
Reset:
0
KBIE7
0
0
0
0
KBIE4
0
0
KBIE3
0
0
KBIE1
0
0
KBIE0
0
Read:
Keyboard Interrupt
KBIE6
KBIE5
KBIE2
Enable Register Write:
(KBIER)
Reset:
0
0
0
PCEL
0
Read:
STOP_
IRCDIS XCLKEN
STOP_
PEE
0
DIV2CLK PCEH
LVISEL1 LVISEL0
Configuration Register 2
Write:
†
(CONFIG2)
††
††
Reset:
0
0
0
0
0
1
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 3 of 13)
Data Sheet
54
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Memory Map
Memory Map
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
6
5
4
3
2
0
1
IMASK
0
Bit 0
MODE
0
Read:
0
0
0
0
IRQF
IRQ Status and Control
$001E
Register Write:
(INTSCR)
ACK
0
Reset:
0
0
0
0
0
Read:
0
COPRS LVISTOP LVIRSTD LVIPWRD
SSREC
0
STOP
0
COPD
0
Configuration Register 1
$001F
Write:
†
(CONFIG1)
††
Reset:
0
0
0
0
0
0
† One-time writable register after each reset.
†† Reset by POR only.
Read:
TOF
0
Timer 1 Status and Control
TOIE
TSTOP
PS2
PS1
PS0
$0020
$0021
$0022
$0023
$0024
$0025
$0026
Register Write:
0
0
TRST
0
(T1SC)
Reset:
0
1
0
0
0
9
0
Read: Bit 15
14
13
12
11
10
Bit 8
Timer 1 Counter
Register High Write:
(T1CNTH)
Reset:
0
0
6
0
5
0
4
0
3
0
2
0
1
0
Read:
Bit 7
Bit 0
Timer 1 Counter
Register Low Write:
(T1CNTL)
Reset:
0
Bit 15
1
0
0
0
0
0
0
0
Read:
Timer 1 Counter Modulo
14
13
12
11
10
9
Bit 8
Register High Write:
(T1MODH)
Reset:
1
1
1
1
1
1
1
Read:
Timer 1 Counter Modulo
Bit 7
6
5
1
4
1
3
2
1
Bit 0
Register Low Write:
(T1MODL)
Reset:
1
1
CH0IE
0
1
ELS0B
0
1
ELS0A
0
1
1
Read: CH0F
Timer 1 Channel 0 Status
MS0B
0
MS0A
0
TOV0
CH0MAX
and Control Register Write:
0
0
(T1SC0)
Reset:
0
9
X
0
Bit 8
X
Read:
Timer 1 Channel 0
Bit 15
X
14
13
X
12
X
11
10
Register High Write:
(T1CH0H)
Reset:
X
X
X
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 4 of 13)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
55
Memory Map
Memory Map
Addr.
Register Name
Bit 7
Bit 7
X
6
5
4
3
2
1
Bit 0
Bit 0
X
Read:
Timer 1 Channel 0
6
5
4
3
2
1
$0027
Register Low Write:
(T1CH0L)
Reset:
X
CH1IE
0
X
0
X
MS1A
0
X
X
X
Read: CH1F
Timer 1 Channel 1 Status
ELS1B
ELS1A
TOV1
CH1MAX
0
$0028
$0029
$002A
$002B
$002C
$002D
$002E
$002F
$0030
and Control Register Write:
0
0
(T1SC1)
Reset:
0
0
11
X
0
10
X
0
9
Read:
Timer 1 Channel 1
Bit 15
X
14
13
12
X
Bit 8
X
Register High Write:
(T1CH1H)
Reset:
X
X
X
Read:
Timer 1 Channel 1
Bit 7
6
5
X
4
3
2
1
Bit 0
X
Register Low Write:
(T1CH1L)
Reset:
X
TOF
0
X
X
0
X
0
X
X
Read:
Timer 2 Status and Control
TOIE
TSTOP
PS2
PS1
PS0
Register Write:
(T2SC)
TRST
0
Reset:
0
0
1
0
0
0
9
0
Read: Bit 15
14
13
12
11
10
Bit 8
Timer 2 Counter
Register High Write:
(T2CNTH)
Reset:
0
0
6
0
5
0
4
0
3
0
2
0
1
0
Read:
Bit 7
Bit 0
Timer 2 Counter
Register Low Write:
(T2CNTL)
Reset:
0
Bit 15
1
0
0
0
0
0
0
0
Read:
Timer 2 Counter Modulo
14
13
12
11
10
9
Bit 8
Register High Write:
(T2MODH)
Reset:
1
1
1
1
1
1
1
Read:
Timer 2 Counter Modulo
Bit 7
1
6
5
4
3
2
1
1
Bit 0
Register Low Write:
(T2MODL)
Reset:
1
CH0IE
0
1
MS0B
0
1
MS0A
0
1
ELS0B
0
1
ELS0A
0
1
CH0MAX
0
Read: CH0F
Timer 2 Channel 0 Status
TOV0
0
and Control Register Write:
0
0
(T2SC0)
Reset:
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 5 of 13)
Data Sheet
56
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Memory Map
Memory Map
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
Bit 15
X
6
5
13
X
4
12
X
3
2
1
Bit 0
Read:
Timer 2 Channel 0
14
11
10
9
Bit 8
$0031
Register High Write:
(T2CH0H)
Reset:
X
X
X
X
X
Read:
Timer 2 Channel 0
Bit 7
6
5
4
3
2
1
Bit 0
$0032
$0033
$0034
$0035
$0036
$0037
$0038
$0039
$003A
Register Low Write:
(T2CH0L)
Reset:
X
X
X
0
X
X
X
X
X
Read: CH1F
Timer 2 Channel 1 Status
CH1IE
MS1A
0
ELS1B
ELS1A
TOV1
CH1MAX
and Control Register Write:
0
0
(T2SC1)
Reset:
0
14
X
0
0
11
X
0
10
X
0
0
Bit 8
X
Read:
Timer 2 Channel 1
Bit 15
X
13
12
X
9
Register High Write:
(T2CH1H)
Reset:
X
X
1
Read:
Timer 2 Channel 1
Bit 7
X
6
5
X
4
3
2
Bit 0
X
Register Low Write:
(T2CH1L)
Reset:
X
X
X
X
X
Read:
PLLF
PLLIE
0
PLLON
1
BCS
PRE1
PRE0
VPR1
VPR0
0
PLL Control Register
Write:
(PTCL)
Reset:
0
0
0
0
0
0
0
0
0
Read:
LOCK
PLL Bandwidth Control
AUTO
ACQ
R
Register Write:
(PBWC)
Reset:
0
0
0
0
0
0
0
0
0
MUL11
0
0
MUL10
0
0
MUL9
0
0
Read:
PLL Multiplier Select
MUL8
0
Register High Write:
(PMSH)
Reset:
0
MUL7
0
0
MUL6
1
0
MUL5
0
0
MUL4
0
Read:
PLL Multiplier Select
MUL3
0
MUL2
0
MUL1
0
MUL0
0
Register Low Write:
(PMSL)
Reset:
Read:
PLL VCO Range Select
VRS7
0
VRS6
1
VRS5
0
VRS4
0
VRS3
0
VRS2
0
VRS1
0
VRS0
0
Register Write:
(PMRS)
Reset:
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 6 of 13)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
57
Memory Map
Memory Map
Addr.
Register Name
Bit 7
6
5
4
3
RDS3
0
2
RDS2
0
1
RDS1
0
Bit 0
RDS0
1
Read:
0
0
0
0
PLL Reference Divider
$003B
Select Register Write:
(PMDS)
Reset:
0
0
0
0
Read: COCO
ADC Status and Control
AIEN
ADCO
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
$003C
$003D
$003E
$003F
$0040
$0041
$0042
$0043
Register Write:
(ADCSR)
Reset:
Read:
Write:
Reset:
Read:
0
ADx
R
0
ADx
R
0
ADx
R
1
ADx
R
1
ADx
R
1
ADx
R
1
ADx
R
1
ADx
R
ADC Data Register high
(ADRH)
0
0
0
0
0
0
0
0
ADx
R
ADx
R
ADx
R
ADx
R
ADx
R
ADx
R
ADx
R
ADx
R
ADC Data Register low
(ADRL) Write:
Reset:
0
0
0
0
0
0
0
0
ADC Clock Control Read:
0
0
ADIV2
ADIV1
ADIV0
ADICLK MODE1 MODE0
Register
Write:
R
(ADCLK)
Reset:
0
0
0
0
R
0
0
0
CAL
0
0
0
1
OUTF0
0
0
0
0
Read:
0
RTC Calibration Control
AUTOCAL OUTF1
Register Write:
R
0
RTCWE1 RTCWE0
(RTCCOMR)
Reset:
0
E4
0
E3
1
0
Read: EOVL
RTC Calibration Data
E5
E2
E1
E0
Register Write:
(RTCCDAT)
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
U
ALMIE
0
0
U
U
U
U
U
U
CHRIE
DAYIE
0
HRIE
0
MINIE
0
SECIE
TB1IE
TB2IE
RTC Control Register 1
(RTCCR1)
0
0
0
0
0
0
0
0
CHRCLR
0
COMEN
U
CHRE
0
RTCE
TBH
0
RTC Control Register 2
(RTCCR2)
††
0
0
0
0
†† Reset by POR only.
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 7 of 13)
Data Sheet
58
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Memory Map
Memory Map
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
Read: ALMF
Write:
6
5
4
3
2
1
Bit 0
CHRF
DAYF
HRF
MINF
SECF
TB1F
TB2F
RTC Status Register
(RTCSR)
$0044
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
0
0
0
0
0
0
AM4
U
0
AM3
U
0
AM2
U
0
AM1
U
0
AM0
U
AM5
Alarm Minute register
(ALMR)
$0045
$0046
$0047
$0048
$0049
$004A
$004B
$004C
$004D
0
0
0
0
U
0
AH4
U
AH3
U
AH2
U
AH1
U
AH0
U
Alarm Hour register
(ALHR)
0
0
0
0
0
SEC5
U
SEC4
U
SEC3
U
SEC2
U
SEC1
U
SEC0
U
Second Register
(SECR)
0
0
0
0
MIN5
MIN4
U
MIN3
U
MIN2
U
MIN1
U
MIN0
U
Minute Register
(MINR)
0
0
0
0
U
0
HR4
U
HR3
U
HR2
U
HR1
U
HR0
U
Hour Register
(HRR)
0
0
0
0
0
0
DAY4
DAY3
U
DAY2
U
DAY1
U
DAY0
U
Day Register
(DAYR)
0
0
0
0
0
0
U
0
MTH3
U
MTH2
U
MTH1
U
MTH0
U
Month Register
(MTHR)
0
0
0
0
YR7
YR6
YR5
YR4
YR3
YR2
U
YR1
U
YR0
U
Year Register
(YRR)
U
0
U
0
U
0
U
0
U
0
DOW2
U
DOW1
U
DOW0
U
Day-Of-Week Register
(DOWR)
0
0
0
0
0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 8 of 13)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
59
Memory Map
Memory Map
Addr.
Register Name
Chronograph Data
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
CHR6
CHR5
CHR4
CHR3
CHR2
CHR1
CHR0
$004E
Register Write:
(CHRR)
Reset:
0
0
0
0
0
0
0
0
0
Read:
FCCTL1 FCCTL0 DUTY1
DUTY0
LCLK2
LCLK1
LCLK0
LCD Clock Register
$004F
$0050
$0051
$0052
$0053
$0054
$0055
$0056
$0057
Write:
Reset:
Read:
(LCDCLK)
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
Reserved Write:
Reset:
Read:
0
LCDE
0
FC
0
LC
0
LCCON3 LCCON2 LCCON1 LCCON0
LCD Control Register
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
(LCDCR)
0
F1B2
U
0
F0B3
U
0
F0B2
U
0
F0B1
U
0
F0B0
U
F1B3
U
F1B1
U
F1B0
U
LCD Data Register 1
(LDAT1)
F3B3
U
F3B2
U
F3B1
U
F3B0
U
F2B3
U
F2B2
U
F2B1
U
F2B0
U
LCD Data Register 2
(LDAT2)
F5B3
U
F5B2
U
F5B1
U
F5B0
U
F4B3
U
F4B2
U
F4B1
U
F4B0
U
LCD Data Register 3
(LDAT3)
F7B3
U
F7B2
U
F7B1
U
F7B0
U
F6B3
U
F6B2
U
F6B1
U
F6B0
U
LCD Data Register 4
(LDAT4)
F9B3
U
F9B2
U
F9B1
U
F9B0
U
F8B3
U
F8B2
U
F8B1
U
F8B0
U
LCD Data Register 5
(LDAT5)
F11B3
U
F11B2
U
F11B1
U
F11B0
U
F10B3
U
F10B2
U
F10B1
U
F10B0
U
LCD Data Register 6
(LDAT6)
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 9 of 13)
Data Sheet
60
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Memory Map
Memory Map
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
F13B3
U
6
F13B2
U
5
F13B1
U
4
F13B0
U
3
F12B3
U
2
F12B2
U
1
F12B1
U
Bit 0
F12B0
U
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
LCD Data Register 7
(LDAT7)
$0058
F15B3
U
F15B2
U
F15B1
U
F15B0
U
F14B3
U
F14B2
U
F14B1
U
F14B0
U
LCD Data Register 8
(LDAT8)
$0059
$005A
$005B
$005C
$005D
$005E
$005F
$0060
$0061
F17B3
U
F17B2
U
F17B1
U
F17B0
U
F16B3
U
F16B2
U
F16B1
U
F16B0
U
LCD Data Register 9
(LDAT9)
F19B3
U
F19B2
U
F19B1
U
F19B0
U
F18B3
U
F18B2
U
F18B1
U
F18B0
U
LCD Data Register 10
(LDAT10)
F21B3
U
F21B2
U
F21B1
U
F21B0
U
F20B3
U
F20B2
U
F20B1
U
F20B0
U
LCD Data Register 11
(LDAT11)
F23B3
U
F23B2
U
F23B1
U
F23B0
U
F22B3
U
F22B2
U
F22B1
U
F22B0
U
LCD Data Register 12
(LDAT12)
F25B3
U
F25B2
U
F25B1
U
F25B0
U
F24B3
U
F24B2
U
F24B1
U
F24B0
U
LCD Data Register 13
(LDAT13)
F27B3
U
F27B2
U
F27B1
U
F27B0
U
F26B3
U
F26B2
U
F26B1
U
F26B0
U
LCD Data Register 14
(LDAT14)
F29B3
U
F29B2
U
F29B1
U
F29B0
U
F28B3
U
F28B2
U
F28B1
U
F28B0
U
LCD Data Register 15
(LDAT15)
F31B3
U
F31B2
U
F31B1
U
F31B0
U
F30B3
U
F30B2
U
F30B1
U
F30B0
U
LCD Data Register 16
(LDAT16)
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 10 of 13)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
61
Memory Map
Memory Map
Addr.
Register Name
Bit 7
6
5
4
3
F32B3
U
2
F32B2
U
1
F32B1
U
Bit 0
F32B0
U
Read:
Write:
Reset:
Read:
LCD Data Register 17
(LDAT17)
$0062
$0063
to
$0069
Unimplemented Write:
Reset:
Read: MMALIF MMNAKIF MMBB
MMIIC Master Control
MMAST MMRW MMBR2 MMBR1 MMBR0
$006A
$006B
$006C
$006D
$006E
$006F
Register Write:
0
0
0
0
(MIMCR)
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
0
0
0
0
0
0
MMAD7 MMAD6 MMAD5 MMAD4 MMAD3 MMAD2 MMAD1 MMEXTAD
MMIIC Address Register
(MMADR)
1
MMEN
0
0
MMIEN
0
1
0
0
0
0
0
0
0
0
0
MMTXAK REPSEN
MMIIC Control Register
(MMCR)
0
0
0
0
0
0
0
Read: MMRXIF MMTXIF MMATCH MMSRW MMRXAK
MMTXBE MMRXBF
MMIIC Status Register
(MMSR)
Write:
Reset:
Read:
0
0
0
0
0
0
1
0
1
0
MMIIC Data Transmit
MMTD7 MMTD6 MMTD5 MMTD4 MMTD3 MMTD2 MMTD1 MMTD0
Register Write:
(MMDTR)
Reset:
1
1
1
1
1
1
1
1
Read: MMRD7 MMRD6 MMRD5 MMRD4 MMRD3 MMRD2 MMRD1 MMRD0
MMIIC Data Receive
Register Write:
(MMDRR)
Reset:
Read:
0
0
0
0
0
0
0
0
$0070
to
$007F
R
R
R
R
R
R
R
R
Reserved Write:
Reset:
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 11 of 13)
Data Sheet
62
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Memory Map
Memory Map
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
6
5
4
3
2
1
SBSW
Note
0
Bit 0
Read:
Write:
Reset:
R
R
R
R
R
R
R
SIM Break Status Register
(SBSR)
$FE00
Note: Writing a logic 0 clears SBSW.
Read: POR
Write:
PIN
COP
ILOP
ILAD
0
LVI
0
SIM Reset Status Register
$FE01
(SRSR)
POR:
Read:
1
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
$FE02
$FE03
$FE04
$FE05
$FE06
$FE07
$FE08
Reserved Write:
Reset:
Read:
SIM Break Flag Control
BCFE
R
R
R
R
R
R
R
Register Write:
(SBFCR)
Reset:
0
IF6
R
Read:
IF5
R
IF4
R
IF3
R
IF2
R
IF1
R
0
R
0
R
Interrupt Status Register 1
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
(INT1)
0
0
0
0
0
0
0
0
IF14
R
IF13
R
IF12
R
IF11
R
IF10
R
IF9
R
IF8
R
IF7
R
Interrupt Status Register 2
(INT2)
0
0
0
0
0
0
0
0
0
0
0
0
IF18
R
IF17
R
IF16
R
IF15
R
Interrupt Status Register 3
(INT3)
R
R
R
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
R
Reserved Write:
Reset:
Read:
0
0
0
0
0
0
0
0
HVEN
0
MASS
0
ERASE
0
PGM
0
FLASH Control Register
Write:
(FLCR)
Reset:
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 12 of 13)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
63
Memory Map
Memory Map
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Reserved Write:
Reset:
R
R
R
R
R
R
R
R
$FE09
Read:
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
$FE0A
$FE0B
$FE0C
$FE0D
$FE0E
$FE0F
$FFCF
Reserved Write:
Reset:
Read:
Reserved Write:
Reset:
Read:
Break Address
Bit 15
0
14
13
0
12
0
11
0
10
0
9
0
1
Bit 8
0
Register High Write:
(BRKH)
Reset:
0
Read:
Break Address
Bit 7
0
6
0
5
4
3
2
Bit 0
Register Low Write:
(BRKL)
Reset:
0
0
0
0
0
0
0
0
0
0
0
0
Read:
Break Status and Control
BRKE
0
BRKA
0
Register Write:
(BRKSCR)
Reset:
0
0
0
0
0
0
0
0
0
0
Read: LVIOUT
LVIIF
0
LVIIACK
0
Low-Voltage Inhibit Status
LVIIE
0
Register Write:
(LVISR)
Reset:
Read:
0
0
0
0
0
0
FLASH Block Protect
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
Register Write:
#
(FLBPR)
Reset:
Unaffected by reset; $FF when blank
# Non-volatile FLASH register; write by programming.
Read:
Low byte of reset vector
Writing clears COP counter (any value)
Unaffected by reset
COP Control Register
$FFFF
Write:
(COPCTL)
Reset:
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 13 of 13)
Data Sheet
64
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Memory Map
Memory Map
Input/Output (I/O) Section
.
Table 2-1. Vector Addresses
Priority
INT Flag Address
Vector
Lowest
$FFD8
$FFD9
$FFDA
$FFDB
$FFDC
$FFDD
$FFDE
$FFDF
$FFE0
$FFE1
$FFE2
$FFE3
$FFE4
$FFE5
$FFE6
$FFE7
$FFE8
$FFE9
$FFEA
$FFEB
$FFEC
$FFED
$FFEE
$FFEF
$FFF0
$FFF1
$FFF2
$FFF3
$FFF4
$FFF5
$FFF6
$FFF7
$FFF8
$FFF9
$FFFA
$FFFB
$FFFC
$FFFD
$FFFE
$FFFF
IF18
IF17
IF16
IF15
IF14
IF13
IF12
IF11
IF10
IF9
Real Time Clock
ADC Conversion Complete
Keyboard
MMIIC
SCI Transmit
SCI Receive
SCI Error
SPI Receive
SPI Transmit
TIM2 Overflow
TIM2 Channel 1
TIM2 Channel 0
TIM1 Overflow
TIM1 Channel 1
TIM1 Channel 0
PLL
IF8
IF7
IF6
IF5
IF4
IF3
IF2
LVI
IRQ Vector (High)
IRQ Vector (Low)
SWI Vector (High)
SWI Vector (Low)
Reset Vector (High)
Reset Vector (Low)
IF1
—
—
Highest
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
65
Memory Map
Memory Map
Data Sheet
66
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Memory Map
Data Sheet — MC68HC908LJ24
Section 3. Random-Access Memory (RAM)
3.1 Contents
3.2
3.3
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
3.2 Introduction
This section describes the 768 bytes of RAM (random-access memory).
3.3 Functional Description
Addresses $0080 through $037F are RAM locations. The location of the
stack RAM is programmable. The 16-bit stack pointer allows the stack to
be anywhere in the 64K-byte memory space.
NOTE: For correct operation, the stack pointer must point only to RAM
locations.
Within page zero are 128 bytes of RAM. Because the location of the
stack RAM is programmable, all page zero RAM locations can be used
for I/O control and user data or code. When the stack pointer is moved
from its reset location at $00FF out of page zero, direct addressing mode
instructions can efficiently access all page zero RAM locations. Page
zero RAM, therefore, provides ideal locations for frequently accessed
global variables.
Before processing an interrupt, the CPU uses five bytes of the stack to
save the contents of the CPU registers.
NOTE: For M6805 compatibility, the H register is not stacked.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
67
Random-Access Memory (RAM)
Random-Access Memory (RAM)
During a subroutine call, the CPU uses two bytes of the stack to store
the return address. The stack pointer decrements during pushes and
increments during pulls.
NOTE: Be careful when using nested subroutines. The CPU may overwrite data
in the RAM during a subroutine or during the interrupt stacking
operation.
Data Sheet
68
MC68HC908LJ24/LK24 — Rev. 2.1
Random-Access Memory (RAM)
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 4. FLASH Memory (FLASH)
4.1 Contents
4.2
4.3
4.4
4.5
4.6
4.7
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70
FLASH Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
FLASH Page Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . .72
FLASH Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . .73
FLASH Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . .74
4.8
4.8.1
FLASH Block Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76
FLASH Block Protect Register . . . . . . . . . . . . . . . . . . . . . . .77
4.2 Introduction
This section describes the operation of the embedded FLASH memory.
This memory can be read, programmed, and erased from a single
external supply. The program and erase operations are enabled through
the use of an internal charge pump.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
69
FLASH Memory (FLASH)
FLASH Memory (FLASH)
Addr.
Register Name
Bit 7
6
5
4
3
2
1
ERASE
0
Bit 0
PGM
0
Read:
Write:
Reset:
Read:
0
0
0
0
HVEN
0
MASS
0
FLASH Control Register
(FLCR)
$FE08
0
0
0
0
FLASH Block Protect
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
$FFCF
Register Write:
(FLBPR)
#
Reset:
Unaffected by reset; $FF when blank
# Non-volatile FLASH register; write by programming.
= Unimplemented
Figure 4-1. FLASH I/O Register Summary
4.3 Functional Description
The FLASH memory consists of an array of 24,576 bytes for user
memory plus a block of 48 bytes for user interrupt vectors. An erased bit
reads as logic 1 and a programmed bit reads as a logic 0. The FLASH
memory page size is defined as 128 bytes, and is the minimum size that
can be erased in a page erase operation. Program and erase operations
are facilitated through control bits in FLASH control register (FLCR). The
address ranges for the FLASH memory are:
• $9000–$EFFF; user memory, 24,576 bytes
• $FFD0–$FFFF; user interrupt vectors, 48 bytes
Programming tools are available from Freescale. Contact your local
Freescale representative for more information.
1
NOTE: A security feature prevents viewing of the FLASH contents.
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Data Sheet
70
MC68HC908LJ24/LK24 — Rev. 2.1
FLASH Memory (FLASH)
Freescale Semiconductor
FLASH Memory (FLASH)
FLASH Control Register
4.4 FLASH Control Register
The FLASH control register (FLCR) controls FLASH program and erase
operations.
Address: $FE08
Bit 7
0
6
0
5
0
4
0
3
HVEN
0
2
MASS
0
1
ERASE
0
Bit 0
PGM
0
Read:
Write:
Reset:
0
0
0
0
Figure 4-2. FLASH Control Register (FLCR)
HVEN — High Voltage Enable Bit
This read/write bit enables the charge pump to drive high voltages for
program and erase operations in the array. HVEN can only be set if
either PGM = 1 or ERASE = 1 and the proper sequence for program
or erase is followed.
1 = High voltage enabled to array and charge pump on
0 = High voltage disabled to array and charge pump off
MASS — Mass Erase Control Bit
This read/write bit configures the memory for mass erase operation or
block erase operation when the ERASE bit is set.
1 = Mass Erase operation selected
0 = Block Erase operation selected
ERASE — Erase Control Bit
This read/write bit configures the memory for erase operation.
ERASE is interlocked with the PGM bit such that both bits cannot be
equal to 1 or set to 1 at the same time.
1 = Erase operation selected
0 = Erase operation not selected
PGM — Program Control Bit
This read/write bit configures the memory for program operation.
PGM is interlocked with the ERASE bit such that both bits cannot be
equal to 1 or set to 1 at the same time.
1 = Program operation selected
0 = Program operation not selected
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
71
FLASH Memory (FLASH)
FLASH Memory (FLASH)
4.5 FLASH Page Erase Operation
Use the following procedure to erase a page of FLASH memory. A page
consists of 128 consecutive bytes starting from addresses $xx00 or
$xx80. The 48-byte user interrupt vectors area also forms a page. The
48-byte user interrupt vectors cannot be erased by the page erase
operation because of security reasons. Mass erase is required to erase
this page.
1. Set the ERASE bit and clear the MASS bit in the FLASH control
register.
2. Read the FLASH block protect register.
3. Write any data to any FLASH address within the page address
range desired.
4. Wait for a time, t
(min. 10µs).
nvs
5. Set the HVEN bit.
6. Wait for a time, t
(1ms).
erase
7. Clear the ERASE bit.
8. Wait for a time, t (5µs).
nvh
9. Clear the HVEN bit.
10. After time, t (1µs), the memory can be accessed in read mode
rcv
again.
NOTE: Programming and erasing of FLASH locations cannot be performed by
code being executed from the FLASH memory; the code must be
executed from RAM. While these operations must be performed in the
order as shown, but other unrelated operations may occur between the
steps.
Data Sheet
72
MC68HC908LJ24/LK24 — Rev. 2.1
FLASH Memory (FLASH)
Freescale Semiconductor
FLASH Memory (FLASH)
FLASH Mass Erase Operation
4.6 FLASH Mass Erase Operation
Use the following procedure to erase the entire FLASH memory:
1. Set both the ERASE bit and the MASS bit in the FLASH control
register.
2. Read the FLASH block protect register.
3. Write any data to any FLASH address within the FLASH memory
address range.
4. Wait for a time, t
(10µs).
nvs
5. Set the HVEN bit.
6. Wait for a time t
(4ms).
merase
7. Clear the ERASE bit.
8. Wait for a time, t
(100µs).
nvh1
9. Clear the HVEN bit.
10. After time, t (1µs), the memory can be accessed again in read
rcv
mode.
NOTE: Programming and erasing of FLASH locations cannot be performed by
code being executed from the FLASH memory; the code must be
executed from RAM. While these operations must be performed in the
order as shown, but other unrelated operations may occur between the
steps.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
73
FLASH Memory (FLASH)
FLASH Memory (FLASH)
4.7 FLASH Program Operation
Programming of the FLASH memory is done on a row basis. A row
consists of 64 consecutive bytes starting from addresses $xx00, $xx40,
$xx80, or $xxC0. Use the following procedure to program a row of
FLASH memory. (Figure 4-3 shows a flowchart of the programming
algorithm.)
1. Set the PGM bit. This configures the memory for program
operation and enables the latching of address and data for
programming.
2. Read the FLASH block protect register.
3. Write any data to any FLASH address within the row address
range desired.
4. Wait for a time, t
(10µs).
nvs
5. Set the HVEN bit.
6. Wait for a time, t
(5µs).
pgs
7. Write data to the FLASH address to be programmed.
8. Wait for time, t (30µs).
prog
9. Repeat steps 7 and 8 until all bytes within the row are programmed.
10. Clear the PGM bit.
11. Wait for time, t
(5µs).
nvh
12. Clear the HVEN bit.
13. After time, t (1µs), the memory can be accessed in read mode
rcv
again.
This program sequence is repeated throughout the memory until all data
is programmed.
NOTE: The time between each FLASH address change (step 7 to step 7), or the
time between the last FLASH addressed programmed to clearing the
PGM bit (step 7 to step 10), must not exceed the maximum programming
time, t
max.
prog
NOTE: Programming and erasing of FLASH locations cannot be performed by
code being executed from the FLASH memory. While these operations
must be performed in the order shown, other unrelated operations may
occur between the steps.
Data Sheet
74
MC68HC908LJ24/LK24 — Rev. 2.1
FLASH Memory (FLASH)
Freescale Semiconductor
FLASH Memory (FLASH)
FLASH Program Operation
1
2
3
Set PGM bit
Algorithm for programming
a row (64 bytes) of FLASH memory
Read the FLASH block protect register
Write any data to any FLASH location
within the address range of the row to
be programmed
4
5
6
Wait for a time, tnvs
Set HVEN bit
Wait for a time, tpgs
7
8
Write data to the FLASH address
to be programmed
Wait for a time, tprog
Completed
Y
programming
this row?
N
10
Clear PGM bit
Wait for a time, tnvh
Clear HVEN bit
NOTE:
The time between each FLASH address change (step 7 to step 7), or
the time between the last FLASH address programmed
to clearing PGM bit (step 7 to step 10)
must not exceed the maximum programming
time, tprog max.
11
12
13
This row program algorithm assumes the row/s
to be programmed are initially erased.
Wait for a time, trcv
End of programming
Figure 4-3. FLASH Programming Flowchart
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
75
FLASH Memory (FLASH)
FLASH Memory (FLASH)
4.8 FLASH Block Protection
Due to the ability of the on-board charge pump to erase and program the
FLASH memory in the target application, provision is made to protect
pages of memory from unintentional erase or program operations due to
system malfunction. This protection is done by use of a FLASH block
protect register (FLBPR). The FLBPR determines the range of the
FLASH memory which is to be protected. The range of the protected
area starts from a location defined by FLBPR and ends to the bottom of
the FLASH memory ($FFFF). When the memory is protected, the HVEN
bit cannot be set in either erase or program operations.
NOTE: The 48 bytes of user interrupt vectors are always protected, regardless
of the value in the FLASH block protect register. A mass erase is
required to erase the vectors.
When the FLBPR is program with $20, the entire memory is protected
from being programmed and erased. When the FLBPR is erased ($FF),
the entire memory is accessible for program and erase.
Once the FLBPR is programmed with a value other than $FF, the FLBPR
itself is protected. It can only be erased using a mass erase operation.
NOTE: In performing a program or erase operation, the FLASH block protect
register must be read after setting the PGM or ERASE bit and before
asserting the HVEN bit
Data Sheet
76
MC68HC908LJ24/LK24 — Rev. 2.1
FLASH Memory (FLASH)
Freescale Semiconductor
FLASH Memory (FLASH)
FLASH Block Protection
4.8.1 FLASH Block Protect Register
The FLASH block protect register (FLBPR) is implemented as a byte
within the FLASH memory, and therefore can only be written during a
programming sequence of the FLASH memory. The value in this register
determines the starting location of the protected range within the FLASH
memory.
Address: $FFCF
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
Unaffected by reset; $FF when blank
Non-volatile FLASH register; write by programming.
Figure 4-4. FLASH Block Protect Register (FLBPR)
BPR[7:0] — FLASH Block Protect Bits
BPR[7:0] represent bits [14:7] of a 16-bit memory address. Bits
[15:14] are logic 1’s and bits [6:0] are logic 0’s.
16-bit memory address
Start address of FLASH block protect
1
0 0 0 0 0 0 0
BPR[7:0]
The resultant 16-bit address is used for specifying the start address
of the FLASH memory for block protection. The FLASH is protected
from this start address to the end of FLASH memory, at $FFFF. With
this mechanism, the protect start address can be $XX00 or $XX80 (at
page boundaries — 128 bytes) within the FLASH memory.
Examples of protect start address is shown in Table 4-1:
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
77
FLASH Memory (FLASH)
FLASH Memory (FLASH)
Table 4-1. FLASH Block Protect Register to Physical Address
(1)
BPR[7:0]
Start Address of Protection Range
(2)
$00 to $1F
The entire FLASH memory is NOT protected.
$9000 (1001 0000 0000 0000)
The entire FLASH memory is protected.
$20
$21
$22
$23
$24
$9080 (1001 0000 1000 0000)
$9100 (1001 0001 0000 0000)
$9180 (1001 0001 1000 0000)
$9200 (1001 0010 0000 0000)
and so on...
$DE
$DF
$EF00 (1110 1111 0000 0000)
$EF80 (1110 1111 1000 0000)
(2)
$E0 to $FF
The entire FLASH memory is NOT protected.
Notes:
1. The end address of the protected range is always $FFFF.
2. Except the 48-byte user vectors, which is always protected.
Data Sheet
78
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
FLASH Memory (FLASH)
Data Sheet — MC68HC908LJ24
Section 5. Configuration Registers (CONFIG)
5.1 Contents
5.2
5.3
5.4
5.5
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80
Configuration Register 1 (CONFIG1) . . . . . . . . . . . . . . . . . . . .81
Configuration Register 2 (CONFIG2) . . . . . . . . . . . . . . . . . . . .82
5.2 Introduction
This section describes the configuration registers, CONFIG1 and
CONFIG2. The configuration registers enable or disable these options:
• Computer operating properly module (COP)
18
4
13
4
• COP timeout period (2 – 2 or 2 – 2 ICLK cycles)
• Low-voltage inhibit (LVI) module power
• LVI module reset
• LVI module in stop mode
• LVI module voltage trip point selection
• STOP instruction
• Stop mode recovery time (32 ICLK cycles or 4096 ICLK cycles)
• Oscillator during stop mode
• LCD frontplanes FP19–FP26 on port C
• LCD frontplanes FP11–FP18 on port E
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
79
Configuration Registers (CONFIG)
Configuration Registers (CONFIG)
Addr.
Register Name
Bit 7
PEE
0
6
5
4
3
2
PCEL
0
1
Bit 0
Read:
Write:
Reset:
Read:
Write:
Reset:
STOP_
IRCDIS XCLKEN
STOP_
DIV2CLK PCEH
LVISEL1 LVISEL0
Configuration Register 2
$001D
†
(CONFIG2)
††
††
0
0
0
0
0
0
1
COPRS LVISTOP LVIRSTD LVIPWRD
SSREC
0
STOP
0
COPD
0
Configuration Register 1
$001F
†
(CONFIG1)
††
0
0
0
0
0
† One-time writable register after each reset.
†† Reset by POR only.
= Unimplemented
Figure 5-1. CONFIG Registers Summary
5.3 Functional Description
The configuration registers are used in the initialization of various
options. Since the various options affect the operation of the MCU, it is
recommended that these registers be written immediately after reset.
The configuration registers are located at $001D and $001F. The
configuration registers may be read at anytime.
NOTE: The CONFIG registers are one-time writable by the user after each
reset. These registers are not in the FLASH memory but are special
registers containing one-time writable latches after each reset. Upon a
reset, the CONFIG registers default to predetermined settings as shown
in Figure 5-2 and Figure 5-3.
Although the LVISEL[1:0] bits default to predetermined setting of
LVISEL[1:0] = 0:1 by a POR only, these bits can still be written once after
each reset other than POR.
Data Sheet
80
MC68HC908LJ24/LK24 — Rev. 2.1
Configuration Registers (CONFIG)
Freescale Semiconductor
Configuration Registers (CONFIG)
Configuration Register 1 (CONFIG1)
5.4 Configuration Register 1 (CONFIG1)
The CONFIG1 register can be written once after each reset.
Address: $001F
Bit 7
6
5
4
3
0
2
SSREC
0
1
STOP
0
Bit 0
COPD
0
Read:
COPRS LVISTOP LVIRSTD LVIPWRD
Write:
††
Reset:
0
0
0
0
0
†† Reset by POR only.
= Unimplemented
Figure 5-2. Configuration Register 1 (CONFIG1)
COPRS — COP Rate Select
COPRS selects the COP time-out period. Reset clears COPRS. (See
Section 21. Computer Operating Properly (COP).)
13
4
1 = COP time out period = 2 – 2 ICLK cycles
18
4
0 = COP time out period = 2 – 2 ICLK cycles
LVISTOP — LVI Enable in Stop Mode
When the LVIPWRD bit is clear, setting the LVISTOP bit enables the
LVI to operate during stop mode. Reset clears LVISTOP. (See
Section 22. Low-Voltage Inhibit (LVI).)
1 = LVI enabled during stop mode
0 = LVI disabled during stop mode
LVIRSTD — LVI Reset Disable
LVIRSTD disables the reset signal from the LVI module. (See
Section 22. Low-Voltage Inhibit (LVI).)
1 = LVI module resets disabled
0 = LVI module resets enabled
LVIPWRD — LVI Power Disable Bit
LVIPWRD disables the LVI module. (See Section 22. Low-Voltage
Inhibit (LVI).)
1 = LVI module power disabled
0 = LVI module power enabled
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
81
Configuration Registers (CONFIG)
Configuration Registers (CONFIG)
SSREC — Short Stop Recovery
SSREC enables the CPU to exit stop mode with a delay of 32 ICLK
cycles instead of a 4096 ICLK cycle delay.
1 = Stop mode recovery after 32 ICLK cycles
0 = Stop mode recovery after 4096 ICLK cycles
NOTE: Exiting stop mode by pulling reset will result in the long stop recovery.
If using an external crystal oscillator, do not set the SSREC bit.
NOTE: When the LVISTOP is enabled, the system stabilization time for power
on reset and long stop recovery (both 4096 ICLK cycles) gives a delay
longer than the enable time for the LVI. There is no period where the
MCU is not protected from a low power condition. However, when using
the short stop recovery configuration option, the 32 ICLK delay is less
than the LVI’s turn-on time and there exists a period in start-up where the
LVI is not protecting the MCU.
STOP — STOP Instruction Enable
STOP enables the STOP instruction.
1 = STOP instruction enabled
0 = STOP instruction treated as illegal opcode
COPD — COP Disable Bit
COPD disables the COP module. (See Section 21. Computer
Operating Properly (COP).)
1 = COP module disabled
0 = COP module enabled
5.5 Configuration Register 2 (CONFIG2)
The CONFIG2 register can be written once after each reset.
Address: $001D
Bit 7
PEE
0
6
5
4
3
2
PCEL
0
1
Bit 0
Read:
Write:
Reset:
STOP_
IRCDIS XCLKEN
STOP_
DIV2CLK PCEH
LVISEL1 LVISEL0
††
††
0
0
0
0
0
1
†† Reset by POR only.
Figure 5-3. Configuration Register 2 (CONFIG2)
Data Sheet
82
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Configuration Registers (CONFIG)
Configuration Registers (CONFIG)
Configuration Register 2 (CONFIG2)
PEE — Port E Enable
Setting PEE configures the PTE0/FP11–PTE7/FP18 pins for LCD
frontplane driver use. Reset clears this bit.
1 = PTE0/FP11–PTE7/FP18 pins configured as LCD frontplane
driver pins: FP11–FP18
0 = PTE0/FP11–PTE7/FP18 pins configured as standard I/O pins:
PTE0–PTE7
STOP_IRCDIS — Internal RC Oscillator Stop Mode Disable
Setting STOP_IRCDIS disables the internal RC oscillator during stop
mode. When this bit is cleared, the internal RC oscillator continues to
operate in stop mode. Reset clears this bit.
1 = Internal RC oscillator disabled during stop mode
0 = Internal RC oscillator enabled during stop mode
STOP_XCLKEN — Crystal Oscillator Stop Mode Enable
Setting STOP_XCLKEN enables the external crystal (XTAL) oscillator
to continue operating in stop mode. This is useful for driving the real
time clock module to allow it to generate periodic wake up while in
stop mode. When this bit is cleared, the external XTAL oscillator will
be disabled during stop mode. Reset clears this bit.
1 = XTAL oscillator enabled during stop mode
0 = XTAL oscillator disabled during stop mode
DIV2CLK — Divide-by-2 Clock Bypass
When CGMXCLK is selected to drive the system clocks (BCS=0),
setting DIV2CLK allows the CGMXCLK to bypass the divide-by-2
divider in the CGM module; CGMOUT will equal CGMXCLK and bus
clock will equal CGMXCLK divide-by-2.
DIV2CLK bit has no effect when the BCS=1 in the PLL control
register (CGMVCLK selected and divide-by-2 always enabled). Reset
clears this bit.
1 = Divide-by-2 divider bypassed;
When BSC=0, CGMOUT equals CGMXCLK
0 = Divide-by-2 divider enabled;
When BSC=0, CGMOUT equals CGMXCLK divide-by-2
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
83
Configuration Registers (CONFIG)
Configuration Registers (CONFIG)
PCEH — Port C Enable High Nibble
Setting PCEH configures the PTC4/FP23–PTC7/FP26 pins for LCD
frontplane driver use. Reset clears this bit.
1 = PTC4/FP23–PTC7/FP26 pins configured as LCD frontplane
driver pins: FP23–FP26
0 = PTC4/FP23–PTC7/FP26 pins configured as standard I/O pins:
PTC4–PTC7
PCEL — Port C Enable Low Nibble
Setting PCEL configures the PTC0/FP19–PTC3/FP22 pins for LCD
frontplane driver use. Reset clears this bit.
1 = PTC0/FP19–PTC3/FP22 pins configured as LCD frontplane
driver pins: FP19–FP22
0 = PTC0/FP19–PTC3/FP22 pins configured as standard I/O pins:
PTC0–PTC3
LVISEL[1:0] — LVI Operating Mode Selection
LVISEL[1:0] selects the voltage operating mode of the LVI module.
(See Section 22. Low-Voltage Inhibit (LVI).) The voltage mode
selected for the LVI should match the operating V . See Section 24.
DD
Electrical Specifications for the LVI voltage trip points for each of
the modes.
Table 5-1. LVI Trip Point Selection
LVISEL1
LVISEL0
Operating Mode
0
0
1
1
0
1
0
1
Reserved
(1)
3.3V
5V
Reserved
Notes:
1. Default setting after a power-on-reset.
Data Sheet
84
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Configuration Registers (CONFIG)
Data Sheet — MC68HC908LJ24
Section 6. Central Processor Unit (CPU)
6.1 Contents
6.2
6.3
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
6.4
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . .90
6.4.1
6.4.2
6.4.3
6.4.4
6.4.5
6.5
Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . .92
6.6
6.6.1
6.6.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
6.7
6.8
6.9
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . .93
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
Central Processor Unit (CPU)
85
Central Processor Unit (CPU)
6.2 Introduction
The M68HC08 CPU (central processor unit) is an enhanced and fully
object-code-compatible version of the M68HC05 CPU. The CPU08
Reference Manual (Freescale document order number CPU08RM/AD)
contains a description of the CPU instruction set, addressing modes,
and architecture.
6.3 Features
Feature of the CPU include:
• Object code fully upward-compatible with M68HC05 Family
• 16-bit stack pointer with stack manipulation instructions
• 16-Bit index register with X-register manipulation instructions
• 8-MHz CPU internal bus frequency
• 64-Kbyte program/data memory space
• 16 addressing modes
• Memory-to-memory data moves without using accumulator
• Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions
• Enhanced binary-coded decimal (BCD) data handling
• Modular architecture with expandable internal bus definition for
extension of addressing range beyond 64-Kbytes
• Low-power stop and wait modes
Data Sheet
86
MC68HC908LJ24/LK24 — Rev. 2.1
Central Processor Unit (CPU)
Freescale Semiconductor
Central Processor Unit (CPU)
CPU Registers
6.4 CPU Registers
Figure 6-1 shows the five CPU registers. CPU registers are not part of
the memory map.
7
0
0
0
0
ACCUMULATOR (A)
15
15
15
H
X
INDEX REGISTER (H:X)
STACK POINTER (SP)
PROGRAM COUNTER (PC)
CONDITION CODE REGISTER (CCR)
7
V
0
C
1
1
H
I
N
Z
CARRY/BORROW FLAG
ZERO FLAG
NEGATIVE FLAG
INTERRUPT MASK
HALF-CARRY FLAG
TWO’S COMPLEMENT OVERFLOW FLAG
Figure 6-1. CPU Registers
6.4.1 Accumulator
The accumulator is a general-purpose 8-bit register. The CPU uses the
accumulator to hold operands and the results of arithmetic/logic
operations.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
Unaffected by reset
Figure 6-2. Accumulator (A)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
87
Central Processor Unit (CPU)
Central Processor Unit (CPU)
6.4.2 Index Register
The 16-bit index register allows indexed addressing of a 64K-byte
memory space. H is the upper byte of the index register, and X is the
lower byte. H:X is the concatenated 16-bit index register.
In the indexed addressing modes, the CPU uses the contents of the
index register to determine the conditional address of the operand.
The index register can serve also as a temporary data storage location.
Bit
15
Bit
0
14 13 12 11 10
9
8
7
6
5
4
3
2
1
Read:
Write:
Reset:
0
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
X = Indeterminate
Figure 6-3. Index Register (H:X)
6.4.3 Stack Pointer
The stack pointer is a 16-bit register that contains the address of the next
location on the stack. During a reset, the stack pointer is preset to
$00FF. The reset stack pointer (RSP) instruction sets the least
significant byte to $FF and does not affect the most significant byte. The
stack pointer decrements as data is pushed onto the stack and
increments as data is pulled from the stack.
In the stack pointer 8-bit offset and 16-bit offset addressing modes, the
stack pointer can function as an index register to access data on the
stack. The CPU uses the contents of the stack pointer to determine the
conditional address of the operand.
Bit
15
Bit
0
14 13 12 11 10
9
8
7
6
5
4
3
2
1
Read:
Write:
Reset:
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Figure 6-4. Stack Pointer (SP)
Data Sheet
88
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Central Processor Unit (CPU)
Central Processor Unit (CPU)
CPU Registers
NOTE: The location of the stack is arbitrary and may be relocated anywhere in
RAM. Moving the SP out of page 0 ($0000 to $00FF) frees direct
address (page 0) space. For correct operation, the stack pointer must
point only to RAM locations.
6.4.4 Program Counter
The program counter is a 16-bit register that contains the address of the
next instruction or operand to be fetched.
Normally, the program counter automatically increments to the next
sequential memory location every time an instruction or operand is
fetched. Jump, branch, and interrupt operations load the program
counter with an address other than that of the next sequential location.
During reset, the program counter is loaded with the reset vector
address located at $FFFE and $FFFF. The vector address is the
address of the first instruction to be executed after exiting the reset state.
Bit
15
Bit
0
14 13 12 11 10
9
8
7
6
5
4
3
2
1
Read:
Write:
Reset:
Loaded with Vector from $FFFE and $FFFF
Figure 6-5. Program Counter (PC)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
89
Central Processor Unit (CPU)
Central Processor Unit (CPU)
6.4.5 Condition Code Register
The 8-bit condition code register contains the interrupt mask and five
flags that indicate the results of the instruction just executed. Bits 6 and
5 are set permanently to logic 1. The following paragraphs describe the
functions of the condition code register.
Bit 7
V
6
1
1
5
1
1
4
H
X
3
I
2
N
X
1
Z
X
Bit 0
C
Read:
Write:
Reset:
X
1
X
X = Indeterminate
Figure 6-6. Condition Code Register (CCR)
V — Overflow Flag
The CPU sets the overflow flag when a two's complement overflow
occurs. The signed branch instructions BGT, BGE, BLE, and BLT use
the overflow flag.
1 = Overflow
0 = No overflow
H — Half-Carry Flag
The CPU sets the half-carry flag when a carry occurs between
accumulator bits 3 and 4 during an add-without-carry (ADD) or add-
with-carry (ADC) operation. The half-carry flag is required for binary-
coded decimal (BCD) arithmetic operations. The DAA instruction
uses the states of the H and C flags to determine the appropriate
correction factor.
1 = Carry between bits 3 and 4
0 = No carry between bits 3 and 4
Data Sheet
90
MC68HC908LJ24/LK24 — Rev. 2.1
Central Processor Unit (CPU)
Freescale Semiconductor
Central Processor Unit (CPU)
CPU Registers
I — Interrupt Mask
When the interrupt mask is set, all maskable CPU interrupts are
disabled. CPU interrupts are enabled when the interrupt mask is
cleared. When a CPU interrupt occurs, the interrupt mask is set
automatically after the CPU registers are saved on the stack, but
before the interrupt vector is fetched.
1 = Interrupts disabled
0 = Interrupts enabled
NOTE: To maintain M6805 Family compatibility, the upper byte of the index
register (H) is not stacked automatically. If the interrupt service routine
modifies H, then the user must stack and unstack H using the PSHH and
PULH instructions.
After the I bit is cleared, the highest-priority interrupt request is
serviced first.
A return-from-interrupt (RTI) instruction pulls the CPU registers from
the stack and restores the interrupt mask from the stack. After any
reset, the interrupt mask is set and can be cleared only by the clear
interrupt mask software instruction (CLI).
N — Negative Flag
The CPU sets the negative flag when an arithmetic operation, logic
operation, or data manipulation produces a negative result, setting
bit 7 of the result.
1 = Negative result
0 = Non-negative result
Z — Zero Flag
The CPU sets the zero flag when an arithmetic operation, logic
operation, or data manipulation produces a result of $00.
1 = Zero result
0 = Non-zero result
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
91
Central Processor Unit (CPU)
Central Processor Unit (CPU)
C — Carry/Borrow Flag
The CPU sets the carry/borrow flag when an addition operation
produces a carry out of bit 7 of the accumulator or when a subtraction
operation requires a borrow. Some instructions — such as bit test and
branch, shift, and rotate — also clear or set the carry/borrow flag.
1 = Carry out of bit 7
0 = No carry out of bit 7
6.5 Arithmetic/Logic Unit (ALU)
The ALU performs the arithmetic and logic operations defined by the
instruction set.
Refer to the CPU08 Reference Manual (Freescale document order
number CPU08RM/AD) for a description of the instructions and
addressing modes and more detail about the architecture of the CPU.
6.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption
standby modes.
6.6.1 Wait Mode
The WAIT instruction:
• Clears the interrupt mask (I bit) in the condition code register,
enabling interrupts. After exit from wait mode by interrupt, the I bit
remains clear. After exit by reset, the I bit is set.
• Disables the CPU clock.
Data Sheet
92
MC68HC908LJ24/LK24 — Rev. 2.1
Central Processor Unit (CPU)
Freescale Semiconductor
Central Processor Unit (CPU)
CPU During Break Interrupts
6.6.2 Stop Mode
The STOP instruction:
• Clears the interrupt mask (I bit) in the condition code register,
enabling external interrupts. After exit from stop mode by external
interrupt, the I bit remains clear. After exit by reset, the I bit is set.
• Disables the CPU clock.
After exiting stop mode, the CPU clock begins running after the oscillator
stabilization delay.
6.7 CPU During Break Interrupts
If the break module is enabled, a break interrupt causes the CPU to
execute the software interrupt instruction (SWI) at the completion of the
current CPU instruction. (See Section 23. Break Module (BRK).) The
program counter vectors to $FFFC–$FFFD ($FEFC–$FEFD in monitor
mode).
A return-from-interrupt instruction (RTI) in the break routine ends the
break interrupt and returns the MCU to normal operation if the break
interrupt has been deasserted.
6.8 Instruction Set Summary
Table 6-1 provides a summary of the M68HC08 instruction set.
6.9 Opcode Map
The opcode map is provided in Table 6-2.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
93
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Table 6-1. Instruction Set Summary (Sheet 1 of 8)
Effect on
CCR
Source
Form
Operation
Description
V H
I
N Z C
ADC #opr
ADC opr
ADC opr
ADC opr,X
ADC opr,X
ADC ,X
ADC opr,SP
ADC opr,SP
IMM
DIR
EXT
IX2
IX1
IX
A9
B9
C9
D9
E9
F9
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Add with Carry
A ← (A) + (M) + (C)
R
R
–
R R R
SP1
SP2
9EE9 ff
9ED9 ee ff
ADD #opr
ADD opr
ADD opr
ADD opr,X
ADD opr,X
ADD ,X
ADD opr,SP
ADD opr,SP
IMM
DIR
EXT
IX2
IX1
IX
AB
BB
CB
DB
EB
FB
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Add without Carry
A ← (A) + (M)
R
R
–
R R R
SP1
SP2
9EEB ff
9EDB ee ff
AIS #opr
AIX #opr
Add Immediate Value (Signed) to SP
Add Immediate Value (Signed) to H:X
SP ← (SP) + (16 « M)
H:X ← (H:X) + (16 « M)
–
–
–
–
–
–
–
–
–
–
– IMM
– IMM
A7
AF
ii
ii
2
2
AND #opr
AND opr
AND opr
AND opr,X
AND opr,X
AND ,X
AND opr,SP
AND opr,SP
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A4
B4
C4
D4
E4
F4
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Logical AND
A ← (A) & (M)
0
–
–
–
–
R R –
9EE4 ff
9ED4 ee ff
ASL opr
ASLA
ASLX
ASL opr,X
ASL ,X
ASL opr,SP
DIR
INH
INH
IX1
IX
38
48
58
68
78
dd
ff
4
1
1
4
3
5
Arithmetic Shift Left
(Same as LSL)
R
R R R
C
0
b7
b7
b0
b0
SP1
9E68 ff
ASR opr
ASRA
ASRX
ASR opr,X
ASR opr,X
ASR opr,SP
DIR
INH
INH
IX1
IX
37
47
57
67
77
dd
4
1
1
4
3
5
C
Arithmetic Shift Right
R
–
–
–
–
R
R
R
ff
SP1
9E67 ff
BCC rel
Branch if Carry Bit Clear
PC ← (PC) + 2 + rel ? (C) = 0
–
–
–
– REL
24
rr
3
DIR (b0)
11
13
15
17
19
1B
1D
1F
dd
dd
dd
dd
dd
dd
dd
dd
4
4
4
4
4
4
4
4
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
BCLR n, opr
Clear Bit n in M
Mn ← 0
–
–
–
–
–
–
Data Sheet
94
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Opcode Map
Table 6-1. Instruction Set Summary (Sheet 2 of 8)
Effect on
CCR
Source
Form
Operation
Description
V H
I
N Z C
BCS rel
Branch if Carry Bit Set (Same as BLO)
Branch if Equal
PC ← (PC) + 2 + rel ? (C) = 1
PC ← (PC) + 2 + rel ? (Z) = 1
–
–
–
–
–
–
–
–
–
–
– REL
– REL
25
27
rr
rr
3
3
BEQ rel
BGE opr
Branch if Greater Than or Equal To
(Signed Operands)
PC ← (PC) + 2 + rel ? (N ⊕ V) = 0
PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 0
–
–
–
–
–
–
–
–
–
–
– REL
– REL
90
92
rr
rr
3
3
Branch if Greater Than (Signed
Operands)
BGT opr
BHCC rel
BHCS rel
BHI rel
Branch if Half Carry Bit Clear
Branch if Half Carry Bit Set
Branch if Higher
PC ← (PC) + 2 + rel ? (H) = 0
PC ← (PC) + 2 + rel ? (H) = 1
PC ← (PC) + 2 + rel ? (C) | (Z) = 0
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
– REL
– REL
– REL
28
29
22
rr
rr
rr
3
3
3
Branch if Higher or Same
(Same as BCC)
BHS rel
PC ← (PC) + 2 + rel ? (C) = 0
–
–
–
–
–
– REL
24
rr
3
BIH rel
BIL rel
Branch if IRQ Pin High
Branch if IRQ Pin Low
PC ← (PC) + 2 + rel ? IRQ = 1
PC ← (PC) + 2 + rel ? IRQ = 0
–
–
–
–
–
–
–
–
–
–
– REL
– REL
2F
2E
rr
rr
3
3
BIT #opr
BIT opr
BIT opr
BIT opr,X
BIT opr,X
BIT ,X
BIT opr,SP
BIT opr,SP
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A5
B5
C5
D5
E5
F5
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Bit Test
(A) & (M)
0
–
–
R
R
–
9EE5 ff
9ED5 ee ff
Branch if Less Than or Equal To
(Signed Operands)
BLE opr
PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 1
–
–
–
–
–
– REL
93
rr
3
BLO rel
BLS rel
BLT opr
BMC rel
BMI rel
BMS rel
BNE rel
BPL rel
BRA rel
Branch if Lower (Same as BCS)
Branch if Lower or Same
PC ← (PC) + 2 + rel ? (C) = 1
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
– REL
– REL
– REL
– REL
– REL
– REL
– REL
– REL
– REL
25
23
91
2C
2B
2D
26
2A
20
rr
rr
rr
rr
rr
rr
rr
rr
rr
3
3
3
3
3
3
3
3
3
PC ← (PC) + 2 + rel ? (C) | (Z) = 1
Branch if Less Than (Signed Operands) PC ← (PC) + 2 + rel ? (N ⊕ V) =1
Branch if Interrupt Mask Clear
Branch if Minus
PC ← (PC) + 2 + rel ? (I) = 0
PC ← (PC) + 2 + rel ? (N) = 1
PC ← (PC) + 2 + rel ? (I) = 1
PC ← (PC) + 2 + rel ? (Z) = 0
PC ← (PC) + 2 + rel ? (N) = 0
PC ← (PC) + 2 + rel
Branch if Interrupt Mask Set
Branch if Not Equal
Branch if Plus
Branch Always
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
95
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Table 6-1. Instruction Set Summary (Sheet 3 of 8)
Effect on
CCR
Source
Form
Operation
Description
V H
I
N Z C
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
01
03
05
07
09
0B
0D
0F
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
5
5
5
5
5
5
5
5
BRCLR n,opr,rel Branch if Bit n in M Clear
PC ← (PC) + 3 + rel ? (Mn) = 0
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
R
BRN rel
Branch Never
PC ← (PC) + 2
– REL
21
rr
3
DIR (b0)
00
02
04
06
08
0A
0C
0E
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
5
5
5
5
5
5
5
5
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
BRSET n,opr,rel Branch if Bit n in M Set
PC ← (PC) + 3 + rel ? (Mn) = 1
R
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
10
12
14
16
18
1A
1C
1E
dd
dd
dd
dd
dd
dd
dd
dd
4
4
4
4
4
4
4
4
BSET n,opr
Set Bit n in M
Mn ← 1
–
–
–
–
–
–
PC ← (PC) + 2; push (PCL)
SP ← (SP) – 1; push (PCH)
SP ← (SP) – 1
BSR rel
Branch to Subroutine
–
–
–
–
–
–
–
–
–
–
– REL
AD
rr
4
PC ← (PC) + rel
CBEQ opr,rel
PC ← (PC) + 3 + rel ? (A) – (M) = $00
PC ← (PC) + 3 + rel ? (A) – (M) = $00
PC ← (PC) + 3 + rel ? (X) – (M) = $00
PC ← (PC) + 3 + rel ? (A) – (M) = $00
PC ← (PC) + 2 + rel ? (A) – (M) = $00
PC ← (PC) + 4 + rel ? (A) – (M) = $00
DIR
IMM
31
41
51
61
71
dd rr
ii rr
ii rr
ff rr
rr
5
4
4
5
4
6
CBEQA #opr,rel
CBEQX #opr,rel
CBEQ opr,X+,rel
CBEQ X+,rel
IMM
IX1+
Compare and Branch if Equal
–
IX+
SP1
CBEQ opr,SP,rel
9E61 ff rr
CLC
CLI
Clear Carry Bit
C ← 0
I ← 0
–
–
–
–
–
0
–
–
–
–
0 INH
– INH
98
9A
1
2
Clear Interrupt Mask
CLR opr
CLRA
CLRX
CLRH
CLR opr,X
CLR ,X
M ← $00
A ← $00
X ← $00
H ← $00
M ← $00
M ← $00
M ← $00
DIR
INH
INH
– INH
IX1
IX
3F
4F
5F
8C
6F
7F
dd
ff
3
1
1
1
3
2
4
Clear
0
–
–
0
1
CLR opr,SP
SP1
9E6F ff
Data Sheet
96
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Opcode Map
Table 6-1. Instruction Set Summary (Sheet 4 of 8)
Effect on
CCR
Source
Form
Operation
Description
V H
I
N Z C
CMP #opr
CMP opr
CMP opr
CMP opr,X
CMP opr,X
CMP ,X
CMP opr,SP
CMP opr,SP
IMM
DIR
EXT
IX2
IX1
IX
A1
B1
C1
D1
E1
F1
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Compare A with M
(A) – (M)
R
–
–
R
R
R
SP1
SP2
9EE1 ff
9ED1 ee ff
COM opr
COMA
COMX
COM opr,X
COM ,X
COM opr,SP
M ← (M) = $FF – (M)
A ← (A) = $FF – (M)
X ← (X) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
DIR
INH
INH
IX1
IX
33
43
53
63
73
dd
ff
4
1
1
4
3
5
Complement (One’s Complement)
Compare H:X with M
0
–
–
–
–
R
R
R
R
1
SP1
9E63 ff
CPHX #opr
CPHX opr
IMM
DIR
65
75
ii ii+1
dd
3
4
(H:X) – (M:M + 1)
R
R
CPX #opr
CPX opr
CPX opr
IMM
DIR
EXT
IX2
IX1
IX
A3
B3
C3
D3
E3
F3
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
CPX ,X
Compare X with M
(X) – (M)
R
–
–
R
R
R
CPX opr,X
CPX opr,X
CPX opr,SP
CPX opr,SP
SP1
SP2
9EE3 ff
9ED3 ee ff
DAA
Decimal Adjust A
(A)10
U
–
–
–
–
–
R
R
R INH
72
2
A ← (A) – 1 or M ← (M) – 1 or X ← (X) – 1
PC ← (PC) + 3 + rel ? (result) ≠ 0
PC ← (PC) + 2 + rel ? (result) ≠ 0
PC ← (PC) + 2 + rel ? (result) ≠ 0
PC ← (PC) + 3 + rel ? (result) ≠ 0
PC ← (PC) + 2 + rel ? (result) ≠ 0
PC ← (PC) + 4 + rel ? (result) ≠ 0
DBNZ opr,rel
DBNZA rel
DBNZX rel
DBNZ opr,X,rel
DBNZ X,rel
DBNZ opr,SP,rel
DIR
INH
– INH
IX1
IX
SP1
3B
4B
5B
6B
7B
dd rr
rr
rr
ff rr
rr
5
3
3
5
4
6
Decrement and Branch if Not Zero
–
–
9E6B ff rr
DEC opr
DECA
DECX
DEC opr,X
DEC ,X
DEC opr,SP
M ← (M) – 1
A ← (A) – 1
X ← (X) – 1
M ← (M) – 1
M ← (M) – 1
M ← (M) – 1
DIR
INH
INH
IX1
IX
3A
4A
5A
6A
7A
dd
ff
4
1
1
4
3
5
Decrement
Divide
R
–
–
–
–
R
R
R
–
SP1
9E6A ff
A ← (H:A)/(X)
H ← Remainder
DIV
–
–
R INH
52
7
EOR #opr
EOR opr
EOR opr
EOR opr,X
EOR opr,X
EOR ,X
EOR opr,SP
EOR opr,SP
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A8
B8
C8
D8
E8
F8
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Exclusive OR M with A
A ← (A ⊕ M)
0
–
–
R
R
–
9EE8 ff
9ED8 ee ff
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
97
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Table 6-1. Instruction Set Summary (Sheet 5 of 8)
Effect on
CCR
Source
Form
Operation
Description
V H
I
N Z C
INC opr
INCA
INCX
INC opr,X
INC ,X
M ← (M) + 1
A ← (A) + 1
X ← (X) + 1
M ← (M) + 1
M ← (M) + 1
M ← (M) + 1
DIR
INH
INH
IX1
IX
3C
4C
5C
6C
7C
dd
ff
4
1
1
4
3
5
Increment
R
–
–
R
R
–
INC opr,SP
SP1
9E6C ff
JMP opr
JMP opr
JMP opr,X
JMP opr,X
JMP ,X
DIR
EXT
– IX2
IX1
IX
BC
CC
DC
EC
FC
dd
2
3
4
3
2
hh ll
ee ff
ff
Jump
PC ← Jump Address
–
–
–
–
–
–
–
–
–
–
JSR opr
JSR opr
JSR opr,X
JSR opr,X
JSR ,X
DIR
EXT
– IX2
IX1
BD
CD
DD
ED
FD
dd
4
5
6
5
4
PC ← (PC) + n (n = 1, 2, or 3)
Push (PCL); SP ← (SP) – 1
Push (PCH); SP ← (SP) – 1
PC ← Unconditional Address
hh ll
ee ff
ff
Jump to Subroutine
IX
LDA #opr
LDA opr
LDA opr
LDA opr,X
LDA opr,X
LDA ,X
LDA opr,SP
LDA opr,SP
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A6
B6
C6
D6
E6
F6
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Load A from M
Load H:X from M
Load X from M
A ← (M)
H:X ← (M:M + 1)
X ← (M)
0
0
0
–
–
–
–
–
–
R
R
R
R
R
R
–
9EE6 ff
9ED6 ee ff
LDHX #opr
LDHX opr
IMM
–
45
55
ii jj
dd
3
4
DIR
LDX #opr
LDX opr
LDX opr
LDX opr,X
LDX opr,X
LDX ,X
LDX opr,SP
LDX opr,SP
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
AE
BE
CE
DE
EE
FE
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
–
9EEE ff
9EDE ee ff
LSL opr
LSLA
LSLX
LSL opr,X
LSL ,X
LSL opr,SP
DIR
INH
INH
IX1
IX
38
48
58
68
78
dd
ff
4
1
1
4
3
5
Logical Shift Left
(Same as ASL)
C
0
R
R
–
–
–
–
R
R
R
R
b7
b0
SP1
9E68 ff
LSR opr
LSRA
LSRX
LSR opr,X
LSR ,X
LSR opr,SP
DIR
INH
INH
IX1
IX
34
44
54
64
74
dd
4
1
1
4
3
5
0
C
Logical Shift Right
0
R
ff
b7
b0
SP1
9E64 ff
Data Sheet
98
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Opcode Map
Table 6-1. Instruction Set Summary (Sheet 6 of 8)
Effect on
CCR
Source
Form
Operation
Description
V H
I
N Z C
MOV opr,opr
MOV opr,X+
MOV #opr,opr
MOV X+,opr
DD
4E
5E
6E
7E
dd dd
dd
ii dd
dd
5
4
4
4
(M)Destination ← (M)Source
DIX+
IMD
IX+D
Move
0
–
–
0
–
–
R
R
–
H:X ← (H:X) + 1 (IX+D, DIX+)
MUL
Unsigned multiply
X:A ← (X) × (A)
–
–
0 INH
42
5
NEG opr
NEGA
NEGX
NEG opr,X
NEG ,X
NEG opr,SP
DIR
INH
INH
IX1
IX
30
40
50
60
70
dd
ff
4
1
1
4
3
5
M ← –(M) = $00 – (M)
A ← –(A) = $00 – (A)
X ← –(X) = $00 – (X)
M ← –(M) = $00 – (M)
M ← –(M) = $00 – (M)
Negate (Two’s Complement)
R
–
–
R
R
R
SP1
9E60 ff
NOP
NSA
No Operation
Nibble Swap A
None
–
–
–
–
–
–
–
–
–
–
– INH
– INH
9D
1
3
A ← (A[3:0]:A[7:4])
62
ORA #opr
ORA opr
ORA opr
ORA opr,X
ORA opr,X
ORA ,X
ORA opr,SP
ORA opr,SP
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
AA
BA
CA
DA
EA
FA
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Inclusive OR A and M
A ← (A) | (M)
0
–
–
R
R
–
9EEA ff
9EDA ee ff
PSHA
PSHH
PSHX
PULA
PULH
PULX
Push A onto Stack
Push H onto Stack
Push X onto Stack
Pull A from Stack
Pull H from Stack
Pull X from Stack
Push (A); SP ← (SP) – 1
Push (H); SP ← (SP) – 1
Push (X); SP ← (SP) – 1
SP ← (SP + 1); Pull (A)
SP ← (SP + 1); Pull (H)
SP ← (SP + 1); Pull (X)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
– INH
– INH
– INH
– INH
– INH
– INH
87
8B
89
86
8A
88
2
2
2
2
2
2
ROL opr
ROLA
ROLX
ROL opr,X
ROL ,X
ROL opr,SP
DIR
INH
INH
IX1
IX
39
49
59
69
79
dd
ff
4
1
1
4
3
5
C
Rotate Left through Carry
R
–
–
R
R
R
b7
b0
SP1
9E69 ff
ROR opr
RORA
RORX
ROR opr,X
ROR ,X
ROR opr,SP
DIR
INH
INH
IX1
IX
36
46
56
66
76
dd
4
1
1
4
3
5
C
Rotate Right through Carry
Reset Stack Pointer
R
–
–
–
–
R
R
R
ff
b7
b0
SP1
9E66 ff
RSP
SP ← $FF
–
–
–
– INH
9C
1
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
99
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Table 6-1. Instruction Set Summary (Sheet 7 of 8)
Effect on
CCR
Source
Form
Operation
Description
V H
I
N Z C
SP ← (SP) + 1; Pull (CCR)
SP ← (SP) + 1; Pull (A)
SP ← (SP) + 1; Pull (X)
SP ← (SP) + 1; Pull (PCH)
SP ← (SP) + 1; Pull (PCL)
RTI
Return from Interrupt
R
R
R
R
R
R INH
80
81
7
4
SP ← SP + 1; Pull (PCH)
SP ← SP + 1; Pull (PCL)
RTS
Return from Subroutine
–
–
–
–
–
–
– INH
SBC #opr
SBC opr
SBC opr
SBC opr,X
SBC opr,X
SBC ,X
SBC opr,SP
SBC opr,SP
IMM
DIR
EXT
A2
B2
C2
D2
E2
F2
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
IX2
IX1
Subtract with Carry
A ← (A) – (M) – (C)
R
–
R
R
R
IX
SP1
SP2
9EE2 ff
9ED2 ee ff
SEC
SEI
Set Carry Bit
C ← 1
I ← 1
–
–
–
–
–
1
–
–
–
–
1 INH
– INH
99
9B
1
2
Set Interrupt Mask
STA opr
STA opr
DIR
EXT
IX2
– IX1
IX
B7
C7
D7
E7
F7
dd
3
4
4
3
2
4
5
hh ll
ee ff
ff
STA opr,X
STA opr,X
STA ,X
STA opr,SP
STA opr,SP
Store A in M
M ← (A)
0
–
–
R
R
SP1
SP2
9EE7 ff
9ED7 ee ff
STHX opr
Store H:X in M
(M:M + 1) ← (H:X)
0
–
–
–
–
0
R
R
– DIR
– INH
35
8E
dd
4
1
STOP
Enable IRQ Pin; Stop Oscillator
I ← 0; Stop Oscillator
–
–
STX opr
STX opr
DIR
EXT
IX2
– IX1
IX
BF
CF
DF
EF
FF
dd
3
4
4
3
2
4
5
hh ll
ee ff
ff
STX opr,X
STX opr,X
STX ,X
STX opr,SP
STX opr,SP
Store X in M
M ← (X)
0
–
–
R
R
SP1
SP2
9EEF ff
9EDF ee ff
SUB #opr
SUB opr
SUB opr
SUB opr,X
SUB opr,X
SUB ,X
SUB opr,SP
SUB opr,SP
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A0
B0
C0
D0
E0
F0
ii
2
3
4
4
3
2
4
5
dd
hh ll
ee ff
ff
Subtract
A ← (A) – (M)
R
– – R R R
9EE0 ff
9ED0 ee ff
Data Sheet
100
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Opcode Map
Table 6-1. Instruction Set Summary (Sheet 8 of 8)
Effect on
CCR
Source
Form
Operation
Description
V H
I
N Z C
PC ← (PC) + 1; Push (PCL)
SP ← (SP) – 1; Push (PCH)
SP ← (SP) – 1; Push (X)
SP ← (SP) – 1; Push (A)
SP ← (SP) – 1; Push (CCR)
SP ← (SP) – 1; I ← 1
SWI
Software Interrupt
–
–
1
–
–
– INH
83
9
PCH ← Interrupt Vector High Byte
PCL ← Interrupt Vector Low Byte
TAP
TAX
TPA
Transfer A to CCR
Transfer A to X
CCR ← (A)
X ← (A)
R
–
–
R
–
–
R
–
–
R
–
–
R
–
–
R INH
– INH
– INH
84
97
85
2
1
1
Transfer CCR to A
A ← (CCR)
TST opr
TSTA
TSTX
TST opr,X
TST ,X
TST opr,SP
DIR
INH
INH
IX1
IX
3D
4D
5D
6D
7D
dd
ff
3
1
1
3
2
4
Test for Negative or Zero
(A) – $00 or (X) – $00 or (M) – $00
0
–
–
R
R
–
SP1
9E6D ff
TSX
TXA
TXS
Transfer SP to H:X
Transfer X to A
H:X ← (SP) + 1
A ← (X)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
– INH
– INH
– INH
95
9F
94
2
1
2
Transfer H:X to SP
(SP) ← (H:X) – 1
A
C
Accumulator
Carry/borrow bit
n
Any bit
opr Operand (one or two bytes)
PC Program counter
PCH Program counter high byte
PCL Program counter low byte
REL Relative addressing mode
CCR Condition code register
dd Direct address of operand
dd rr Direct address of operand and relative offset of branch instruction
DD Direct to direct addressing mode
DIR Direct addressing mode
rel
rr
Relative program counter offset byte
Relative program counter offset byte
DIX+ Direct to indexed with post increment addressing mode
ee ff High and low bytes of offset in indexed, 16-bit offset addressing
EXT Extended addressing mode
SP1 Stack pointer, 8-bit offset addressing mode
SP2 Stack pointer 16-bit offset addressing mode
SP Stack pointer
U
V
X
Z
ff
H
H
Offset byte in indexed, 8-bit offset addressing
Half-carry bit
Index register high byte
Undefined
Overflow bit
Index register low byte
Zero bit
hh ll High and low bytes of operand address in extended addressing
I
Interrupt mask
ii
Immediate operand byte
&
|
⊕
( )
Logical AND
Logical OR
Logical EXCLUSIVE OR
Contents of
IMD Immediate source to direct destination addressing mode
IMM Immediate addressing mode
INH Inherent addressing mode
IX
Indexed, no offset addressing mode
–( ) Negation (two’s complement)
IX+
Indexed, no offset, post increment addressing mode
#
Immediate value
Sign extend
Loaded with
If
IX+D Indexed with post increment to direct addressing mode
IX1 Indexed, 8-bit offset addressing mode
IX1+ Indexed, 8-bit offset, post increment addressing mode
«
←
?
IX2
M
N
Indexed, 16-bit offset addressing mode
Memory location
Negative bit
:
R
—
Concatenated with
Set or cleared
Not affected
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
101
Central Processor Unit (CPU)
Table 6-2. Opcode Map
Bit Manipulation Branch
Read-Modify-Write
Control
Register/Memory
DIR
DIR
REL
DIR
3
INH
4
INH
IX1
SP1
9E6
IX
7
INH
INH
IMM
A
DIR
B
EXT
C
IX2
SP2
IX1
E
SP1
9EE
IX
F
MSB
0
1
2
5
6
8
9
D
9ED
LSB
5
4
3
4
1
NEGA
INH
1
NEGX
INH
4
5
3
7
3
2
3
4
4
5
3
4
2
0
BRSET0 BSET0
BRA
NEG
NEG
NEG
NEG
RTI
BGE
SUB
SUB
SUB
SUB
SUB
SUB
SUB
SUB
3
DIR
5
2
DIR
4
2
2
2
2
2
2
2
2
REL 2 DIR
3
BRN
REL 3 DIR
3
BHI
REL
3
BLS
REL 2 DIR
3
BCC
REL 2 DIR
3
BCS
REL 2 DIR
3
BNE
REL 2 DIR
3
BEQ
1
1
2
IX1 3 SP1 1 IX
5
1
1
INH
4
RTS
INH
2
2
2
2
1
1
REL 2 IMM 2 DIR
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
EXT 3 IX2
4
CMP
EXT 3 IX2
4
SBC
EXT 3 IX2
4
CPX
EXT 3 IX2
4
AND
EXT 3 IX2
4
BIT
EXT 3 IX2
4
LDA
EXT 3 IX2
4
STA
EXT 3 IX2
4
EOR
EXT 3 IX2
4
ADC
EXT 3 IX2
4
ORA
EXT 3 IX2
4
ADD
EXT 3 IX2
3
JMP
EXT 3 IX2
5
JSR
4
4
4
4
4
4
4
4
4
4
4
4
SP2 2 IX1
5
CMP
SP2 2 IX1
5
SBC
SP2 2 IX1
5
CPX
SP2 2 IX1
5
AND
SP2 2 IX1
5
BIT
SP2 2 IX1
5
LDA
SP2 2 IX1
5
STA
SP2 2 IX1
5
EOR
SP2 2 IX1
5
ADC
SP2 2 IX1
5
ORA
SP2 2 IX1
5
ADD
SP2 2 IX1
3
3
3
3
3
3
3
3
3
3
3
3
SP1 1 IX
4
CMP
SP1 1 IX
4
SBC
SP1 1 IX
4
CPX
SP1 1 IX
4
AND
SP1 1 IX
4
BIT
SP1 1 IX
4
LDA
SP1 1 IX
4
STA
SP1 1 IX
4
EOR
SP1 1 IX
4
ADC
SP1 1 IX
4
ORA
SP1 1 IX
4
ADD
SP1 1 IX
5
4
4
6
4
2
3
4
3
2
1
2
BRCLR0 BCLR0
CBEQ CBEQA CBEQX CBEQ
CBEQ
CBEQ
BLT
CMP
CMP
CMP
CMP
CMP
3
DIR
5
2
DIR
4
3
IMM 3 IMM 3 IX1+
4
SP1 2 IX+
REL 2 IMM 2 DIR
5
7
3
2
DAA
3
BGT
2
SBC
3
SBC
4
SBC
3
SBC
2
SBC
BRSET1 BSET1
MUL
INH
DIV
INH
NSA
3
DIR
5
2
DIR
4
1
1
1
2
2
3
2
2
2
2
2
INH
1
INH
3
REL 2 IMM 2 DIR
3
4
1
1
4
COM
IX1
4
LSR
IX1
3
CPHX
IMM
4
ROR
IX1
4
ASR
IX1
4
LSL
IX1
4
ROL
IX1
4
DEC
IX1
5
9
2
CPX
3
CPX
4
CPX
3
CPX
2
CPX
3
BRCLR1 BCLR1
COM
COMA
COMX
COM
COM
SWI
BLE
3
DIR
5
2
DIR
4
1
INH
1
INH
3
3
SP1 1 IX
1
1
1
1
1
1
1
1
1
1
INH
REL 2 IMM 2 DIR
4
LSR
1
LSRA
INH
1
LSRX
INH
5
LSR
SP1 1 IX
3
LSR
2
2
2
AND
IMM 2 DIR
2
BIT
IMM 2 DIR
2
LDA
IMM 2 DIR
2
AIS
IMM 2 DIR
2
EOR
IMM 2 DIR
2
ADC
IMM 2 DIR
3
AND
4
AND
3
AND
2
AND
4
BRSET2 BSET2
TAP
TXS
3
DIR
5
2
DIR
4
1
3
1
INH
INH
2
2
2
2
2
2
2
2
4
3
4
4
1
2
3
BIT
4
BIT
3
BIT
2
BIT
5
BRCLR2 BCLR2
STHX
LDHX
LDHX
CPHX
TPA
TSX
3
DIR
5
2
DIR
4
IMM 2 DIR
2
DIR
3
INH
INH
4
ROR
1
1
5
2
PULA
INH
2
PSHA
INH
2
PULX
INH
2
PSHX
INH
2
PULH
INH
2
PSHH
INH
1
CLRH
INH
3
LDA
4
LDA
3
LDA
2
LDA
6
BRSET3 BSET3
RORA
RORX
ROR
SP1 1 IX
5
ASR
SP1 1 IX
5
LSL
SP1 1 IX
5
ROL
SP1 1 IX
5
DEC
SP1 1 IX
ROR
3
DIR
5
2
DIR
4
1
INH
1
INH
3
3
3
3
3
4
3
3
4
ASR
1
ASRA
INH
1
LSLA
INH
1
ROLA
INH
1
DECA
INH
1
ASRX
INH
1
LSLX
INH
1
ROLX
INH
1
DECX
INH
3
ASR
1
3
STA
4
STA
3
STA
2
STA
7
BRCLR3 BCLR3
TAX
3
DIR
5
2
DIR
4
REL 2 DIR
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
INH
4
LSL
3
LSL
1
CLC
INH
1
3
EOR
4
EOR
3
EOR
2
EOR
8
BRSET4 BSET4 BHCC
3
DIR
5
2
DIR
4
2
REL 2 DIR
3
4
ROL
3
ROL
3
ADC
4
ADC
3
ADC
2
ADC
9
BRCLR4 BCLR4 BHCS
SEC
INH
2
CLI
INH
2
SEI
INH
1
RSP
INH
3
DIR
5
2
DIR
4
2
2
2
2
2
2
2
REL 2 DIR
3
BPL
REL 2 DIR
3
BMI
REL 3 DIR
3
BMC
REL 2 DIR
3
BMS
REL 2 DIR
3
BIL
4
DEC
3
DEC
2
ORA
IMM 2 DIR
2
ADD
IMM 2 DIR
3
ORA
4
ORA
3
ORA
2
ORA
A
B
C
D
E
F
BRSET5 BSET5
3
DIR
5
2
DIR
4
5
3
3
5
6
4
3
ADD
4
ADD
3
ADD
2
ADD
BRCLR5 BCLR5
DBNZ DBNZA DBNZX DBNZ
DBNZ
DBNZ
3
DIR
5
2
DIR
4
2
1
1
3
1
INH
1
2
1
1
2
1
INH
1
3
2
2
3
2
IX1
4
INC
IX1
3
TST
IX1
4
MOV
IMD
3
CLR
IX1
SP1 2 IX
5
4
INC
3
INC
2
JMP
DIR
4
JSR
4
JMP
3
JMP
IX1
5
JSR
IX1
3
LDX
2
BRSET6 BSET6
INCA
INCX
INC
SP1 1 IX
4
TST
SP1 1 IX
JMP
3
DIR
5
2
DIR
4
INH
1
TSTA
INH
5
MOV
DD
1
CLRA
INH
INH
1
TSTX
INH
4
MOV
DIX+
1
CLRX
INH
2
2
2
1
1
IX
3
TST
2
TST
1
4
BSR
REL 2 DIR
2
LDX
IMM 2 DIR
2
AIX
IMM 2 DIR
6
JSR
4
JSR
IX
2
LDX
BRCLR6 BCLR6
NOP
3
DIR
5
2
DIR
4
INH
2
2
2
EXT 3 IX2
4
LDX
EXT 3 IX2
4
STX
EXT 3 IX2
4
1
STOP
INH
1
WAIT
INH
3
LDX
4
LDX
5
LDX
4
LDX
BRSET7 BSET7
MOV
*
1
TXA
INH
3
DIR
5
2
DIR
4
REL
3
BIH
2
IX+D
1
1
4
4
SP2 2 IX1
5
3
3
SP1 1 IX
4
3
CLR
4
CLR
SP1 1 IX
2
CLR
3
STX
4
STX
3
STX
2
STX
BRCLR7 BCLR7
DIR DIR
STX
SP2 2 IX1
STX
SP1 1 IX
3
2
REL 2 DIR
3
1
INH Inherent
REL Relative
SP1 Stack Pointer, 8-Bit Offset
SP2 Stack Pointer, 16-Bit Offset
IX+ Indexed, No Offset with
Post Increment
IX1+ Indexed, 1-Byte Offset with
Post Increment
MSB
LSB
0
High Byte of Opcode in Hexadecimal
Cycles
IMM Immediate
DIR Direct
IX
Indexed, No Offset
IX1 Indexed, 8-Bit Offset
IX2 Indexed, 16-Bit Offset
IMD Immediate-Direct
EXT Extended
DD Direct-Direct
IX+D Indexed-Direct DIX+ Direct-Indexed
*Pre-byte for stack pointer indexed instructions
5
Low Byte of Opcode in Hexadecimal
0
BRSET0 Opcode Mnemonic
DIR Number of Bytes / Addressing Mode
3
Data Sheet — MC68HC908LJ24
Section 7. Oscillator (OSC)
7.1 Contents
7.2
7.3
7.4
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
Internal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105
X-tal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105
7.5
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105
Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . .106
Crystal Amplifier Output Pin (OSC2) . . . . . . . . . . . . . . . . .106
Oscillator Enable Signal (SIMOSCEN). . . . . . . . . . . . . . . .106
Internal RC Clock (ICLK) . . . . . . . . . . . . . . . . . . . . . . . . . .106
CGM Oscillator Clock (CGMXCLK) . . . . . . . . . . . . . . . . . .106
CGM Reference Clock (CGMRCLK) . . . . . . . . . . . . . . . . .106
7.5.1
7.5.2
7.5.3
7.5.4
7.5.5
7.5.6
7.6
7.6.1
7.6.2
Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107
7.7
Oscillator During Break Mode. . . . . . . . . . . . . . . . . . . . . . . . .107
7.2 Introduction
The oscillator module provides the reference clock for the clock
generator module (CGM), the real time clock module (RTC), and other
MCU sub-systems.
The oscillator module consist of two types of oscillator circuits:
• Internal RC oscillator
• 32.768kHz crystal (x-tal) oscillator
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
103
Oscillator (OSC)
Oscillator (OSC)
The reference clock for the CGM, real time clock module (RTC) and
other MCU sub-systems is driven by the crystal oscillator. The COP
module is always driven by internal RC clock.
The internal RC oscillator runs continuously after a POR or reset and is
always available in run and wait modes. In stop mode, it can be disabled
by setting the STOP_IRCDIS bit in CONFIG2 register.
Figure 7-1. shows the block diagram of the oscillator module.
From SIM
CONFIG2
EN
ICLK
STOP_IRCDIS
INTERNAL RC
OSCILLATOR
To SIM, COP
To CGM PLL
INTERNAL RC OSCILLATOR
CGMRCLK
CGMXCLK
CONFIG2
STOP_XCLKEN
To RTC, ADC, LCD,
CGM Clock Selection MUX
CRYSTAL OSCILLATOR
MCU
OSC1
OSC2
RB
RS*
*RS can be zero (shorted) when used with higher-frequency crystals.
Refer to manufacturer’s data.
X1
See Section 24. for component value requirements.
32.768kHz
(typical)
C1
C2
Figure 7-1. Oscillator Module Block Diagram
Data Sheet
104
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Oscillator (OSC)
Oscillator (OSC)
Internal Oscillator
7.3 Internal Oscillator
The internal RC oscillator clock (ICLK) is a free running 64kHz clock (at
= 5V) that requires no external components. It is the reference clock
V
DD
input to the computer operating properly (COP) module.
The ICLK can be turned off in stop mode by setting the STOP_IRCDIS
bit in CONFIG2. After reset, the bit is clear by default and ICLK is
enabled during stop mode.
7.4 X-tal Oscillator
The crystal (x-tal) oscillator circuit is designed for use with an external
32.768kHz crystal or ceramic resonator to provide an accurate clock
source.
In its typical configuration, the X-tal oscillator is connected in a Pierce
oscillator configuration, as shown in Figure 7-1. This figure shows only
the logical representation of the internal components and may not
represent actual circuitry. The oscillator configuration uses five
components:
• Crystal, X (32.768kHz)
1
• Fixed capacitor, C
1
• Tuning capacitor, C (can also be a fixed capacitor)
2
• Feedback resistor, RB
• Series resistor, RS (optional)
The series resistor (RS) is included in the diagram to follow strict Pierce
oscillator guidelines and may not be required for all ranges of operation,
especially with high frequency crystals. Refer to the crystal
manufacturer’s data for more information.
7.5 I/O Signals
The following paragraphs describe the oscillator I/O signals.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
105
Oscillator (OSC)
Oscillator (OSC)
7.5.1 Crystal Amplifier Input Pin (OSC1)
OSC1 pin is an input to the crystal oscillator amplifier. Schmitt trigger and
glitch filter are implemented on this pin to improve EMC performance.
See Section 24. Electrical Specifications for detail specification of the
glitch filter.
7.5.2 Crystal Amplifier Output Pin (OSC2)
OSC2 pin is the output of the crystal oscillator inverting amplifier.
7.5.3 Oscillator Enable Signal (SIMOSCEN)
The SIMOSCEN signal from the system integration module (SIM)
enables/disables the x-tal oscillator circuit.
7.5.4 Internal RC Clock (ICLK)
The ICLK clock is the output from the internal RC oscillator. This clock
drives the SIM and COP modules.
7.5.5 CGM Oscillator Clock (CGMXCLK)
The CGMXCLK clock is the output from the x-tal oscillator. This clock
drives to CGM, real time clock module, analog-to-digital converter, liquid
crystal display driver module, and other MCU sub-systems.
7.5.6 CGM Reference Clock (CGMRCLK)
This is buffered signal of CGMXCLK, it is used by the CGM as the
phase-locked-loop (PLL) reference clock.
7.6 Low Power Modes
The WAIT and STOP instructions put the MCU in low-power
consumption standby modes.
Data Sheet
106
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Oscillator (OSC)
Oscillator (OSC)
Oscillator During Break Mode
7.6.1 Wait Mode
7.6.2 Stop Mode
The WAIT instruction has no effect on the oscillator module. CGMXCLK,
CGMRCLK, and ICLK continues to drive the MCU modules.
The STOP instruction clears the SIMOSCEN signal, and hence the
CGMXCLK (and CGMRCLK) clock stops running. For continuous
CGMXCLK operation in stop mode, set the STOP_XCLKEN to logic 1
before entering stop mode. Continuous CGMXCLK operation in stop
mode allows the RTC module to generate interrupts to wake up the CPU.
By default, the internal RC oscillator clock, ICLK, continues to run in stop
mode. To disable the ICLK in stop mode, set the STOP_IRCDIS bit to
logic 1 before entering stop mode.
7.7 Oscillator During Break Mode
The oscillator circuits continue to drive CGMXCLK, CGMRCLK, and
ICLK when the device enters the break state.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
107
Oscillator (OSC)
Oscillator (OSC)
Data Sheet
108
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Oscillator (OSC)
Data Sheet — MC68HC908LJ24
Section 8. Clock Generator Module (CGM)
8.1 Contents
8.2
8.3
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
8.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
Oscillator Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114
Phase-Locked Loop Circuit (PLL) . . . . . . . . . . . . . . . . . . .114
PLL Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114
Acquisition and Tracking Modes . . . . . . . . . . . . . . . . . . . .116
Manual and Automatic PLL Bandwidth Modes. . . . . . . . . .116
Programming the PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . .118
Special Programming Exceptions . . . . . . . . . . . . . . . . . . .122
Base Clock Selector Circuit . . . . . . . . . . . . . . . . . . . . . . . .122
CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . .123
8.4.1
8.4.2
8.4.3
8.4.4
8.4.5
8.4.6
8.4.7
8.4.8
8.4.9
8.5
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . .124
8.5.1
8.5.2
8.5.3
8.5.4
8.5.5
8.5.6
8.5.7
8.5.8
PLL Analog Power Pin (V
) . . . . . . . . . . . . . . . . . . . . . .124
DDA
PLL Analog Ground Pin (V
) . . . . . . . . . . . . . . . . . . . . .124
SSA
Oscillator Output Frequency Signal (CGMXCLK) . . . . . . .124
CGM Reference Clock (CGMRCLK) . . . . . . . . . . . . . . . . .124
CGM VCO Clock Output (CGMVCLK) . . . . . . . . . . . . . . . .125
CGM Base Clock Output (CGMOUT). . . . . . . . . . . . . . . . .125
CGM CPU Interrupt (CGMINT) . . . . . . . . . . . . . . . . . . . . .125
8.6
CGM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125
PLL Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
PLL Bandwidth Control Register . . . . . . . . . . . . . . . . . . . .128
PLL Multiplier Select Registers . . . . . . . . . . . . . . . . . . . . .130
PLL VCO Range Select Register . . . . . . . . . . . . . . . . . . . .131
PLL Reference Divider Select Register . . . . . . . . . . . . . . .132
8.6.1
8.6.2
8.6.3
8.6.4
8.6.5
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
Clock Generator Module (CGM)
109
Clock Generator Module (CGM)
8.7
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
8.8
Special Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134
CGM During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . .134
8.8.1
8.8.2
8.8.3
8.9
Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . .135
Acquisition/Lock Time Definitions. . . . . . . . . . . . . . . . . . . .135
Parametric Influences on Reaction Time . . . . . . . . . . . . . .135
Choosing a Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
8.9.1
8.9.2
8.9.3
8.2 Introduction
This section describes the clock generator module (CGM). The CGM
generates the base clock signal, CGMOUT, which is based on either the
oscillator clock divided by two or the divided phase-locked loop (PLL)
clock, CGMPCLK, divided by two. CGMOUT is the clock from which the
SIM derives the system clocks, including the bus clock, which is at a
frequency of CGMOUT÷2.
The PLL is a frequency generator designed for use with a low frequency
crystal (typically 32.768kHz) to generate a base frequency and dividing
to a maximum bus frequency of 8MHz.
Data Sheet
110
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
Features
8.3 Features
Features of the CGM include:
• Phase-locked loop with output frequency in integer multiples of an
integer dividend of the crystal reference
• Low-frequency crystal operation with low-power operation and
high-output frequency resolution
• Programmable prescaler for power-of-two increases in frequency
• Programmable hardware voltage-controlled oscillator (VCO) for
low-jitter operation
• Automatic bandwidth control mode for low-jitter operation
• Automatic frequency lock detector
• CPU interrupt on entry or exit from locked condition
• Configuration register bit to allow oscillator operation during stop
mode
8.4 Functional Description
The CGM consists of three major sub-modules:
• Oscillator module — The oscillator module generates the constant
reference frequency clock, CGMRCLK (buffered CGMXCLK).
• Phase-locked loop (PLL) — The PLL generates the
programmable VCO frequency clock, CGMVCLK, and the divided,
CGMPCLK. The CGMPCLK is one of the reference clocks to the
base clock selector circuit.
• Base clock selector circuit — This software-controlled circuit
selects the one of three clocks as the base clock, CGMOUT:
CGMXCLK, CGMXCLK divided by two, or CGMPCLK divided by
two.
Figure 8-1 shows the structure of the CGM.
Figure 8-2 is a summary of the CGM registers.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
111
Clock Generator Module (CGM)
Clock Generator Module (CGM)
OSCILLATOR (OSC) MODULE
See Section 7. Oscillator (OSC).
SIMOSCEN
From SIM
ICLK
INTERNAL RC OSC
To SIM (and COP)
T0 RTC, ADC, LCD
CGMXCLK
CGMRCLK
OSC2
CRYSTAL OSCILLATOR
OSC1
USER MODE:
CGMOUT = B
RESET: A
A
PHASE-LOCKED LOOP (PLL)
CGMOUT
A
RESET: A
A
÷ 2
B1
To SIM
S
B1
S
B1
S
CGMRDV
SIMDIV2
From SIM
CGMRCLK
CGMXFC
REFERENCE
DIVIDER
BASE
CLOCK
SELECT
CIRCUIT
BCS
CGMPCLK
VPR[1:0]
R
DIV2CLK
CONFIG2
RDS[3:0]
VDDA
VSSA
VRS[7:0]
2E
L
VOLTAGE
CONTROLLED
OSCILLATOR
PHASE
DETECTOR
LOOP
FILTER
PLL ANALOG
AUTOMATIC
MODE
CONTROL
CGMINT
To SIM
LOCK
DETECTOR
INTERRUPT
CONTROL
LOCK
AUTO
ACQ
PLLIE
PLLF
MUL[11:0]
PRE[1:0]
2P
N
CGMVCLK
CGMVDV
FREQUENCY
DIVIDER
FREQUENCY
DIVIDER
CGMPCLK
Figure 8-1. CGM Block Diagram
Data Sheet
112
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Clock Generator Module (CGM)
Clock Generator Module (CGM)
Functional Description
Addr.
Register Name
Bit 7
PLLIE
0
6
5
PLLON
1
4
3
2
1
Bit 0
Read:
Write:
Reset:
Read:
PLLF
BCS
PRE1
PRE0
VPR1
VPR0
PLL Control Register
(PTCL)
$0036
0
0
0
0
0
0
0
0
0
0
LOCK
PLL Bandwidth Control
AUTO
ACQ
R
$0037
$0038
$0039
$003A
$003B
NOTES:
Register Write:
(PBWC)
Reset:
0
0
0
0
0
0
0
0
0
MUL11
0
0
MUL10
0
0
MUL9
0
0
MUL8
0
Read:
PLL Multiplier Select
Register High Write:
(PMSH)
Reset:
0
0
0
0
Read:
PLL Multiplier Select
MUL7
0
MUL6
1
MUL5
0
MUL4
0
MUL3
0
MUL2
0
MUL1
0
MUL0
0
Register Low Write:
(PMSL)
Reset:
Read:
PLL VCO Range Select
VRS7
VRS6
VRS5
VRS4
VRS3
0
VRS2
0
VRS1
0
VRS0
0
Register Write:
(PMRS)
Reset:
0
0
1
0
0
0
0
0
Read:
PLL Reference Divider
RDS3
RDS2
RDS1
0
RDS0
1
Select Register Write:
(PMDS)
0
0
Reset:
0
0
0
0
= Unimplemented
R
= Reserved
1. When AUTO = 0, PLLIE is forced clear and is read-only.
2. When AUTO = 0, PLLF and LOCK read as clear.
3. When AUTO = 1, ACQ is read-only.
4. When PLLON = 0 or VRS7:VRS0 = $0, BCS is forced clear and is read-only.
5. When PLLON = 1, the PLL programming register is read-only.
6. When BCS = 1, PLLON is forced set and is read-only.
Figure 8-2. CGM I/O Register Summary
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
113
Clock Generator Module (CGM)
Clock Generator Module (CGM)
8.4.1 Oscillator Module
The oscillator module provides two clock outputs CGMXCLK and
CGMRCLK to the CGM module. CGMXCLK or CGMXCLK divide-by-two
can be selected to drive the SIM module to generate the system bus
clocks. CGMRCLK is the reference clock for the phase-lock-loop, to
generate a higher frequency clock. The oscillator module also provides
the reference clock for the real time clock (RTC) module.
See Section 7. Oscillator (OSC) for detailed description on oscillator
module. See Section 12. Real Time Clock (RTC) for detailed
description on RTC.
8.4.2 Phase-Locked Loop Circuit (PLL)
The PLL is a frequency generator that can operate in either acquisition
mode or tracking mode, depending on the accuracy of the output
frequency. The PLL can change between acquisition and tracking
modes either automatically or manually.
8.4.3 PLL Circuits
The PLL consists of these circuits:
• Voltage-controlled oscillator (VCO)
• Reference divider
• Frequency pre-scaler
• Modulo VCO frequency divider
• Phase detector
• Loop filter
• Lock detector
Data Sheet
114
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
Functional Description
The operating range of the VCO is programmable for a wide range of
frequencies and for maximum immunity to external noise, including
supply and CGMXFC noise. The VCO frequency is bound to a range
from roughly one-half to twice the center-of-range frequency, f
.
VRS
Modulating the voltage on the CGMXFC pin changes the frequency
within this range. By design, f is equal to the nominal center-of-range
VRS
frequency, f
factor, E, or (L × 2 )f
, (38.4 kHz) times a linear factor, L, and a power-of-two
NOM
E
.
NOM
CGMRCLK is the PLL reference clock, a buffered version of CGMXCLK.
CGMRCLK runs at a frequency, f , and is fed to the PLL through a
RCLK
programmable modulo reference divider, which divides f
by a
RCLK
factor, R. The divider’s output is the final reference clock, CGMRDV,
running at a frequency, f = f /R. With an external crystal
RDV
RCLK
(30kHz–100kHz), always set R = 1 for specified performance. With an
external high-frequency clock source, use R to divide the external
frequency to between 30kHz and 100kHz.
The VCO’s output clock, CGMVCLK, running at a frequency, f
fed back through a programmable pre-scaler divider and a
, is
VCLK
programmable modulo divider. The pre-scaler divides the VCO clock by
a power-of-two factor P (the CGMPCLK) and the modulo divider reduces
the VCO clock by a factor, N. The dividers’ output is the VCO feedback
P
clock, CGMVDV, running at a frequency, f
= f
/(N × 2 ). (See
VDV
VCLK
8.4.6 Programming the PLL for more information.)
The phase detector then compares the VCO feedback clock, CGMVDV,
with the final reference clock, CGMRDV. A correction pulse is generated
based on the phase difference between the two signals. The loop filter
then slightly alters the DC voltage on the external capacitor connected
to CGMXFC based on the width and direction of the correction pulse.
The filter can make fast or slow corrections depending on its mode,
described in 8.4.4 Acquisition and Tracking Modes. The value of the
external capacitor and the reference frequency determines the speed of
the corrections and the stability of the PLL.
The lock detector compares the frequencies of the VCO feedback clock,
CGMVDV, and the final reference clock, CGMRDV. Therefore, the
speed of the lock detector is directly proportional to the final reference
frequency, f
. The circuit determines the mode of the PLL and the lock
RDV
condition based on this comparison.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
115
Clock Generator Module (CGM)
Clock Generator Module (CGM)
8.4.4 Acquisition and Tracking Modes
The PLL filter is manually or automatically configurable into one of two
operating modes:
• Acquisition mode — In acquisition mode, the filter can make large
frequency corrections to the VCO. This mode is used at PLL start
up or when the PLL has suffered a severe noise hit and the VCO
frequency is far off the desired frequency. When in acquisition
mode, the ACQ bit is clear in the PLL bandwidth control register.
(See 8.6.2 PLL Bandwidth Control Register.)
• Tracking mode — In tracking mode, the filter makes only small
corrections to the frequency of the VCO. PLL jitter is much lower
in tracking mode, but the response to noise is also slower. The
PLL enters tracking mode when the VCO frequency is nearly
correct, such as when the PLL is selected as the base clock
source. (See 8.4.8 Base Clock Selector Circuit.) The PLL is
automatically in tracking mode when not in acquisition mode or
when the ACQ bit is set.
8.4.5 Manual and Automatic PLL Bandwidth Modes
The PLL can change the bandwidth or operational mode of the loop filter
manually or automatically. Automatic mode is recommended for most
users.
In automatic bandwidth control mode (AUTO = 1), the lock detector
automatically switches between acquisition and tracking modes.
Automatic bandwidth control mode also is used to determine when the
VCO clock, CGMVCLK, is safe to use as the source for the base clock,
CGMOUT. (See 8.6.2 PLL Bandwidth Control Register.) If PLL
interrupts are enabled, the software can wait for a PLL interrupt request
and then check the LOCK bit. If interrupts are disabled, software can poll
the LOCK bit continuously (during PLL start-up, usually) or at periodic
intervals. In either case, when the LOCK bit is set, the VCO clock is safe
to use as the source for the base clock. (See 8.4.8 Base Clock Selector
Circuit.) If the VCO is selected as the source for the base clock and the
LOCK bit is clear, the PLL has suffered a severe noise hit and the
software must take appropriate action, depending on the application.
(See 8.7 Interrupts for information and precautions on using interrupts.)
Data Sheet
116
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
Functional Description
The following conditions apply when the PLL is in automatic bandwidth
control mode:
• The ACQ bit (See 8.6.2 PLL Bandwidth Control Register.) is a
read-only indicator of the mode of the filter. (See 8.4.4
Acquisition and Tracking Modes.)
• The ACQ bit is set when the VCO frequency is within a certain
tolerance and is cleared when the VCO frequency is out of a
certain tolerance. (See 8.9 Acquisition/Lock Time
Specifications for more information.)
• The LOCK bit is a read-only indicator of the locked state of the
PLL.
• The LOCK bit is set when the VCO frequency is within a certain
tolerance and is cleared when the VCO frequency is out of a
certain tolerance. (See 8.9 Acquisition/Lock Time
Specifications for more information.)
• CPU interrupts can occur if enabled (PLLIE = 1) when the PLL’s
lock condition changes, toggling the LOCK bit. (See 8.6.1 PLL
Control Register.)
The PLL also may operate in manual mode (AUTO = 0). Manual mode
is used by systems that do not require an indicator of the lock condition
for proper operation. Such systems typically operate well below
f
.
BUSMAX
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
117
Clock Generator Module (CGM)
Clock Generator Module (CGM)
The following conditions apply when in manual mode:
• ACQ is a writable control bit that controls the mode of the filter.
Before turning on the PLL in manual mode, the ACQ bit must be
clear.
• Before entering tracking mode (ACQ = 1), software must wait a
given time, tACQ (See 8.9 Acquisition/Lock Time
Specifications.), after turning on the PLL by setting PLLON in the
PLL control register (PCTL).
• Software must wait a given time, tAL, after entering tracking mode
before selecting the PLL as the clock source to CGMOUT
(BCS = 1).
• The LOCK bit is disabled.
• CPU interrupts from the CGM are disabled.
8.4.6 Programming the PLL
The following procedure shows how to program the PLL.
NOTE: The round function in the following equations means that the real
number should be rounded to the nearest integer number.
1. Choose the desired bus frequency, f
.
BUSDES
2. Calculate the desired VCO frequency, f
.
VCLKDES
P
P
f
= 2 × f
= 2 × 4 × f
CGMPCLK BUSDES
VCLKDES
where P is the power of two multiplier, and can be 0, 1, 2, or 3
3. Choose a practical PLL reference frequency, f , and the
RCLK
reference clock divider, R. Typically, the reference is 32.768kHz
and R = 1.
Frequency errors to the PLL are corrected at a rate of f
/R. For
RCLK
stability and lock time reduction, this rate must be as fast as
possible. The VCO frequency must be an integer multiple of this
rate.
Data Sheet
118
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
Functional Description
The relationship between the VCO frequency, f
, and the
VCLK
reference frequency, f
, is
RCLK
P
2 N
= ----------- (f
f
)
RCLK
VCLK
R
where N is the integer range multiplier, between 1 and 4095.
In cases where desired bus frequency has some tolerance,
choose f
to a value determined either by other module
RCLK
requirements (such as modules which are clocked by CGMXCLK),
cost requirements, or ideally, as high as the specified range
allows. See Section 24. Electrical Specifications. Choose the
reference divider, R = 1.
When the tolerance on the bus frequency is tight, choose f
to
RCLK
an integer divisor of f
, and R = 1. If f
cannot meet this
RCLK
BUSDES
requirement, use the following equation to solve for R with
practical choices of f
lowest R.
, and choose the f
that gives the
RCLK
RCLK
f
f
VCLKDES
VCLKDES
-------------------------
-------------------------
R = round R
×
– integer
MAX
f
f
RCLK
RCLK
4. Calculate N:
R × f
VCLKDES
------------------------------------
N = round
P
f
× 2
RCLK
5. Calculate and verify the adequacy of the VCO and bus
frequencies f
and f
.
VCLK
BUS
P
2 N
R
f
= ----------- (f
)
RCLK
VCLK
f
VCLK
f
=
-----------
BUS
P
2 × 4
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
119
Clock Generator Module (CGM)
Clock Generator Module (CGM)
6. Select the VCO’s power-of-two range multiplier E, according to
this table:
Frequency Range
E
0
1
2
0 < f
< 9,830,400
VCLK
9,830,400 ≤ f
< 19,660,800
VCLK
19,660,800 ≤ f
< 39,321,600
VCLK
NOTE: Do not program E to a value of 3.
7. Select a VCO linear range multiplier, L, where f
= 38.4kHz
NOM
f
VCLK
--------------------------
L = round
E
2 × f
NOM
8. Calculate and verify the adequacy of the VCO programmed
center-of-range frequency, f . The center-of-range frequency is
VRS
the midpoint between the minimum and maximum frequencies
attainable by the PLL.
E
f
= (L × 2 )f
VRS
NOM
For proper operation,
E
f
× 2
NOM
--------------------------
f
– f
≤
VCLK
VRS
2
9. Verify the choice of P, R, N, E, and L by comparing f
to f
VRS
VCLK
and f
. For proper operation, f
must be within the
VCLKDES
VCLK
application’s tolerance of f
, and f
must be as close as
VCLKDES
VRS
possible to f
VCLK.
NOTE: Exceeding the recommended maximum bus frequency or VCO
frequency can crash the MCU.
Data Sheet
120
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Clock Generator Module (CGM)
Clock Generator Module (CGM)
Functional Description
10. Program the PLL registers accordingly:
a. In the PRE bits of the PLL control register (PCTL), program
the binary equivalent of P.
b. In the VPR bits of the PLL control register (PCTL), program
the binary equivalent of E.
c. In the PLL multiplier select register low (PMSL) and the PLL
multiplier select register high (PMSH), program the binary
equivalent of N.
d. In the PLL VCO range select register (PMRS), program the
binary coded equivalent of L.
e. In the PLL reference divider select register (PMDS), program
the binary coded equivalent of R.
NOTE: The values for P, E, N, L, and R can only be programmed when the PLL
is off (PLLON = 0).
Table 8-1 provides numeric examples (numbers are in hexadecimal
notation):
Table 8-1. Numeric Examples
f
f
RCLK
CGMVCLK
8.0 MHz
CGMPCLK
8.0 MHz
R
1
1
1
1
1
1
1
1
1
1
1
N
P
0
0
0
0
0
0
0
0
1
2
3
E
0
1
1
1
2
2
2
2
2
2
2
L
BUS
2.0 MHz
32.768 kHz
F5
D1
80
83
D1
80
82
C0
D0
D0
D0
D0
9.8304 MHz
10.0 MHz
16 MHz
9.8304 MHz
10.0 MHz
16 MHz
2.4576 MHz 32.768 kHz
12C
132
1E9
258
263
384
3D1
1E9
F5
2.5 MHz
4.0 MHz
32.768 kHz
32.768 kHz
19.6608 MHz 19.6608 MHz 4.9152 MHz 32.768 kHz
20 MHz 20 MHz 5.0 MHz 32.768 kHz
29.4912 MHz 29.4912 MHz 7.3728 MHz 32.768 kHz
32 MHz
32 MHz
32 MHz
32 MHz
32 MHz
16 MHz
8 MHz
4 MHz
8.0 MHz
4.0 MHz
2.0 MHz
1.0 MHz
32.768 kHz
32.768 kHz
32.768 kHz
32.768 kHz
7B
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
121
Clock Generator Module (CGM)
Clock Generator Module (CGM)
8.4.7 Special Programming Exceptions
The programming method described in 8.4.6 Programming the PLL
does not account for three possible exceptions. A value of 0 for R, N, or
L is meaningless when used in the equations given. To account for these
exceptions:
• A 0 value for R or N is interpreted exactly the same as a value of 1.
• A 0 value for L disables the PLL and prevents its selection as the
source for the base clock.
(See 8.4.8 Base Clock Selector Circuit.)
8.4.8 Base Clock Selector Circuit
This circuit is used to select either the oscillator clock, CGMXCLK, or the
divided VCO clock, CGMPCLK, as the source of the base clock,
CGMOUT. The two input clocks go through a transition control circuit
that waits up to three CGMXCLK cycles and three CGMPCLK cycles to
change from one clock source to the other. During this time, CGMOUT
is held in stasis. The output of the transition control circuit is then divided
by two to correct the duty cycle. Therefore, the bus clock frequency,
which is one-half of CGMOUT, is one-fourth the frequency of the
selected clock (CGMXCLK or CGMPCLK).
For the CGMXCLK, the divide-by-2 can be by-passed by setting the
DIV2CLK bit in the CONFIG2 register. Therefore, the bus clock
frequency can be one-half of CGMXCLK.
The BCS bit in the PLL control register (PCTL) selects which clock drives
CGMOUT. The divided VCO clock cannot be selected as the base clock
source if the PLL is not turned on. The PLL cannot be turned off if the
divided VCO clock is selected. The PLL cannot be turned on or off
simultaneously with the selection or deselection of the divided VCO
clock. The divided VCO clock also cannot be selected as the base clock
source if the factor L is programmed to a 0. This value would set up a
condition inconsistent with the operation of the PLL, so that the PLL
would be disabled and the oscillator clock would be forced as the source
of the base clock.
Data Sheet
122
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
I/O Signals
8.4.9 CGM External Connections
In its typical configuration, the CGM requires up to four external
components.
Figure 8-3 shows the external components for the PLL:
• Bypass capacitor, C
• Filter network
BYP
Care should be taken with PCB routing in order to minimize signal cross
talk and noise. (See 8.9 Acquisition/Lock Time Specifications for
routing information, filter network and its effects on PLL performance.)
MCU
CGMXFC
VSSA
VDDA
VDD
10 kΩ
CBYP
0.1 µF
0.01 µF
0.033 µF
Note: Filter network in box can be replaced with a 0.47µF capacitor, but will degrade stability.
Figure 8-3. CGM External Connections
8.5 I/O Signals
The following paragraphs describe the CGM I/O signals.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
123
Clock Generator Module (CGM)
Clock Generator Module (CGM)
8.5.1 External Filter Capacitor Pin (CGMXFC)
The CGMXFC pin is required by the loop filter to filter out phase
corrections. An external filter network is connected to this pin. (See
Figure 8-3.)
NOTE: To prevent noise problems, the filter network should be placed as close
to the CGMXFC pin as possible, with minimum routing distances and no
routing of other signals across the network.
8.5.2 PLL Analog Power Pin (V
)
DDA
V
V
is a power pin used by the analog portions of the PLL. Connect the
DDA
DDA
pin to the same voltage potential as the V pin.
DD
NOTE: Route V
carefully for maximum noise immunity and place bypass
DDA
capacitors as close as possible to the package.
8.5.3 PLL Analog Ground Pin (V
)
SSA
V
is a ground pin used by the analog portions of the PLL. Connect
SSA
the V
pin to the same voltage potential as the V pin.
SSA
SS
NOTE: Route V
carefully for maximum noise immunity and place bypass
SSA
capacitors as close as possible to the package.
NOTE: On this MCU, the V
is physically bonded to the V pin.
SS
SSA
8.5.4 Oscillator Output Frequency Signal (CGMXCLK)
CGMXCLK is the oscillator output signal. It runs at the full speed of the
oscillator, and is generated directly from the crystal oscillator circuit, the
RC oscillator circuit, or the internal oscillator circuit.
8.5.5 CGM Reference Clock (CGMRCLK)
CGMRCLK is a buffered version of CGMXCLK, this clock is the
reference clock for the phase-locked-loop circuit.
Data Sheet
124
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Clock Generator Module (CGM)
Clock Generator Module (CGM)
CGM Registers
8.5.6 CGM VCO Clock Output (CGMVCLK)
CGMVCLK is the clock output from the VCO.
8.5.7 CGM Base Clock Output (CGMOUT)
CGMOUT is the clock output of the CGM. This signal goes to the SIM,
which generates the MCU clocks. CGMOUT is a 50 percent duty cycle
clock running at twice the bus frequency. CGMOUT is software
programmable to be equal to CGMXCLK, CGMXCLK divided by two, or
CGMPCLK divided by two.
8.5.8 CGM CPU Interrupt (CGMINT)
CGMINT is the interrupt signal generated by the PLL lock detector.
The following registers control and monitor operation of the CGM:
8.6 CGM Registers
• PLL control register (PCTL)
(See 8.6.1 PLL Control Register.)
• PLL bandwidth control register (PBWC)
(See 8.6.2 PLL Bandwidth Control Register.)
• PLL multiplier select registers (PMSH and PMSL)
(See 8.6.3 PLL Multiplier Select Registers.)
• PLL VCO range select register (PMRS)
(See 8.6.4 PLL VCO Range Select Register.)
• PLL reference divider select register (PMDS)
(See 8.6.5 PLL Reference Divider Select Register.)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
125
Clock Generator Module (CGM)
Clock Generator Module (CGM)
8.6.1 PLL Control Register
The PLL control register (PCTL) contains the interrupt enable and flag
bits, the on/off switch, the base clock selector bit, the prescaler bits, and
the VCO power-of-two range selector bits.
Address: $0036
Bit 7
PLLIE
0
6
5
PLLON
1
4
BCS
0
3
PRE1
0
2
PRE0
0
1
VPR1
0
Bit 0
VPR0
0
Read:
Write:
Reset:
PLLF
0
= Unimplemented
Figure 8-4. PLL Control Register (PCTL)
PLLIE — PLL Interrupt Enable Bit
This read/write bit enables the PLL to generate an interrupt request
when the LOCK bit toggles, setting the PLL flag, PLLF. When the
AUTO bit in the PLL bandwidth control register (PBWC) is clear,
PLLIE cannot be written and reads as logic 0. Reset clears the PLLIE
bit.
1 = PLL interrupts enabled
0 = PLL interrupts disabled
PLLF — PLL Interrupt Flag Bit
This read-only bit is set whenever the LOCK bit toggles. PLLF
generates an interrupt request if the PLLIE bit also is set. PLLF
always reads as logic 0 when the AUTO bit in the PLL bandwidth
control register (PBWC) is clear. Clear the PLLF bit by reading the
PLL control register. Reset clears the PLLF bit.
1 = Change in lock condition
0 = No change in lock condition
NOTE: Do not inadvertently clear the PLLF bit. Any read or read-modify-write
operation on the PLL control register clears the PLLF bit.
Data Sheet
126
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
CGM Registers
PLLON — PLL On Bit
This read/write bit activates the PLL and enables the VCO clock,
CGMVCLK. PLLON cannot be cleared if the VCO clock is driving the
base clock, CGMOUT (BCS = 1). (See 8.4.8 Base Clock Selector
Circuit.) Reset sets this bit so that the loop can stabilize as the MCU
is powering up.
1 = PLL on
0 = PLL off
BCS — Base Clock Select Bit
This read/write bit selects either the oscillator output, CGMXCLK, or
the divided VCO clock, CGMPCLK, as the source of the CGM output,
CGMOUT. CGMOUT frequency is one-half the frequency of the
selected clock. BCS cannot be set while the PLLON bit is clear. After
toggling BCS, it may take up to three CGMXCLK and three
CGMPCLK cycles to complete the transition from one source clock to
the other. During the transition, CGMOUT is held in stasis. (See 8.4.8
Base Clock Selector Circuit.) Reset clears the BCS bit.
1 = CGMPCLK divided by two drives CGMOUT
0 = CGMXCLK divided by two drives CGMOUT
NOTE: PLLON and BCS have built-in protection that prevents the base clock
selector circuit from selecting the VCO clock as the source of the base
clock if the PLL is off. Therefore, PLLON cannot be cleared when BCS
is set, and BCS cannot be set when PLLON is clear. If the PLL is off
(PLLON = 0), selecting CGMPCLK requires two writes to the PLL control
register. (See 8.4.8 Base Clock Selector Circuit.)
PRE1 and PRE0 — Prescaler Program Bits
These read/write bits control a prescaler that selects the prescaler
power-of-two multiplier, P. (See 8.4.3 PLL Circuits and 8.4.6
Programming the PLL.) PRE1 and PRE0 cannot be written when
the PLLON bit is set. Reset clears these bits.
These prescaler bits affects the relationship between the VCO clock
and the final system bus clock.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
127
Clock Generator Module (CGM)
Clock Generator Module (CGM)
Table 8-2. PRE 1 and PRE0 Programming
PRE1 and PRE0
P
0
1
2
3
Prescaler Multiplier
00
01
10
11
1
2
4
8
VPR1 and VPR0 — VCO Power-of-Two Range Select Bits
These read/write bits control the VCO’s hardware power-of-two range
multiplier E that, in conjunction with L (See 8.4.3 PLL Circuits, 8.4.6
Programming the PLL, and 8.6.4 PLL VCO Range Select
Register.) controls the hardware center-of-range frequency, fVRS
.
VPR1:VPR0 cannot be written when the PLLON bit is set. Reset
clears these bits.
Table 8-3. VPR1 and VPR0 Programming
VCO Power-of-Two
Range Multiplier
VPR1 and VPR0
E
00
01
10
0
1
2
1
2
4
NOTE: Do not program E to a value of 3.
8.6.2 PLL Bandwidth Control Register
The PLL bandwidth control register (PBWC):
• Selects automatic or manual (software-controlled) bandwidth
control mode
• Indicates when the PLL is locked
• In automatic bandwidth control mode, indicates when the PLL is in
acquisition or tracking mode
• In manual operation, forces the PLL into acquisition or tracking
mode
Data Sheet
128
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
CGM Registers
Address: $0037
Bit 7
6
5
ACQ
0
4
0
3
0
2
0
1
0
Bit 0
R
Read:
AUTO
Write:
LOCK
Reset:
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 8-5. PLL Bandwidth Control Register (PBWCR)
AUTO — Automatic Bandwidth Control Bit
This read/write bit selects automatic or manual bandwidth control.
When initializing the PLL for manual operation (AUTO = 0), clear the
ACQ bit before turning on the PLL. Reset clears the AUTO bit.
1 = Automatic bandwidth control
0 = Manual bandwidth control
LOCK — Lock Indicator Bit
When the AUTO bit is set, LOCK is a read-only bit that becomes set
when the VCO clock, CGMVCLK, is locked (running at the
programmed frequency). When the AUTO bit is clear, LOCK reads as
logic 0 and has no meaning. The write one function of this bit is
reserved for test, so this bit must always be written a 0. Reset clears
the LOCK bit.
1 = VCO frequency correct or locked
0 = VCO frequency incorrect or unlocked
ACQ — Acquisition Mode Bit
When the AUTO bit is set, ACQ is a read-only bit that indicates
whether the PLL is in acquisition mode or tracking mode. When the
AUTO bit is clear, ACQ is a read/write bit that controls whether the
PLL is in acquisition or tracking mode.
In automatic bandwidth control mode (AUTO = 1), the last-written
value from manual operation is stored in a temporary location and is
recovered when manual operation resumes. Reset clears this bit,
enabling acquisition mode.
1 = Tracking mode
0 = Acquisition mode
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
129
Clock Generator Module (CGM)
Clock Generator Module (CGM)
8.6.3 PLL Multiplier Select Registers
The PLL multiplier select registers (PMSH and PMSL) contain the
programming information for the modulo feedback divider.
Address: $0038
Bit 7
0
6
0
5
0
4
0
3
MUL11
0
2
MUL10
0
1
MUL9
0
Bit 0
MUL8
0
Read:
Write:
Reset:
0
0
0
0
= Unimplemented
Figure 8-6. PLL Multiplier Select Register High (PMSH)
Address: $0039
Bit 7
6
MUL6
1
5
MUL5
0
4
MUL4
0
3
MUL3
0
2
MUL2
0
1
MUL1
0
Bit 0
MUL0
0
Read:
MUL7
Write:
Reset:
0
Figure 8-7. PLL Multiplier Select Register Low (PMSL)
MUL[11:0] — Multiplier Select Bits
These read/write bits control the modulo feedback divider that selects
the VCO frequency multiplier N. (See 8.4.3 PLL Circuits and 8.4.6
Programming the PLL.) A value of $0000 in the multiplier select
registers configure the modulo feedback divider the same as a value
of $0001. Reset initializes the registers to $0040 for a default multiply
value of 64.
NOTE: The multiplier select bits have built-in protection such that they cannot
be written when the PLL is on (PLLON = 1).
Data Sheet
130
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
CGM Registers
8.6.4 PLL VCO Range Select Register
The PLL VCO range select register (PMRS) contains the programming
information required for the hardware configuration of the VCO.
Address: $003A
Bit 7
VRS7
0
6
VRS6
1
5
VRS5
0
4
VRS4
0
3
VRS3
0
2
VRS2
0
1
VRS1
0
Bit 0
VRS0
0
Read:
Write:
Reset:
Figure 8-8. PLL VCO Range Select Register (PMRS)
VRS[7:0] — VCO Range Select Bits
These read/write bits control the hardware center-of-range linear
multiplier L which, in conjunction with E (See 8.4.3 PLL Circuits,
8.4.6 Programming the PLL, and 8.6.1 PLL Control Register.),
controls the hardware center-of-range frequency, f
. VRS[7:0]
VRS
cannot be written when the PLLON bit in the PCTL is set. (See 8.4.7
Special Programming Exceptions.) A value of $00 in the VCO
range select register disables the PLL and clears the BCS bit in the
PLL control register (PCTL). (See 8.4.8 Base Clock Selector Circuit
and 8.4.7 Special Programming Exceptions.). Reset initializes the
register to $40 for a default range multiply value of 64.
NOTE: The VCO range select bits have built-in protection such that they cannot
be written when the PLL is on (PLLON = 1) and such that the VCO clock
cannot be selected as the source of the base clock (BCS = 1) if the VCO
range select bits are all clear.
The PLL VCO range select register must be programmed correctly.
Incorrect programming can result in failure of the PLL to achieve lock.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
131
Clock Generator Module (CGM)
Clock Generator Module (CGM)
8.6.5 PLL Reference Divider Select Register
The PLL reference divider select register (PMDS) contains the
programming information for the modulo reference divider.
Address: $003B
Bit 7
0
6
0
5
0
4
0
3
RDS3
0
2
RDS2
0
1
RDS1
0
Bit 0
RDS0
1
Read:
Write:
Reset:
0
0
0
0
= Unimplemented
Figure 8-9. PLL Reference Divider Select Register (PMDS)
RDS[3:0] — Reference Divider Select Bits
These read/write bits control the modulo reference divider that selects
the reference division factor, R. (See 8.4.3 PLL Circuits and 8.4.6
Programming the PLL.) RDS[3:0] cannot be written when the
PLLON bit in the PCTL is set. A value of $00 in the reference divider
select register configures the reference divider the same as a value of
$01. (See 8.4.7 Special Programming Exceptions.) Reset
initializes the register to $01 for a default divide value of 1.
NOTE: The reference divider select bits have built-in protection such that they
cannot be written when the PLL is on (PLLON = 1).
NOTE: The default divide value of 1 is recommended for all applications.
Data Sheet
132
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
Interrupts
8.7 Interrupts
When the AUTO bit is set in the PLL bandwidth control register (PBWC),
the PLL can generate a CPU interrupt request every time the LOCK bit
changes state. The PLLIE bit in the PLL control register (PCTL) enables
CPU interrupts from the PLL. PLLF, the interrupt flag in the PCTL,
becomes set whether interrupts are enabled or not. When the AUTO bit
is clear, CPU interrupts from the PLL are disabled and PLLF reads as
logic 0.
Software should read the LOCK bit after a PLL interrupt request to see
if the request was due to an entry into lock or an exit from lock. When the
PLL enters lock, the divided VCO clock, CGMPCLK, divided by two can
be selected as the CGMOUT source by setting BCS in the PCTL. When
the PLL exits lock, the VCO clock frequency is corrupt, and appropriate
precautions should be taken. If the application is not frequency sensitive,
interrupts should be disabled to prevent PLL interrupt service routines
from impeding software performance or from exceeding stack
limitations.
NOTE: Software can select the CGMPCLK divided by two as the CGMOUT
source even if the PLL is not locked (LOCK = 0). Therefore, software
should make sure the PLL is locked before setting the BCS bit.
8.8 Special Modes
The WAIT instruction puts the MCU in low power-consumption standby
modes.
8.8.1 Wait Mode
The WAIT instruction does not affect the CGM. Before entering wait
mode, software can disengage and turn off the PLL by clearing the BCS
and PLLON bits in the PLL control register (PCTL) to save power. Less
power-sensitive applications can disengage the PLL without turning it
off, so that the PLL clock is immediately available at WAIT exit. This
would be the case also when the PLL is to wake the MCU from wait
mode, such as when the PLL is first enabled and waiting for LOCK or
LOCK is lost.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
133
Clock Generator Module (CGM)
Clock Generator Module (CGM)
8.8.2 Stop Mode
If the oscillator stop mode enable bit (STOP_XCLKEN in CONFIG2
register) is configured to disabled the oscillator in stop mode, then the
STOP instruction disables the CGM (oscillator and phase locked loop)
and holds low all CGM outputs (CGMOUT, CGMVCLK, CGMPCLK, and
CGMINT).
If the STOP instruction is executed with the divided VCO clock,
CGMPCLK, divided by two driving CGMOUT, the PLL automatically
clears the BCS bit in the PLL control register (PCTL), thereby selecting
the oscillator clock, CGMXCLK, divided by two as the source of
CGMOUT. When the MCU recovers from STOP, the crystal clock
divided by two drives CGMOUT and BCS remains clear.
If the oscillator stop mode enable bit is configured for continuous
oscillator operation in stop mode, then the phase locked loop is shut off
but the CGMXCLK will continue to drive the SIM and other MCU sub-
systems.
8.8.3 CGM During Break Interrupts
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state. (See 9.8.3 SIM Break Flag Control
Register.)
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect the PLLF bit during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
the PLL control register during the break state without affecting the PLLF
bit.
Data Sheet
134
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
Acquisition/Lock Time Specifications
8.9 Acquisition/Lock Time Specifications
The acquisition and lock times of the PLL are, in many applications, the
most critical PLL design parameters. Proper design and use of the PLL
ensures the highest stability and lowest acquisition/lock times.
8.9.1 Acquisition/Lock Time Definitions
Typical control systems refer to the acquisition time or lock time as the
reaction time, within specified tolerances, of the system to a step input.
In a PLL, the step input occurs when the PLL is turned on or when it
suffers a noise hit. The tolerance is usually specified as a percent of the
step input or when the output settles to the desired value plus or minus
a percent of the frequency change. Therefore, the reaction time is
constant in this definition, regardless of the size of the step input. For
example, consider a system with a 5 percent acquisition time tolerance.
If a command instructs the system to change from 0Hz to 1MHz, the
acquisition time is the time taken for the frequency to reach
1MHz ±50kHz. 50kHz = 5% of the 1MHz step input. If the system is
operating at 1MHz and suffers a –100kHz noise hit, the acquisition time
is the time taken to return from 900kHz to 1MHz ±5kHz. 5kHz = 5% of
the 100kHz step input.
Other systems refer to acquisition and lock times as the time the system
takes to reduce the error between the actual output and the desired
output to within specified tolerances. Therefore, the acquisition or lock
time varies according to the original error in the output. Minor errors may
not even be registered. Typical PLL applications prefer to use this
definition because the system requires the output frequency to be within
a certain tolerance of the desired frequency regardless of the size of the
initial error.
8.9.2 Parametric Influences on Reaction Time
Acquisition and lock times are designed to be as short as possible while
still providing the highest possible stability. These reaction times are not
constant, however. Many factors directly and indirectly affect the
acquisition time.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
135
Clock Generator Module (CGM)
Clock Generator Module (CGM)
The most critical parameter which affects the reaction times of the PLL
is the reference frequency, f . This frequency is the input to the phase
RDV
detector and controls how often the PLL makes corrections. For stability,
the corrections must be small compared to the desired frequency, so
several corrections are required to reduce the frequency error.
Therefore, the slower the reference the longer it takes to make these
corrections. This parameter is under user control via the choice of crystal
frequency f
and the R value programmed in the reference divider.
XCLK
(See 8.4.3 PLL Circuits, 8.4.6 Programming the PLL, and 8.6.5 PLL
Reference Divider Select Register.)
Another critical parameter is the external filter network. The PLL
modifies the voltage on the VCO by adding or subtracting charge from
capacitors in this network. Therefore, the rate at which the voltage
changes for a given frequency error (thus change in charge) is
proportional to the capacitance. The size of the capacitor also is related
to the stability of the PLL. If the capacitor is too small, the PLL cannot
make small enough adjustments to the voltage and the system cannot
lock. If the capacitor is too large, the PLL may not be able to adjust the
voltage in a reasonable time. (See 8.9.3 Choosing a Filter.)
Also important is the operating voltage potential applied to V
. The
DDA
power supply potential alters the characteristics of the PLL. A fixed value
is best. Variable supplies, such as batteries, are acceptable if they vary
within a known range at very slow speeds. Noise on the power supply is
not acceptable, because it causes small frequency errors which
continually change the acquisition time of the PLL.
Temperature and processing also can affect acquisition time because
the electrical characteristics of the PLL change. The part operates as
specified as long as these influences stay within the specified limits.
External factors, however, can cause drastic changes in the operation of
the PLL. These factors include noise injected into the PLL through the
filter capacitor, filter capacitor leakage, stray impedances on the circuit
board, and even humidity or circuit board contamination.
Data Sheet
136
MC68HC908LJ24/LK24 — Rev. 2.1
Clock Generator Module (CGM)
Freescale Semiconductor
Clock Generator Module (CGM)
Acquisition/Lock Time Specifications
8.9.3 Choosing a Filter
As described in 8.9.2 Parametric Influences on Reaction Time, the
external filter network is critical to the stability and reaction time of the
PLL. The PLL is also dependent on reference frequency and supply
voltage.
Either of the filter networks in Figure 8-10 is recommended when using
a 32.768kHz reference clock (CGMRCLK). Figure 8-10 (a) is used for
applications requiring better stability. Figure 8-10 (b) is used in low-cost
applications where stability is not critical.
CGMXFC
CGMXFC
10 kΩ
0.01 µF
0.47 µF
0.033 µF
VSSA
VSSA
(a)
(b)
Figure 8-10. PLL Filter
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
137
Clock Generator Module (CGM)
Clock Generator Module (CGM)
Data Sheet
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
138
Clock Generator Module (CGM)
Data Sheet — MC68HC908LJ24
Section 9. System Integration Module (SIM)
9.1 Contents
9.2
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .140
9.3
SIM Bus Clock Control and Generation . . . . . . . . . . . . . . . . .142
Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143
Clock Start-up from POR or LVI Reset. . . . . . . . . . . . . . . .143
Clocks in Stop Mode and Wait Mode . . . . . . . . . . . . . . . . .144
9.3.1
9.3.2
9.3.3
9.4
9.4.1
9.4.2
9.4.2.1
9.4.2.2
9.4.2.3
9.4.2.4
9.4.2.5
9.4.2.6
Reset and System Initialization. . . . . . . . . . . . . . . . . . . . . . . .144
External Pin Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145
Active Resets from Internal Sources . . . . . . . . . . . . . . . . .145
Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146
Computer Operating Properly (COP) Reset. . . . . . . . . .147
Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . .148
Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . .148
Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . .148
Monitor Mode Entry Module Reset (MODRST) . . . . . . .148
9.5
SIM Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149
SIM Counter During Power-On Reset . . . . . . . . . . . . . . . .149
SIM Counter During Stop Mode Recovery. . . . . . . . . . . . .149
SIM Counter and Reset States. . . . . . . . . . . . . . . . . . . . . .149
9.5.1
9.5.2
9.5.3
9.6
9.6.1
Exception Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . .152
SWI Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153
Interrupt Status Registers . . . . . . . . . . . . . . . . . . . . . . .153
Interrupt Status Register 1. . . . . . . . . . . . . . . . . . . . . . .153
Interrupt Status Register 2. . . . . . . . . . . . . . . . . . . . . . .155
Interrupt Status Register 3. . . . . . . . . . . . . . . . . . . . . . .155
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156
Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156
9.6.1.1
9.6.1.2
9.6.1.3
9.6.1.4
9.6.1.5
9.6.1.6
9.6.2
9.6.3
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
System Integration Module (SIM)
139
System Integration Module (SIM)
9.6.4
Status Flag Protection in Break Mode . . . . . . . . . . . . . . . .156
9.7
9.7.1
9.7.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158
9.8
SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
SIM Break Status Register. . . . . . . . . . . . . . . . . . . . . . . . .160
SIM Reset Status Register . . . . . . . . . . . . . . . . . . . . . . . .161
SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . .162
9.8.1
9.8.2
9.8.3
9.2 Introduction
This section describes the system integration module (SIM). Together
with the CPU, the SIM controls all MCU activities. A block diagram of the
SIM is shown in Figure 9-1. Table 9-1 is a summary of the SIM
input/output (I/O) registers. The SIM is a system state controller that
coordinates CPU and exception timing. The SIM is responsible for:
• Bus clock generation and control for CPU and peripherals:
– Stop/wait/reset/break entry and recovery
– Internal clock control
• Master reset control, including power-on reset (POR) and COP
timeout
• Interrupt control:
– Acknowledge timing
– Arbitration control timing
– Vector address generation
• CPU enable/disable timing
• Modular architecture expandable to 128 interrupt sources
Table 9-1 shows the internal signal names used in this section.
Data Sheet
140
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
Introduction
MODULE STOP
MODULE WAIT
CPU STOP (FROM CPU)
CPU WAIT (FROM CPU)
STOP/WAIT
CONTROL
SIMOSCEN (TO CGM, OSC)
SIM
COUNTER
COP CLOCK
ICLK (FROM OSC)
CGMOUT (FROM CGM)
÷ 2
CLOCK
CONTROL
VDD
CLOCK GENERATORS
INTERNAL CLOCKS
INTERNAL
PULLUP
DEVICE
LVI (FROM LVI MODULE)
RESET
PIN LOGIC
POR CONTROL
MASTER
ILLEGAL OPCODE (FROM CPU)
RESET
RESET PIN CONTROL
ILLEGAL ADDRESS
(FROM ADDRESS MAP DECODERS)
CONTROL
SIM RESET STATUS REGISTER
COP (FROM COP MODULE)
RESET
INTERRUPT SOURCES
CPU INTERFACE
INTERRUPT CONTROL
AND PRIORITY DECODE
Figure 9-1. SIM Block Diagram
Table 9-1. Signal Name Conventions
Signal Name
Description
Internal RC oscillator clock
ICLK
CGMXCLK
CGMPCLK
Buffered version of OSC1 from the oscillator module
The divided PLL output
PLL-based or oscillator-based clock output from CGM module
(Bus clock = CGMOUT ÷ 2)
CGMOUT
IAB
IDB
Internal address bus
Internal data bus
PORRST
IRST
Signal from the power-on reset module to the SIM
Internal reset signal
R/W
Read/write signal
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
141
System Integration Module (SIM)
System Integration Module (SIM)
Addr.
Register Name
Bit 7
6
5
4
3
2
1
SBSW
Note
0
Bit 0
Read:
Write:
Reset:
R
R
R
R
R
R
R
SIM Break Status Register
(SBSR)
$FE00
Note: Writing a logic 0 clears SBSW.
Read: POR
Write:
PIN
COP
ILOP
ILAD
0
LVI
0
SIM Reset Status Register
$FE01
(SRSR)
POR:
Read:
1
0
0
0
0
0
0
0
SIM Break Flag Control
BCFE
R
R
R
R
R
R
R
$FE03
$FE04
$FE05
$FE06
Register Write:
(SBFCR)
Reset:
0
IF6
R
Read:
IF5
R
IF4
R
IF3
R
IF2
R
IF1
0
R
0
R
Interrupt Status Register 1
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
R
(INT1)
0
0
0
0
0
0
0
0
IF14
R
IF13
R
IF12
R
IF11
R
IF10
R
IF9
IF8
R
IF7
R
Interrupt Status Register 2
(INT2)
R
0
0
0
0
0
0
0
0
0
0
0
0
IF18
R
IF17
IF16
R
IF15
R
Interrupt Status Register 3
(INT3)
R
R
R
R
R
0
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 9-2. SIM I/O Register Summary
9.3 SIM Bus Clock Control and Generation
The bus clock generator provides system clock signals for the CPU and
peripherals on the MCU. The system clocks are generated from an
incoming clock, CGMOUT, as shown in Figure 9-3. This clock can come
from either the oscillator module or from the on-chip PLL. (See Section
8. Clock Generator Module (CGM).)
Data Sheet
142
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
SIM Bus Clock Control and Generation
OSC2
OSC1
OSCILLATOR (OSC) MODULE
CGMXCLK
ICLK
TO RTC, ADC
SIM COUNTER
SIMOSCEN
STOP MODE CLOCK
ENABLE SIGNALS
FROM CONFIG2
SYSTEM INTEGRATION MODULE
IT12
TO REST
OF MCU
CGMRCLK
CGMOUT
BUS CLOCK
GENERATORS
IT23
TO REST
OF MCU
÷ 2
PHASE-LOCKED LOOP (PLL)
PTC1
SIMDIV2
MONITOR MODE
USER MODE
Figure 9-3. CGM Clock Signals
9.3.1 Bus Timing
In user mode, the internal bus frequency is either the oscillator output
(CGMXCLK) divided by four, CGMXCLK divided by two, or the PLL
output (CGMPCLK) divided by four.
9.3.2 Clock Start-up from POR or LVI Reset
When the power-on reset module or the low-voltage inhibit module
generates a reset, the clocks to the CPU and peripherals are inactive
and held in an inactive phase until after the 4096 ICLK cycle POR
timeout has completed. The RST pin is driven low by the SIM during this
entire period. The IBUS clocks start upon completion of the timeout.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
143
System Integration Module (SIM)
System Integration Module (SIM)
9.3.3 Clocks in Stop Mode and Wait Mode
Upon exit from stop mode by an interrupt, break, or reset, the SIM allows
ICLK to clock the SIM counter. The CPU and peripheral clocks do not
become active until after the stop delay timeout. This timeout is
selectable as 4096 or 32 ICLK cycles. (See 9.7.2 Stop Mode.)
In wait mode, the CPU clocks are inactive. The SIM also produces two
sets of clocks for other modules. Refer to the wait mode subsection of
each module to see if the module is active or inactive in wait mode.
Some modules can be programmed to be active in wait mode.
9.4 Reset and System Initialization
The MCU has these reset sources:
• Power-on reset module (POR)
• External reset pin (RST)
• Computer operating properly module (COP)
• Low-voltage inhibit module (LVI)
• Illegal opcode
• Illegal address
All of these resets produce the vector $FFFE:$FFFF ($FEFE:$FEFF in
monitor mode) and assert the internal reset signal (IRST). IRST causes
all registers to be returned to their default values and all modules to be
returned to their reset states.
An internal reset clears the SIM counter (see 9.5 SIM Counter), but an
external reset does not. Each of the resets sets a corresponding bit in
the SIM reset status register (SRSR). (See 9.8 SIM Registers.)
Data Sheet
144
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
Reset and System Initialization
9.4.1 External Pin Reset
The RST pin circuit includes an internal pull-up device. Pulling the
asynchronous RST pin low halts all processing. The PIN bit of the SIM
reset status register (SRSR) is set as long as RST is held low for a
minimum of 67 ICLK cycles, assuming that neither the POR nor the LVI
was the source of the reset. See Table 9-2 for details.
Figure 9-4 shows the relative timing.
Table 9-2. PIN Bit Set Timing
Reset Type
POR/LVI
Number of Cycles Required to Set PIN
4163 (4096 + 64 + 3)
All others
67 (64 + 3)
CGMOUT
RST
IAB
VECT H VECT L
PC
Figure 9-4. External Reset Timing
9.4.2 Active Resets from Internal Sources
All internal reset sources actively pull the RST pin low for 32 ICLK cycles
to allow resetting of external peripherals. The internal reset signal IRST
continues to be asserted for an additional 32 cycles (see Figure 9-5). An
internal reset can be caused by an illegal address, illegal opcode, COP
timeout, LVI, or POR (see Figure 9-6).
NOTE: For LVI or POR resets, the SIM cycles through 4096 + 32 ICLK cycles
during which the SIM forces the RST pin low. The internal reset signal
then follows the sequence from the falling edge of RST shown in
Figure 9-5.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
145
System Integration Module (SIM)
System Integration Module (SIM)
IRST
RST
ICLK
RST PULLED LOW BY MCU
32 CYCLES
32 CYCLES
IAB
VECTOR HIGH
Figure 9-5. Internal Reset Timing
The COP reset is asynchronous to the bus clock.
ILLEGAL ADDRESS RST
ILLEGAL OPCODE RST
COPRST
LVI
INTERNAL RESET
POR
Figure 9-6. Sources of Internal Reset
The active reset feature allows the part to issue a reset to peripherals
and other chips within a system built around the MCU.
9.4.2.1 Power-On Reset
When power is first applied to the MCU, the power-on reset module
(POR) generates a pulse to indicate that power-on has occurred. The
external reset pin (RST) is held low while the SIM counter counts out
4096 + 32 ICLK cycles. Thirty-two ICLK cycles later, the CPU and
memories are released from reset to allow the reset vector sequence to
occur.
At power-on, these events occur:
• A POR pulse is generated.
• The internal reset signal is asserted.
• The SIM enables CGMOUT.
• Internal clocks to the CPU and modules are held inactive for 4096
ICLK cycles to allow stabilization of the oscillator.
• The RST pin is driven low during the oscillator stabilization time.
• The POR bit of the SIM reset status register (SRSR) is set and all
other bits in the register are cleared.
Data Sheet
146
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
Reset and System Initialization
OSC1
PORRST
4096
CYCLES
32
CYCLES
32
CYCLES
ICLK
CGMOUT
RST
IRST
IAB
$FFFE
$FFFF
Figure 9-7. POR Recovery
9.4.2.2 Computer Operating Properly (COP) Reset
An input to the SIM is reserved for the COP reset signal. The overflow of
the COP counter causes an internal reset and sets the COP bit in the
SIM reset status register (SRSR). The SIM actively pulls down the RST
pin for all internal reset sources.
To prevent a COP module timeout, write any value to location $FFFF.
Writing to location $FFFF clears the COP counter and bits 12 through 5
of the SIM counter. The SIM counter output, which occurs at least every
13
4
2 – 2 ICLK cycles, drives the COP counter. The COP should be
serviced as soon as possible out of reset to guarantee the maximum
amount of time before the first timeout.
The COP module is disabled if the RST pin or the IRQ pin is held at V
TST
while the MCU is in monitor mode. The COP module can be disabled
only through combinational logic conditioned with the high voltage signal
on the RST or the IRQ pin. This prevents the COP from becoming
disabled as a result of external noise. During a break state, V
RST pin disables the COP module.
on the
TST
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
147
System Integration Module (SIM)
System Integration Module (SIM)
9.4.2.3 Illegal Opcode Reset
The SIM decodes signals from the CPU to detect illegal instructions. An
illegal instruction sets the ILOP bit in the SIM reset status register
(SRSR) and causes a reset.
If the stop enable bit, STOP, in the mask option register is logic 0, the
SIM treats the STOP instruction as an illegal opcode and causes an
illegal opcode reset. The SIM actively pulls down the RST pin for all
internal reset sources.
9.4.2.4 Illegal Address Reset
An opcode fetch from an unmapped address generates an illegal
address reset. The SIM verifies that the CPU is fetching an opcode prior
to asserting the ILAD bit in the SIM reset status register (SRSR) and
resetting the MCU. A data fetch from an unmapped address does not
generate a reset. The SIM actively pulls down the RST pin for all internal
reset sources.
9.4.2.5 Low-Voltage Inhibit (LVI) Reset
The low-voltage inhibit module (LVI) asserts its output to the SIM when
the V voltage falls to the LVI trip falling voltage, V . The LVI bit in
DD
TRIPF
the SIM reset status register (SRSR) is set, and the external reset pin
(RST) is held low while the SIM counter counts out 4096 + 32 ICLK
cycles. Thirty-two ICLK cycles later, the CPU is released from reset to
allow the reset vector sequence to occur. The SIM actively pulls down
the RST pin for all internal reset sources.
9.4.2.6 Monitor Mode Entry Module Reset (MODRST)
The monitor mode entry module reset (MODRST) asserts its output to
the SIM when monitor mode is entered in the condition where the reset
vectors are blank ($FF). (See Section 10. Monitor ROM (MON).) When
MODRST gets asserted, an internal reset occurs. The SIM actively pulls
down the RST pin for all internal reset sources.
Data Sheet
148
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
SIM Counter
9.5 SIM Counter
The SIM counter is used by the power-on reset module (POR) and in
stop mode recovery to allow the oscillator time to stabilize before
enabling the internal bus (IBUS) clocks. The SIM counter also serves as
a prescaler for the computer operating properly module (COP). The SIM
counter overflow supplies the clock for the COP module. The SIM
counter is 12 bits long and is clocked by the falling edge of ICLK.
9.5.1 SIM Counter During Power-On Reset
The power-on reset module (POR) detects power applied to the MCU.
At power-on, the POR circuit asserts the signal PORRST. Once the SIM
is initialized, it enables the clock generation module (CGM) to drive the
bus clock state machine.
9.5.2 SIM Counter During Stop Mode Recovery
The SIM counter also is used for stop mode recovery. The STOP
instruction clears the SIM counter. After an interrupt, break, or reset, the
SIM senses the state of the short stop recovery bit, SSREC, in the
configuration register 1 (CONFIG1). If the SSREC bit is a logic 1, then
the stop recovery is reduced from the normal delay of 4096 ICLK cycles
down to 32 ICLK cycles. This is ideal for applications using canned
oscillators that do not require long start-up times from stop mode.
External crystal applications should use the full stop recovery time, that
is, with SSREC cleared.
9.5.3 SIM Counter and Reset States
External reset has no effect on the SIM counter. (See 9.7.2 Stop Mode
for details.) The SIM counter is free-running after all reset states. (See
9.4.2 Active Resets from Internal Sources for counter control and
internal reset recovery sequences.)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
149
System Integration Module (SIM)
System Integration Module (SIM)
9.6 Exception Control
Normal, sequential program execution can be changed in three different
ways:
• Interrupts:
– Maskable hardware CPU interrupts
– Non-maskable software interrupt instruction (SWI)
• Reset
• Break interrupts
9.6.1 Interrupts
At the beginning of an interrupt, the CPU saves the CPU register
contents on the stack and sets the interrupt mask (I bit) to prevent
additional interrupts. At the end of an interrupt, the RTI instruction
recovers the CPU register contents from the stack so that normal
processing can resume. Figure 9-8 shows interrupt entry timing, and
Figure 9-9 shows interrupt recovery timing.
MODULE
INTERRUPT
I-BIT
IAB
DUMMY
SP
SP – 1
SP – 2
SP – 3
SP – 4
VECT H
VECT L START ADDR
IDB
DUMMY PC – 1[7:0] PC – 1[15:8]
X
A
CCR V DATA H V DATA L OPCODE
R/W
Figure 9-8. Interrupt Entry Timing
MODULE
INTERRUPT
I-BIT
IAB
SP – 4
SP – 3
SP – 2
SP – 1
SP
PC
PC + 1
IDB
CCR
A
X PC – 1[15:8] PC – 1[7:0] OPCODE OPERAND
R/W
Figure 9-9. Interrupt Recovery Timing
Data Sheet
150
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
System Integration Module (SIM)
System Integration Module (SIM)
Exception Control
Interrupts are latched, and arbitration is performed in the SIM at the start
of interrupt processing. The arbitration result is a constant that the CPU
uses to determine which vector to fetch. Once an interrupt is latched by
the SIM, no other interrupt can take precedence, regardless of priority,
until the latched interrupt is serviced (or the I bit is cleared).
(See Figure 9-10.)
FROM RESET
BREAK
YES
INTERRUPT?
NO
YES
I-BIT SET?
NO
IRQ
INTERRUPT?
YES
NO
STACK CPU REGISTERS
SET I-BIT
LOAD PC WITH INTERRUPT VECTOR
AS MANY INTERRUPTS
AS EXIST ON CHIP
FETCH NEXT
INSTRUCTION
SWI
INSTRUCTION?
YES
NO
RTI
YES
UNSTACK CPU REGISTERS
EXECUTE INSTRUCTION
INSTRUCTION?
NO
Figure 9-10. Interrupt Processing
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
151
System Integration Module (SIM)
System Integration Module (SIM)
9.6.1.1 Hardware Interrupts
A hardware interrupt does not stop the current instruction. Processing of
a hardware interrupt begins after completion of the current instruction.
When the current instruction is complete, the SIM checks all pending
hardware interrupts. If interrupts are not masked (I bit clear in the
condition code register) and if the corresponding interrupt enable bit is
set, the SIM proceeds with interrupt processing; otherwise, the next
instruction is fetched and executed.
If more than one interrupt is pending at the end of an instruction
execution, the highest priority interrupt is serviced first. Figure 9-11
demonstrates what happens when two interrupts are pending. If an
interrupt is pending upon exit from the original interrupt service routine,
the pending interrupt is serviced before the LDA instruction is executed.
CLI
BACKGROUND
LDA #$FF
ROUTINE
INT1
PSHH
INT1 INTERRUPT SERVICE ROUTINE
PULH
RTI
INT2
PSHH
INT2 INTERRUPT SERVICE ROUTINE
PULH
RTI
Figure 9-11. Interrupt Recognition Example
The LDA opcode is prefetched by both the INT1 and INT2 RTI
instructions. However, in the case of the INT1 RTI prefetch, this is a
redundant operation.
NOTE: To maintain compatibility with the M6805 Family, the H register is not
pushed on the stack during interrupt entry. If the interrupt service routine
modifies the H register or uses the indexed addressing mode, software
should save the H register and then restore it prior to exiting the routine.
Data Sheet
152
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
Exception Control
9.6.1.2 SWI Instruction
The SWI instruction is a non-maskable instruction that causes an
interrupt regardless of the state of the interrupt mask (I bit) in the
condition code register.
NOTE: A software interrupt pushes PC onto the stack. A software interrupt does
not push PC – 1, as a hardware interrupt does.
9.6.1.3 Interrupt Status Registers
The flags in the interrupt status registers identify maskable interrupt
sources. Table 9-3 summarizes the interrupt sources and the interrupt
status register flags that they set. The interrupt status registers can be
useful for debugging.
9.6.1.4 Interrupt Status Register 1
Address: $FE04
Bit 7
6
5
IF4
R
4
IF3
R
3
IF2
R
2
IF1
R
1
0
Bit 0
0
Read:
Write:
Reset:
IF6
R
IF5
R
R
0
R
0
0
0
0
0
0
0
R
= Reserved
Figure 9-12. Interrupt Status Register 1 (INT1)
IF6–IF1 — Interrupt Flags 6–1
These flags indicate the presence of interrupt requests from the
sources shown in Table 9-3.
1 = Interrupt request present
0 = No interrupt request present
Bit 0 and Bit 1 — Always read 0
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
153
System Integration Module (SIM)
System Integration Module (SIM)
Table 9-3. Vector Addresses
Priority
INT Flag Address
Vector
Lowest
$FFD8
$FFD9
$FFDA
$FFDB
$FFDC
$FFDD
$FFDE
$FFDF
$FFE0
$FFE1
$FFE2
$FFE3
$FFE4
$FFE5
$FFE6
$FFE7
$FFE8
$FFE9
$FFEA
$FFEB
$FFEC
$FFED
$FFEE
$FFEF
$FFF0
$FFF1
$FFF2
$FFF3
$FFF4
$FFF5
$FFF6
$FFF7
$FFF8
$FFF9
$FFFA
$FFFB
$FFFC
$FFFD
$FFFE
$FFFF
Real Time Clock Vector (High)
Real Time Clock Vector (Low)
ADC Conversion Complete Vector (High)
ADC Conversion Complete Vector (Low)
Keyboard Vector (High)
Keyboard Vector (Low)
IF18
IF17
IF16
IF15
IF14
IF13
IF12
IF11
IF10
IF9
MMIIC Vector (High)
MMIIC Vector (Low)
SCI Transmit Vector (High)
SCI Transmit Vector (Low)
SCI Receive Vector (High)
SCI Receive Vector (Low)
SCI Error Vector (High)
SCI Error Vector (Low)
SPI Receive Vector (High)
SPI Receive Vector (Low)
SPI Transmit Vector (High)
SPI Transmit Vector (Low)
TIM2 Overflow Vector (High)
TIM2 Overflow Vector (Low)
TIM2 Channel 1 Vector (High)
TIM2 Channel 1 Vector (Low)
TIM2 Channel 0 Vector (High)
TIM2 Channel 0 Vector (Low)
TIM1 Overflow Vector (High)
TIM1 Overflow Vector (Low)
TIM1 Channel 1 Vector (High)
TIM1 Channel 1 Vector (Low)
TIM1 Channel 0 Vector (High)
TIM1 Channel 0 Vector (Low)
PLL Vector (High)
IF8
IF7
IF6
IF5
IF4
IF3
PLL Vector (Low)
LVI Vector (High)
IF2
LVI Vector (Low)
IRQ Vector (High)
IF1
IRQ Vector (Low)
SWI Vector (High)
—
SWI Vector (Low)
Reset Vector (High)
—
Highest
Reset Vector (Low)
Data Sheet
154
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
Exception Control
9.6.1.5 Interrupt Status Register 2
Address: $FE05
Bit 7
6
5
IF12
R
4
IF11
R
3
IF10
R
2
IF9
R
1
IF8
R
Bit 0
IF7
R
Read:
Write:
Reset:
IF14
R
IF13
R
0
0
0
0
0
0
0
0
R
= Reserved
Figure 9-13. Interrupt Status Register 2 (INT2)
IF14–IF7 — Interrupt Flags 14–7
These flags indicate the presence of interrupt requests from the
sources shown in Table 9-3.
1 = Interrupt request present
0 = No interrupt request present
9.6.1.6 Interrupt Status Register 3
Address: $FE06
Bit 7
6
5
0
4
0
3
IF18
R
2
IF17
R
1
IF16
R
Bit 0
IF15
R
Read:
Write:
Reset:
0
R
0
0
R
R
0
R
0
0
0
0
0
0
R
= Reserved
Figure 9-14. Interrupt Status Register 3 (INT3)
IF18–IF15 — Interrupt Flags 18–15
These flags indicate the presence of an interrupt request from the
source shown in Table 9-3.
1 = Interrupt request present
0 = No interrupt request present
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
155
System Integration Module (SIM)
System Integration Module (SIM)
9.6.2 Reset
All reset sources always have equal and highest priority and cannot be
arbitrated.
9.6.3 Break Interrupts
The break module can stop normal program flow at a software-
programmable break point by asserting its break interrupt output. (See
Section 23. Break Module (BRK).) The SIM puts the CPU into the
break state by forcing it to the SWI vector location. Refer to the break
interrupt subsection of each module to see how each module is affected
by the break state.
9.6.4 Status Flag Protection in Break Mode
The SIM controls whether status flags contained in other modules can
be cleared during break mode. The user can select whether flags are
protected from being cleared by properly initializing the break clear flag
enable bit (BCFE) in the SIM break flag control register (SBFCR).
Protecting flags in break mode ensures that set flags will not be cleared
while in break mode. This protection allows registers to be freely read
and written during break mode without losing status flag information.
Setting the BCFE bit enables the clearing mechanisms. Once cleared in
break mode, a flag remains cleared even when break mode is exited.
Status flags with a 2-step clearing mechanism — for example, a read of
one register followed by the read or write of another — are protected,
even when the first step is accomplished prior to entering break mode.
Upon leaving break mode, execution of the second step will clear the flag
as normal.
Data Sheet
156
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
Low-Power Modes
9.7 Low-Power Modes
Executing the WAIT or STOP instruction puts the MCU in a low power-
consumption mode for standby situations. The SIM holds the CPU in a
non-clocked state. The operation of each of these modes is described in
the following subsections. Both STOP and WAIT clear the interrupt mask
(I) in the condition code register, allowing interrupts to occur.
9.7.1 Wait Mode
In wait mode, the CPU clocks are inactive while the peripheral clocks
continue to run. Figure 9-15 shows the timing for wait mode entry.
A module that is active during wait mode can wake up the CPU with an
interrupt if the interrupt is enabled. Stacking for the interrupt begins one
cycle after the WAIT instruction during which the interrupt occurred. In
wait mode, the CPU clocks are inactive. Refer to the wait mode
subsection of each module to see if the module is active or inactive in
wait mode. Some modules can be programmed to be active in wait
mode.
Wait mode also can be exited by a reset or break. A break interrupt
during wait mode sets the SIM break stop/wait bit, SBSW, in the SIM
break status register (SBSR). If the COP disable bit, COPD, in the mask
option register is logic 0, then the computer operating properly module
(COP) is enabled and remains active in wait mode.
IAB
IDB
WAIT ADDR
WAIT ADDR + 1
SAME
SAME
PREVIOUS DATA
NEXT OPCODE
SAME
SAME
R/W
NOTE: Previous data can be operand data or the WAIT opcode, depending on the
last instruction.
Figure 9-15. Wait Mode Entry Timing
Figure 9-16 and Figure 9-17 show the timing for WAIT recovery.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
157
System Integration Module (SIM)
System Integration Module (SIM)
IAB
$6E0B
$A6
$6E0C
$00FF
$00FE
$00FD
$00FC
IDB
$A6
$A6
$01
$0B
$6E
EXITSTOPWAIT
NOTE: EXITSTOPWAIT = RST pin OR CPU interrupt OR break interrupt
Figure 9-16. Wait Recovery from Interrupt or Break
32
CYCLES
32
CYCLES
IAB
$6E0B
$A6
RST VCT H RST VCT L
IDB $A6
RST
$A6
ICLK
Figure 9-17. Wait Recovery from Internal Reset
9.7.2 Stop Mode
In stop mode, the SIM counter is reset and the system clocks are
disabled. An interrupt request from a module can cause an exit from stop
mode. Stacking for interrupts begins after the selected stop recovery
time has elapsed. Reset or break also causes an exit from stop mode.
The SIM disables the clock generator module output (CGMOUT) in stop
mode, stopping the CPU and peripherals. Stop recovery time is
selectable using the SSREC bit in the configuration register 1
(CONFIG1). If SSREC is set, stop recovery is reduced from the normal
delay of 4096 ICLK cycles down to 32. This is ideal for applications using
canned oscillators that do not require long start-up times from stop
mode.
NOTE: External crystal applications should use the full stop recovery time by
clearing the SSREC bit.
Data Sheet
158
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
SIM Registers
A break interrupt during stop mode sets the SIM break stop/wait bit
(SBSW) in the SIM break status register (SBSR).
The SIM counter is held in reset from the execution of the STOP
instruction until the beginning of stop recovery. It is then used to time the
recovery period. Figure 9-18 shows stop mode entry timing.
NOTE: To minimize stop current, all pins configured as inputs should be driven
to a logic 1 or logic 0.
CPUSTOP
IAB
IDB
STOP ADDR
STOP ADDR + 1
SAME
SAME
PREVIOUS DATA
NEXT OPCODE
SAME
SAME
R/W
NOTE: Previous data can be operand data or the STOP opcode, depending on the last
instruction.
Figure 9-18. Stop Mode Entry Timing
STOP RECOVERY PERIOD
ICLK
INT/BREAK
IAB
STOP + 2 STOP + 2
SP
SP – 1
SP – 2
SP – 3
STOP +1
Figure 9-19. Stop Mode Recovery from Interrupt or Break
9.8 SIM Registers
The SIM has three memory-mapped registers:
• SIM Break Status Register (SBSR) — $FE00
• SIM Reset Status Register (SRSR) — $FE01
• SIM Break Flag Control Register (SBFCR) — $FE03
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
159
System Integration Module (SIM)
System Integration Module (SIM)
9.8.1 SIM Break Status Register
The SIM break status register (SBSR) contains a flag to indicate that a
break caused an exit from stop mode or wait mode.
Address: $FE00
Bit 7
6
5
4
3
2
1
SBSW
Note
0
Bit 0
R
Read:
Write:
Reset:
R
R
R
R
R
R
Note: Writing a logic 0 clears SBSW.
R
= Reserved
Figure 9-20. SIM Break Status Register (SBSR)
SBSW — Break Wait Bit
This status bit is set when a break interrupt causes an exit from wait
mode or stop mode. Clear SBSW by writing a logic 0 to it. Reset clears
SBSW.
1 = Stop mode or wait mode was exited by break interrupt
0 = Stop mode or wait mode was not exited by break interrupt
SBSW can be read within the break interrupt routine. The user can
modify the return address on the stack by subtracting 1 from it. The
following code is an example.
This code works if the H register has been pushed onto the stack in the break
service routine software. This code should be executed at the end of the break
service routine software.
HIBYTE
LOBYTE
EQU
EQU
If not SBSW, do RTI
BRCLR
SBSW,SBSR, RETURN
;See if wait mode or stop mode was exited by
;break.
TST
BNE
DEC
DEC
LOBYTE,SP
DOLO
;If RETURNLO is not zero,
;then just decrement low byte.
;Else deal with high byte, too.
;Point to WAIT/STOP opcode.
;Restore H register.
HIBYTE,SP
LOBYTE,SP
DOLO
RETURN
PULH
RTI
Data Sheet
160
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
System Integration Module (SIM)
SIM Registers
9.8.2 SIM Reset Status Register
This register contains six flags that show the source of the last reset
provided all previous reset status bits have been cleared. Clear the SIM
reset status register by reading it. A power-on reset sets the POR bit and
clears all other bits in the register.
Address: $FE01
Bit 7
POR
6
5
4
3
2
0
1
Bit 0
0
Read:
Write:
Reset:
PIN
COP
ILOP
ILAD
LVI
1
0
0
0
0
0
0
0
= Unimplemented
Figure 9-21. SIM Reset Status Register (SRSR)
POR — Power-On Reset Bit
1 = Last reset caused by POR circuit
0 = Read of SRSR
PIN — External Reset Bit
1 = Last reset caused by external reset pin (RST)
0 = POR or read of SRSR
COP — Computer Operating Properly Reset Bit
1 = Last reset caused by COP counter
0 = POR or read of SRSR
ILOP — Illegal Opcode Reset Bit
1 = Last reset caused by an illegal opcode
0 = POR or read of SRSR
ILAD — Illegal Address Reset Bit (opcode fetches only)
1 = Last reset caused by an opcode fetch from an illegal address
0 = POR or read of SRSR
LVI — Low-Voltage Inhibit Reset Bit
1 = Last reset caused by the LVI circuit
0 = POR or read of SRSR
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
161
System Integration Module (SIM)
System Integration Module (SIM)
9.8.3 SIM Break Flag Control Register
The SIM break control register contains a bit that enables software to
clear status bits while the MCU is in a break state.
Address: $FE03
Bit 7
6
5
4
3
2
1
Bit 0
R
Read:
Write:
Reset:
BCFE
R
R
R
R
R
R
0
R
= Reserved
Figure 9-22. SIM Break Flag Control Register (SBFCR)
BCFE — Break Clear Flag Enable Bit
This read/write bit enables software to clear status bits by accessing
status registers while the MCU is in a break state. To clear status bits
during the break state, the BCFE bit must be set.
1 = Status bits clearable during break
0 = Status bits not clearable during break
Data Sheet
162
MC68HC908LJ24/LK24 — Rev. 2.1
System Integration Module (SIM)
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 10. Monitor ROM (MON)
10.1 Contents
10.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164
10.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164
10.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165
10.4.1 Entering Monitor Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . .167
10.4.2 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
10.4.3 Break Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
10.4.4 Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
10.4.5 Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172
10.5 Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177
10.6 ROM-Resident Routines. . . . . . . . . . . . . . . . . . . . . . . . . . . . .179
10.6.1 PRGRNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181
10.6.2 ERARNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183
10.6.3 LDRNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184
10.6.4 MON_PRGRNGE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .185
10.6.5 MON_ERARNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .186
10.6.6 MON_LDRNGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187
10.6.7 EE_WRITE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .188
10.6.8 EE_READ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
163
Monitor ROM (MON)
Monitor ROM (MON)
10.2 Introduction
This section describes the monitor ROM (MON) and the monitor mode
entry methods. The monitor ROM allows complete testing of the MCU
through a single-wire interface with a host computer. Monitor mode entry
can be achieved without use of the higher test voltage, V
, as long as
TST
vector addresses $FFFE and $FFFF are blank, thus reducing the
hardware requirements for in-circuit programming.
In addition, to simplify user coding, routines are also stored in the
monitor ROM area for FLASH memory program /erase and EEPROM
emulation.
10.3 Features
Features of the monitor ROM include:
• Normal user-mode pin functionality
• One pin dedicated to serial communication between monitor ROM
and host computer
• Standard mark/space non-return-to-zero (NRZ) communication
with host computer
• Execution of code in RAM or FLASH
1
• FLASH memory security feature
• FLASH memory programming interface
• Enhanced PLL (phase-locked loop) option to allow use of external
32.768-kHz crystal to generate internal frequency of 2.4576 MHz
• 959 bytes monitor ROM code size
($FC00–$FDFF and $FE10–$FFCE)
• Monitor mode entry without high voltage, V
blank ($FFFE and $FFFF contain $FF)
, if reset vector is
TST
• Standard monitor mode entry if high voltage, V
IRQ
, is applied to
TST
• Resident routines for in-circuit programming and EEPROM
emulation
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Data Sheet
164
MC68HC908LJ24/LK24 — Rev. 2.1
Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
Functional Description
10.4 Functional Description
The monitor ROM receives and executes commands from a host
computer. Figure 10-1 shows an example circuit used to enter monitor
mode and communicate with a host computer via a standard RS-232
interface.
Simple monitor commands can access any memory address. In monitor
mode, the MCU can execute code downloaded into RAM by a host
computer while most MCU pins retain normal operating mode functions.
All communication between the host computer and the MCU is through
the PTA0 pin. A level-shifting and multiplexing interface is required
between PTA0 and the host computer. PTA0 is used in a wired-OR
configuration and requires a pullup resistor.
The monitor code allows enabling the PLL to generate the internal clock,
provided the reset vector is blank, when the device is being clocked by
a low-frequency crystal. This entry method, which is enabled when IRQ
is held low out of reset, is intended to support serial communication/
programming at 9600 baud in monitor mode by stepping up the external
frequency (assumed to be 32.768 kHz) by a fixed amount to generate
the desired internal frequency (2.4576 MHz). Since this feature is
enabled only when IRQ is held low out of reset, it cannot be used when
the reset vector is non-zero because entry into monitor mode in this case
requires V
on IRQ.
TST
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
165
Monitor ROM (MON)
Monitor ROM (MON)
RST
0.1 µF
HC908LJ24
VDD
VDD
VDDA
VLCD
VREFH
0.1 µF
VSS
VREFL
VDD
4.9152MHz/9.8304MHz
(50% DUTY)
CGMXFC
OSC1
0.01 µF
10k
0.033 µF
MUST BE USED IF SW2 IS AT POSITION C.
CONNECT TO OSC1, WITH OSC2 UNCONNECTED.
EXT OSC
32.768kHz
OSC1
OSC2
6–30 pF
330k
MAX232
VDD
1
16
6–30 pF
VCC
C1+
+
+
+
1 µF
1 µF
1 µF
3
4
15
1 µF
C1–
C2+
GND
XTAL CIRCUIT
+
VTST
C
2
6
SW2
V+
V–
(SEE NOTE 1)
VDD
1 k
IRQ
8.5 V
D
5
C2–
1 µF
10 k
+
74HC125
6
DB9
5
10
9
2
3
7
8
PTA0
74HC125
4
3
VDD
2
VDD
10 k
1
5
10 k
PTA1
PTC1
PTA2
SW1
A
(SEE NOTE 2)
B
NOTES:
1. Monitor mode entry method:
10 k
SW2: Position C — High voltage entry (VTST); must use external OSC
Bus clock depends on SW1 (note 2).
10 k
SW2: Position D — Reset vector must be blank ($FFFE:$FFFF = $FF)
Bus clock = 2.4576MHz.
2. Affects high voltage entry to monitor mode only (SW2 at position C):
SW1: Position A — Bus clock = OSC1 ÷ 4
SW1: Position B — Bus clock = OSC1 ÷ 2
5. See Table 24-4 for VTST voltage level requirements.
Figure 10-1. Monitor Mode Circuit
Data Sheet
166
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Monitor ROM (MON)
Monitor ROM (MON)
Functional Description
10.4.1 Entering Monitor Mode
Table 10-1 shows the pin conditions for entering monitor mode. As
specified in the table, monitor mode may be entered after a POR and will
allow communication at 9600 baud provided one of the following sets of
conditions is met:
1. If $FFFE and $FFFF do not contain $FF (programmed state):
– The external clock is 4.9152 MHz with PTC1 low or
9.8304 MHz with PTC1 high
– IRQ = V
(PLL off)
TST
2. If $FFFE and $FFFF both contain $FF (erased state):
– The external clock is 9.8304 MHz
– IRQ = V (this can be implemented through the internal IRQ
DD
pullup; PLL off)
3. If $FFFE and $FFFF both contain $FF (erased state):
– The external clock is 32.768 kHz (crystal)
– IRQ = V (this setting initiates the PLL to boost the external
SS
32.768 kHz to an internal bus frequency of 2.4576 MHz)
If V
is applied to IRQ and PTC1 is low upon monitor mode entry
TST
(above condition set 1), the bus frequency is a divide-by-two of the input
clock. If PTC1 is high with V applied to IRQ upon monitor mode entry,
TST
the bus frequency will be a divide-by-four of the input clock. Holding the
PTC1 pin low when entering monitor mode causes a bypass of a divide-
by-two stage at the oscillator only if V
is applied to IRQ. In this event,
TST
the CGMOUT frequency is equal to the CGMXCLK frequency, and the
OSC1 input directly generates internal bus clocks. In this case, the
OSC1 signal must have a 50% duty cycle at maximum bus frequency.
If entering monitor mode without high voltage on IRQ (above condition
set 2 or 3, where applied voltage is either V or V ), then all port A pin
DD
SS
requirements and conditions, including the PTC1 frequency divisor
selection, are not in effect. This is to reduce circuit requirements when
performing in-circuit programming.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
167
Monitor ROM (MON)
Table 10-1. Monitor Mode Signal Requirements and Options
Address
$FFFE/
$FFFF
External
Clock(2)
Bus
Frequency
Baud
Rate
IRQ
RST
PTA2
PTA1 PTA0(1) PTC1
PLL
COP
Comment
X
GND
X
X
X
1
X
1
X
0
X
0
X
Disabled
0
No operation until
reset goes high
(3)
VDD
X
0
0
4.9152
MHz
2.4576
MHz
OFF
OFF
Disabled
Disabled
9600
PTA1 and PTA2
voltages only
required if
VTST
or
VTST
IRQ = VTST
;
PTC1 determines
frequency divider
(3)
VDD
X
1
1
1
9.8304
MHz
2.4576
MHz
9600
PTA1 and PTA2
voltages only
required if
VTST
or
VTST
IRQ = VTST
;
PTC1 determines
frequency divider
VDD
VDD
Blank
"$FFFF"
X
X
X
X
1
1
X
X
9.8304
MHz
2.4576
MHz
OFF
ON
Disabled
Disabled
9600
9600
External frequency
always divided by 4
GND
VDD
Blank
"$FFFF"
32.768
kHz
2.4576
MHz
PLL enabled
(BCS set)
in monitor code
VDD
or
VTST
Blank
"$FFFF"
X
X
X
X
X
X
X
X
X
—
OFF
OFF
Enabled
Enabled
—
—
Enters user
mode — will
encounter an illegal
address reset
GND
VDD
VDD
Not Blank
X
—
Enters user mode
or
or
GND
VTST
Notes:
1. PTA0 = 1 if serial communication; PTA0 = 0 if parallel communication
2. External clock is derived by a 32.768 kHz crystal or a 4.9152/9.8304 MHz off-chip oscillator
3. Monitor mode entry by IRQ = VTST, a 4.9152/9.8304 MHz off-chip oscillator must be used. The MCU internal crystal oscillator circuit is bypassed.
Monitor ROM (MON)
Functional Description
NOTE: If the reset vector is blank and monitor mode is entered, the chip will see
an additional reset cycle after the initial POR reset. Once the part has
been programmed, the traditional method of applying a voltage, V
IRQ must be used to enter monitor mode.
, to
TST
The COP module is disabled in monitor mode based on these
conditions:
• If monitor mode was entered as a result of the reset vector being
blank (above condition set 2 or 3), the COP is always disabled
regardless of the state of IRQ or RST.
• If monitor mode was entered with V
on IRQ (condition set 1),
TST
then the COP is disabled as long as V
or RST.
is applied to either IRQ
TST
The second condition states that as long as V
is maintained on the
TST
IRQ pin after entering monitor mode, or if V
is applied to RST after
TST
the initial reset to get into monitor mode (when V
was applied to IRQ),
TST
then the COP will be disabled. In the latter situation, after V
is applied
TST
to the RST pin, V
can be removed from the IRQ pin in the interest of
TST
freeing the IRQ for normal functionality in monitor mode.
Figure 10-2 shows a simplified diagram of the monitor mode entry when
the reset vector is blank and just 1 x V voltage is applied to the IRQ
DD
pin. An external oscillator of 9.8304 MHz is required for a baud rate of
9600, as the internal bus frequency is automatically set to the external
frequency divided by four.
Enter monitor mode with pin configuration shown in Figure 10-1 by
pulling RST low and then high. The rising edge of RST latches monitor
mode. Once monitor mode is latched, the values on the specified pins
can change.
Once out of reset, the MCU waits for the host to send eight security
bytes. (See 10.5 Security.) After the security bytes, the MCU sends a
break signal (10 consecutive logic 0s) to the host, indicating that it is
ready to receive a command.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
169
Monitor ROM (MON)
Monitor ROM (MON)
POR RESET
NO
NORMAL USER
MODE
IS VECTOR
BLANK?
YES
MONITOR MODE
EXECUTE
MONITOR
CODE
POR
TRIGGERED?
NO
YES
Figure 10-2. Low-Voltage Monitor Mode Entry Flowchart
In monitor mode, the MCU uses different vectors for reset, SWI
(software interrupt), and break interrupt than those for user mode. The
alternate vectors are in the $FE page instead of the $FF page and allow
code execution from the internal monitor firmware instead of user code.
NOTE: Exiting monitor mode after it has been initiated by having a blank reset
vector requires a power-on reset (POR). Pulling RST low will not exit
monitor mode in this situation.
Table 10-2 summarizes the differences between user mode and monitor
mode vectors.
Table 10-2. Mode Differences (Vectors)
Functions
Modes
Reset
Vector
High
Reset
Vector
Low
Break
Vector
High
Break
Vector
Low
SWI
Vector
High
SWI
Vector
Low
User
$FFFE
$FEFE
$FFFF
$FEFF
$FFFC
$FEFC
$FFFD
$FEFD
$FFFC
$FEFC
$FFFD
$FEFD
Monitor
Data Sheet
170
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Monitor ROM (MON)
Monitor ROM (MON)
Functional Description
10.4.2 Data Format
Communication with the monitor ROM is in standard non-return-to-zero
(NRZ) mark/space data format. Transmit and receive baud rates must
be identical.
NEXT
START
BIT
START
BIT
STOP
BIT
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
Figure 10-3. Monitor Data Format
10.4.3 Break Signal
A start bit (logic 0) followed by nine logic 0 bits is a break signal. When
the monitor receives a break signal, it drives the PTA0 pin high for the
duration of two bits and then echoes back the break signal.
MISSING STOP BIT
2-STOP BIT DELAY BEFORE ZERO ECHO
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
Figure 10-4. Break Transaction
10.4.4 Baud Rate
The communication baud rate is controlled by the crystal frequency and
the state of the PTC1 pin (when IRQ is set to V ) upon entry into
TST
monitor mode. When PTC1 is high, the divide by ratio is 1024. If the
PTC1 pin is at logic 0 upon entry into monitor mode, the divide by ratio
is 512.
If monitor mode was entered with V on IRQ, then the divide by ratio is
DD
set at 1024, regardless of PTC1. If monitor mode was entered with V
SS
on IRQ, then the internal PLL steps up the external frequency, presumed
to be 32.768 kHz, to 2.4576 MHz. These latter two conditions for monitor
mode entry require that the reset vector is blank.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
171
Monitor ROM (MON)
Monitor ROM (MON)
Table 10-3 lists external frequencies required to achieve a standard
baud rate of 9600 BPS. Other standard baud rates can be accomplished
using proportionally higher or lower frequency generators. If using a
crystal as the clock source, be aware of the upper frequency limit that the
internal clock module can handle.
Table 10-3. Monitor Baud Rate Selection
External
Frequency
Internal
Frequency
Baud Rate
(BPS)
IRQ
PTC1
V
4.9152 MHz
9.8304 MHz
9.8304 MHz
32.768 kHz
0
1
2.4576 MHz
2.4576 MHz
2.4576 MHz
2.4576 MHz
9600
9600
9600
9600
TST
TST
V
V
X
X
DD
V
SS
10.4.5 Commands
The monitor ROM firmware uses these commands:
• READ (read memory)
• WRITE (write memory)
• IREAD (indexed read)
• IWRITE (indexed write)
• READSP (read stack pointer)
• RUN (run user program)
The monitor ROM firmware echoes each received byte back to the PTA0
pin for error checking. An 11-bit delay at the end of each command
allows the host to send a break character to cancel the command. A
delay of two bit times occurs before each echo and before READ,
IREAD, or READSP data is returned. The data returned by a read
command appears after the echo of the last byte of the command.
NOTE: Wait one bit time after each echo before sending the next byte.
Data Sheet
172
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Monitor ROM (MON)
Monitor ROM (MON)
Functional Description
FROM HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
READ
1
READ
DATA
4
4
1
4
1
3, 2
4
ECHO
RETURN
Notes:
1 = Echo delay, 2 bit times
2 = Data return delay, 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
Figure 10-5. Read Transaction
FROM HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
DATA
WRITE
1
WRITE
3
3
1
3
1
3
1
2, 3
ECHO
Notes:
1 = Echo delay, 2 bit times
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
Figure 10-6. Write Transaction
A brief description of each monitor mode command is given in
Table 10-4 through Table 10-9.
Table 10-4. READ (Read Memory) Command
Description Read byte from memory
Operand
2-byte address in high-byte:low-byte order
Returns contents of specified address
Data
Returned
Opcode
$4A
Command Sequence
SENT TO
MONITOR
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
READ
READ
DATA
ECHO
RETURN
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
173
Monitor ROM (MON)
Monitor ROM (MON)
Table 10-5. WRITE (Write Memory) Command
Description Write byte to memory
2-byte address in high-byte:low-byte order;
low byte followed by data byte
Operand
Data
Returned
None
Opcode
$49
Command Sequence
FROM
HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
DATA
WRITE
ECHO
WRITE
Table 10-6. IREAD (Indexed Read) Command
Description Read next 2 bytes in memory from last address accessed
Operand
2-byte address in high byte:low byte order
Returns contents of next two addresses
Data
Returned
Opcode
$1A
Command Sequence
FROM
HOST
IREAD
IREAD
DATA
DATA
ECHO
RETURN
Data Sheet
174
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Monitor ROM (MON)
Monitor ROM (MON)
Functional Description
Table 10-7. IWRITE (Indexed Write) Command
Description Write to last address accessed + 1
Operand
Single data byte
Data
None
$19
Returned
Opcode
Command Sequence
FROM
HOST
DATA
DATA
IWRITE
IWRITE
ECHO
A sequence of IREAD or IWRITE commands can access a block of
memory sequentially over the full 64-Kbyte memory map.
Table 10-8. READSP (Read Stack Pointer) Command
Description Reads stack pointer
Operand
None
Returns incremented stack pointer value (SP + 1) in
high-byte:low-byte order
Data
Returned
Opcode
$0C
Command Sequence
FROM
HOST
SP
HIGH
SP
LOW
READSP
READSP
ECHO
RETURN
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
175
Monitor ROM (MON)
Monitor ROM (MON)
Table 10-9. RUN (Run User Program) Command
Description Executes PULH and RTI instructions
Operand
None
None
$28
Data
Returned
Opcode
Command Sequence
FROM
HOST
RUN
RUN
ECHO
The MCU executes the SWI and PSHH instructions when it enters
monitor mode. The RUN command tells the MCU to execute the PULH
and RTI instructions. Before sending the RUN command, the host can
modify the stacked CPU registers to prepare to run the host program.
The READSP command returns the incremented stack pointer value,
SP + 1. The high and low bytes of the program counter are at addresses
SP + 5 and SP + 6.
SP
HIGH BYTE OF INDEX REGISTER
CONDITION CODE REGISTER
ACCUMULATOR
SP + 1
SP + 2
SP + 3
SP + 4
LOW BYTE OF INDEX REGISTER
HIGH BYTE OF PROGRAM COUNTER SP + 5
LOW BYTE OF PROGRAM COUNTER SP + 6
SP + 7
Figure 10-7. Stack Pointer at Monitor Mode Entry
Data Sheet
176
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Monitor ROM (MON)
Monitor ROM (MON)
Security
10.5 Security
A security feature discourages unauthorized reading of FLASH locations
while in monitor mode. The host can bypass the security feature at
monitor mode entry by sending eight security bytes that match the bytes
at locations $FFF6–$FFFD. Locations $FFF6–$FFFD contain user-
defined data.
NOTE: Do not leave locations $FFF6–$FFFD blank. For security reasons,
program locations $FFF6–$FFFD even if they are not used for vectors.
During monitor mode entry, the MCU waits after the power-on reset for
the host to send the eight security bytes on pin PTA0. If the received
bytes match those at locations $FFF6–$FFFD, the host bypasses the
security feature and can read all FLASH locations and execute code
from FLASH. Security remains bypassed until a power-on reset occurs.
If the reset was not a power-on reset, security remains bypassed and
security code entry is not required. (See Figure 10-8.)
VDD
4096 + 32 ICLK CYCLES
RST
256 BUS CYCLES (MINIMUM)
FROM HOST
PTA0
1
1
4
1
4
2
1
FROM MCU
NOTES:
1 = Echo delay, 2 bit times.
2 = Data return delay, 2 bit times.
4 = Wait 1 bit time before sending next byte.
Figure 10-8. Monitor Mode Entry Timing
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
177
Monitor ROM (MON)
Monitor ROM (MON)
Upon power-on reset, if the received bytes of the security code do not
match the data at locations $FFF6–$FFFD, the host fails to bypass the
security feature. The MCU remains in monitor mode, but reading a
FLASH location returns an invalid value and trying to execute code from
FLASH causes an illegal address reset. After receiving the eight security
bytes from the host, the MCU transmits a break character, signifying that
it is ready to receive a command.
NOTE: The MCU does not transmit a break character until after the host sends
the eight security bits.
To determine whether the security code entered is correct, check to see
if bit 6 of RAM address $40 is set. If it is, then the correct security code
has been entered and FLASH can be accessed.
If the security sequence fails, the device should be reset by a power-on
reset and brought up in monitor mode to attempt another entry. After
failing the security sequence, the FLASH module can also be mass
erased by executing an erase routine that was downloaded into internal
RAM. The mass erase operation clears the security code locations so
that all eight security bytes become $FF (blank).
Data Sheet
178
MC68HC908LJ24/LK24 — Rev. 2.1
Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
ROM-Resident Routines
10.6 ROM-Resident Routines
Eight routines stored in the monitor ROM area (thus ROM-resident) are
provided for FLASH memory manipulation. Six of the eight routines are
intended to simplify FLASH program, erase, and load operations. The
other two routines are intended to simplify the use of the FLASH memory
as EEPROM. Table 10-10 shows a summary of the ROM-resident
routines.
Table 10-10. Summary of ROM-Resident Routines
Call
Address
Stack Used
(bytes)
Routine Name
Routine Description
PRGRNGE
ERARNGE
LDRNGE
Program a range of locations
$FC06
$FCBE
$FF30
14
9
Erase a page or the entire array
Loads data from a range of locations
9
Program a range of locations in
monitor mode
MON_PRGRNGE
MON_ERARNGE
MON_LDRNGE
EE_WRITE
$FF28
$FF2C
$FF24
$FC00
$FC03
16
11
11
17
15
Erase a page or the entire array in
monitor mode
Loads data from a range of locations
in monitor mode
Emulated EEPROM write. Data size
ranges from 2 to 15 bytes at a time.
Emulated EEPROM read. Data size
ranges from 2 to 15 bytes at a time.
EE_READ
The routines are designed to be called as stand-alone subroutines in the
user program or monitor mode. The parameters that are passed to a
routine are in the form of a contiguous data block, stored in RAM. The
index register (H:X) is loaded with the address of the first byte of the data
block (acting as a pointer), and the subroutine is called (JSR). Using the
start address as a pointer, multiple data blocks can be used, any area of
RAM be used. A data block has the control and data bytes in a defined
order, as shown in Figure 10-9.
During the software execution, it does not consume any dedicated RAM
location, the run-time heap will extend the system stack, all other RAM
location will not be affected.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
179
Monitor ROM (MON)
Monitor ROM (MON)
R
A
M
FILE_PTR
$XXXX
BUS SPEED (BUS_SPD)
DATA SIZE (DATASIZE)
START ADDRESS HIGH (ADDRH)
START ADDRESS LOW (ADDRL)
DATA 0
ADDRESS AS POINTER
DATA
DATA 1
BLOCK
DATA
ARRAY
DATA N
Figure 10-9. Data Block Format for ROM-Resident Routines
The control and data bytes are described below.
• Bus speed — This one byte indicates the operating bus speed of
the MCU. The value of this byte should be equal to 4 times the bus
speed. E.g., for a 4MHz bus, the value is 16 ($10). This control
byte is useful where the MCU clock source is switched between
the PLL clock and the crystal clock.
• Data size — This one byte indicates the number of bytes in the
data array that are to be manipulated. The maximum data array
size is 255. Routines EE_WRITE and EE_READ are restricted to
manipulate a data array between 2 to 15 bytes. Whereas routines
ERARNGE and MON_ERARNGE do not manipulate a data array,
thus, this data size byte has no meaning.
• Start address — These two bytes, high byte followed by low byte,
indicate the start address of the FLASH memory to be
manipulated.
• Data array — This data array contains data that are to be
manipulated. Data in this array are programmed to FLASH
memory by the programming routines: PRGRNGE,
MON_PRGRNGE, EE_WRITE. For the read routines: LDRNGE,
MON_LDRNGE, and EE_READ, data is read from FLASH and
stored in this array.
Data Sheet
180
MC68HC908LJ24/LK24 — Rev. 2.1
Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
ROM-Resident Routines
10.6.1 PRGRNGE
PRGRNGE is used to program a range of FLASH locations with data
loaded into the data array.
Table 10-11. PRGRNGE Routine
Routine Name
PRGRNGE
Routine Description Program a range of locations
Calling Address
Stack Used
$FC06
14 bytes
Data Block Format
Bus speed (BUS_SPD)
Data size (DATASIZE)
Start address high (ADDRH)
Start address (ADDRL)
Data 1 (DATA1)
:
Data N (DATAN)
The start location of the FLASH to be programmed is specified by the
address ADDRH:ADDRL and the number of bytes from this location is
specified by DATASIZE. The maximum number of bytes that can be
programmed in one routine call is 255 bytes (max. DATASIZE is 255).
ADDRH:ADDRL do not need to be at a page boundary, the routine
handles any boundary misalignment during programming. A check to
see that all bytes in the specified range are erased is not performed by
this routine prior programming. Nor does this routine do a verification
after programming, so there is no return confirmation that programming
was successful. User must assure that the range specified is first
erased.
The coding example below is to program 64 bytes of data starting at
FLASH location $EF00, with a bus speed of 4.9152 MHz. The coding
assumes the data block is already loaded in RAM, with the address
pointer, FILE_PTR, pointing to the first byte of the data block.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
181
Monitor ROM (MON)
Monitor ROM (MON)
ORG
RAM
:
FILE_PTR:
BUS_SPD
DATASIZE
START_ADDR
DATAARRAY
DS.B
DS.B
DS.W
DS.B
1
1
1
64
; Indicates 4x bus frequency
; Data size to be programmed
; FLASH start address
; Reserved data array
PRGRNGE
FLASH_START
EQU
EQU
$FC06
$EF00
ORG
FLASH
INITIALISATION:
MOV
MOV
#20,
#64,
BUS_SPD
DATASIZE
LDHX
STHX
RTS
#FLASH_START
START_ADDR
MAIN:
BSR
:
INITIALISATION
:
LDHX
JSR
#FILE_PTR
PRGRNGE
Data Sheet
182
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Monitor ROM (MON)
Monitor ROM (MON)
ROM-Resident Routines
10.6.2 ERARNGE
ERARNGE is used to erase a range of locations in FLASH.
Table 10-12. ERARNGE Routine
Routine Name
ERARNGE
Routine Description Erase a page or the entire array
Calling Address
Stack Used
$FCBE
9 bytes
Data Block Format
Bus speed (BUS_SPD)
Data size (DATASIZE)
Starting address (ADDRH)
Starting address (ADDRL)
There are two sizes of erase ranges: a page or the entire array. The
ERARNGE will erase the page (128 consecutive bytes) in FLASH
specified by the address ADDRH:ADDRL. This address can be any
address within the page. Calling ERARNGE with ADDRH:ADDRL equal
to $FFFF will erase the entire FLASH array (mass erase). Therefore,
care must be taken when calling this routine to prevent an accidental
mass erase.
The ERARNGE routine do not use a data array. The DATASIZE byte is
a dummy byte that is also not used.
The coding example below is to perform a page erase, from
$EF00–$EF7F. The Initialization subroutine is the same as the coding
example for PRGRNGE (see 10.6.1 PRGRNGE).
ERARNGE
MAIN:
EQU
$FCBE
BSR
:
INITIALISATION
:
LDHX
JSR
:
#FILE_PTR
ERARNGE
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
183
Monitor ROM (MON)
Monitor ROM (MON)
10.6.3 LDRNGE
LDRNGE is used to load the data array in RAM with data from a range
of FLASH locations.
Table 10-13. LDRNGE Routine
Routine Name
LDRNGE
Routine Description Loads data from a range of locations
Calling Address
Stack Used
$FF30
9 bytes
Data Block Format
Bus speed (BUS_SPD)
Data size (DATASIZE)
Starting address (ADDRH)
Starting address (ADDRL)
Data 1
:
Data N
The start location of FLASH from where data is retrieved is specified by
the address ADDRH:ADDRL and the number of bytes from this location
is specified by DATASIZE. The maximum number of bytes that can be
retrieved in one routine call is 255 bytes. The data retrieved from FLASH
is loaded into the data array in RAM. Previous data in the data array will
be overwritten. User can use this routine to retrieve data from FLASH
that was previously programmed.
The coding example below is to retrieve 64 bytes of data starting from
$EF00 in FLASH. The Initialization subroutine is the same as the coding
example for PRGRNGE (see 10.6.1 PRGRNGE).
LDRNGE
MAIN:
EQU
$FF30
BSR
:
INITIALIZATION
:
LDHX
JSR
:
#FILE_PTR
LDRNGE
Data Sheet
184
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Monitor ROM (MON)
Monitor ROM (MON)
ROM-Resident Routines
10.6.4 MON_PRGRNGE
In monitor mode, MON_PRGRNGE is used to program a range of
FLASH locations with data loaded into the data array.
Table 10-14. MON_PRGRNGE Routine
Routine Name
MON_PRGRNGE
Routine Description Program a range of locations, in monitor mode
Calling Address
Stack Used
$FC28
16 bytes
Data Block Format
Bus speed
Data size
Starting address (high byte)
Starting address (low byte)
Data 1
:
Data N
The MON_PRGRNGE routine is designed to be used in monitor mode.
It performs the same function as the PRGRNGE routine (see 10.6.1
PRGRNGE), except that MON_PRGRNGE returns to the main program
via an SWI instruction. After a MON_PRGRNGE call, the SWI instruction
will return the control back to the monitor code.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
185
Monitor ROM (MON)
Monitor ROM (MON)
10.6.5 MON_ERARNGE
In monitor mode, ERARNGE is used to erase a range of locations in
FLASH.
Table 10-15. MON_ERARNGE Routine
Routine Name
MON_ERARNGE
Routine Description Erase a page or the entire array, in monitor mode
Calling Address
Stack Used
$FF2C
11 bytes
Data Block Format
Bus speed
Data size
Starting address (high byte)
Starting address (low byte)
The MON_ERARNGE routine is designed to be used in monitor mode.
It performs the same function as the ERARNGE routine (see 10.6.2
ERARNGE), except that MON_ERARNGE returns to the main program
via an SWI instruction. After a MON_ERARNGE call, the SWI instruction
will return the control back to the monitor code.
Data Sheet
186
MC68HC908LJ24/LK24 — Rev. 2.1
Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
ROM-Resident Routines
10.6.6 MON_LDRNGE
In monitor mode, LDRNGE is used to load the data array in RAM with
data from a range of FLASH locations.
Table 10-16. ICP_LDRNGE Routine
Routine Name
MON_LDRNGE
Routine Description Loads data from a range of locations, in monitor mode
Calling Address
Stack Used
$FF24
11 bytes
Data Block Format
Bus speed
Data size
Starting address (high byte)
Starting address (low byte)
Data 1
:
Data N
The MON_LDRNGE routine is designed to be used in monitor mode. It
performs the same function as the LDRNGE routine (see 10.6.3
LDRNGE), except that MON_LDRNGE returns to the main program via
an SWI instruction. After a MON_LDRNGE call, the SWI instruction will
return the control back to the monitor code.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
187
Monitor ROM (MON)
Monitor ROM (MON)
10.6.7 EE_WRITE
EE_WRITE is used to write a set of data from the data array to FLASH.
Table 10-17. EE_WRITE Routine
Routine Name
EE_WRITE
Emulated EEPROM write. Data size ranges from 2 to 15
bytes at a time.
Routine Description
Calling Address
Stack Used
$FC00
17 bytes
Data Block Format
Bus speed (BUS_SPD)
(1)
Data size (DATASIZE)
(2)
Starting address (ADDRH)
(1)
Starting address (ADDRL)
Data 1
:
Data N
Notes:
1. The minimum data size is 2 bytes. The maximum data size is 15 bytes.
2. The start address must be a page boundary start address, e.g. $xx00 or $xx80.
The start location of the FLASH to be programmed is specified by the
address ADDRH:ADDRL and the number of bytes in the data array is
specified by DATASIZE. The minimum number of bytes that can be
programmed in one routine call is 2 bytes, the maximum is 15 bytes.
ADDRH:ADDRL must always be the start of boundary address (the page
start address: $XX00 or $0080) and DATASIZE must be the same size
when accessing the same page.
In some applications, the user may want to repeatedly store and read a
set of data from an area of non-volatile memory. This is easily possible
when using an EEPROM array. As the write and erase operations can
be executed on a byte basis. For FLASH memory, the minimum erase
size is the page — 128 bytes per page for MC68HC908LJ24. If the data
array size is less than the page size, writing and erasing to the same
page cannot fully utilize the page. Unused locations in the page will be
wasted. The EE_WRITE routine is designed to emulate the properties
similar to the EEPROM. Allowing a more efficient use of the FLASH page
for data storage.
Data Sheet
188
MC68HC908LJ24/LK24 — Rev. 2.1
Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
ROM-Resident Routines
When the user dedicates a page of FLASH for data storage, and the size
of the data array defined, each call of the EE_WRTIE routine will
automatically transfer the data in the data array (in RAM) to the next
blank block of locations in the FLASH page. Once a page is filled up, the
EE_WRITE routine automatically erases the page, and starts reuse the
page again. In the 128-byte page, an 8-byte control block is used by the
routine to monitor the utilization of the page. In effect, only 120 bytes are
used for data storage. (see Figure 10-10). The page control operations
are transparent to the user.
F L A S H
PAGE BOUNDARY
CONTROL: 8 BYTES
DATA ARRAY
$XX00 OR $XX80
DATA ARRAY
DATA ARRAY
ONE PAGE = 128 BYTES
PAGE BOUNDARY
Figure 10-10. EE_WRITE FLASH Memory Usage
When using this routine to store a 2-byte data array, the FLASH page
can be programmed 60 times before the an erase is required. In effect,
the write/erase endurance is increased by 60 times. When a 15-byte
data array is used, the write/erase endurance is increased by 8 times.
Due to the FLASH page size limitation, the data array is limited from 2
bytes to 15 bytes.
The coding example below uses the $EF00–$EE7F page for data
storage. The data array size is 15 bytes, and the bus speed is
4.9152 MHz. The coding assumes the data block is already loaded in
RAM, with the address pointer, FILE_PTR, pointing to the first byte of the
data block.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
189
Monitor ROM (MON)
Monitor ROM (MON)
ORG
RAM
:
FILE_PTR:
BUS_SPD
DATASIZE
START_ADDR
DATAARRAY
DS.B
DS.B
DS.W
DS.B
1
1
1
15
; Indicates 4x bus frequency
; Data size to be programmed
; FLASH starting address
; Reserved data array
EE_WRITE
FLASH_START
EQU
EQU
$FC00
$EF00
ORG
FLASH
INITIALISATION:
MOV
MOV
#20,
#15,
BUS_SPD
DATASIZE
LDHX
STHX
RTS
#FLASH_START
START_ADDR
MAIN:
BSR
:
INITIALISATION
:
LHDX
JSR
#FILE_PTR
EE_WRITE
NOTE: The EE_WRITE routine is unable to check for incorrect data blocks,
such as the FLASH page boundary address and data size. It is the
responsibility of the user to ensure the starting address indicated in the
data block is at the FLASH page boundary and the data size is 2 to 15.
If the FLASH page is already programmed with a data array with a
different size, the EE_WRITE call will be ignored.
Data Sheet
190
MC68HC908LJ24/LK24 — Rev. 2.1
Monitor ROM (MON)
Freescale Semiconductor
Monitor ROM (MON)
ROM-Resident Routines
10.6.8 EE_READ
EE_READ is used to load the data array in RAM with a set of data from
FLASH.
Table 10-18. EE_READ Routine
Routine Name
EE_READ
Emulated EEPROM read. Data size ranges from 2 to 15
bytes at a time.
Routine Description
Calling Address
Stack Used
$FC03
15 bytes
Data Block Format
Bus speed (BUS_SPD)
Data size (DATASIZE)
(1)
Starting address (ADDRH)
(1)
Starting address (ADDRL)
Data 1
:
Data N
Notes:
1. The start address must be a page boundary start address, e.g. $xx00 or $xx80.
The EE_READ routine reads data stored by the EE_WRITE routine. An
EE_READ call will retrieve the last data written to a FLASH page and
loaded into the data array in RAM. Same as EE_WRITE, the data size
indicated by DATASIZE is 2 to 15, and the start address
ADDRH:ADDRL must the FLASH page boundary address.
The coding example below uses the data stored by the EE_WRITE
coding example (see 10.6.7 EE_WRITE). It loads the 15-byte data set
stored in the $EF00–$EE7F page to the data array in RAM. The
initialization subroutine is the same as the coding example for
EE_WRITE (see 10.6.7 EE_WRITE).
EE_READ
MAIN:
EQU
$FC03
BSR
:
INITIALIZATION
:
LDHX
JSR
:
#FILE_PTR
EE_READ
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
191
Monitor ROM (MON)
Monitor ROM (MON)
NOTE: The EE_READ routine is unable to check for incorrect data blocks, such
as the FLASH page boundary address and data size. It is the
responsibility of the user to ensure the starting address indicated in the
data block is at the FLASH page boundary and the data size is 2 to 15.
If the FLASH page is programmed with a data array with a different size,
the EE_READ call will be ignored.
Data Sheet
192
MC68HC908LJ24/LK24 — Rev. 2.1
Monitor ROM (MON)
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 11. Timer Interface Module (TIM)
11.1 Contents
11.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194
11.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194
11.4 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195
11.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195
11.5.1 TIM Counter Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . .199
11.5.2 Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .199
11.5.3 Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200
11.5.3.1
11.5.3.2
Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . .200
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . .201
11.5.4 Pulse Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . .201
11.5.4.1
11.5.4.2
11.5.4.3
Unbuffered PWM Signal Generation . . . . . . . . . . . . . . .202
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . .203
PWM Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . .204
11.6 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .205
11.7 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .205
11.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206
11.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206
11.8 TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . .206
11.9 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .207
11.9.1 TIM Clock Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .207
11.9.2 TIM Channel I/O Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . .207
11.10 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208
11.10.1 TIM Status and Control Register . . . . . . . . . . . . . . . . . . . .208
11.10.2 TIM Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . .210
11.10.3 TIM Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . .211
11.10.4 TIM Channel Status and Control Registers . . . . . . . . . . . .212
11.10.5 TIM Channel Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . .215
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
193
Timer Interface Module (TIM)
Timer Interface Module (TIM)
11.2 Introduction
This section describes the timer interface (TIM) module. The TIM is a
two-channel timer that provides a timing reference with input capture,
output compare, and pulse-width-modulation functions. Figure 11-1 is a
block diagram of the TIM.
This particular MCU has two timer interface modules which are denoted
as TIM1 and TIM2.
11.3 Features
Features of the TIM include:
• Two input capture/output compare channels:
– Rising-edge, falling-edge, or any-edge input capture trigger
– Set, clear, or toggle output compare action
• Buffered and unbuffered pulse-width-modulation (PWM) signal
generation
• Programmable TIM clock input
– 7-frequency internal bus clock prescaler selection
– External TIM clock input (bus frequency ÷2 maximum)
• Free-running or modulo up-count operation
• Toggle any channel pin on overflow
• TIM counter stop and reset bits
Data Sheet
194
MC68HC908LJ24/LK24 — Rev. 2.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
Pin Name Conventions
11.4 Pin Name Conventions
The text that follows describes both timers, TIM1 and TIM2. The TIM
input/output (I/O) pin names are T[1,2]CH0 (timer channel 0). T[1,2]CH1
(timer channel 1), and T[1,2]CLK (external timer clock), where “1” is
used to indicate TIM1 and “2” is used to indicate TIM2. The full names of
the TIM I/O pins are listed in Table 11-1. The generic pin names appear
in the text that follows.
Table 11-1. Pin Name Conventions
TIM Generic Pin Names:
T[1,2]CH0
PTB2/T1CH0
PTB4/T2CH0
T[1,2]CH1
T[1,2]CLK
TIM1
PTB3/T1CH1 PTD4/KBI4/T1CLK
PTB5/T2CH1 PTD5/KBI5/T2CLK
Full TIM
Pin Names:
TIM2
NOTE: References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TCH0 may refer generically
to T1CH0 and T2CH0, and TCH1 may refer to T1CH1 and T2CH1.
The T1CLK and T2CLK pins are also shared with KBI4 and KBI5
respectively. To avoid erratic behavior, these two pins should never be
configured for use as TCLK and KBI inputs simultaneously.
11.5 Functional Description
Figure 11-1 shows the structure of the TIM. The central component of
the TIM is the 16-bit TIM counter that can operate as a free-running
counter or a modulo up-counter. The TIM counter provides the timing
reference for the input capture and output compare functions. The TIM
counter modulo registers, TMODH:TMODL, control the modulo value of
the TIM counter. Software can read the TIM counter value at any time
without affecting the counting sequence.
The two TIM channels (per timer) are programmable independently as
input capture or output compare channels.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
195
Timer Interface Module (TIM)
Timer Interface Module (TIM)
T[1,2]CLK
PRESCALER SELECT
INTERNAL
PRESCALER
BUS CLOCK
TSTOP
TRST
PS2
PS1
PS0
16-BIT COUNTER
TOF
INTERRUPT
LOGIC
TOIE
16-BIT COMPARATOR
TMODH:TMODL
TOV0
ELS0B
ELS0A
ELS1A
PORT
CHANNEL 0
CH0MAX
T[1,2]CH0
T[1,2]CH1
LOGIC
16-BIT COMPARATOR
TCH0H:TCH0L
CH0F
INTERRUPT
LOGIC
16-BIT LATCH
CH0IE
MS0A
MS0B
CH1F
TOV1
ELS1B
PORT
LOGIC
CHANNEL 1
16-BIT COMPARATOR
TCH1H:TCH1L
CH1MAX
INTERRUPT
LOGIC
16-BIT LATCH
CH1IE
MS1A
Figure 11-1. TIM Block Diagram
Figure 11-2 summarizes the timer registers.
NOTE: References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TSC may generically refer to
both T1SC and T2SC.
Data Sheet
196
MC68HC908LJ24/LK24 — Rev. 2.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
Functional Description
Addr.
Register Name
Bit 7
TOF
0
6
5
4
0
3
2
1
Bit 0
Read:
0
Timer 1 Status and
TOIE
TSTOP
PS2
PS1
PS0
$0020
Control Register Write:
TRST
0
(T1SC)
Reset:
0
0
1
0
0
0
9
0
Read: Bit 15
14
13
12
11
10
Bit 8
Timer 1 Counter
$0021
$0022
$0023
$0024
$0025
$0026
$0027
$0028
Register High Write:
(T1CNTH)
Reset:
0
0
6
0
5
0
4
0
3
0
2
0
1
0
Read:
Bit 7
Bit 0
Timer 1 Counter
Register Low Write:
(T1CNTL)
Reset:
0
Bit 15
1
0
0
0
0
0
0
0
Read:
Timer 1 Counter Modulo
14
13
12
11
10
9
Bit 8
Register High Write:
(T1MODH)
Reset:
1
1
1
1
1
1
1
Bit 0
1
Read:
Timer 1 Counter Modulo
Bit 7
1
6
1
5
1
4
1
3
2
1
Register Low Write:
(T1MODL)
Reset:
1
ELS0B
0
1
ELS0A
0
1
TOV0
0
Read: CH0F
Timer 1 Channel 0 Status
CH0IE
0
MS0B
0
MS0A
0
CH0MAX
0
and Control Register Write:
0
0
(T1SC0)
Reset:
Read:
Timer 1 Channel 0
Bit 15
14
13
12
11
10
9
Bit 8
Register High Write:
(T1CH0H)
Reset:
Indeterminate after reset
Read:
Timer 1 Channel 0
Bit 7
6
5
4
3
2
1
Bit 0
Register Low Write:
(T1CH0L)
Reset:
Indeterminate after reset
Read: CH1F
0
0
Timer 1 Channel 1 Status
CH1IE
0
MS1A
0
ELS1B
0
ELS1A
0
TOV1
0
CH1MAX
0
and Control Register Write:
0
0
(T1SC1)
Reset:
= Unimplemented
Figure 11-2. TIM I/O Register Summary (Sheet 1 of 3)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
197
Timer Interface Module (TIM)
Timer Interface Module (TIM)
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Timer 1 Channel 1
Bit 15
14
13
12
11
10
9
Bit 8
$0029
Register High Write:
(T1CH1H)
Reset:
Indeterminate after reset
Read:
Timer 1 Channel 1
Bit 7
6
5
4
3
2
1
Bit 0
PS0
$002A
$002B
$002C
$002D
$002E
$002F
$0030
$0031
Register Low Write:
(T1CH1L)
Reset:
Indeterminate after reset
Read:
TOF
0
TRST
0
0
Timer 2 Status and
TOIE
TSTOP
PS2
PS1
Control Register Write:
0
0
(T2SC)
Reset:
0
1
0
0
0
9
0
Read: Bit 15
14
13
12
11
10
Bit 8
Timer 2 Counter
Register High Write:
(T2CNTH)
Reset:
0
0
6
0
5
0
4
0
3
0
2
0
1
0
Read:
Bit 7
Bit 0
Timer 2 Counter
Register Low Write:
(T2CNTL)
Reset:
0
Bit 15
1
0
0
0
0
0
0
0
Read:
Timer 2 Counter Modulo
14
13
12
11
10
9
Bit 8
Register High Write:
(T2MODH)
Reset:
1
1
1
1
1
1
1
Bit 0
1
Read:
Timer 2 Counter Modulo
Bit 7
6
1
5
1
4
1
3
2
1
Register Low Write:
(T2MODL)
Reset:
1
1
ELS0B
0
1
ELS0A
0
1
TOV0
0
Read: CH0F
Timer 2 Channel 0 Status
CH0IE
0
MS0B
0
MS0A
0
CH0MAX
0
and Control Register Write:
0
0
(T2SC0)
Reset:
Read:
Timer 2 Channel 0
Bit 15
14
13
12
11
10
9
Bit 8
Register High Write:
(T2CH0H)
Reset:
Indeterminate after reset
= Unimplemented
Figure 11-2. TIM I/O Register Summary (Sheet 2 of 3)
Data Sheet
198
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Timer Interface Module (TIM)
Timer Interface Module (TIM)
Functional Description
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Timer 2 Channel 0
Bit 7
6
5
4
3
2
1
Bit 0
$0032
Register Low Write:
(T2CH0L)
Reset:
Indeterminate after reset
Read: CH1F
0
Timer 2 Channel 1 Status
CH1IE
MS1A
0
ELS1B
ELS1A
TOV1
CH1MAX
$0033
$0034
$0035
and Control Register Write:
0
0
(T2SC1)
Reset:
0
0
0
0
0
9
0
Read:
Timer 2 Channel 1
Bit 15
14
13
12
11
10
Bit 8
Register High Write:
(T2CH1H)
Reset:
Indeterminate after reset
Read:
Timer 2 Channel 1
Bit 7
6
5
4
3
2
1
Bit 0
Register Low Write:
(T2CH1L)
Reset:
Indeterminate after reset
= Unimplemented
Figure 11-2. TIM I/O Register Summary (Sheet 3 of 3)
11.5.1 TIM Counter Prescaler
The TIM clock source can be one of the seven prescaler outputs or the
TIM clock pin, TCLK. The prescaler generates seven clock rates from
the internal bus clock. The prescaler select bits, PS[2:0], in the TIM
status and control register select the TIM clock source.
11.5.2 Input Capture
With the input capture function, the TIM can capture the time at which an
external event occurs. When an active edge occurs on the pin of an input
capture channel, the TIM latches the contents of the TIM counter into the
TIM channel registers, TCHxH:TCHxL. The polarity of the active edge is
programmable. Input captures can generate TIM CPU interrupt
requests.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
199
Timer Interface Module (TIM)
Timer Interface Module (TIM)
11.5.3 Output Compare
With the output compare function, the TIM can generate a periodic pulse
with a programmable polarity, duration, and frequency. When the
counter reaches the value in the registers of an output compare channel,
the TIM can set, clear, or toggle the channel pin. Output compares can
generate TIM CPU interrupt requests.
11.5.3.1 Unbuffered Output Compare
Any output compare channel can generate unbuffered output compare
pulses as described in 11.5.3 Output Compare. The pulses are
unbuffered because changing the output compare value requires writing
the new value over the old value currently in the TIM channel registers.
An unsynchronized write to the TIM channel registers to change an
output compare value could cause incorrect operation for up to two
counter overflow periods. For example, writing a new value before the
counter reaches the old value but after the counter reaches the new
value prevents any compare during that counter overflow period. Also,
using a TIM overflow interrupt routine to write a new, smaller output
compare value may cause the compare to be missed. The TIM may pass
the new value before it is written.
Use the following methods to synchronize unbuffered changes in the
output compare value on channel x:
• When changing to a smaller value, enable channel x output
compare interrupts and write the new value in the output compare
interrupt routine. The output compare interrupt occurs at the end
of the current output compare pulse. The interrupt routine has until
the end of the counter overflow period to write the new value.
• When changing to a larger output compare value, enable TIM
overflow interrupts and write the new value in the TIM overflow
interrupt routine. The TIM overflow interrupt occurs at the end of
the current counter overflow period. Writing a larger value in an
output compare interrupt routine (at the end of the current pulse)
could cause two output compares to occur in the same counter
overflow period.
Data Sheet
200
MC68HC908LJ24/LK24 — Rev. 2.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
Functional Description
11.5.3.2 Buffered Output Compare
Channels 0 and 1 can be linked to form a buffered output compare
channel whose output appears on the TCH0 pin. The TIM channel
registers of the linked pair alternately control the output.
Setting the MS0B bit in TIM channel 0 status and control register (TSC0)
links channel 0 and channel 1. The output compare value in the TIM
channel 0 registers initially controls the output on the TCH0 pin. Writing
to the TIM channel 1 registers enables the TIM channel 1 registers to
synchronously control the output after the TIM overflows. At each
subsequent overflow, the TIM channel registers (0 or 1) that control the
output are the ones written to last. TSC0 controls and monitors the
buffered output compare function, and TIM channel 1 status and control
register (TSC1) is unused. While the MS0B bit is set, the channel 1 pin,
TCH1, is available as a general-purpose I/O pin.
NOTE: In buffered output compare operation, do not write new output compare
values to the currently active channel registers. User software should
track the currently active channel to prevent writing a new value to the
active channel. Writing to the active channel registers is the same as
generating unbuffered output compares.
11.5.4 Pulse Width Modulation (PWM)
By using the toggle-on-overflow feature with an output compare channel,
the TIM can generate a PWM signal. The value in the TIM counter
modulo registers determines the period of the PWM signal. The channel
pin toggles when the counter reaches the value in the TIM counter
modulo registers. The time between overflows is the period of the PWM
signal.
As Figure 11-3 shows, the output compare value in the TIM channel
registers determines the pulse width of the PWM signal. The time
between overflow and output compare is the pulse width. Program the
TIM to clear the channel pin on output compare if the state of the PWM
pulse is logic 1. Program the TIM to set the pin if the state of the PWM
pulse is logic 0.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
201
Timer Interface Module (TIM)
Timer Interface Module (TIM)
The value in the TIM counter modulo registers and the selected
prescaler output determines the frequency of the PWM output. The
frequency of an 8-bit PWM signal is variable in 256 increments. Writing
$00FF (255) to the TIM counter modulo registers produces a PWM
period of 256 times the internal bus clock period if the prescaler select
value is $000. See 11.10.1 TIM Status and Control Register.
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
PULSE
WIDTH
TCHx
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 11-3. PWM Period and Pulse Width
The value in the TIM channel registers determines the pulse width of the
PWM output. The pulse width of an 8-bit PWM signal is variable in 256
increments. Writing $0080 (128) to the TIM channel registers produces
a duty cycle of 128/256 or 50%.
11.5.4.1 Unbuffered PWM Signal Generation
Any output compare channel can generate unbuffered PWM pulses as
described in 11.5.4 Pulse Width Modulation (PWM). The pulses are
unbuffered because changing the pulse width requires writing the new
pulse width value over the old value currently in the TIM channel
registers.
An unsynchronized write to the TIM channel registers to change a pulse
width value could cause incorrect operation for up to two PWM periods.
For example, writing a new value before the counter reaches the old
value but after the counter reaches the new value prevents any compare
during that PWM period. Also, using a TIM overflow interrupt routine to
write a new, smaller pulse width value may cause the compare to be
missed. The TIM may pass the new value before it is written.
Data Sheet
202
MC68HC908LJ24/LK24 — Rev. 2.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
Functional Description
Use the following methods to synchronize unbuffered changes in the
PWM pulse width on channel x:
• When changing to a shorter pulse width, enable channel x output
compare interrupts and write the new value in the output compare
interrupt routine. The output compare interrupt occurs at the end
of the current pulse. The interrupt routine has until the end of the
PWM period to write the new value.
• When changing to a longer pulse width, enable TIM overflow
interrupts and write the new value in the TIM overflow interrupt
routine. The TIM overflow interrupt occurs at the end of the current
PWM period. Writing a larger value in an output compare interrupt
routine (at the end of the current pulse) could cause two output
compares to occur in the same PWM period.
NOTE: In PWM signal generation, do not program the PWM channel to toggle
on output compare. Toggling on output compare prevents reliable 0%
duty cycle generation and removes the ability of the channel to self-
correct in the event of software error or noise. Toggling on output
compare also can cause incorrect PWM signal generation when
changing the PWM pulse width to a new, much larger value.
11.5.4.2 Buffered PWM Signal Generation
Channels 0 and 1 can be linked to form a buffered PWM channel whose
output appears on the TCH0 pin. The TIM channel registers of the linked
pair alternately control the pulse width of the output.
Setting the MS0B bit in TIM channel 0 status and control register (TSC0)
links channel 0 and channel 1. The TIM channel 0 registers initially
control the pulse width on the TCH0 pin. Writing to the TIM channel 1
registers enables the TIM channel 1 registers to synchronously control
the pulse width at the beginning of the next PWM period. At each
subsequent overflow, the TIM channel registers (0 or 1) that control the
pulse width are the ones written to last. TSC0 controls and monitors the
buffered PWM function, and TIM channel 1 status and control register
(TSC1) is unused. While the MS0B bit is set, the channel 1 pin, TCH1,
is available as a general-purpose I/O pin.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
203
Timer Interface Module (TIM)
Timer Interface Module (TIM)
NOTE: In buffered PWM signal generation, do not write new pulse width values
to the currently active channel registers. User software should track the
currently active channel to prevent writing a new value to the active
channel. Writing to the active channel registers is the same as
generating unbuffered PWM signals.
11.5.4.3 PWM Initialization
To ensure correct operation when generating unbuffered or buffered
PWM signals, use the following initialization procedure:
1. In the TIM status and control register (TSC):
a. Stop the TIM counter by setting the TIM stop bit, TSTOP.
b. Reset the TIM counter and prescaler by setting the TIM reset
bit, TRST.
2. In the TIM counter modulo registers (TMODH:TMODL), write the
value for the required PWM period.
3. In the TIM channel x registers (TCHxH:TCHxL), write the value for
the required pulse width.
4. In TIM channel x status and control register (TSCx):
a. Write 0:1 (for unbuffered output compare or PWM signals) or
1:0 (for buffered output compare or PWM signals) to the
mode select bits, MSxB:MSxA. (See Table 11-3.)
b. Write 1 to the toggle-on-overflow bit, TOVx.
c. Write 1:0 (to clear output on compare) or 1:1 (to set output on
compare) to the edge/level select bits, ELSxB:ELSxA. The
output action on compare must force the output to the
complement of the pulse width level. (See Table 11-3.)
NOTE: In PWM signal generation, do not program the PWM channel to toggle
on output compare. Toggling on output compare prevents reliable 0%
duty cycle generation and removes the ability of the channel to self-
correct in the event of software error or noise. Toggling on output
compare can also cause incorrect PWM signal generation when
changing the PWM pulse width to a new, much larger value.
5. In the TIM status control register (TSC), clear the TIM stop bit,
TSTOP.
Data Sheet
204
MC68HC908LJ24/LK24 — Rev. 2.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
Interrupts
Setting MS0B links channels 0 and 1 and configures them for buffered
PWM operation. The TIM channel 0 registers (TCH0H:TCH0L) initially
control the buffered PWM output. TIM channel 0 status and control
register (TSC0) controls and monitors the PWM signal from the linked
channels.
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIM
overflows. Subsequent output compares try to force the output to a state
it is already in and have no effect. The result is a 0% duty cycle output.
Setting the channel x maximum duty cycle bit (CHxMAX) and setting the
TOVx bit generates a 100% duty cycle output. (See 11.10.4 TIM
Channel Status and Control Registers.)
11.6 Interrupts
The following TIM sources can generate interrupt requests:
• TIM overflow flag (TOF) — The TOF bit is set when the TIM
counter reaches the modulo value programmed in the TIM counter
modulo registers. The TIM overflow interrupt enable bit, TOIE,
enables TIM overflow CPU interrupt requests. TOF and TOIE are
in the TIM status and control register.
• TIM channel flags (CH1F:CH0F) — The CHxF bit is set when an
input capture or output compare occurs on channel x. Channel x
TIM CPU interrupt requests are controlled by the channel x
interrupt enable bit, CHxIE. Channel x TIM CPU interrupt requests
are enabled when CHxIE = 1. CHxF and CHxIE are in the TIM
channel x status and control register.
11.7 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
205
Timer Interface Module (TIM)
Timer Interface Module (TIM)
11.7.1 Wait Mode
The TIM remains active after the execution of a WAIT instruction. In wait
mode, the TIM registers are not accessible by the CPU. Any enabled
CPU interrupt request from the TIM can bring the MCU out of wait mode.
If TIM functions are not required during wait mode, reduce power
consumption by stopping the TIM before executing the WAIT instruction.
11.7.2 Stop Mode
The TIM is inactive after the execution of a STOP instruction. The STOP
instruction does not affect register conditions or the state of the TIM
counter. TIM operation resumes when the MCU exits stop mode after an
external interrupt.
11.8 TIM During Break Interrupts
A break interrupt stops the TIM counter.
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state. (See 9.8.3 SIM Break Flag Control
Register.)
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
I/O registers during the break state without affecting status bits. Some
status bits have a 2-step read/write clearing procedure. If software does
the first step on such a bit before the break, the bit cannot change during
the break state as long as BCFE is at logic 0. After the break, doing the
second step clears the status bit.
Data Sheet
206
MC68HC908LJ24/LK24 — Rev. 2.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
I/O Signals
11.9 I/O Signals
Port B shares four of its pins with the TIM channel I/O pins: T1CH0,
T1CH1, T2CH0, and T2CH1.
Port D shares two of its pins with the TIM clock input pins: T1CLK and
T2CLK
11.9.1 TIM Clock Pins (PTD4/KBI4/T1CLK, PTD5/KBI5/T2CLK)
T[1,2]CLK is an external clock input that can be the clock source for the
TIM[1,2] counter instead of the prescaled internal bus clock. Select the
T[1,2]CLK input by writing logic 1’s to the three prescaler select bits,
PS[2:0]. (See 11.10.1 TIM Status and Control Register.) The minimum
T[1,2]CLK pulse width, T[1,2]CLKLMIN or T[1,2]CLKHMIN, is:
1
------------------------------------- + t SU
bus frequency
The maximum T[1,2]CLK frequency is:
bus frequency ÷ 2
T1CLK and T2CLK are available as standard I/Os or KBI pins when not
used as the TIM clock inputs.
11.9.2 TIM Channel I/O Pins (PTB2/T1CH0, PTB3/T1CH1, PTB4/T2CH0, PTB5/T2CH1)
Each channel I/O pin is programmable independently as an input
capture pin or an output compare pin. T1CH0 and T2CH0 can be
configured as buffered output compare or buffered PWM pins.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
207
Timer Interface Module (TIM)
Timer Interface Module (TIM)
11.10 I/O Registers
NOTE: References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TSC may generically refer to
both T1SC AND T2SC.
These I/O registers control and monitor operation of the TIM:
• TIM status and control register (TSC)
• TIM counter registers (TCNTH:TCNTL)
• TIM counter modulo registers (TMODH:TMODL)
• TIM channel status and control registers (TSC0, TSC1)
• TIM channel registers (TCH0H:TCH0L, TCH1H:TCH1L)
11.10.1 TIM Status and Control Register
The TIM status and control register (TSC):
• Enables TIM overflow interrupts
• Flags TIM overflows
• Stops the TIM counter
• Resets the TIM counter
• Prescales the TIM counter clock
Address: T1SC, $0020 and T2SC, $002B
Bit 7
TOF
0
6
TOIE
0
5
TSTOP
1
4
0
3
0
2
PS2
0
1
PS1
0
Bit 0
PS0
0
Read:
Write:
Reset:
TRST
0
0
0
= Unimplemented
Figure 11-4. TIM Status and Control Register (TSC)
Data Sheet
208
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Timer Interface Module (TIM)
Timer Interface Module (TIM)
I/O Registers
TOF — TIM Overflow Flag Bit
This read/write flag is set when the TIM counter reaches the modulo
value programmed in the TIM counter modulo registers. Clear TOF by
reading the TIM status and control register when TOF is set and then
writing a logic 0 to TOF. If another TIM overflow occurs before the
clearing sequence is complete, then writing logic 0 to TOF has no
effect. Therefore, a TOF interrupt request cannot be lost due to
inadvertent clearing of TOF. Reset clears the TOF bit. Writing a
logic 1 to TOF has no effect.
1 = TIM counter has reached modulo value
0 = TIM counter has not reached modulo value
TOIE — TIM Overflow Interrupt Enable Bit
This read/write bit enables TIM overflow interrupts when the TOF bit
becomes set. Reset clears the TOIE bit.
1 = TIM overflow interrupts enabled
0 = TIM overflow interrupts disabled
TSTOP — TIM Stop Bit
This read/write bit stops the TIM counter. Counting resumes when
TSTOP is cleared. Reset sets the TSTOP bit, stopping the TIM
counter until software clears the TSTOP bit.
1 = TIM counter stopped
0 = TIM counter active
NOTE: Do not set the TSTOP bit before entering wait mode if the TIM is required
to exit wait mode.
TRST — TIM Reset Bit
Setting this write-only bit resets the TIM counter and the TIM
prescaler. Setting TRST has no effect on any other registers.
Counting resumes from $0000. TRST is cleared automatically after
the TIM counter is reset and always reads as logic 0. Reset clears the
TRST bit.
1 = Prescaler and TIM counter cleared
0 = No effect
NOTE: Setting the TSTOP and TRST bits simultaneously stops the TIM counter
at a value of $0000.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
209
Timer Interface Module (TIM)
Timer Interface Module (TIM)
PS[2:0] — Prescaler Select Bits
These read/write bits select one of the seven prescaler outputs as the
input to the TIM counter as Table 11-2 shows. Reset clears the
PS[2:0] bits.
Table 11-2. Prescaler Selection
PS2
0
PS1
0
PS0
0
TIM Clock Source
Internal bus clock ÷ 1
Internal bus clock ÷ 2
Internal bus clock ÷ 4
Internal bus clock ÷ 8
Internal bus clock ÷ 16
Internal bus clock ÷ 32
Internal bus clock ÷ 64
TCLK
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
11.10.2 TIM Counter Registers
The two read-only TIM counter registers contain the high and low bytes
of the value in the TIM counter. Reading the high byte (TCNTH) latches
the contents of the low byte (TCNTL) into a buffer. Subsequent reads of
TCNTH do not affect the latched TCNTL value until TCNTL is read.
Reset clears the TIM counter registers. Setting the TIM reset bit (TRST)
also clears the TIM counter registers.
NOTE: If you read TCNTH during a break interrupt, be sure to unlatch TCNTL
by reading TCNTL before exiting the break interrupt. Otherwise, TCNTL
retains the value latched during the break.
Address: T1CNTH, $0021 and T2CNTH, $002C
Bit 7
Read: Bit 15
Write:
6
5
4
3
2
1
9
Bit 0
Bit 8
14
13
12
11
10
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 11-5. TIM Counter Registers High (TCNTH)
Data Sheet
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MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Timer Interface Module (TIM)
Timer Interface Module (TIM)
I/O Registers
Address: T1CNTL, $0022 and T2CNTL, $002D
Bit 7
Bit 7
6
6
5
5
4
4
3
3
2
2
1
1
Bit 0
Bit 0
Read:
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 11-6. TIM Counter Registers Low (TCNTL)
11.10.3 TIM Counter Modulo Registers
The read/write TIM modulo registers contain the modulo value for the
TIM counter. When the TIM counter reaches the modulo value, the
overflow flag (TOF) becomes set, and the TIM counter resumes counting
from $0000 at the next timer clock. Writing to the high byte (TMODH)
inhibits the TOF bit and overflow interrupts until the low byte (TMODL) is
written. Reset sets the TIM counter modulo registers.
Address: T1MODH, $0023 and T2MODH, $002E
Bit 7
Bit 15
1
6
14
1
5
13
1
4
12
1
3
11
1
2
10
1
1
9
1
Bit 0
Bit 8
1
Read:
Write:
Reset:
Figure 11-7. TIM Counter Modulo Register High (TMODH)
Address: T1MODL, $0024 and T2MODL, $002F
Bit 7
Bit 7
1
6
6
1
5
5
1
4
4
1
3
3
1
2
2
1
1
1
1
Bit 0
Bit 0
1
Read:
Write:
Reset:
Figure 11-8. TIM Counter Modulo Register Low (TMODL)
NOTE: Reset the TIM counter before writing to the TIM counter modulo registers.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
211
Timer Interface Module (TIM)
Timer Interface Module (TIM)
11.10.4 TIM Channel Status and Control Registers
Each of the TIM channel status and control registers:
• Flags input captures and output compares
• Enables input capture and output compare interrupts
• Selects input capture, output compare, or PWM operation
• Selects high, low, or toggling output on output compare
• Selects rising edge, falling edge, or any edge as the active input
capture trigger
• Selects output toggling on TIM overflow
• Selects 0% and 100% PWM duty cycle
• Selects buffered or unbuffered output compare/PWM operation
Address: T1SC0, $0025 and T2SC0, $0030
Bit 7
6
CH0IE
0
5
MS0B
0
4
MS0A
0
3
ELS0B
0
2
ELS0A
0
1
TOV0
0
Bit 0
CH0MAX
0
Read: CH0F
Write:
0
0
Reset:
Figure 11-9. TIM Channel 0 Status and Control Register (TSC0)
Address: T1SC1, $0028 and T2SC1, $0033
Bit 7
6
CH1IE
0
5
0
4
MS1A
0
3
ELS1B
0
2
ELS1A
0
1
TOV1
0
Bit 0
CH1MAX
0
Read: CH1F
Write:
0
0
Reset:
0
= Unimplemented
Figure 11-10. TIM Channel 1 Status and Control Register (TSC1)
Data Sheet
212
MC68HC908LJ24/LK24 — Rev. 2.1
Timer Interface Module (TIM)
Freescale Semiconductor
Timer Interface Module (TIM)
I/O Registers
CHxF — Channel x Flag Bit
When channel x is an input capture channel, this read/write bit is set
when an active edge occurs on the channel x pin. When channel x is
an output compare channel, CHxF is set when the value in the TIM
counter registers matches the value in the TIM channel x registers.
When TIM CPU interrupt requests are enabled (CHxIE = 1), clear
CHxF by reading TIM channel x status and control register with CHxF
set and then writing a logic 0 to CHxF. If another interrupt request
occurs before the clearing sequence is complete, then writing logic 0
to CHxF has no effect. Therefore, an interrupt request cannot be lost
due to inadvertent clearing of CHxF.
Reset clears the CHxF bit. Writing a logic 1 to CHxF has no effect.
1 = Input capture or output compare on channel x
0 = No input capture or output compare on channel x
CHxIE — Channel x Interrupt Enable Bit
This read/write bit enables TIM CPU interrupt service requests on
channel x.
Reset clears the CHxIE bit.
1 = Channel x CPU interrupt requests enabled
0 = Channel x CPU interrupt requests disabled
MSxB — Mode Select Bit B
This read/write bit selects buffered output compare/PWM operation.
MSxB exists only in the TIM1 channel 0 and TIM2 channel 0 status
and control registers.
Setting MS0B disables the channel 1 status and control register and
reverts TCH1 to general-purpose I/O.
Reset clears the MSxB bit.
1 = Buffered output compare/PWM operation enabled
0 = Buffered output compare/PWM operation disabled
MSxA — Mode Select Bit A
When ELSxB:ELSxA ≠ 0:0, this read/write bit selects either input
capture operation or unbuffered output compare/PWM operation.
See Table 11-3.
1 = Unbuffered output compare/PWM operation
0 = Input capture operation
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
213
Timer Interface Module (TIM)
Timer Interface Module (TIM)
When ELSxB:ELSxA = 0:0, this read/write bit selects the initial output
level of the TCHx pin. See Table 11-3. Reset clears the MSxA bit.
1 = Initial output level low
0 = Initial output level high
NOTE: Before changing a channel function by writing to the MSxB or MSxA bit,
set the TSTOP and TRST bits in the TIM status and control register
(TSC).
ELSxB and ELSxA — Edge/Level Select Bits
When channel x is an input capture channel, these read/write bits
control the active edge-sensing logic on channel x.
When channel x is an output compare channel, ELSxB and ELSxA
control the channel x output behavior when an output compare
occurs.
When ELSxB and ELSxA are both clear, channel x is not connected
to an I/O port, and pin TCHx is available as a general-purpose I/O pin.
Table 11-3 shows how ELSxB and ELSxA work. Reset clears the
ELSxB and ELSxA bits.
Table 11-3. Mode, Edge, and Level Selection
MSxB:MSxA ELSxB:ELSxA
Mode
Configuration
Pin under port control;
initial output level high
X0
X1
00
00
Output preset
Pin under port control;
initial output level low
00
00
01
10
Capture on rising edge only
Capture on falling edge only
Input capture
Capture on rising or
falling edge
00
11
01
01
01
1X
1X
1X
01
10
11
01
10
11
Toggle output on compare
Clear output on compare
Set output on compare
Toggle output on compare
Clear output on compare
Set output on compare
Output
compare or
PWM
Buffered
output
compare or
buffered PWM
Data Sheet
214
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Timer Interface Module (TIM)
Timer Interface Module (TIM)
I/O Registers
NOTE: Before enabling a TIM channel register for input capture operation, make
sure that the TCHx pin is stable for at least two bus clocks. User software
should also clear CHxF before setting CHxIE to avoid any false
interrupts.
TOVx — Toggle On Overflow Bit
When channel x is an output compare channel, this read/write bit
controls the behavior of the channel x output when the TIM counter
overflows. When channel x is an input capture channel, TOVx has no
effect. Reset clears the TOVx bit.
1 = Channel x pin toggles on TIM counter overflow
0 = Channel x pin does not toggle on TIM counter overflow
NOTE: When TOVx is set, a TIM counter overflow takes precedence over a
channel x output compare if both occur at the same time.
CHxMAX — Channel x Maximum Duty Cycle Bit
When the TOVx bit is at logic 1, setting the CHxMAX bit forces the
duty cycle of buffered and unbuffered PWM signals to 100%. As
Figure 11-11 shows, the CHxMAX bit takes effect in the cycle after it
is set or cleared. The output stays at the 100% duty cycle level until
the cycle after CHxMAX is cleared.
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
TCHx
OUTPUT
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
COMPARE
CHxMAX
Figure 11-11. CHxMAX Latency
11.10.5 TIM Channel Registers
These read/write registers contain the captured TIM counter value of the
input capture function or the output compare value of the output
compare function. The state of the TIM channel registers after reset is
unknown.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
215
Timer Interface Module (TIM)
Timer Interface Module (TIM)
In input capture mode (MSxB:MSxA = 0:0), reading the high byte of the
TIM channel x registers (TCHxH) inhibits input captures until the low
byte (TCHxL) is read.
In output compare mode (MSxB:MSxA ≠ 0:0), writing to the high byte of
the TIM channel x registers (TCHxH) inhibits output compares until the
low byte (TCHxL) is written.
Address: T1CH0H, $0026 and T2CH0H, $0031
Bit 7
6
5
4
3
2
1
9
Bit 0
Bit 8
Read:
Write:
Reset:
Bit 15
14
13
12
11
10
Indeterminate after reset
Figure 11-12. TIM Channel 0 Register High (TCH0H)
Address: T1CH0L, $0027 and T2CH0L $0032
Bit 7
6
5
4
4
3
3
2
2
1
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
6
5
Indeterminate after reset
Figure 11-13. TIM Channel 0 Register Low (TCH0L)
Address: T1CH1H, $0029 and T2CH1H, $0034
Bit 7
6
5
4
3
2
1
9
Bit 0
Bit 8
Read:
Write:
Reset:
Bit 15
14
13
12
11
10
Indeterminate after reset
Figure 11-14. TIM Channel 1 Register High (TCH1H)
Address: T1CH1L, $002A and T2CH1L, $0035
Bit 7
6
5
4
4
3
3
2
2
1
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
6
5
Indeterminate after reset
Figure 11-15. TIM Channel 1 Register Low (TCH1L)
Data Sheet
216
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Timer Interface Module (TIM)
Data Sheet — MC68HC908LJ24
Section 12. Real Time Clock (RTC)
12.1 Contents
12.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218
12.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218
12.4 I/O Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219
12.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
12.5.1 Time Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223
12.5.2 Calendar Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223
12.5.3 Alarm Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223
12.5.4 Chronograph Functions . . . . . . . . . . . . . . . . . . . . . . . . . . .223
12.5.5 Timebase Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224
12.6 RTC Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224
12.7 RTC Clock Calibration and Compensation. . . . . . . . . . . . . . .225
12.7.1 Calibration Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .226
12.8 RTC Register and Bit Write Protection . . . . . . . . . . . . . . . . . .227
12.9 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229
12.9.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229
12.9.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230
12.10 RTC Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230
12.10.1 RTC Calibration Control Register (RTCCOMR). . . . . . . . .231
12.10.2 RTC Calibration Data Register (RTCCDAT) . . . . . . . . . . .233
12.10.3 RTC Control Register 1 (RTCCR1) . . . . . . . . . . . . . . . . . .234
12.10.4 RTC Control Register 2 (RTCCR2) . . . . . . . . . . . . . . . . . .235
12.10.5 RTC Status Register (RTCSR). . . . . . . . . . . . . . . . . . . . . .237
12.10.6 Alarm Minute and Hour Registers (ALMR and ALHR) . . . .240
12.10.7 Second Register (SECR) . . . . . . . . . . . . . . . . . . . . . . . . . .241
12.10.8 Minute Register (MINR) . . . . . . . . . . . . . . . . . . . . . . . . . . .241
12.10.9 Hour Register (HRR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
217
Real Time Clock (RTC)
Real Time Clock (RTC)
12.10.10 Day Register (DAYR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242
12.10.11 Month Register (MTHR) . . . . . . . . . . . . . . . . . . . . . . . . . . .243
12.10.12 Year Register (YRR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243
12.10.13 Day-Of-Week Register (DOWR) . . . . . . . . . . . . . . . . . . . .244
12.10.14 Chronograph Data Register (CHRR) . . . . . . . . . . . . . . . . .244
12.2 Introduction
This section describes the real time clock (RTC) module. The RTC
provides real time clock and calendar functions with automatic leap year
adjustments. Other functions include alarm interrupt, periodic interrupts,
and a chronograph timer.
NOTE: This module is designed for a 32.768-kHz oscillator.
12.3 Features
Features of the RTC module include:
• 32.768kHz clock input with frequency compensation
• Counter registers for:
– Second
– Minute
– Hour
– Day
– Day-of-week
– Month
– Year
• Day counter with automatic month and leap year adjustment
• 1/100 seconds chronograph counter
• Seven periodic interrupts
• Alarm interrupt
Data Sheet
218
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Real Time Clock (RTC)
I/O Pins
12.4 I/O Pins
Two RTC clock calibration pins are shared with standard port I/O pins.
Table 12-1. Pin Name Conventions
RTC
Pin Selected for RTC Function by
Full MCU Pin Name
Generic Pin Name
Bits in RTCCOMR ($0040)
AUTOCAL
CALIN
PTD0/SS/CALIN
(1)
CALOUT
PTD3/SPSCK/CALOUT
OUTF[1:0}
Notes:
1. Do not enable the SPI function if the pin is used for RTC calibration.
Addr.
Register Name
Bit 7
6
0
R
0
0
5
CAL
0
4
3
2
OUTF0
0
1
Bit 0
Read:
0
R
0
0
0
RTC Calibration Control
AUTOCAL OUTF1
$0040
Register Write:
(RTCCOMR)
RTCWE1 RTCWE0
Reset:
0
E4
0
E3
0
0
Read: EOVL
RTC Calibration Data
E5
E2
E1
E0
$0041
$0042
$0043
$0044
$0045
Register Write:
(RTCCDAT)
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
U
ALMIE
0
0
U
U
U
U
U
U
CHRIE
DAYIE
0
HRIE
0
MINIE
0
SECIE
TB1IE
TB2IE
RTC Control Register 1
(RTCCR1)
0
0
0
0
0
0
0
0
CHRCLR
0
COMEN
U
CHRE
RTCE
TBH
RTC Control Register 2
(RTCCR2)
††
0
0
0
0
0
0
Read: ALMF
Write:
CHRF
DAYF
HRF
MINF
SECF
TB1F
TB2F
RTC Status Register
(RTCSR)
Reset:
Read:
Write:
Reset:
0
0
0
0
0
AM5
U
0
AM4
U
0
AM3
U
0
AM2
U
0
AM1
U
0
AM0
U
Alarm Minute Register
(ALMR)
0
0
†† Reset by POR only.
U = Unaffected
= Unimplemented
R
= Reserved
Figure 12-1. RTC I/O Register Summary
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
219
Real Time Clock (RTC)
Real Time Clock (RTC)
Read:
0
0
0
AH4
U
AH3
U
AH2
U
AH1
U
AH0
U
Alarm Hour Register
(ALHR)
$0046
$0047
$0048
$0049
$004A
$004B
$004C
$004D
$004E
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
0
0
0
0
0
SEC5
U
SEC4
U
SEC3
U
SEC2
U
SEC1
U
SEC0
U
Second Register
(SECR)
0
0
0
0
MIN5
MIN4
U
MIN3
U
MIN2
U
MIN1
U
MIN0
U
Minute Register
(MINR)
0
0
0
0
U
0
HR4
U
HR3
U
HR2
U
HR1
U
HR0
U
Hour Register
(HRR)
0
0
0
0
0
0
DAY4
DAY3
U
DAY2
U
DAY1
U
DAY0
U
Day Register
(DAYR)
0
0
0
0
0
0
U
0
MTH3
U
MTH2
U
MTH1
U
MTH0
U
Month Register
(MTHR)
0
0
0
0
YR7
YR6
YR5
YR4
YR3
YR2
U
YR1
U
YR0
U
Year Register
(YRR)
U
0
U
0
U
0
U
0
U
0
DOW2
DOW1
DOW0
Day-Of-Week Register
(DOWR)
0
0
0
0
0
0
U
U
U
CHR6
CHR5
CHR4
CHR3
CHR2
CHR1
CHR0
Chronograph Data
Register Write:
(CHRR)
Reset:
0
0
0
0
0
0
0
0
U = Unaffected
= Unimplemented
R
= Reserved
Figure 12-1. RTC I/O Register Summary
Data Sheet
220
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Real Time Clock (RTC)
Real Time Clock (RTC)
Functional Description
12.5 Functional Description
The RTC module provides clock indications in seconds, minutes, and
hours; calendar indications in day-of-week, day-of-month, month, and
year; with automatic adjustment for month and leap year. Reading the
clock and calendar registers return the current time and date. Writing to
these registers set the time and date, and the counters will continue to
count from the new settings.
The alarm interrupt is set for the hour and minute. When the hour and
minute counters matches the time set in the alarm hour and minute
registers, the alarm flag is set. The alarm can be configured to generate
a CPU interrupt request.
A 1/100 seconds chronograph counter is provided for timing
applications. This counter can be independently enabled or disabled,
and cleared at any time.
RTC module interrupts include the alarm interrupt and seven periodic
interrupts from the clock and chronograph counters.
A frequency compensation mechanism is built into this RTC module to
allow adjustments made to the RTC clock when a less accurate
32.768kHz crystal is used.
The 1-Hz clock that drives the clock and calendar could make use of the
built-in compensation mechanism for crystal frequency error
compensation so that the 1-Hz clock could be made more accurate than
the frequency accuracy of the crystal that drive the module. The
compensation value can be provided by application software or acquire
automatically during calibration operation of the module.
Figure 12-2 shows the structure of the RTC module.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
221
Real Time Clock (RTC)
Real Time Clock (RTC)
CALOUT
1Hz
CLOCK CALIBRATION
CALIN
REFERENCE
AND
1Hz
TBH = 0 => X,Y = A
TBH = 1 => X,Y = B
TBH
SL
COMPENSATION CIRCUIT
TO CLOCK
COUNTERS
2Hz
÷ 256
÷ 2
÷ 2
÷ 2
÷ 2
÷ 2
÷ 2
XA
CGMXCLK
(32.768kHz)
X
Y
TB1F
4Hz
8Hz
YA
XB
YB
TB1IE
TB2F
16Hz
TB2IE
128 Hz
CHRF
CHRIE
25 16
×
+
CHRONOGRAPH COUNTER
FROM CLOCK
32 32
1/100 SECONDS
CHRONOGRAPH DATA REGISTER
COMPENSATION CIRCUIT
CHRE
CHRCLR
1Hz
SECF
SECIE
SECOND COUNTER REGISTER
MINUTE COUNTER REGISTER
HOUR COUNTER REGISTER
INTERRUPT
LOGIC
ALARM MINUTE REGISTER
COMPARATOR
MINF
MINIE
HRF
ALARM HOUR REGISTER
COMPARATOR
HRIE
ALMF
ALMIE
DAYF
DAYIE
DAY-OF-WEEK COUNTER REGISTER
DAY COUNTER REGISTER
MONTH COUNTER REGISTER
YEAR COUNTER REGISTER
Figure 12-2. RTC Block Diagram
Data Sheet
222
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Real Time Clock (RTC)
Real Time Clock (RTC)
Functional Description
12.5.1 Time Functions
Real time clock functions are provided by the second, minute, and hour
counter registers. All three clock counters are able to generate interrupts
on every counter increment, providing periodic interrupts for the second
(SECF), minute (MINF), and hour (HRF). A CPU interrupt request is
generated if the corresponding enable bit (SECIE, MINIE, and HRIE) is
also set.
12.5.2 Calendar Functions
Calendar functions are provided by the day, day-of-week, month, and
year counter registers. The roll over of the day counter is automatically
adjusted for the month and leap years. The setting for the year counter
ranges from 1901 to 2099.
The day flag (DAYF) is set on every increment of the day counter. A CPU
interrupt request is generated if the day interrupt enable bit (DAYIE) is
also set.
12.5.3 Alarm Functions
An alarm function is provided for the minute and hour counters. When
minute counter matches the value stored in the alarm minute register,
and the hour counter matches the value stored in the alarm hour register,
the alarm flag (ALMF) will be set. A CPU interrupt request is generated
if the alarm interrupt enable bit (ALMIE) is also set.
12.5.4 Chronograph Functions
The chronograph function is provided by a counter clocked at 128Hz
(CGMXCLK/256). This counter can be started, stopped, and cleared at
any time. The value of this chronograph counter is converted to 100Hz
resolution and stored in the chronograph data register. Hence, the value
in the chronograph register counts from 0 to 99 (and rolls over), with
each increment representing 1/100th of a second (10ms).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
223
Real Time Clock (RTC)
Real Time Clock (RTC)
The value in the chronograph data register satisfies the following
equation:
(128Hz counter value × 25) + 16
-------------------------------------------------------------------------------------
32
The accuracy of the chronograph counter is ±5ms (max).
12.5.5 Timebase Interrupts
In addition to the second, minute, hour, and day periodic interrupts
generated by the clock functions, the divider circuits generates four
periodic clocks, separated into two groups: 2Hz and 4Hz; 8Hz and
16Hz. The TBH bit in the RTC control register 2 (RTCCR2) selects the
group for the timebase interrupts, indicated by TB1F and TB2F flags. A
CPU interrupt request is generated if the corresponding enable bits
(TB1IE and TB2IE) are also set.
12.6 RTC Interrupts
The RTC has one alarm interrupt and seven periodic interrupts:
• Alarm interrupt
• Periodic interrupts:
– Second
– Minute
– Hour
– Day
– 1/128 seconds (chronograph)
– Timebase 1 and 2:
1/2 seconds and 1/4 seconds, or
1/8 seconds and 1/16 seconds
A CPU interrupt request is generated if the corresponding interrupt
enable bits are also set.
Data Sheet
224
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Real Time Clock (RTC)
RTC Clock Calibration and Compensation
12.7 RTC Clock Calibration and Compensation
The RTC module is built with a calibration and compensation circuit for
the CGMXCLK. The circuit is used to compensate frequency errors of
the 32.768kHz crystal so that a more accurate 1-Hz RTC clock can be
achieved. Using this method, it is possible to use a less expensive
crystal. If the crystal temperature profile and the current temperature is
known, the calibration circuit can also be used to compensate crystal
frequency errors due to ambient temperature change and crystal aging.
The circuit provides a ±60ppm compensation range, which is suitable for
common 30ppm crystals, and can achieve a compensated RTC clock
accuracy between –3ppm and +2ppm.
1-Hz REF
÷ 30
CALIN
EVOL
tdiff
÷ 983040
CGMXCLK
(32.768-kHz)
E-REGISTER
÷ 32766
÷ 32767
÷ 32768
÷ 32769
÷ 32770
1-Hz FROM
CGMXCLK ÷ 32768
1-Hz
RTC CLOCK
A
B1
COMPENSATED
1-Hz
S
COMEN
Figure 12-3. RTC Clock Calibration and Compensation
The automatic calibration process works by comparing an external 1-Hz
(1ppm) signal driven into the CALIN pin, with the CGMXCLK signal
driven by the 32.768kHz crystal. The calibration is started by setting the
CAL bit followed by the AUTOCAL bit in the RTC calibration register
(RTCCOMR). During calibration, the tdiff block compares the time
difference between the two clock sources for 15 seconds. This time
difference is expressed in the number of CGMXCLK clock cycles and
stored in two’s complement format in the 6-bit E-register (the RTC
calibration data register, RTCCDAT).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
225
Real Time Clock (RTC)
Real Time Clock (RTC)
A negative E-value indicates the number of CGMXCLK cycles that
needs to be subtracted, because the CGMXCLK is slower than the ideal
32.768kHz; 32768 CGMXCLK cycles will be more longer than 1-second.
A positive E-value indicates the number of CGMXCLK cycles that needs
to be added, because the CGMXCLK is faster than the ideal 32.768kHz;
32768 CGMXCLK cycles will be more shorter than 1-second.
If the time difference is more than 31 CGMXCLK cycles, the E-register
will overflow, causing the EVOL flag to be set. The maximum (+30) or
minimum (–30) value will remain in the E-register.
After calibration, with the E-value stored in the calibration data register,
clock compensation is only enabled when the COMEN bit is set in
RTCCR2. As the E-value is the time difference for 15 seconds, the
CGMXCLK is modified for every 15-second intervals. The CGMXCLK
additions and subtractions are simulated using programmable dividers,
therefore, the compensated clock does not have the same period within
the 15-second, but is consistent for every 15-second periods. See Table
12-2 and Figure 12-4.
12.7.1 Calibration Error
During clock calibration, the reference signal to the CALIN pin is not
synchronized to the CGMXCLK being measured. A maximum
inaccuracy of minus 1.5×CGMXCLK period or plus 1×CGMXCLK period
will be introduced to the time difference measured.
Table 12-2. Compensation Algorithm for Different Values of E
Period A
Period B
Number of
CGMXCLK
Divider A
Number of
CGMXCLK
Divider B
E
CGMXCLK Cycles
(|E| – 15) × 32766
|E| × 32767
CGMXCLK Cycles
(30 – |E|) × 32767
(15 – |E|) × 32768
–30 ≤ E ≤ –16
–15 ≤ E ≤ –1
E = 0
32766
32767
32767
32768
No compensation is required: Divider is 32768 throughout.
1 ≤ E ≤ 15
16 ≤ E ≤ 30
|E| × 32769
32769
32770
(15 – |E|) × 32768
(30 – |E|) × 32769
32769
32769
(|E| – 15) × 32770
Data Sheet
226
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Real Time Clock (RTC)
Real Time Clock (RTC)
RTC Register and Bit Write Protection
TRUE 15 SECONDS
CGMXCLK
UNCOMPENSATED
1-Hz CLOCK
(CGMXCLK ÷ 32768)
COMPENSATED
1-Hz CLOCK
PERIOD A
PERIOD B
1-Hz CLOCK = CGMXCLK ÷ A
1-Hz CLOCK = CGMXCLK ÷ B
Figure 12-4. 1-Hz Clock Compensation
12.8 RTC Register and Bit Write Protection
A write-protect mechanism is implemented to prevent accidental writes
to the RTC clock registers, calendar registers, and other control bits. The
protected RTC registers and bits are listed in Table 12-3.
Table 12-3. Write-Protected RTC Registers and Bits
Register
Bit
CAL
RTC Control Register 1
AUTOCAL
OUTF[1:0]
COMEN
RTCE
RTC Control Register 2
Second Register
Minute Register
Hour Register
(All Bits)
(All Bits)
(All Bits)
(All Bits)
(All Bits)
(All Bits)
(All Bits)
Day-Of-Week Register
Day Register
Month Register
Year Register
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
227
Real Time Clock (RTC)
Real Time Clock (RTC)
The mechanism uses the RTCWE[1:0] bits in the RTC calibration control
register (RTCCOMR) in a state machine, which requires a bit-write
sequence to disable the write-protection. A block diagram of the state
machine is shown in Figure 12-5.
Write-Protect ENABLED
Write-Protect
DISABLED
Write any value
other than 10
to RTWE
RTCWE = 10
Note: Reading RTCWE[1:0]
always return 00.
RTCWE = 00
Write any value
other than 00
to RTWE
RTCWE = 11
RTCWE 01
Figure 12-5. RTC Write Protect State Diagram
After a reset, the write-protect mechanism is disabled, allowing the user
code to calibrate the RTC clock, set the time in the clock registers, and
set the date in the calendar registers.
To enable write-protect after reset or write-protect is disabled execute
the following code:
RTCWE1 EQU
RTCWE0 EQU
1
0
;RTCWE1 bit
;RTCWE0 bit
Data Sheet
228
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Real Time Clock (RTC)
Real Time Clock (RTC)
Low-Power Modes
RTCWE_REQU
...
$40
;RTCCOMR register
RTC_WRTIE_PROTECT
...
BSET RTCWE1,RTCWE_R ;write %10
BSET RTCWE1,RTCWE_R ;write %10 again
To disable write-protect after write-protect is enabled execute the
following code:
RTCWE1 EQU
RTCWE0 EQU
RTCWE_REQU
...
1
0
$40
;RTCWE1 bit
;RTCWE0 bit
;RTCCOMR register
RTC_WRITE_ENABLE
...
BSET RTCWE1,RTCWE_R ;write %10 twice to
BSET RTCWE1,RTCWE_R ;ensure protected
BCLR RTCWE1,RTCWE_R ;write %00
BSET RTCWE0,RTCWE_R ;write %01
LDA
ORA
STA
RTCWE_R
#%00000011
RTCWE_R
;write %11
BSET RTCWE1,RTCWE_R ;write %10
...
; Write-protect is disabled, RTC registers/bits can be written.
...
; Protect register/bits again after write access.
RTC_WRTIE_PROTECT
...
BSET RTCWE1,RTCWE_R ;write %10
BSET RTCWE1,RTCWE_R ;write %10 again
12.9 Low-Power Modes
The STOP and WAIT instructions put the MCU in low power-
consumption standby modes.
12.9.1 Wait Mode
The RTC module continues normal operation in wait mode. Any enabled
CPU interrupt request from the RTC can bring the MCU out of wait
mode. If the RTC is not required to bring the MCU out of wait mode,
power down the RTC by clearing the RTCE bit before executing the
WAIT instruction.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
229
Real Time Clock (RTC)
Real Time Clock (RTC)
12.9.2 Stop Mode
For continuous RTC operation in stop mode, the oscillator stop mode
enable bit (STOP_XCLKEN in CONFIG2 register) must be set before
executing the STOP instruction. When STOP_XCLKEN is set,
CGMXCLK continues to drive the RTC module, and any enabled CPU
interrupt request from the RTC can bring the MCU out of stop mode.
If STOP_XCLKEN bit is cleared, the RTC module is inactive after the
execution of a STOP instruction. The STOP instruction does not affect
RTC register states. RTC module operation resumes after an external
interrupt. To further reduce power consumption, the RTC module should
be powered-down by clearing the RTCE bit before executing the STOP
instruction.
12.10 RTC Registers
The RTC module has fifteen memory-mapped registers:
• RTC calibration control register (RTCCOMR)
• RTC calibration data register (RTCCDAT)
• RTC control register 1 (RTCCR1)
• RTC control register 2 (RTCCR2)
• RTC status register (RTCSR)
• Alarm minute and hour registers (ALMR and ALHR)
• Second register (SECR)
• Minute register (MINR)
• Hour register (HRR)
• Day register (DAY)
• Month register (MTHR)
• Year register (YRR)
• Day of the week register (DOWR)
• Chronograph data register (CHRR)
Data Sheet
230
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Real Time Clock (RTC)
RTC Registers
12.10.1 RTC Calibration Control Register (RTCCOMR)
The RTC calibration control register (RTCCOMR) contains control bits
for RTC calibration, output option for the CALOUT pin, and registers/bits
write-protect enable.
Address: $0040
Read:
Write:
Reset:
0
R
0
0
R
0
0
0
AUTOCAL*
CAL*
0
OUTF1* OUTF0*
RTCWE1 RTCWE0
0
0
0
0
0
* CAL, AUTOCAL, and OUTF{1:0] bits are write-protected; unprotect by a write sequence to RTCWE[1:0].
Figure 12-6. RTC Calibration Control Register (RTCCOMR)
CAL — RTC Calibration Mode
This read/write bit enables the RTC calibration circuit. The CAL bit is
cleared automatically after completion of automatic calibration if
AUTOCAL is also set when CAL bit is set.
1 = RTC calibration mode enabled
0 = RTC calibration mode disabled
AUTOCAL — RTC Automatic Calibration Enable
This read/write bit enables the CALIN pin to accept an incoming
1-Hz signal and calibration circuits for RTC automatic calibration. This
bit can only be set when the CAL bit is set. After calibration (approx.
15 seconds), the AUTOCAL bit is automatically cleared.
1 = RTC automatic calibration enabled
0 = RTC automatic calibration disabled
NOTE: RTC clock and calendar functions are not affected when calibration is
enabled.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
231
Real Time Clock (RTC)
Real Time Clock (RTC)
OUTF[1:0] — Calibration Mode CALOUT Pin Output Selection
These two bits select the output option for the CALOUT pin.
When CAL = 0, OUTF[1:0] is always 00.
Table 12-4. CALOUT Pin Output Option
OUTF[1:0]
CALOUT Pin Output
CALOUT pin is disconnected.
00
01
10
11
CALOUT pin outputs compensated 1-Hz.
CALOUT pin outputs CGMXCLK clock.
Reserved
RTCWE[1:0] — RTC Module Write Enable
These two write-only bits control the write-protect function of several
RTC registers and bits. After a reset, write-protect is disabled,
allowing full write access to RTC registers and bits. These two bits
always read as 0.
To enable write-protect, perform the following sequence:
1. Write %10 to RTCWE[1:0] bits
2. Write %10 to RTCWE[1:0] bits
To disable write-protect, perform the following sequence:
1. Write %00 to RTCWE[1:0] bits
2. Write %01 to RTCWE[1:0] bits
3. Write %11 to RTCWE[1:0] bits
4. Write %10 to RTCWE[1:0] bits
To disable write-protect from an unsure protection state, first perform
the enable write-protect sequence, followed by the disable write-
protect sequence.
Data Sheet
232
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Real Time Clock (RTC)
RTC Registers
12.10.2 RTC Calibration Data Register (RTCCDAT)
The RTC calibration data register (RTCCDAT) contains the RTC
calibration data.
Address: $0041
Read: EOVL
Write:
0
0
E5
U
E4
U
E3
U
E2
U
E1
U
E0
U
Reset:
U
Figure 12-7. RTC Calibration Data Register (RTCCDAT)
EOVL — E Register Overflow
This read-only bit indicates that the time difference recorded between
CALIN and CGMXCLK after 15 seconds during the last automatic
calibration had exceeded 31 CGMXCLK cycles. Clear this flag by
writing to the E register after the CAL bit is set. Setting the AUTOCAL
bit will also clear this flag, but subsequent automatic calibration may
set this flag again.
1 = E register overflow detected during the last automatic
calibration
0 = No E register overflow detected during last automatic
calibration
E[5:0] — RTC Compensation Value (E register)
E[5:0] is a two’s complement number which indicates the number of
CGMXCLK cycles the RTC requires to compensate for a 15 second
duration. If the compensation exceeds the limit of ±31 CGMXCLK
cycles, the E[5:0] bits remain at the maximum value of –30 (%100010)
or +30 (%011110), and the EOVL flag will be set.
When compensation is enabled (COMEN = 1): If E is negative, an E
number of cycles will be subtracted from the 491520 CGMXCLK
cycles (32768 × 15).
When compensation is enabled (COMEN = 1): If E is positive, an E
number of cycles will be added to the 491520 CGMXCLK cycles
(32768 × 15).
E[5:0] is written by the RTC compensation circuit during automatic
calibration (AUTOCAL = 1). User can only write to E{5:0] when
AUTOCAL = 0 and CAL = 1. Reset has no effect on E[1:0] bits.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
233
Real Time Clock (RTC)
Real Time Clock (RTC)
12.10.3 RTC Control Register 1 (RTCCR1)
The RTC control register 1 (RTCCR1) contains the eight interrupt enable
bits for RTC interrupt functions.
Address: $0042
Read:
ALMIE
CHRIE
0
DAYIE
0
HRIE
0
MINIE
0
SECIE
0
TB1IE
0
TB2IE
0
Write:
Reset:
0
Figure 12-8. RTC Control Register 1 (RTCCR1)
ALMIE — Alarm Interrupt Enable
This read/write bit enables the alarm flag, ALMF, to generate CPU
interrupt requests. Reset clears the ALMIE bit.
1 = ALMF enabled to generate CPU interrupt
0 = ALMF not enabled to generate CPU interrupt
CHRIE — Chronograph Interrupt Enable
This read/write bit enables the chronograph flag, CHRF, to generate
CPU interrupt requests. Reset clears the CHRIE bit.
1 = CHRF enabled to generate CPU interrupt
0 = CHRF not enabled to generate CPU interrupt
DAYIE — Day Interrupt Enable
This read/write bit enables the day flag, DAYF, to generate CPU
interrupt requests. Reset clears the DAYIE bit.
1 = DAYF enabled to generate CPU interrupt
0 = DAYF not enabled to generate CPU interrupt
HRIE — Hour Interrupt Enable
This read/write bit enables the hour flag, HRF, to generate CPU
interrupt requests. Reset clears the HRIE bit.
1 = HRF enabled to generate CPU interrupt
0 = HRF not enabled to generate CPU interrupt
MINIE — Minute Interrupt Enable
This read/write bit enables the minute flag, MINF, to generate CPU
interrupt requests. Reset clears the MINIE bit.
1 = MINF enabled to generate CPU interrupt
0 = MINF not enabled to generate CPU interrupt
Data Sheet
234
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Real Time Clock (RTC)
RTC Registers
SECIE — Second Interrupt Enable
This read/write bit enables the second flag, SECF, to generate CPU
interrupt requests. Reset clears the SECIE bit.
1 = SECF enabled to generate CPU interrupt
0 = SECF not enabled to generate CPU interrupt
TB1IE — Timebase 1 Interrupt Enable
This read/write bit enables the timebase1 flag, TB1F, to generate
CPU interrupt requests. Reset clears the TB1IE bit.
1 = TB1F enabled to generate CPU interrupt
0 = TB1F not enabled to generate CPU interrupt
TB2IE — Timebase 2 Interrupt Enable
This read/write bit enables the timebase2 flag, TB2F, to generate
CPU interrupt requests. Reset clears the TB2IE bit.
1 = TB2F enabled to generate CPU interrupt
0 = TB2F not enabled to generate CPU interrupt
12.10.4 RTC Control Register 2 (RTCCR2)
The RTC control register 2 (RTCCR2) contains control and clock
selection bits for RTC operation.
Address: $0043
Read:
Write:
Reset:
0
CHRCLR
0
0
0
0
0
0
0
COMEN*
U
CHRE
0
RTCE*
TBH
0
††
0
= Unimplemented
†† Reset by POR only.
* COMEN and RTCE bits are write-protected; unprotect by a write sequence to RTCWE[1:0] in RTCCOMR.
Figure 12-9. RTC Control Register 2 (RTCCR2)
COMEN — RTC Compensation Enable
This read/write bit enables the clock compensation mechanism for
CGMXCLK frequency errors. Reset has no effect on COMEN bit.
1 = Compensation mechanism enabled
0 = Compensation mechanism not enabled
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
235
Real Time Clock (RTC)
Real Time Clock (RTC)
NOTE: With compensation enabled, the RTC clock and calendar register
updates may not be synchronized to the timebase and chronograph
clocks, since their clocks are derived from the uncompensated
CGMXCLK.
Hence, time intervals for timebase ticks may not align with the RTC clock
and calendar register updates.
CHRCLR — Chronograph counter clear
Setting this write-only bit resets the chronograph counter and the
chronograph data register (CHRR). Setting CHRCLR has no effect on
any other registers. Counting resumes from $00. CHRCLR is cleared
automatically after the chronograph counter is reset and always reads
as logic 0. Reset clears the CHRCLR bit.
1 = Chronograph counter cleared
0 = No effect
CHRE — Chronograph Enable
This read/write bit enables the chronograph counter. When the
chronograph counter is disabled (CHRE = 0), the value in the
chronograph data register is held at the count value. Reset clears the
CHRE bit.
1 = Chronograph counter enabled
0 = Chronograph counter disabled
RTCE — Real Time Clock Enable
This read/write bit enables the entire RTC module, allowing all RTC
and chronograph operations. Disabling the RTC module does not
affect the contents in the RTC registers. Reset clears the RTCE bit.
1 = RTC module enabled
0 = RTC module disabled
TBH — Timebase High Frequency Select
This read/write bit selects the timebase interrupt period for TB1 and
TB2. Reset clears the TBH bit.
1 = TB1 interrupt is 0.125s; TB2 interrupt is 0.0625s
0 = TB1 interrupt is 0.5s; TB2 interrupt is 0.25s
Data Sheet
236
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Real Time Clock (RTC)
RTC Registers
12.10.5 RTC Status Register (RTCSR)
The RTC status register contains eight status flags. When a flag is set
and the corresponding interrupt enable bit is also set, a CPU interrupt
request is generated.
Address: $0044
Read: ALMF
Write:
CHRF
0
DAYF
0
HRF
0
MINF
0
SECF
0
TB1F
0
TB2F
0
Reset:
0
= Unimplemented
Figure 12-10. RTC Status Register (RTCSR)
ALMF — Alarm Flag
This clearable, read-only bit is set when the value in the RTC hour and
minute counters matches the value in the alarm hour and alarm
minute registers. When the ALMIE bit in RTCCR1 is set, ALMF
generates a CPU interrupt request. In normal operation, clear the
ALMF bit by reading RTCSR with ALMF set and then reading the
alarm hour register (ALHR). Reset clears ALMF.
1 = RTC hour and minute counters matches the
alarm hour and minute registers
0 = No matching between hour and minute counters and alarm
hour and minute registers
CHRF — Chronograph Flag
This clearable, read-only bit is set on every tick of the chronograph
counter (every counter count). The tick is on every 1/128 seconds
(see 12.5.4 Chronograph Functions). When the CHRIE bit in
RTCCR1 is set, CHRF generates a CPU interrupt request. In normal
operation, clear the CHRF bit by reading RTCSR with CHRF set and
then reading the chronograph data register (CHRR). Reset clears
CHRF.
1 = A chronograph counter tick has occurred
0 = No chronograph counter tick has occurred
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
237
Real Time Clock (RTC)
Real Time Clock (RTC)
DAYF — Day Flag
This clearable, read-only bit is set on every increment of the day
counter. When the DAYIE bit in RTCCR1 is set, DAYF generates a
CPU interrupt request. In normal operation, clear the DAYF bit by
reading RTCSR with DAYF set and then reading the day register
(DAYR). Reset clears DAYF.
1 = Day counter incremented
0 = No day counter incremented
HRF — Hour Flag
This clearable, read-only bit is set on every increment of the hour
counter. When the HRIE bit in RTCCR1 is set, HRF generates a CPU
interrupt request. In normal operation, clear the HRF bit by reading
RTCSR with HRF set and then reading the hour register (HRR). Reset
clears HRF.
1 = Hour counter incremented
0 = No hour counter incremented
MINF — Minute Flag
This clearable, read-only bit is set on every increment of the minute
counter. When the MINIE bit in RTCCR1 is set, MINF generates a
CPU interrupt request. In normal operation, clear the MINF bit by
reading RTCSR with MINF set and then reading the minute register
(MINR). Reset clears MINF.
1 = Minute counter incremented
0 = No minute counter incremented
SECF — Second Flag
This clearable, read-only bit is set on every increment of the second
counter. When the SECIE bit in RTCCR1 is set, SECF generates a
CPU interrupt request. In normal operation, clear the SECF bit by
reading RTCSR with SECF set and then reading the second register
(SECR). Reset clears SECF.
1 = Second counter incremented
0 = No second counter incremented
Data Sheet
238
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Real Time Clock (RTC)
RTC Registers
TB1F — Timebase 1 Flag
This clearable, read-only bit is set on every tick of the timebase 1
counter (every 0.5 or 0.125 seconds). When the TB1IE bit in RTCCR1
is set, TB1F generates a CPU interrupt request. In normal operation,
clear the TB1F bit by reading RTCSR with TB1F set and then reading
the chronograph data register (CHRR). Reset clears TB1F.
1 = A timebase 1 tick has occurred
0 = No timebase 1 tick has occurred
NOTE: Timebase 1 is not synchronized to the compensated RTC 1-Hz clock.
Hence, time intervals for timebase ticks may not align with the RTC clock
and calendar register updates.
TB2F — Timebase 2 Flag
This clearable, read-only bit is set on every tick of the timebase 2
counter (every 0.25 or 0.0625 seconds). When the TB2IE bit in
RTCCR1 is set, TB2F generates a CPU interrupt request. In normal
operation, clear the TB2F bit by reading RTCSR with TB2F set and
then reading the chronograph register (CHRR). Reset clears TB2F.
1 = A timebase 2 tick has occurred
0 = No timebase 2 tick has occurred
NOTE: Timebase 2 is not synchronized to the compensated RTC 1-Hz clock.
Hence, time intervals for timebase ticks may not align with the RTC clock
and calendar register updates.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
239
Real Time Clock (RTC)
Real Time Clock (RTC)
12.10.6 Alarm Minute and Hour Registers (ALMR and ALHR)
These read/write registers contain the alarm minute and hour values for
the hour and minute alarm function. When the hour counter matches the
value in the alarm hour register (ALHR) and the minute counter matches
the value in the alarm minute register (ALMR), the alarm flag, ALMF, is
set. When ALMF is set and the alarm interrupt enable bit, ALMIE, is also
set, a CPU interrupt request is generated.
Address: $0045
Read:
Write:
Reset:
0
0
0
AM5
U
AM4
U
AM3
U
AM2
U
AM1
U
AM0
U
0
= Unimplemented
Figure 12-11. Alarm Minute Register (ALMR)
NOTE: Writing values other than 0 to 59, to ALMR is possible, but the alarm flag
will never be set.
Address: $0046
Read:
Write:
Reset:
0
0
0
0
0
AH4
U
AH3
U
AH2
U
AH1
U
AH0
U
0
= Unimplemented
Figure 12-12. Alarm Hour Register (ALHR)
NOTE: Writing values other than 0 to 23, to ALHR is possible, but the alarm flag
will never be set.
Data Sheet
240
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Real Time Clock (RTC)
RTC Registers
12.10.7 Second Register (SECR)
This read/write register contains the current value of the second counter.
This register can be read at any time without affecting the counter count.
Writing to this register loads the value to the second counter and the
counter continues to count from this new value.
The second counter rolls over to 0 ($00) after reaching 59 ($4B). Writing
a value other than 0 to 59 to this register has no effect.
Address: $0047
Read:
Write:
Reset:
0
0
0
SEC5
U
SEC4
U
SEC3
U
SEC2
U
SEC1
U
SEC0
U
0
= Unimplemented
This register is write-protected; unprotect by a write sequence to RTCWE[1:0] in RTCCOMR.
Figure 12-13. Second Register (SECR)
12.10.8 Minute Register (MINR)
This read/write register contains the current value of the minute counter.
This register can be read at any time without affecting the counter count.
Writing to this register loads the value to the minute counter and the
counter continues to count from this new value.
The minute counter rolls over to 0 ($00) after reaching 59 ($4B). Writing
a value other than 0 to 59 to this register has no effect.
Address: $0048
Read:
Write:
Reset:
0
0
0
MIN5
U
MIN4
U
MIN3
U
MIN2
U
MIN1
U
MIN0
U
0
= Unimplemented
This register is write-protected; unprotect by a write sequence to RTCWE[1:0] in RTCCOMR.
Figure 12-14. Minute Register (MINR)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
241
Real Time Clock (RTC)
Real Time Clock (RTC)
12.10.9 Hour Register (HRR)
This read/write register contains the current value of the hour counter.
This register can be read at any time without affecting the counter count.
Writing to this register loads the value to the hour counter and the
counter continues to count from this new value.
The hour counter rolls over to 0 ($00) after reaching 23 ($17). Writing a
value other than 0 to 23 to this register has no effect.
Address: $0049
Read:
Write:
Reset:
0
0
0
0
0
HR4
U
HR3
U
HR2
U
HR1
U
HR0
U
0
= Unimplemented
This register is write-protected; unprotect by a write sequence to RTCWE[1:0] in RTCCOMR.
Figure 12-15. Hour Register (HRR)
12.10.10 Day Register (DAYR)
This read/write register contains the current value of the day-of-month
counter. This register can be read at any time without affecting the
counter count. Writing to this register loads the value to the day counter
and the counter continues to count from this new value.
The day counter rolls over to 1 ($01) after reaching 28 ($1B), 29 ($1C),
30 ($1D), or 31 ($1E), depending on the value in the month and year
registers. Writing a value that is not valid for the month and year to this
register has no effect.
Address: $004A
Read:
Write:
Reset:
0
0
0
0
0
DAY4
U
DAY3
U
DAY2
U
DAY1
U
DAY0
U
0
= Unimplemented
This register is write-protected; unprotect by a write sequence to RTCWE[1:0] in RTCCOMR.
Figure 12-16. Day Register (DAYR)
Data Sheet
242
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Real Time Clock (RTC)
Real Time Clock (RTC)
RTC Registers
12.10.11 Month Register (MTHR)
This read/write register contains the current value of the month counter.
This register can be read at any time without affecting the counter count.
Writing to this register loads the value to the month counter and the
counter continues to count from this new value.
The month counter rolls over to 1 ($01) after reaching 12 ($0B). Writing
a value other than 1 to 12 to this register has no effect.
Address: $004B
Read:
Write:
Reset:
0
0
0
0
0
0
0
MTH3
U
MTH2
U
MTH1
U
MTH0
U
0
= Unimplemented
This register is write-protected; unprotect by a write sequence to RTCWE[1:0] in RTCCOMR.
Figure 12-17. Month Register (MTHR)
12.10.12 Year Register (YRR)
This read/write register contains the current value of the year counter.
This register can be read at any time without affecting the counter count.
Writing to this register loads the value to the year counter and the
counter continues to count from this new value.
The value stored in this register is a two’s complement representation of
the year, relative to 2000. For example, the year 2008 is represented
by 8 ($08), and the year 1979 is presented by –11 ($F5). The range of
this register is only valid for –99 to +99.
Address: $004C
Read:
YR7
YR6
U
YR5
U
YR4
U
YR3
U
YR2
U
YR1
U
YR0
U
Write:
Reset:
U
This register is write-protected; unprotect by a write sequence to RTCWE[1:0] in RTCCOMR.
Figure 12-18. Year Register (YRR)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
243
Real Time Clock (RTC)
Real Time Clock (RTC)
12.10.13 Day-Of-Week Register (DOWR)
This read/write register contains the current value of the day-of-week
counter. This register can be read at any time without affecting the
counter count. Writing to this register loads the value to the day-of-week
counter and the counter continues to count from this new value.
The day-of-week counter value rolls over to 0 ($00) after reaching 6
($06). Writing a value other than 0 to 6 to this register has no effect.
Address: $004D
Read:
Write:
Reset:
0
0
0
0
0
0
0
0
0
DOW2
U
DOW1
U
DOW0
U
0
= Unimplemented
This register is write-protected; unprotect by a write sequence to RTCWE[1:0] in RTCCOMR.
Figure 12-19. Day-Of-Week Register (DOWR)
12.10.14 Chronograph Data Register (CHRR)
This read-only chronograph data register contains the value in the
chronograph counter. Reset clears the chronograph data register.
Setting the chronograph counter reset bit (CHRCLR) also clears the
chronograph data register.
The chronograph data register has a resolution of 1/100 seconds. The
chronograph counter value rolls over to $00 after reaching $63.
Address: $004E
Read:
Write:
Reset:
0
CHR6
0
CHR5
0
CHR4
0
CHR3
0
CHR2
0
CHR1
0
CHR0
0
0
= Unimplemented
Figure 12-20. Chronograph Data Register (CHRR)
NOTE: The chronograph counter is not synchronized to the compensated RTC
1-Hz clock. Hence, chronograph ticks may not align with the RTC clock
and calendar register updates.
Data Sheet
244
MC68HC908LJ24/LK24 — Rev. 2.1
Real Time Clock (RTC)
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 13. Infrared Serial Communications
Interface Module (IRSCI)
13.1 Contents
13.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .246
13.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .247
13.4 Pin Name Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
13.5 IRSCI Module Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249
13.6 Infrared Functional Description. . . . . . . . . . . . . . . . . . . . . . . .250
13.6.1 Infrared Transmit Encoder . . . . . . . . . . . . . . . . . . . . . . . . .251
13.6.2 Infrared Receive Decoder . . . . . . . . . . . . . . . . . . . . . . . . .251
13.7 SCI Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . .252
13.7.1 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253
13.7.2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254
13.7.2.1
13.7.2.2
13.7.2.3
13.7.2.4
13.7.2.5
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .255
Character Transmission. . . . . . . . . . . . . . . . . . . . . . . . .255
Break Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .256
Idle Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .256
Transmitter Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . .257
13.7.3 Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .257
13.7.3.1
13.7.3.2
13.7.3.3
13.7.3.4
13.7.3.5
13.7.3.6
13.7.3.7
13.7.3.8
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .257
Character Reception . . . . . . . . . . . . . . . . . . . . . . . . . . .259
Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .259
Framing Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
Baud Rate Tolerance. . . . . . . . . . . . . . . . . . . . . . . . . . .261
Receiver Wakeup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .264
Receiver Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . .265
Error Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .265
13.8 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266
13.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266
13.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266
MC68HC908LJ24/LK24 — Rev. 2.1
Data Sheet
245
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Infrared Serial Communications
13.9 SCI During Break Module Interrupts. . . . . . . . . . . . . . . . . . . .267
13.10 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .267
13.10.1 PTB0/TxD (Transmit Data). . . . . . . . . . . . . . . . . . . . . . . . .267
13.10.2 PTB1/RxD (Receive Data) . . . . . . . . . . . . . . . . . . . . . . . . .267
13.11 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .268
13.11.1 SCI Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .269
13.11.2 SCI Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . .271
13.11.3 SCI Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . .274
13.11.4 SCI Status Register 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .276
13.11.5 SCI Status Register 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .280
13.11.6 SCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281
13.11.7 SCI Baud Rate Register. . . . . . . . . . . . . . . . . . . . . . . . . . .282
13.11.8 SCI Infrared Control Register. . . . . . . . . . . . . . . . . . . . . . .285
13.2 Introduction
This section describes the infrared serial communications interface
(IRSCI) module which allows high-speed asynchronous
communications with peripheral devices and other MCUs. This IRSCI
consists of an SCI module for conventional SCI functions and a software
programmable infrared encoder/decoder sub-module for
encoding/decoding the serial data for connection to infrared LEDs in
remote control applications.
NOTE: References to DMA (direct-memory access) and associated functions
are only valid if the MCU has a DMA module. This MCU does not have
the DMA function. Any DMA-related register bits should be left in their
reset state for normal MCU operation.
Data Sheet
246
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
Features
13.3 Features
Features of the SCI module include the following:
• Full duplex operation
• Standard mark/space non-return-to-zero (NRZ) format
• Programmable 8-bit or 9-bit character length
• Separately enabled transmitter and receiver
• Separate receiver and transmitter CPU interrupt requests
• Two receiver wakeup methods:
– Idle line wakeup
– Address mark wakeup
• Interrupt-driven operation with eight interrupt flags:
– Transmitter empty
– Transmission complete
– Receiver full
– Idle receiver input
– Receiver overrun
– Noise error
– Framing error
– Parity error
• Receiver framing error detection
• Hardware parity checking
• 1/16 bit-time noise detection
Features of the infrared (IR) sub-module include the following:
• IR sub-module enable/disable for infrared SCI or conventional SCI
on TxD and RxD pins
• Software selectable infrared modulation/demodulation
(3/16, 1/16 or 1/32 width pulses)
MC68HC908LJ24/LK24 — Rev. 2.1
Data Sheet
247
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Infrared Serial Communications
Addr.
Register Name
Bit 7
LOOPS
0
6
ENSCI
0
5
4
M
3
WAKE
0
2
ILTY
0
1
PEN
0
Bit 0
PTY
0
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
0
SCI Control Register 1
(SCC1)
$0013
0
SCRIE
0
0
SCTIE
TCIE
0
ILIE
0
TE
RE
0
RWU
0
SBK
0
SCI Control Register 2
(SCC2)
$0014
$0015
$0016
$0017
$0018
$0019
$001A
0
0
R8
T8
DMARE DMATE
ORIE
NEIE
FEIE
PEIE
SCI Control Register 3
(SCC3)
U
U
0
0
0
0
0
0
Read: SCTE
Write:
TC
SCRF
IDLE
OR
NF
FE
PE
SCI Status Register 1
(SCS1)
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
1
0
1
0
0
0
0
0
0
0
0
0
0
0
BKF
RPF
SCI Status Register 2
(SCS2)
0
0
0
0
0
0
0
0
R7
T7
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
R0
T0
SCI Data Register
(SCDR)
Unaffected by reset
0
CKS
0
SCP1
SCP0
R
0
SCR2
SCR1
0
SCR0
0
SCI Baud Rate Register
(SCBR)
0
0
0
0
0
0
0
TNP1
0
SCI Infrared Control
R
R
0
TNP0
IREN
0
Register Write:
(SCIRCR)
Reset:
0
0
0
0
0
= Unimplemented
R = Reserved
U = Unaffected
Figure 13-1. IRSCI I/O Registers Summary
Data Sheet
248
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
Pin Name Conventions
13.4 Pin Name Conventions
The generic names of the IRSCI I/O pins are:
• RxD (receive data)
• TxD (transmit data)
IRSCI I/O (input/output) lines are implemented by sharing parallel I/O
port pins. The full name of an IRSCI input or output reflects the name of
the shared port pin. Table 13-1 shows the full names and the generic
names of the IRSCI I/O pins.
The generic pin names appear in the text of this section.
Table 13-1. Pin Name Conventions
Generic Pin Names:
Full Pin Names:
RxD
TxD
PTB0/TxD
PTB1/RxD
13.5 IRSCI Module Overview
The IRSCI consists of a serial communications interface (SCI) and a
infrared interface sub-module as shown in Figure 13-2.
INTERNAL BUS
SCI_TxD
TxD
SERIAL
CGMXCLK
SCI_R32XCLK
SCI_R16XCLK
COMMUNICATIONS
INTERFACE MODULE
(SCI)
INFRARED
SUB-MODULE
BUS CLOCK
SCI_RxD
RxD
Figure 13-2. IRSCI Block Diagram
The SCI module provides serial data transmission and reception, with a
programmable baud rate clock based on the bus clock or the
CGMXCLK.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
249
Infrared Serial Communications
The infrared sub-module receives two clock sources from the SCI
module: SCI_R16XCLK and SCI_R32XCLK. Both reference clocks are
used to generate the narrow pulses during data transmission.
The SCI_R16XCLK and SCI_R32XCLK are internal clocks with
frequencies that are 16 and 32 times the baud rate respectively. Both
SCI_R16XCLK and SCI_R32XCLK clocks are used for transmitting
data. The SCI_R16XCLK clock is used only for receiving data.
NOTE: For proper SCI function (transmit or receive), the bus clock MUST be
programmed to at least 32 times that of the selected baud rate.
When the infrared sub-module is disabled, signals on the TxD and RxD
pins pass through unchanged to the SCI module.
13.6 Infrared Functional Description
Figure 13-3 shows the structure of the infrared sub-module.
TNP[1:0]
IREN
IR_TxD
TRANSMIT
ENCODER
SCI_TxD
TxD
RxD
MUX
SCI_R32XCLK
SCI_R16XCLK
IR_RxD
RECEIVE
DECODER
SCI_RxD
MUX
Figure 13-3. Infrared Sub-Module Diagram
The infrared sub-module provides the capability of transmitting narrow
pulses to an infrared LED and receiving narrow pulses and transforming
them to serial bits, which are sent to the SCI module. The infrared sub-
module receives two clocks from the SCI. One of these two clocks is
selected as the base clock to generate the 3/16, 1/16, or 1/32 bit width
narrow pulses during transmission.
Data Sheet
250
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
Infrared Functional Description
The sub-module consists of two main blocks: the transmit encoder and
the receive decoder. When transmitting data, the SCI data stream is
encoded by the infrared sub-module. For every "0" bit, a narrow "low"
pulse is transmitted; no pulse is transmitted for "1" bits. When receiving
data, the infrared pulses should be detected using an infrared photo
diode for conversion to CMOS voltage levels before connecting to the
RxD pin for the infrared decoder. The SCI data stream is reconstructed
by stretching the "0" pulses.
13.6.1 Infrared Transmit Encoder
The infrared transmit encoder converts the "0" bits in the serial data
stream from the SCI module to narrow "low" pulses, to the TxD pin. The
narrow pulse is sent with a duration of 1/32, 1/16, or 3/16 of a data bit
width. When two consecutive zeros are sent, the two consecutive narrow
pulses will be separated by a time equal to a data bit width.
DATA BIT WIDTH DETERMINED BY BAUD RATE
SCI DATA
INFRARED
SCI DATA
PULSE WIDTH = 1/32, 1/16, OR 3/16 DATA BIT WIDTH
Figure 13-4. Infrared SCI Data Example
13.6.2 Infrared Receive Decoder
The infrared receive decoder converts low narrow pulses from the RxD
pin to standard SCI data bits. The reference clock, SCI_R16XCLK,
clocks a four bit internal counter which counts from 0 to 15. An incoming
pulse starts the internal counter and a "0" is sent out to the IR_RxD
output. Subsequent incoming pulses are ignored when the counter count
is between 0 and 7; IR_RxD remains "0". Once the counter passes 7, an
incoming pulse will reset the counter; IR_RxD remains "0". When the
counter reaches 15, the IR_RxD output returns to "1", the counter stops
and waits for further pulses. A pulse is interpreted as jitter if it arrives
shortly after the counter reaches 15; IR_RxD remains "1".
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
251
Infrared Serial Communications
13.7 SCI Functional Description
Figure 13-5 shows the structure of the SCI.
INTERNAL BUS
SCI DATA
REGISTER
SCI DATA
REGISTER
RECEIVE
SHIFT REGISTER
TRANSMIT
SHIFT REGISTER
SCI_TxD
SCI_RxD
SCTIE
TCIE
SCRIE
ILIE
R8
T8
DMARE
DMATE
TE
SCTE
TC
RE
RWU
SBK
SCRF
IDLE
OR
NF
FE
PE
ORIE
NEIE
FEIE
PEIE
LOOPS
ENSCI
LOOPS
RECEIVE
CONTROL
FLAG
CONTROL
TRANSMIT
CONTROL
WAKEUP
CONTROL
M
BKF
RPF
CKS
SL
ENSCI
WAKE
ILTY
PEN
PTY
BAUD RATE
CGMXCLK
BUS CLOCK
A
X
GENERATOR
B
SL = 0 => X = A
SL = 1 => X = B
DATA SELECTION
CONTROL
÷16
SCI_R32XCLK
SCI_R16XCLK
Figure 13-5. SCI Module Block Diagram
Data Sheet
252
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
SCI Functional Description
The SCI allows full-duplex, asynchronous, NRZ serial communication
between the MCU and remote devices, including other MCUs. The
transmitter and receiver of the SCI operate independently, although they
use the same baud rate generator. During normal operation, the CPU
monitors the status of the SCI, writes the data to be transmitted, and
processes received data.
NOTE: For SCI operations, the IR sub-module is transparent to the SCI module.
Data at going out of the SCI transmitter and data going into the SCI
receiver is always in SCI format. It makes no difference to the SCI
module whether the IR sub-module is enabled or disabled.
NOTE: This SCI module is a standard HC08 SCI module with the following
modifications:
•
•
A control bit, CKS, is added to the SCI baud rate control register
to select between two input clocks for baud rate clock generation
The TXINV bit is removed from the SCI control register 1
13.7.1 Data Format
The SCI uses the standard non-return-to-zero mark/space data format
illustrated in Figure 13-6.
8-BIT DATA FORMAT
PARITY
BIT M IN SCC1 CLEAR
NEXT
START
BIT
BIT
START
BIT
STOP
BIT
BIT 0
BIT 0
BIT 1
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
9-BIT DATA FORMAT
BIT M IN SCC1 SET
PARITY
BIT
BIT 8
NEXT
START
BIT
START
BIT
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
STOP
BIT
Figure 13-6. SCI Data Formats
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
253
Infrared Serial Communications
13.7.2 Transmitter
Figure 13-7 shows the structure of the SCI transmitter.
The baud rate clock source for the SCI can be selected by the CKS bit,
in the SCI baud rate register (see 13.11.7 SCI Baud Rate Register).
CKS
SL
INTERNAL BUS
PRE-
BAUD
CGMXCLK
BUS CLOCK
A
÷
16
SCI DATA REGISTER
X
SCALER DIVIDER
B
SL = 0 => X = A
SL = 1 => X = B
SCP1
SCP0
SCR1
SCR2
SCR0
11-BIT
TRANSMIT
SHIFT REGISTER
H
8
7
6
5
4
3
2
1
0
L
SCI_TxD
M
PEN
PTY
PARITY
GENERATION
T8
DMATE
TRANSMITTER
CONTROL LOGIC
DMATE
SCTIE
SCTE
SCTE
SBK
DMATE
SCTE
SCTIE
LOOPS
ENSCI
TE
SCTIE
TC
TC
TCIE
TCIE
Figure 13-7. SCI Transmitter
Data Sheet
254
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
SCI Functional Description
13.7.2.1 Character Length
The transmitter can accommodate either 8-bit or 9-bit data. The state of
the M bit in SCI control register 1 (SCC1) determines character length.
When transmitting 9-bit data, bit T8 in SCI control register 3 (SCC3) is
the ninth bit (bit 8).
13.7.2.2 Character Transmission
During an SCI transmission, the transmit shift register shifts a character
out to the TxD pin. The SCI data register (SCDR) is the write-only buffer
between the internal data bus and the transmit shift register. To initiate
an SCI transmission:
1. Enable the SCI by writing a logic 1 to the enable SCI bit (ENSCI)
in SCI control register 1 (SCC1).
2. Enable the transmitter by writing a logic 1 to the transmitter enable
bit (TE) in SCI control register 2 (SCC2).
3. Clear the SCI transmitter empty bit by first reading SCI status
register 1 (SCS1) and then writing to the SCDR.
4. Repeat step 3 for each subsequent transmission.
At the start of a transmission, transmitter control logic automatically
loads the transmit shift register with a preamble of logic 1s. After the
preamble shifts out, control logic transfers the SCDR data into the
transmit shift register. A logic 0 start bit automatically goes into the least
significant bit position of the transmit shift register. A logic 1 stop bit goes
into the most significant bit position.
The SCI transmitter empty bit, SCTE, in SCS1 becomes set when the
SCDR transfers a byte to the transmit shift register. The SCTE bit
indicates that the SCDR can accept new data from the internal data bus.
If the SCI transmit interrupt enable bit, SCTIE, in SCC2 is also set, the
SCTE bit generates a transmitter interrupt request.
When the transmit shift register is not transmitting a character, the TxD
pin goes to the idle condition, logic 1. If at any time software clears the
ENSCI bit in SCI control register 1 (SCC1), the transmitter and receiver
relinquish control of the port pins.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
255
Infrared Serial Communications
13.7.2.3 Break Characters
Writing a logic 1 to the send break bit, SBK, in SCC2 loads the transmit
shift register with a break character. A break character contains all logic
0s and has no start, stop, or parity bit. Break character length depends
on the M bit in SCC1. As long as SBK is at logic 1, transmitter logic
continuously loads break characters into the transmit shift register. After
software clears the SBK bit, the shift register finishes transmitting the
last break character and then transmits at least one logic 1. The
automatic logic 1 at the end of a break character guarantees the
recognition of the start bit of the next character.
The SCI recognizes a break character when a start bit is followed by
eight or nine logic 0 data bits and a logic 0 where the stop bit should be.
Receiving a break character has the following effects on SCI registers:
• Sets the framing error bit (FE) in SCS1
• Sets the SCI receiver full bit (SCRF) in SCS1
• Clears the SCI data register (SCDR)
• Clears the R8 bit in SCC3
• Sets the break flag bit (BKF) in SCS2
• May set the overrun (OR), noise flag (NF), parity error (PE), or
reception in progress flag (RPF) bits
13.7.2.4 Idle Characters
An idle character contains all logic 1s and has no start, stop, or parity bit.
Idle character length depends on the M bit in SCC1. The preamble is a
synchronizing idle character that begins every transmission.
If the TE bit is cleared during a transmission, the TxD pin becomes idle
after completion of the transmission in progress. Clearing and then
setting the TE bit during a transmission queues an idle character to be
sent after the character currently being transmitted.
Data Sheet
256
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
SCI Functional Description
NOTE: When queueing an idle character, return the TE bit to logic 1 before the
stop bit of the current character shifts out to the TxD pin. Setting TE after
the stop bit appears on TxD causes data previously written to the SCDR
to be lost.
Toggle the TE bit for a queued idle character when the SCTE bit
becomes set and just before writing the next byte to the SCDR.
13.7.2.5 Transmitter Interrupts
The following conditions can generate CPU interrupt requests from the
SCI transmitter:
• SCI transmitter empty (SCTE) — The SCTE bit in SCS1 indicates
that the SCDR has transferred a character to the transmit shift
register. SCTE can generate a transmitter CPU interrupt request.
Setting the SCI transmit interrupt enable bit, SCTIE, in SCC2
enables the SCTE bit to generate transmitter CPU interrupt
requests.
• Transmission complete (TC) — The TC bit in SCS1 indicates that
the transmit shift register and the SCDR are empty and that no
break or idle character has been generated. The transmission
complete interrupt enable bit, TCIE, in SCC2 enables the TC bit to
generate transmitter CPU interrupt requests.
13.7.3 Receiver
Figure 13-8 shows the structure of the SCI receiver.
13.7.3.1 Character Length
The receiver can accommodate either 8-bit or 9-bit data. The state of the
M bit in SCI control register 1 (SCC1) determines character length.
When receiving 9-bit data, bit R8 in SCI control register 2 (SCC2) is the
ninth bit (bit 8). When receiving 8-bit data, bit R8 is a copy of the eighth
bit (bit 7).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
257
Infrared Serial Communications
INTERNAL BUS
SCR1
SCR2
SCR0
CKS
SL
SCP1
SCP0
SCI DATA REGISTER
PRE-
BAUD
CGMXCLK
BUS CLOCK
A
÷
16
X
SCALER DIVIDER
B
11-BIT
RECEIVE SHIFT REGISTER
SL = 0 => X = A
SL = 1 => X = B
DATA
RECOVERY
H
8
7
6
5
4
3
2
1
0
L
SCI_RxD
ALL 0s
BKF
RPF
M
RWU
SCRF
IDLE
WAKE
ILTY
WAKEUP
LOGIC
PEN
PTY
R8
PARITY
CHECKING
IDLE
ILIE
DMARE
ILIE
SCRF
SCRIE
DMARE
SCRIE
SCRF
SCRIE
DMARE
DMARE
OR
OR
ORIE
ORIE
NF
NF
NEIE
NEIE
FE
FE
FEIE
FEIE
PE
PE
PEIE
PEIE
Figure 13-8. SCI Receiver Block Diagram
Data Sheet
258
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
SCI Functional Description
13.7.3.2 Character Reception
During an SCI reception, the receive shift register shifts characters in
from the RxD pin. The SCI data register (SCDR) is the read-only buffer
between the internal data bus and the receive shift register.
After a complete character shifts into the receive shift register, the data
portion of the character transfers to the SCDR. The SCI receiver full bit,
SCRF, in SCI status register 1 (SCS1) becomes set, indicating that the
received byte can be read. If the SCI receive interrupt enable bit, SCRIE,
in SCC2 is also set, the SCRF bit generates a receiver CPU interrupt
request.
13.7.3.3 Data Sampling
The receiver samples the RxD pin at the RT clock rate. The RT clock is
an internal signal with a frequency 16 times the baud rate. To adjust for
baud rate mismatch, the RT clock is resynchronized at the following
times (see Figure 13-9):
• After every start bit
• After the receiver detects a data bit change from logic 1 to logic 0
(after the majority of data bit samples at RT8, RT9, and RT10
returns a valid logic 1 and the majority of the next RT8, RT9, and
RT10 samples returns a valid logic 0)
START BIT
LSB
SCI_RxD
START BIT
START BIT
DATA
SAMPLES
QUALIFICATION
VERIFICATION
SAMPLING
RT
CLOCK
RT CLOCK
STATE
RT CLOCK
RESET
Figure 13-9. Receiver Data Sampling
MC68HC908LJ24/LK24 — Rev. 2.1
Data Sheet
259
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Infrared Serial Communications
To locate the start bit, data recovery logic does an asynchronous search
for a logic 0 preceded by three logic 1s. When the falling edge of a
possible start bit occurs, the RT clock begins to count to 16.
To verify the start bit and to detect noise, data recovery logic takes
samples at RT3, RT5, and RT7. Table 13-2 summarizes the results of
the start bit verification samples.
Table 13-2. Start Bit Verification
RT3, RT5, and RT7
Samples
Start Bit
Verification
Noise Flag
000
001
010
011
100
101
110
111
Yes
Yes
Yes
No
0
1
1
0
1
0
0
0
Yes
No
No
No
If start bit verification is not successful, the RT clock is reset and a new
search for a start bit begins.
To determine the value of a data bit and to detect noise, recovery logic
takes samples at RT8, RT9, and RT10. Table 13-3 summarizes the
results of the data bit samples.
Table 13-3. Data Bit Recovery
RT8, RT9, and RT10
Samples
Data Bit
Determination
Noise Flag
000
001
010
011
100
101
110
111
0
0
0
1
0
1
1
1
0
1
1
1
1
1
1
0
Data Sheet
260
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
SCI Functional Description
NOTE: The RT8, RT9, and RT10 samples do not affect start bit verification. If
any or all of the RT8, RT9, and RT10 start bit samples are logic 1s
following a successful start bit verification, the noise flag (NF) is set and
the receiver assumes that the bit is a start bit.
To verify a stop bit and to detect noise, recovery logic takes samples at
RT8, RT9, and RT10. Table 13-4 summarizes the results of the stop bit
samples.
Table 13-4. Stop Bit Recovery
RT8, RT9, and RT10
Samples
Framing
Error Flag
Noise Flag
000
001
010
011
100
101
110
111
1
1
1
0
1
0
0
0
0
1
1
1
1
1
1
0
13.7.3.4 Framing Errors
If the data recovery logic does not detect a logic 1 where the stop bit
should be in an incoming character, it sets the framing error bit, FE, in
SCS1. The FE flag is set at the same time that the SCRF bit is set. A
break character that has no stop bit also sets the FE bit.
13.7.3.5 Baud Rate Tolerance
A transmitting device may be operating at a baud rate below or above
the receiver baud rate. Accumulated bit time misalignment can cause
one of the three stop bit data samples to fall outside the actual stop bit.
Then a noise error occurs. If more than one of the samples is outside the
stop bit, a framing error occurs. In most applications, the baud rate
tolerance is much more than the degree of misalignment that is likely to
occur.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
261
Infrared Serial Communications
As the receiver samples an incoming character, it resynchronizes the RT
clock on any valid falling edge within the character. Resynchronization
within characters corrects misalignments between transmitter bit times
and receiver bit times.
Slow Data Tolerance
Figure 13-10 shows how much a slow received character can be
misaligned without causing a noise error or a framing error. The slow
stop bit begins at RT8 instead of RT1 but arrives in time for the stop bit
data samples at RT8, RT9, and RT10.
MSB
STOP
RECEIVER
RT CLOCK
DATA
SAMPLES
Figure 13-10. Slow Data
For an 8-bit character, data sampling of the stop bit takes the receiver
9 bit times × 16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in Figure 13-10, the receiver
counts 154 RT cycles at the point when the count of the transmitting
device is 9 bit times × 16 RT cycles + 3 RT cycles = 147 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a slow 8-bit character with no errors is
154 – 147
× 100 = 4.54%
-------------------------
154
For a 9-bit character, data sampling of the stop bit takes the receiver
10 bit times × 16 RT cycles + 10 RT cycles = 170 RT cycles.
With the misaligned character shown in Figure 13-10, the receiver
counts 170 RT cycles at the point when the count of the transmitting
device is 10 bit times × 16 RT cycles + 3 RT cycles = 163 RT cycles.
Data Sheet
262
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
SCI Functional Description
The maximum percent difference between the receiver count and the
transmitter count of a slow 9-bit character with no errors is
170 – 163
× 100 = 4.12%
-------------------------
170
Fast Data Tolerance
Figure 13-11 shows how much a fast received character can be
misaligned without causing a noise error or a framing error. The fast stop
bit ends at RT10 instead of RT16 but is still there for the stop bit data
samples at RT8, RT9, and RT10.
STOP
IDLE OR NEXT CHARACTER
RECEIVER
RT CLOCK
DATA
SAMPLES
Figure 13-11. Fast Data
For an 8-bit character, data sampling of the stop bit takes the receiver
9 bit times × 16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in Figure 13-11, the receiver
counts 154 RT cycles at the point when the count of the transmitting
device is 10 bit times × 16 RT cycles = 160 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a fast 8-bit character with no errors is
·
154 – 160
× 100 = 3.90%
-------------------------
154
For a 9-bit character, data sampling of the stop bit takes the receiver
10 bit times × 16 RT cycles + 10 RT cycles = 170 RT cycles.
With the misaligned character shown in Figure 13-11, the receiver
counts 170 RT cycles at the point when the count of the transmitting
device is 11 bit times × 16 RT cycles = 176 RT cycles.
MC68HC908LJ24/LK24 — Rev. 2.1
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Data Sheet
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Infrared Serial Communications
The maximum percent difference between the receiver count and the
transmitter count of a fast 9-bit character with no errors is
170 – 176
× 100 = 3.53%
-------------------------
170
13.7.3.6 Receiver Wakeup
So that the MCU can ignore transmissions intended only for other
receivers in multiple-receiver systems, the receiver can be put into a
standby state. Setting the receiver wakeup bit, RWU, in SCC2 puts the
receiver into a standby state during which receiver interrupts are
disabled.
Depending on the state of the WAKE bit in SCC1, either of two
conditions on the RxD pin can bring the receiver out of the standby state:
• Address mark — An address mark is a logic 1 in the most
significant bit position of a received character. When the WAKE bit
is set, an address mark wakes the receiver from the standby state
by clearing the RWU bit. The address mark also sets the SCI
receiver full bit, SCRF. Software can then compare the character
containing the address mark to the user-defined address of the
receiver. If they are the same, the receiver remains awake and
processes the characters that follow. If they are not the same,
software can set the RWU bit and put the receiver back into the
standby state.
• Idle input line condition — When the WAKE bit is clear, an idle
character on the RxD pin wakes the receiver from the standby
state by clearing the RWU bit. The idle character that wakes the
receiver does not set the receiver idle bit, IDLE, or the SCI receiver
full bit, SCRF. The idle line type bit, ILTY, determines whether the
receiver begins counting logic 1s as idle character bits after the
start bit or after the stop bit.
NOTE: Clearing the WAKE bit after the RxD pin has been idle may cause the
receiver to wake up immediately.
Data Sheet
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Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
SCI Functional Description
13.7.3.7 Receiver Interrupts
The following sources can generate CPU interrupt requests from the SCI
receiver:
• SCI receiver full (SCRF) — The SCRF bit in SCS1 indicates that
the receive shift register has transferred a character to the SCDR.
SCRF can generate a receiver interrupt request. Setting the SCI
receive interrupt enable bit, SCRIE, in SCC2 enables the SCRF bit
to generate receiver CPU interrupts.
• Idle input (IDLE) — The IDLE bit in SCS1 indicates that 10 or 11
consecutive logic 1s shifted in from the RxD pin. The idle line
interrupt enable bit, ILIE, in SCC2 enables the IDLE bit to generate
CPU interrupt requests.
13.7.3.8 Error Interrupts
The following receiver error flags in SCS1 can generate CPU interrupt
requests:
• Receiver overrun (OR) — The OR bit indicates that the receive
shift register shifted in a new character before the previous
character was read from the SCDR. The previous character
remains in the SCDR, and the new character is lost. The overrun
interrupt enable bit, ORIE, in SCC3 enables OR to generate SCI
error CPU interrupt requests.
• Noise flag (NF) — The NF bit is set when the SCI detects noise on
incoming data or break characters, including start, data, and stop
bits. The noise error interrupt enable bit, NEIE, in SCC3 enables
NF to generate SCI error CPU interrupt requests.
• Framing error (FE) — The FE bit in SCS1 is set when a logic 0
occurs where the receiver expects a stop bit. The framing error
interrupt enable bit, FEIE, in SCC3 enables FE to generate SCI
error CPU interrupt requests.
• Parity error (PE) — The PE bit in SCS1 is set when the SCI
detects a parity error in incoming data. The parity error interrupt
enable bit, PEIE, in SCC3 enables PE to generate SCI error CPU
interrupt requests.
MC68HC908LJ24/LK24 — Rev. 2.1
Data Sheet
265
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Infrared Serial Communications
13.8 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
13.8.1 Wait Mode
The SCI module remains active after the execution of a WAIT
instruction. In wait mode, the SCI module registers are not accessible by
the CPU. Any enabled CPU interrupt request from the SCI module can
bring the MCU out of wait mode.
If SCI module functions are not required during wait mode, reduce power
consumption by disabling the module before executing the WAIT
instruction.
Refer to 9.7 Low-Power Modes for information on exiting wait mode.
13.8.2 Stop Mode
The SCI module is inactive after the execution of a STOP instruction.
The STOP instruction does not affect SCI register states. SCI module
operation resumes after an external interrupt.
Because the internal clock is inactive during stop mode, entering stop
mode during an SCI transmission or reception results in invalid data.
Refer to 9.7 Low-Power Modes for information on exiting stop mode.
Data Sheet
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Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
SCI During Break Module Interrupts
13.9 SCI During Break Module Interrupts
The system integration module (SIM) controls whether status bits in other
modules can be cleared during interrupts generated by the break
module. The BCFE bit in the SIM break flag control register (SBFCR)
enables software to clear status bits during the break state.
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
I/O registers during the break state without affecting status bits. Some
status bits have a two-step read/write clearing procedure. If software
does the first step on such a bit before the break, the bit cannot change
during the break state as long as BCFE is at logic 0. After the break,
doing the second step clears the status bit.
13.10 I/O Signals
The two IRSCI I/O pins are:
• PTB0/TxD — Transmit data
• PTB1/RxD — Receive data
13.10.1 PTB0/TxD (Transmit Data)
The PTB0/TxD pin is the serial data (standard or infrared) output from
the SCI transmitter. The IRSCI shares the PTB0/TxD pin with port B.
When the IRSCI is enabled, the PTB0/TxD pin is an output regardless of
the state of the DDRB0 bit in data direction register B (DDRB). TxD pin
has high current (15mA) sink capability when the LEDB0 bit is set in the
port B LED control register ($000C).
13.10.2 PTB1/RxD (Receive Data)
The PTB1/RxD pin is the serial data input to the IRSCI receiver. The
IRSCI shares the PTB1/RxD pin with port B. When the IRSCI is enabled,
the PTB1/RxD pin is an input regardless of the state of the DDRB1 bit in
data direction register B (DDRB).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
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Infrared Serial Communications
Table 13-5 shows a summary of I/O pin functions when the SCI is
enabled.
Table 13-5. SCI Pin Functions (Standard and Infrared)
SCC1
[ENSCI]
SCIRCR
[IREN]
SCC2
[TE]
SCC2
[RE]
TxD Pin
RxD Pin
(1)
(1)
1
0
0
0
Input ignored (terminate externally)
Hi-Z
1
1
1
1
0
0
0
1
0
1
1
0
1
0
1
0
Input sampled, pin should idle high
Input ignored (terminate externally)
Input sampled, pin should idle high
Input ignored (terminate externally)
Hi-Z
Output SCI (idle high)
Output SCI (idle high)
(1)
Hi-Z
(1)
1
1
1
1
X
0
1
1
X
1
0
1
X
Input sampled, pin should idle high
Hi-Z
1
Output IR SCI (idle high) Input ignored (terminate externally)
Output IR SCI (idle high) Input sampled, pin should idle high
Pins under port control (standard I/O port)
1
0
Notes:
1. After completion of transmission in progress.
13.11 I/O Registers
The following I/O registers control and monitor SCI operation:
• SCI control register 1 (SCC1)
• SCI control register 2 (SCC2)
• SCI control register 3 (SCC3)
• SCI status register 1 (SCS1)
• SCI status register 2 (SCS2)
• SCI data register (SCDR)
• SCI baud rate register (SCBR)
• SCI infrared control register (SCIRCR)
Data Sheet
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MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
13.11.1 SCI Control Register 1
SCI control register 1:
• Enables loop mode operation
• Enables the SCI
• Controls output polarity
• Controls character length
• Controls SCI wakeup method
• Controls idle character detection
• Enables parity function
• Controls parity type
Address: $0013
Bit 7
6
ENSCI
0
5
0
4
M
0
3
WAKE
0
2
ILTY
0
1
PEN
0
Bit 0
PTY
0
Read:
Write:
Reset:
LOOPS
0
0
Figure 13-12. SCI Control Register 1 (SCC1)
LOOPS — Loop Mode Select Bit
This read/write bit enables loop mode operation for the SCI only. In
loop mode the RxD pin is disconnected from the SCI, and the
transmitter output goes into the receiver input. Both the transmitter
and the receiver must be enabled to use loop mode. The infrared
encoder/decoder is not in the loop. Reset clears the LOOPS bit.
1 = Loop mode enabled
0 = Normal operation enabled
ENSCI — Enable SCI Bit
This read/write bit enables the SCI and the SCI baud rate generator.
Clearing ENSCI sets the SCTE and TC bits in SCI status register 1
and disables transmitter interrupts. Reset clears the ENSCI bit.
1 = SCI enabled
0 = SCI disabled
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Infrared Serial Communications
M — Mode (Character Length) Bit
This read/write bit determines whether SCI characters are eight or
nine bits long. (See Table 13-6.) The ninth bit can serve as an extra
stop bit, as a receiver wakeup signal, or as a parity bit. Reset clears
the M bit.
1 = 9-bit SCI characters
0 = 8-bit SCI characters
WAKE — Wakeup Condition Bit
This read/write bit determines which condition wakes up the SCI: a
logic 1 (address mark) in the most significant bit position of a received
character or an idle condition on the RxD pin. Reset clears the WAKE
bit.
1 = Address mark wakeup
0 = Idle line wakeup
ILTY — Idle Line Type Bit
This read/write bit determines when the SCI starts counting logic 1s
as idle character bits. The counting begins either after the start bit or
after the stop bit. If the count begins after the start bit, then a string of
logic 1s preceding the stop bit may cause false recognition of an idle
character. Beginning the count after the stop bit avoids false idle
character recognition, but requires properly synchronized
transmissions. Reset clears the ILTY bit.
1 = Idle character bit count begins after stop bit
0 = Idle character bit count begins after start bit
PEN — Parity Enable Bit
This read/write bit enables the SCI parity function. (See Table 13-6.)
When enabled, the parity function inserts a parity bit in the most
significant bit position. (See Figure 13-6.) Reset clears the PEN bit.
1 = Parity function enabled
0 = Parity function disabled
Data Sheet
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Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
PTY — Parity Bit
This read/write bit determines whether the SCI generates and checks
for odd parity or even parity. (See Table 13-6.) Reset clears the PTY
bit.
1 = Odd parity
0 = Even parity
NOTE: Changing the PTY bit in the middle of a transmission or reception can
generate a parity error.
Table 13-6. Character Format Selection
Control Bits
PEN:PTY
Character Format
Start
Bits
Data
Bits
Stop
Parity
Character
Length
M
Bits
0
1
0
0
1
1
0X
0X
10
11
10
11
1
1
1
1
1
1
8
9
7
7
8
8
None
None
Even
Odd
1
1
1
1
1
1
10 bits
11 bits
10 bits
10 bits
11 bits
11 bits
Even
Odd
13.11.2 SCI Control Register 2
SCI control register 2:
• Enables the following CPU interrupt requests:
– Enables the SCTE bit to generate transmitter CPU interrupt
requests
– Enables the TC bit to generate transmitter CPU interrupt
requests
– Enables the SCRF bit to generate receiver CPU interrupt
requests
– Enables the IDLE bit to generate receiver CPU interrupt
requests
• Enables the transmitter
• Enables the receiver
• Enables SCI wakeup
• Transmits SCI break characters
MC68HC908LJ24/LK24 — Rev. 2.1
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Infrared Serial Communications
Address: $0014
Bit 7
6
TCIE
0
5
SCRIE
0
4
ILIE
0
3
TE
0
2
RE
0
1
RWU
0
Bit 0
SBK
0
Read:
SCTIE
Write:
Reset:
0
Figure 13-13. SCI Control Register 2 (SCC2)
SCTIE — SCI Transmit Interrupt Enable Bit
This read/write bit enables the SCTE bit to generate SCI transmitter
CPU interrupt requests. Reset clears the SCTIE bit.
1 = SCTE enabled to generate CPU interrupt
0 = SCTE not enabled to generate CPU interrupt
TCIE — Transmission Complete Interrupt Enable Bit
This read/write bit enables the TC bit to generate SCI transmitter CPU
interrupt requests. Reset clears the TCIE bit.
1 = TC enabled to generate CPU interrupt requests
0 = TC not enabled to generate CPU interrupt requests
SCRIE — SCI Receive Interrupt Enable Bit
This read/write bit enables the SCRF bit to generate SCI receiver
CPU interrupt requests. Reset clears the SCRIE bit.
1 = SCRF enabled to generate CPU interrupt
0 = SCRF not enabled to generate CPU interrupt
ILIE — Idle Line Interrupt Enable Bit
This read/write bit enables the IDLE bit to generate SCI receiver CPU
interrupt requests. Reset clears the ILIE bit.
1 = IDLE enabled to generate CPU interrupt requests
0 = IDLE not enabled to generate CPU interrupt requests
TE — Transmitter Enable Bit
Setting this read/write bit begins the transmission by sending a
preamble of 10 or 11 logic 1s from the transmit shift register to the
TxD pin. If software clears the TE bit, the transmitter completes any
transmission in progress before the TxD returns to the idle condition
Data Sheet
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Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
(logic 1). Clearing and then setting TE during a transmission queues
an idle character to be sent after the character currently being
transmitted. Reset clears the TE bit.
1 = Transmitter enabled
0 = Transmitter disabled
NOTE: Writing to the TE bit is not allowed when the enable SCI bit (ENSCI) is
clear. ENSCI is in SCI control register 1.
RE — Receiver Enable Bit
Setting this read/write bit enables the receiver. Clearing the RE bit
disables the receiver but does not affect receiver interrupt flag bits.
Reset clears the RE bit.
1 = Receiver enabled
0 = Receiver disabled
NOTE: Writing to the RE bit is not allowed when the enable SCI bit (ENSCI) is
clear. ENSCI is in SCI control register 1.
RWU — Receiver Wakeup Bit
This read/write bit puts the receiver in a standby state during which
receiver interrupts are disabled. The WAKE bit in SCC1 determines
whether an idle input or an address mark brings the receiver out of the
standby state and clears the RWU bit. Reset clears the RWU bit.
1 = Standby state
0 = Normal operation
SBK — Send Break Bit
Setting and then clearing this read/write bit transmits a break
character followed by a logic 1. The logic 1 after the break character
guarantees recognition of a valid start bit. If SBK remains set, the
transmitter continuously transmits break characters with no logic 1s
between them. Reset clears the SBK bit.
1 = Transmit break characters
0 = No break characters being transmitted
NOTE: Do not toggle the SBK bit immediately after setting the SCTE bit.
Toggling SBK before the preamble begins causes the SCI to send a
break character instead of a preamble.
MC68HC908LJ24/LK24 — Rev. 2.1
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Data Sheet
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Infrared Serial Communications
13.11.3 SCI Control Register 3
SCI control register 3:
• Stores the ninth SCI data bit received and the ninth SCI data bit to
be transmitted
• Enables the following interrupts:
– Receiver overrun interrupts
– Noise error interrupts
– Framing error interrupts
– Parity error interrupts
Address: $0015
Bit 7
R8
6
T8
U
5
4
3
ORIE
0
2
NEIE
0
1
FEIE
0
Bit 0
PEIE
0
Read:
Write:
Reset:
DMARE DMATE
U
0
0
= Unimplemented
U = Unaffected
Figure 13-14. SCI Control Register 3 (SCC3)
R8 — Received Bit 8
When the SCI is receiving 9-bit characters, R8 is the read-only ninth
bit (bit 8) of the received character. R8 is received at the same time
that the SCDR receives the other 8 bits.
When the SCI is receiving 8-bit characters, R8 is a copy of the eighth
bit (bit 7). Reset has no effect on the R8 bit.
T8 — Transmitted Bit 8
When the SCI is transmitting 9-bit characters, T8 is the read/write
ninth bit (bit 8) of the transmitted character. T8 is loaded into the
transmit shift register at the same time that the SCDR is loaded into
the transmit shift register. Reset has no effect on the T8 bit.
Data Sheet
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MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
DMARE — DMA Receive Enable Bit
CAUTION: The DMA module is not included on this MCU. Writing a logic 1 to
DMARE or DMATE may adversely affect MCU performance.
1 = DMA not enabled to service SCI receiver DMA service requests
generated by the SCRF bit (SCI receiver CPU interrupt
requests enabled)
0 = DMA not enabled to service SCI receiver DMA service requests
generated by the SCRF bit (SCI receiver CPU interrupt
requests enabled)
DMATE — DMA Transfer Enable Bit
CAUTION: The DMA module is not included on this MCU. Writing a logic 1 to
DMARE or DMATE may adversely affect MCU performance.
1 = SCTE DMA service requests enabled; SCTE CPU interrupt
requests disabled
0 = SCTE DMA service requests disabled; SCTE CPU interrupt
requests enabled
ORIE — Receiver Overrun Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the receiver overrun bit, OR. Reset clears ORIE.
1 = SCI error CPU interrupt requests from OR bit enabled
0 = SCI error CPU interrupt requests from OR bit disabled
NEIE — Receiver Noise Error Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the noise error bit, NE. Reset clears NEIE.
1 = SCI error CPU interrupt requests from NE bit enabled
0 = SCI error CPU interrupt requests from NE bit disabled
FEIE — Receiver Framing Error Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the framing error bit, FE. Reset clears FEIE.
1 = SCI error CPU interrupt requests from FE bit enabled
0 = SCI error CPU interrupt requests from FE bit disabled
MC68HC908LJ24/LK24 — Rev. 2.1
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Data Sheet
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Infrared Serial Communications
PEIE — Receiver Parity Error Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt
requests generated by the parity error bit, PE. (See 13.11.4 SCI
Status Register 1.) Reset clears PEIE.
1 = SCI error CPU interrupt requests from PE bit enabled
0 = SCI error CPU interrupt requests from PE bit disabled
13.11.4 SCI Status Register 1
SCI status register 1 contains flags to signal these conditions:
• Transfer of SCDR data to transmit shift register complete
• Transmission complete
• Transfer of receive shift register data to SCDR complete
• Receiver input idle
• Receiver overrun
• Noisy data
• Framing error
• Parity error
Address: $0016
Bit 7
Read: SCTE
Write:
6
5
4
3
2
1
Bit 0
PE
TC
SCRF
IDLE
OR
NF
FE
Reset:
1
1
0
0
0
0
0
0
= Unimplemented
Figure 13-15. SCI Status Register 1 (SCS1)
SCTE — SCI Transmitter Empty Bit
This clearable, read-only bit is set when the SCDR transfers a
character to the transmit shift register. SCTE can generate an SCI
transmitter CPU interrupt request. When the SCTIE bit in SCC2 is set,
SCTE generates an SCI transmitter CPU interrupt request. In normal
Data Sheet
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Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
operation, clear the SCTE bit by reading SCS1 with SCTE set and
then writing to SCDR. Reset sets the SCTE bit.
1 = SCDR data transferred to transmit shift register
0 = SCDR data not transferred to transmit shift register
TC — Transmission Complete Bit
This read-only bit is set when the SCTE bit is set, and no data,
preamble, or break character is being transmitted. TC generates an
SCI transmitter CPU interrupt request if the TCIE bit in SCC2 is also
set. TC is automatically cleared when data, preamble or break is
queued and ready to be sent. There may be up to 1.5 transmitter
clocks of latency between queueing data, preamble, and break and
the transmission actually starting. Reset sets the TC bit.
1 = No transmission in progress
0 = Transmission in progress
SCRF — SCI Receiver Full Bit
This clearable, read-only bit is set when the data in the receive shift
register transfers to the SCI data register. SCRF can generate an SCI
receiver CPU interrupt request. When the SCRIE bit in SCC2 is set,
SCRF generates a CPU interrupt request. In normal operation, clear
the SCRF bit by reading SCS1 with SCRF set and then reading the
SCDR. Reset clears SCRF.
1 = Received data available in SCDR
0 = Data not available in SCDR
IDLE — Receiver Idle Bit
This clearable, read-only bit is set when 10 or 11 consecutive logic 1s
appear on the receiver input. IDLE generates an SCI receiver CPU
interrupt request if the ILIE bit in SCC2 is also set. Clear the IDLE bit
by reading SCS1 with IDLE set and then reading the SCDR. After the
receiver is enabled, it must receive a valid character that sets the
SCRF bit before an idle condition can set the IDLE bit. Also, after the
IDLE bit has been cleared, a valid character must again set the SCRF
bit before an idle condition can set the IDLE bit. Reset clears the IDLE
bit.
1 = Receiver input idle
0 = Receiver input active (or idle since the IDLE bit was cleared)
MC68HC908LJ24/LK24 — Rev. 2.1
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Infrared Serial Communications
OR — Receiver Overrun Bit
This clearable, read-only bit is set when software fails to read the
SCDR before the receive shift register receives the next character.
The OR bit generates an SCI error CPU interrupt request if the ORIE
bit in SCC3 is also set. The data in the shift register is lost, but the data
already in the SCDR is not affected. Clear the OR bit by reading SCS1
with OR set and then reading the SCDR. Reset clears the OR bit.
1 = Receive shift register full and SCRF = 1
0 = No receiver overrun
Software latency may allow an overrun to occur between reads of
SCS1 and SCDR in the flag-clearing sequence. Figure 13-16 shows
the normal flag-clearing sequence and an example of an overrun
caused by a delayed flag-clearing sequence. The delayed read of
SCDR does not clear the OR bit because OR was not set when SCS1
was read. Byte 2 caused the overrun and is lost. The next flag-
clearing sequence reads byte 3 in the SCDR instead of byte 2.
In applications that are subject to software latency or in which it is
important to know which byte is lost due to an overrun, the flag-
clearing routine can check the OR bit in a second read of SCS1 after
reading the data register.
NF — Receiver Noise Flag Bit
This clearable, read-only bit is set when the SCI detects noise on the
RxD pin. NF generates an SCI error CPU interrupt request if the NEIE
bit in SCC3 is also set. Clear the NF bit by reading SCS1 and then
reading the SCDR. Reset clears the NF bit.
1 = Noise detected
0 = No noise detected
FE — Receiver Framing Error Bit
This clearable, read-only bit is set when a logic 0 is accepted as the
stop bit. FE generates an SCI error CPU interrupt request if the FEIE
bit in SCC3 also is set. Clear the FE bit by reading SCS1 with FE set
and then reading the SCDR. Reset clears the FE bit.
1 = Framing error detected
0 = No framing error detected
Data Sheet
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MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
NORMAL FLAG CLEARING SEQUENCE
BYTE 1
BYTE 2
BYTE 3
BYTE 4
READ SCS1
SCRF = 1
OR = 0
READ SCS1
SCRF = 1
OR = 0
READ SCS1
SCRF = 1
OR = 0
READ SCDR
BYTE 1
READ SCDR
BYTE 2
READ SCDR
BYTE 3
DELAYED FLAG CLEARING SEQUENCE
BYTE 1
BYTE 2
BYTE 3
BYTE 4
READ SCS1
SCRF = 1
OR = 0
READ SCS1
SCRF = 1
OR = 1
READ SCDR
BYTE 1
READ SCDR
BYTE 3
Figure 13-16. Flag Clearing Sequence
PE — Receiver Parity Error Bit
This clearable, read-only bit is set when the SCI detects a parity error
in incoming data. PE generates an SCI error CPU interrupt request if
the PEIE bit in SCC3 is also set. Clear the PE bit by reading SCS1
with PE set and then reading the SCDR. Reset clears the PE bit.
1 = Parity error detected
0 = No parity error detected
MC68HC908LJ24/LK24 — Rev. 2.1
Data Sheet
279
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Infrared Serial Communications
13.11.5 SCI Status Register 2 (SCS2)
SCI status register 2 contains flags to signal the following conditions:
• Break character detected
• Incoming data
Address: $0017
Bit 7
6
0
5
0
4
0
3
0
2
0
1
Bit 0
RPF
Read:
Write:
Reset:
0
BKF
0
0
0
0
0
0
0
0
= Unimplemented
Figure 13-17. SCI Status Register 2 (SCS2)
BKF — Break Flag Bit
This clearable, read-only bit is set when the SCI detects a break
character on the RxD pin. In SCS1, the FE and SCRF bits are also
set. In 9-bit character transmissions, the R8 bit in SCC3 is cleared.
BKF does not generate a CPU interrupt request. Clear BKF by
reading SCS2 with BKF set and then reading the SCDR. Once
cleared, BKF can become set again only after logic 1s again appear
on the RxD pin followed by another break character. Reset clears the
BKF bit.
1 = Break character detected
0 = No break character detected
RPF — Reception in Progress Flag Bit
This read-only bit is set when the receiver detects a logic 0 during the
RT1 time period of the start bit search. RPF does not generate an
interrupt request. RPF is reset after the receiver detects false start bits
(usually from noise or a baud rate mismatch) or when the receiver
detects an idle character. Polling RPF before disabling the SCI
module or entering stop mode can show whether a reception is in
progress.
1 = Reception in progress
0 = No reception in progress
Data Sheet
280
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
13.11.6 SCI Data Register
The SCI data register is the buffer between the internal data bus and the
receive and transmit shift registers. Reset has no effect on data in the
SCI data register.
Address: $0018
Bit 7
R7
6
5
4
3
2
1
Bit 0
R0
Read:
Write:
Reset:
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
T7
T0
Unaffected by reset
Figure 13-18. SCI Data Register (SCDR)
R7/T7–R0/T0 — Receive/Transmit Data Bits
Reading the SCDR accesses the read-only received data bits,
R7–R0. Writing to the SCDR writes the data to be transmitted, T7–T0.
Reset has no effect on the SCDR.
NOTE: Do not use read/modify/write instructions on the SCI data register.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
281
Infrared Serial Communications
13.11.7 SCI Baud Rate Register
The baud rate register selects the baud rate for both the receiver and the
transmitter.
Address: $0019
Bit 7
6
0
5
SCP1
0
4
SCP0
0
3
2
1
SCR1
0
Bit 0
SCR0
0
Read:
CKS
R
SCR2
Write:
Reset:
0
0
0
0
= Unimplemented
R
= Reserved
Figure 13-19. SCI Baud Rate Register (SCBR)
CKS — Baud Clock Input Select
This read/write bit selects the source clock for the baud rate
generator. Reset clears the CKS bit, selecting CGMXCLK.
1 = Bus clock drives the baud rate generator
0 = CGMXCLK drives the baud rate generator
SCP1 and SCP0 — SCI Baud Rate Prescaler Bits
These read/write bits select the baud rate prescaler divisor as shown
in Table 13-7. Reset clears SCP1 and SCP0.
Table 13-7. SCI Baud Rate Prescaling
SCP1 and SCP0
Prescaler Divisor (PD)
00
01
10
11
1
3
4
13
SCR2–SCR0 — SCI Baud Rate Select Bits
These read/write bits select the SCI baud rate divisor as shown in
Table 13-8. Reset clears SCR2–SCR0.
Data Sheet
282
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
Table 13-8. SCI Baud Rate Selection
SCR2, SCR1, and SCR0
Baud Rate Divisor (BD)
000
001
010
011
100
101
110
111
1
2
4
8
16
32
64
128
Use this formula to calculate the SCI baud rate:
SCI clock source
baud rate = --------------------------------------------
16 × PD × BD
where:
SCI clock source = f
or CGMXCLK
BUS
(selected by CKS bit)
PD = prescaler divisor
BD = baud rate divisor
Table 13-9 shows the SCI baud rates that can be generated with a
4.9152-MHz bus clock when f is selected as SCI clock source.
BUS
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
283
Infrared Serial Communications
Table 13-9. SCI Baud Rate Selection Examples
Baud Rate
BUS
SCP1 and
SCP0
Prescaler
Divisor (PD)
SCR2, SCR1,
and SCR0
Baud Rate
Divisor (BD)
(f
= 4.9152 MHz)
00
00
00
00
00
00
00
00
01
01
01
01
01
01
01
01
10
10
10
10
10
10
10
10
11
11
11
11
11
11
11
11
1
1
000
001
010
011
100
101
110
111
000
001
010
011
100
101
110
111
000
001
010
011
100
101
110
111
000
001
010
011
100
101
110
111
1
2
—
—
1
4
76800
38400
19200
9600
4800
2400
—
1
8
1
16
32
64
128
1
1
1
1
3
3
2
51200
25600
12800
6400
3200
1600
800
3
4
3
8
3
16
32
64
128
1
3
3
3
4
76800
38400
19200
9600
4800
2400
1200
600
4
2
4
4
4
8
4
16
32
64
128
1
4
4
4
13
13
13
13
13
13
13
13
23632
11816
5908
2954
1477
739
2
4
8
16
32
64
128
369
185
Data Sheet
284
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
Infrared Serial Communications Interface Module (IRSCI)
I/O Registers
13.11.8 SCI Infrared Control Register
The infrared control register contains the control bits for the infrared sub-
module.
• Enables the infrared sub-module
• Selects the infrared transmitter narrow pulse width
Address: $001A
Bit 7
6
0
5
0
4
0
3
2
1
TNP0
0
Bit 0
IREN
0
Read:
Write:
Reset:
R
R
TNP1
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 13-20. SCI Infrared Control Register (SCIRCR)
TNP1 and TNP0 — Transmitter Narrow Pulse Bits
These read/write bits select the infrared transmitter narrow pulse
width as shown in Table 13-10. Reset clears TNP1 and TNP0.
Table 13-10. Infrared Narrow Pulse Selection
TNP1 and TNP0
Prescaler Divisor (PD)
00
01
10
11
SCI transmits a 3/16 narrow pulse
SCI transmits a 1/16 narrow pulse
SCI transmits a 1/32 narrow pulse
IREN — Infrared Enable Bit
This read/write bit enables the infrared sub-module for encoding and
decoding the SCI data stream. When this bit is clear, the infrared sub-
module is disabled. Reset clears the IREN bit.
1 = Infrared sub-module enabled
0 = Infrared sub-module disabled
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor Infrared Serial Communications Interface Module (IRSCI)
Data Sheet
285
Infrared Serial Communications
Data Sheet
MC68HC908LJ24/LK24 — Rev. 2.1
Infrared Serial Communications Interface Module (IRSCI) Freescale Semiconductor
286
Data Sheet — MC68HC908LJ24
Section 14. Serial Peripheral Interface Module (SPI)
14.1 Contents
14.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .288
14.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .288
14.4 Pin Name Conventions and I/O Register Addresses . . . . . . .289
14.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .290
14.5.1 Master Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .291
14.5.2 Slave Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .292
14.6 Transmission Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .293
14.6.1 Clock Phase and Polarity Controls. . . . . . . . . . . . . . . . . . .293
14.6.2 Transmission Format When CPHA = 0 . . . . . . . . . . . . . . .294
14.6.3 Transmission Format When CPHA = 1 . . . . . . . . . . . . . . .296
14.6.4 Transmission Initiation Latency . . . . . . . . . . . . . . . . . . . . .297
14.7 Queuing Transmission Data . . . . . . . . . . . . . . . . . . . . . . . . . .299
14.8 Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300
14.8.1 Overflow Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300
14.8.2 Mode Fault Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302
14.9 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .304
14.10 Resetting the SPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306
14.11 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307
14.11.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307
14.11.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307
14.12 SPI During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . .308
14.13 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308
14.13.1 MISO (Master In/Slave Out). . . . . . . . . . . . . . . . . . . . . . . .309
14.13.2 MOSI (Master Out/Slave In). . . . . . . . . . . . . . . . . . . . . . . .309
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
287
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
14.13.3 SPSCK (Serial Clock). . . . . . . . . . . . . . . . . . . . . . . . . . . . .310
14.13.4 SS (Slave Select) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310
14.13.5 CGND (Clock Ground) . . . . . . . . . . . . . . . . . . . . . . . . . . . .311
14.14 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312
14.14.1 SPI Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312
14.14.2 SPI Status and Control Register . . . . . . . . . . . . . . . . . . . .314
14.14.3 SPI Data Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .317
14.2 Introduction
14.3 Features
This section describes the serial peripheral interface (SPI) module,
which allows full-duplex, synchronous, serial communications with
peripheral devices.
Features of the SPI module include the following:
• Full-duplex operation
• Master and slave modes
• Double-buffered operation with separate transmit and receive
registers
• Four master mode frequencies (maximum = bus frequency ÷ 2)
• Maximum slave mode frequency = bus frequency
• Serial clock with programmable polarity and phase
• Two separately enabled interrupts:
– SPRF (SPI receiver full)
– SPTE (SPI transmitter empty)
• Mode fault error flag with CPU interrupt capability
• Overflow error flag with CPU interrupt capability
• Programmable wired-OR mode
Data Sheet
288
MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Pin Name Conventions and I/O Register Addresses
14.4 Pin Name Conventions and I/O Register Addresses
The text that follows describes the SPI. The SPI I/O pin names are SS
(slave select), SPSCK (SPI serial clock), CGND (clock ground), MOSI
(master out slave in), and MISO (master in/slave out). The SPI shares
four I/O pins with four parallel I/O ports.
The full names of the SPI I/O pins are shown in Table 14-1. The generic
pin names appear in the text that follows.
Table 14-1. Pin Name Conventions
SPI Generic
Pin Names:
MISO
MOSI
SS
SPSCK
CGND
PTD0/SS PTD3/SPSCK/
Full SPI
Pin Names:
V
SPI PTD1/MISO PTD2/MOSI
SS
CALIN
CALOUT
NOTE: The SS and SPSCK pins are also shared with CALIN and CALOUT
respectively. To avoid erratic behavior, these two pins should never be
configured for use as SPI and RTC calibration simultaneously.
Figure 14-1 summarizes the SPI I/O registers.
=
Addr.
Register Name
Bit 7
SPRIE
0
6
5
4
3
2
1
SPE
0
Bit 0
SPTIE
0
Read:
Write:
Reset:
R
0
SPMSTR
CPOL
CPHA
SPWOM
0
SPI Control Register
(SPCR)
$0010
1
0
1
Read: SPRF
OVRF
MODF
SPTE
SPI Status and Control
ERRIE
MODFEN
SPR1
SPR0
$0011
$0012
Register Write:
(SPSCR)
Reset:
Read:
Write:
Reset:
0
0
0
0
1
0
0
0
R7
T7
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
R0
T0
SPI Data Register
(SPDR)
Unaffected by reset
R
= Unimplemented
= Reserved
Figure 14-1. SPI I/O Register Summary
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
289
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
14.5 Functional Description
Figure 14-2 shows the structure of the SPI module.
INTERNAL BUS
TRANSMIT DATA REGISTER
SHIFT REGISTER
CGMOUT ÷ 2
FROM SIM
MISO
MOSI
7
6
5
4
3
2
1
0
÷ 2
÷ 8
÷ 32
CLOCK
DIVIDER
RECEIVE DATA REGISTER
PIN
CONTROL
LOGIC
÷ 128
CLOCK
SPSCK
SS
SPMSTR SPE
SELECT
M
CLOCK
LOGIC
S
SPR1
SPR0
SPMSTR CPHA
CPOL
RESERVED
MODFEN
ERRIE
SPTIE
SPRIE
R
SPWOM
TRANSMITTER CPU INTERRUPT REQUEST
RESERVED
SPI
CONTROL
RECEIVER/ERROR CPU INTERRUPT REQUEST
SPE
SPRF
SPTE
OVRF
MODF
Figure 14-2. SPI Module Block Diagram
The SPI module allows full-duplex, synchronous, serial communication
between the MCU and peripheral devices, including other MCUs.
Software can poll the SPI status flags or SPI operation can be interrupt-
driven.
The following paragraphs describe the operation of the SPI module.
Data Sheet
290
MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Functional Description
14.5.1 Master Mode
The SPI operates in master mode when the SPI master bit, SPMSTR, is
set.
NOTE: Configure the SPI modules as master or slave before enabling them.
Enable the master SPI before enabling the slave SPI. Disable the slave
SPI before disabling the master SPI. (See 14.14.1 SPI Control
Register.)
Only a master SPI module can initiate transmissions. Software begins
the transmission from a master SPI module by writing to the transmit
data register. If the shift register is empty, the byte immediately transfers
to the shift register, setting the SPI transmitter empty bit, SPTE. The byte
begins shifting out on the MOSI pin under the control of the serial clock.
(See Figure 14-3.)
MASTER MCU
SLAVE MCU
MISO
MOSI
MISO
MOSI
SHIFT REGISTER
SHIFT REGISTER
SPSCK
SS
SPSCK
SS
BAUD RATE
GENERATOR
VDD
Figure 14-3. Full-Duplex Master-Slave Connections
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
291
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
The SPR1 and SPR0 bits control the baud rate generator and determine
the speed of the shift register. (See 14.14.2 SPI Status and Control
Register.) Through the SPSCK pin, the baud rate generator of the
master also controls the shift register of the slave peripheral.
As the byte shifts out on the MOSI pin of the master, another byte shifts
in from the slave on the master’s MISO pin. The transmission ends when
the receiver full bit, SPRF, becomes set. At the same time that SPRF
becomes set, the byte from the slave transfers to the receive data
register. In normal operation, SPRF signals the end of a transmission.
Software clears SPRF by reading the SPI status and control register with
SPRF set and then reading the SPI data register. Writing to the SPI data
register clears the SPTE bit.
14.5.2 Slave Mode
The SPI operates in slave mode when the SPMSTR bit is clear. In slave
mode, the SPSCK pin is the input for the serial clock from the master
MCU. Before a data transmission occurs, the SS pin of the slave SPI
must be at logic 0. SS must remain low until the transmission is
complete. (See 14.8.2 Mode Fault Error.)
In a slave SPI module, data enters the shift register under the control of
the serial clock from the master SPI module. After a byte enters the shift
register of a slave SPI, it transfers to the receive data register, and the
SPRF bit is set. To prevent an overflow condition, slave software then
must read the receive data register before another full byte enters the
shift register.
The maximum frequency of the SPSCK for an SPI configured as a slave
is the bus clock speed (which is twice as fast as the fastest master
SPSCK clock that can be generated). The frequency of the SPSCK for
an SPI configured as a slave does not have to correspond to any SPI
baud rate. The baud rate only controls the speed of the SPSCK
generated by an SPI configured as a master. Therefore, the frequency
of the SPSCK for an SPI configured as a slave can be any frequency
less than or equal to the bus speed.
Data Sheet
292
MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Transmission Formats
When the master SPI starts a transmission, the data in the slave shift
register begins shifting out on the MISO pin. The slave can load its shift
register with a new byte for the next transmission by writing to its transmit
data register. The slave must write to its transmit data register at least
one bus cycle before the master starts the next transmission. Otherwise,
the byte already in the slave shift register shifts out on the MISO pin.
Data written to the slave shift register during a transmission remains in
a buffer until the end of the transmission.
When the clock phase bit (CPHA) is set, the first edge of SPSCK starts
a transmission. When CPHA is clear, the falling edge of SS starts a
transmission. (See 14.6 Transmission Formats.)
NOTE: SPSCK must be in the proper idle state before the slave is enabled to
prevent SPSCK from appearing as a clock edge.
14.6 Transmission Formats
During an SPI transmission, data is simultaneously transmitted (shifted
out serially) and received (shifted in serially). A serial clock synchronizes
shifting and sampling on the two serial data lines. A slave select line
allows selection of an individual slave SPI device; slave devices that are
not selected do not interfere with SPI bus activities. On a master SPI
device, the slave select line can optionally be used to indicate multiple-
master bus contention.
14.6.1 Clock Phase and Polarity Controls
Software can select any of four combinations of serial clock (SPSCK)
phase and polarity using two bits in the SPI control register (SPCR). The
clock polarity is specified by the CPOL control bit, which selects an
active high or low clock and has no significant effect on the transmission
format.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
293
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
The clock phase (CPHA) control bit selects one of two fundamentally
different transmission formats. The clock phase and polarity should be
identical for the master SPI device and the communicating slave device.
In some cases, the phase and polarity are changed between
transmissions to allow a master device to communicate with peripheral
slaves having different requirements.
NOTE: Before writing to the CPOL bit or the CPHA bit, disable the SPI by
clearing the SPI enable bit (SPE).
14.6.2 Transmission Format When CPHA = 0
Figure 14-4 shows an SPI transmission in which CPHA is logic 0. The
figure should not be used as a replacement for data sheet parametric
information.
Two waveforms are shown for SPSCK: one for CPOL = 0 and another
for CPOL = 1. The diagram may be interpreted as a master or slave
timing diagram since the serial clock (SPSCK), master in/slave out
(MISO), and master out/slave in (MOSI) pins are directly connected
between the master and the slave. The MISO signal is the output from
the slave, and the MOSI signal is the output from the master. The SS line
is the slave select input to the slave. The slave SPI drives its MISO
output only when its slave select input (SS) is at logic 0, so that only the
selected slave drives to the master. The SS pin of the master is not
shown but is assumed to be inactive. The SS pin of the master must be
high or must be reconfigured as general-purpose I/O not affecting the
SPI. (See 14.8.2 Mode Fault Error.) When CPHA = 0, the first SPSCK
edge is the MSB capture strobe. Therefore, the slave must begin driving
its data before the first SPSCK edge, and a falling edge on the SS pin is
used to start the slave data transmission. The slave’s SS pin must be
toggled back to high and then low again between each byte transmitted
as shown in Figure 14-5.
Data Sheet
294
MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Transmission Formats
SPSCK CYCLE #
FOR REFERENCE
1
2
3
4
5
6
7
8
SPSCK; CPOL = 0
SPSCK; CPOL =1
MOSI
MSB
BIT 6
BIT 6
BIT 5
BIT 5
BIT 4
BIT 4
BIT 3
BIT 3
BIT 2
BIT 2
BIT 1
BIT 1
LSB
LSB
FROM MASTER
MISO
FROM SLAVE
MSB
SS; TO SLAVE
CAPTURE STROBE
Figure 14-4. Transmission Format (CPHA = 0)
MISO/MOSI
MASTER SS
BYTE 1
BYTE 2
BYTE 3
SLAVE SS
CPHA = 0
SLAVE SS
CPHA = 1
Figure 14-5. CPHA/SS Timing
When CPHA = 0 for a slave, the falling edge of SS indicates the
beginning of the transmission. This causes the SPI to leave its idle state
and begin driving the MISO pin with the MSB of its data. Once the
transmission begins, no new data is allowed into the shift register from
the transmit data register. Therefore, the SPI data register of the slave
must be loaded with transmit data before the falling edge of SS. Any data
written after the falling edge is stored in the transmit data register and
transferred to the shift register after the current transmission.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
295
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
14.6.3 Transmission Format When CPHA = 1
Figure 14-6 shows an SPI transmission in which CPHA is logic 1. The
figure should not be used as a replacement for data sheet parametric
information. Two waveforms are shown for SPSCK: one for CPOL = 0
and another for CPOL = 1. The diagram may be interpreted as a master
or slave timing diagram since the serial clock (SPSCK), master in/slave
out (MISO), and master out/slave in (MOSI) pins are directly connected
between the master and the slave. The MISO signal is the output from
the slave, and the MOSI signal is the output from the master. The SS line
is the slave select input to the slave. The slave SPI drives its MISO
output only when its slave select input (SS) is at logic 0, so that only the
selected slave drives to the master. The SS pin of the master is not
shown but is assumed to be inactive. The SS pin of the master must be
high or must be reconfigured as general-purpose I/O not affecting the
SPI. (See 14.8.2 Mode Fault Error.) When CPHA = 1, the master
begins driving its MOSI pin on the first SPSCK edge. Therefore, the
slave uses the first SPSCK edge as a start transmission signal. The SS
pin can remain low between transmissions. This format may be
preferable in systems having only one master and only one slave driving
the MISO data line.
SPSCK CYCLE #
FOR REFERENCE
1
2
3
4
5
6
7
8
SPSCK; CPOL = 0
SPSCK; CPOL =1
MOSI
MSB
MSB
BIT 6
BIT 6
BIT 5
BIT 5
BIT 4
BIT 4
BIT 3
BIT 3
BIT 2
BIT 2
BIT 1
BIT 1
LSB
FROM MASTER
MISO
LSB
FROM SLAVE
SS; TO SLAVE
CAPTURE STROBE
Figure 14-6. Transmission Format (CPHA = 1)
Data Sheet
296
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
Transmission Formats
When CPHA = 1 for a slave, the first edge of the SPSCK indicates the
beginning of the transmission. This causes the SPI to leave its idle state
and begin driving the MISO pin with the MSB of its data. Once the
transmission begins, no new data is allowed into the shift register from
the transmit data register. Therefore, the SPI data register of the slave
must be loaded with transmit data before the first edge of SPSCK. Any
data written after the first edge is stored in the transmit data register and
transferred to the shift register after the current transmission.
14.6.4 Transmission Initiation Latency
When the SPI is configured as a master (SPMSTR = 1), writing to the
SPDR starts a transmission. CPHA has no effect on the delay to the start
of the transmission, but it does affect the initial state of the SPSCK
signal. When CPHA = 0, the SPSCK signal remains inactive for the first
half of the first SPSCK cycle. When CPHA = 1, the first SPSCK cycle
begins with an edge on the SPSCK line from its inactive to its active
level. The SPI clock rate (selected by SPR1:SPR0) affects the delay
from the write to SPDR and the start of the SPI transmission. (See
Figure 14-7.) The internal SPI clock in the master is a free-running
derivative of the internal MCU clock. To conserve power, it is enabled
only when both the SPE and SPMSTR bits are set. SPSCK edges occur
halfway through the low time of the internal MCU clock. Since the SPI
clock is free-running, it is uncertain where the write to the SPDR occurs
relative to the slower SPSCK. This uncertainty causes the variation in
the initiation delay shown in Figure 14-7. This delay is no longer than a
single SPI bit time. That is, the maximum delay is two MCU bus cycles
for DIV2, eight MCU bus cycles for DIV8, 32 MCU bus cycles for DIV32,
and 128 MCU bus cycles for DIV128.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
297
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
WRITE
TO SPDR
INITIATION DELAY
BUS
CLOCK
MOSI
MSB
BIT 6
BIT 5
SPSCK
CPHA = 1
SPSCK
CPHA = 0
SPSCK CYCLE
NUMBER
1
2
3
INITIATION DELAY FROM WRITE SPDR TO TRANSFER BEGIN
WRITE
TO SPDR
BUS
CLOCK
SPSCK = INTERNAL CLOCK ÷ 2;
2 POSSIBLE START POINTS
EARLIEST
LATEST
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
SPSCK = INTERNAL CLOCK ÷ 8;
LATEST
LATEST
LATEST
8 POSSIBLE START POINTS
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
SPSCK = INTERNAL CLOCK ÷ 32;
32 POSSIBLE START POINTS
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
SPSCK = INTERNAL CLOCK ÷ 128;
128 POSSIBLE START POINTS
Figure 14-7. Transmission Start Delay (Master)
Data Sheet
298
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
Queuing Transmission Data
14.7 Queuing Transmission Data
The double-buffered transmit data register allows a data byte to be
queued and transmitted. For an SPI configured as a master, a queued
data byte is transmitted immediately after the previous transmission has
completed. The SPI transmitter empty flag (SPTE) indicates when the
transmit data buffer is ready to accept new data. Write to the transmit
data register only when the SPTE bit is high. Figure 14-8 shows the
timing associated with doing back-to-back transmissions with the SPI
(SPSCK has CPHA: CPOL = 1:0).
1
3
8
WRITE TO SPDR
SPTE
5
10
2
SPSCK
CPHA:CPOL = 1:0
MOSI
MSB BIT BIT BIT BIT BIT BIT LSB MSB BIT BIT BIT BIT BIT BIT LSB MSB BIT BIT BIT
6
5
4
3
2
1
6
5
4
3
2
1
6
5
4
BYTE 1
BYTE 2
BYTE 3
4
9
SPRF
READ SPSCR
READ SPDR
6
11
7
12
1
2
CPU WRITES BYTE 1 TO SPDR, CLEARING SPTE BIT.
7
8
CPU READS SPDR, CLEARING SPRF BIT.
CPU WRITES BYTE 3 TO SPDR, QUEUEING BYTE
3 AND CLEARING SPTE BIT.
BYTE 1 TRANSFERS FROM TRANSMIT DATA
REGISTER TO SHIFT REGISTER, SETTING SPTE BIT.
9
SECOND INCOMING BYTE TRANSFERS FROM SHIFT
REGISTER TO RECEIVE DATA REGISTER, SETTING
SPRF BIT.
CPU WRITES BYTE 2 TO SPDR, QUEUEING BYTE 2
AND CLEARING SPTE BIT.
3
4
10
FIRST INCOMING BYTE TRANSFERS FROM SHIFT
REGISTER TO RECEIVE DATA REGISTER, SETTING
SPRF BIT.
BYTE 3 TRANSFERS FROM TRANSMIT DATA
REGISTER TO SHIFT REGISTER, SETTING SPTE BIT.
CPU READS SPSCR WITH SPRF BIT SET.
CPU READS SPDR, CLEARING SPRF BIT.
11
12
5
6
BYTE 2 TRANSFERS FROM TRANSMIT DATA
REGISTER TO SHIFT REGISTER, SETTING SPTE BIT.
CPU READS SPSCR WITH SPRF BIT SET.
Figure 14-8. SPRF/SPTE CPU Interrupt Timing
The transmit data buffer allows back-to-back transmissions without the
slave precisely timing its writes between transmissions as in a system
with a single data buffer. Also, if no new data is written to the data buffer,
the last value contained in the shift register is the next data word to be
transmitted.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
299
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
For an idle master or idle slave that has no data loaded into its transmit
buffer, the SPTE is set again no more than two bus cycles after the
transmit buffer empties into the shift register. This allows the user to
queue up a 16-bit value to send. For an already active slave, the load of
the shift register cannot occur until the transmission is completed. This
implies that a back-to-back write to the transmit data register is not
possible. The SPTE indicates when the next write can occur.
14.8 Error Conditions
The following flags signal SPI error conditions:
• Overflow (OVRF) — Failing to read the SPI data register before
the next full byte enters the shift register sets the OVRF bit. The
new byte does not transfer to the receive data register, and the
unread byte still can be read. OVRF is in the SPI status and control
register.
• Mode fault error (MODF) — The MODF bit indicates that the
voltage on the slave select pin (SS) is inconsistent with the mode
of the SPI. MODF is in the SPI status and control register.
14.8.1 Overflow Error
The overflow flag (OVRF) becomes set if the receive data register still
has unread data from a previous transmission when the capture strobe
of bit 1 of the next transmission occurs. The bit 1 capture strobe occurs
in the middle of SPSCK cycle 7. (See Figure 14-4 and Figure 14-6.) If
an overflow occurs, all data received after the overflow and before the
OVRF bit is cleared does not transfer to the receive data register and
does not set the SPI receiver full bit (SPRF). The unread data that
transferred to the receive data register before the overflow occurred can
still be read. Therefore, an overflow error always indicates the loss of
data. Clear the overflow flag by reading the SPI status and control
register and then reading the SPI data register.
OVRF generates a receiver/error CPU interrupt request if the error
interrupt enable bit (ERRIE) is also set. The SPRF, MODF, and OVRF
Data Sheet
300
MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Error Conditions
interrupts share the same CPU interrupt vector. (See Figure 14-11.) It is
not possible to enable MODF or OVRF individually to generate a
receiver/error CPU interrupt request. However, leaving MODFEN low
prevents MODF from being set.
If the CPU SPRF interrupt is enabled and the OVRF interrupt is not,
watch for an overflow condition. Figure 14-9 shows how it is possible to
miss an overflow. The first part of Figure 14-9 shows how it is possible
to read the SPSCR and SPDR to clear the SPRF without problems.
However, as illustrated by the second transmission example, the OVRF
bit can be set in between the time that SPSCR and SPDR are read.
BYTE 1
1
BYTE 2
4
BYTE 3
6
BYTE 4
8
SPRF
OVRF
READ
2
5
5
SPSCR
READ
SPDR
3
7
1
2
BYTE 1 SETS SPRF BIT.
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
BYTE 3 SETS OVRF BIT. BYTE 3 IS LOST.
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
6
7
3
4
CPU READS BYTE 1 IN SPDR,
CPU READS BYTE 2 IN SPDR, CLEARING SPRF BIT,
BUT NOT OVRF BIT.
BYTE 4 FAILS TO SET SPRF BIT BECAUSE
OVRF BIT IS NOT CLEARED. BYTE 4 IS LOST.
CLEARING SPRF BIT.
BYTE 2 SETS SPRF BIT.
8
Figure 14-9. Missed Read of Overflow Condition
In this case, an overflow can be missed easily. Since no more SPRF
interrupts can be generated until this OVRF is serviced, it is not obvious
that bytes are being lost as more transmissions are completed. To
prevent this, either enable the OVRF interrupt or do another read of the
SPSCR following the read of the SPDR. This ensures that the OVRF
was not set before the SPRF was cleared and that future transmissions
can set the SPRF bit. Figure 14-10 illustrates this process. Generally, to
avoid this second SPSCR read, enable the OVRF to the CPU by setting
the ERRIE bit.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
301
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
BYTE 1
BYTE 2
5
BYTE 3
7
BYTE 4
11
SPI RECEIVE
COMPLETE
1
SPRF
OVRF
READ
2
4
6
9
12
14
SPSCR
READ
SPDR
3
8
10
13
1
2
8
9
BYTE 1 SETS SPRF BIT.
CPU READS BYTE 2 IN SPDR,
CLEARING SPRF BIT.
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
CPU READS SPSCR AGAIN
TO CHECK OVRF BIT.
3
4
CPU READS BYTE 1 IN SPDR,
CLEARING SPRF BIT.
10
CPU READS BYTE 2 SPDR,
CLEARING OVRF BIT.
CPU READS SPSCR AGAIN
TO CHECK OVRF BIT.
11
12
13
BYTE 4 SETS SPRF BIT.
CPU READS SPSCR.
5
6
BYTE 2 SETS SPRF BIT.
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
CPU READS BYTE 4 IN SPDR,
CLEARING SPRF BIT.
7
BYTE 3 SETS OVRF BIT. BYTE 3 IS LOST.
14
CPU READS SPSCR AGAIN
TO CHECK OVRF BIT.
Figure 14-10. Clearing SPRF When OVRF Interrupt Is Not Enabled
14.8.2 Mode Fault Error
Setting the SPMSTR bit selects master mode and configures the
SPSCK and MOSI pins as outputs and the MISO pin as an input.
Clearing SPMSTR selects slave mode and configures the SPSCK and
MOSI pins as inputs and the MISO pin as an output. The mode fault bit,
MODF, becomes set any time the state of the slave select pin, SS, is
inconsistent with the mode selected by SPMSTR.
To prevent SPI pin contention and damage to the MCU, a mode fault
error occurs if:
• The SS pin of a slave SPI goes high during a transmission
• The SS pin of a master SPI goes low at any time
For the MODF flag to be set, the mode fault error enable bit (MODFEN)
must be set. Clearing the MODFEN bit does not clear the MODF flag but
does prevent MODF from being set again after MODF is cleared.
Data Sheet
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MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Error Conditions
MODF generates a receiver/error CPU interrupt request if the error
interrupt enable bit (ERRIE) is also set. The SPRF, MODF, and OVRF
interrupts share the same CPU interrupt vector. (See Figure 14-11.) It is
not possible to enable MODF or OVRF individually to generate a
receiver/error CPU interrupt request. However, leaving MODFEN low
prevents MODF from being set.
In a master SPI with the mode fault enable bit (MODFEN) set, the mode
fault flag (MODF) is set if SS goes to logic 0. A mode fault in a master
SPI causes the following events to occur:
• If ERRIE = 1, the SPI generates an SPI receiver/error CPU
interrupt request.
• The SPE bit is cleared.
• The SPTE bit is set.
• The SPI state counter is cleared.
• The data direction register of the shared I/O port regains control of
port drivers.
NOTE: To prevent bus contention with another master SPI after a mode fault
error, clear all SPI bits of the data direction register of the shared I/O port
before enabling the SPI.
When configured as a slave (SPMSTR = 0), the MODF flag is set if SS
goes high during a transmission. When CPHA = 0, a transmission begins
when SS goes low and ends once the incoming SPSCK goes back to its
idle level following the shift of the eighth data bit. When CPHA = 1, the
transmission begins when the SPSCK leaves its idle level and SS is
already low. The transmission continues until the SPSCK returns to its
idle level following the shift of the last data bit. (See 14.6 Transmission
Formats.)
NOTE: Setting the MODF flag does not clear the SPMSTR bit. The SPMSTR bit
has no function when SPE = 0. Reading SPMSTR when MODF = 1
shows the difference between a MODF occurring when the SPI is a
master and when it is a slave.
When CPHA = 0, a MODF occurs if a slave is selected (SS is at logic 0)
and later unselected (SS is at logic 1) even if no SPSCK is sent to that
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
303
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
slave. This happens because SS at logic 0 indicates the start of the
transmission (MISO driven out with the value of MSB) for CPHA = 0.
When CPHA = 1, a slave can be selected and then later unselected with
no transmission occurring. Therefore, MODF does not occur since a
transmission was never begun.
In a slave SPI (MSTR = 0), the MODF bit generates an SPI
receiver/error CPU interrupt request if the ERRIE bit is set. The MODF
bit does not clear the SPE bit or reset the SPI in any way. Software can
abort the SPI transmission by clearing the SPE bit of the slave.
NOTE: A logic 1 voltage on the SS pin of a slave SPI puts the MISO pin in a high
impedance state. Also, the slave SPI ignores all incoming SPSCK
clocks, even if it was already in the middle of a transmission.
To clear the MODF flag, read the SPSCR with the MODF bit set and then
write to the SPCR register. This entire clearing mechanism must occur
with no MODF condition existing or else the flag is not cleared.
14.9 Interrupts
Four SPI status flags can be enabled to generate CPU interrupt
requests.
Table 14-2. SPI Interrupts
Flag
Request
SPTE
Transmitter empty
SPI transmitter CPU interrupt request
(DMAS = 0, SPTIE = 1, SPE = 1)
SPRF
Receiver full
SPI receiver CPU interrupt request
(DMAS = 0, SPRIE = 1)
OVRF
Overflow
SPI receiver/error interrupt request (ERRIE = 1)
SPI receiver/error interrupt request (ERRIE = 1)
MODF
Mode fault
Data Sheet
304
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
Interrupts
Reading the SPI status and control register with SPRF set and then
reading the receive data register clears SPRF. The clearing mechanism
for the SPTE flag is always just a write to the transmit data register.
The SPI transmitter interrupt enable bit (SPTIE) enables the SPTE flag
to generate transmitter CPU interrupt requests, provided that the SPI is
enabled (SPE = 1).
The SPI receiver interrupt enable bit (SPRIE) enables the SPRF bit to
generate receiver CPU interrupt requests, regardless of the state of the
SPE bit. (See Figure 14-11.)
The error interrupt enable bit (ERRIE) enables both the MODF and
OVRF bits to generate a receiver/error CPU interrupt request.
The mode fault enable bit (MODFEN) can prevent the MODF flag from
being set so that only the OVRF bit is enabled by the ERRIE bit to
generate receiver/error CPU interrupt requests.
NOT AVAILABLE
SPTE
SPTIE
SPE
SPI TRANSMITTER
CPU INTERRUPT REQUEST
R
NOT AVAILABLE
SPRIE
SPRF
SPI RECEIVER/ERROR
CPU INTERRUPT REQUEST
ERRIE
MODF
OVRF
Figure 14-11. SPI Interrupt Request Generation
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
305
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
The following sources in the SPI status and control register can generate
CPU interrupt requests:
• SPI receiver full bit (SPRF) — The SPRF bit becomes set every
time a byte transfers from the shift register to the receive data
register. If the SPI receiver interrupt enable bit, SPRIE, is also set,
SPRF generates an SPI receiver/error CPU interrupt request.
• SPI transmitter empty (SPTE) — The SPTE bit becomes set every
time a byte transfers from the transmit data register to the shift
register. If the SPI transmit interrupt enable bit, SPTIE, is also set,
SPTE generates an SPTE CPU interrupt request.
14.10 Resetting the SPI
Any system reset completely resets the SPI. Partial resets occur
whenever the SPI enable bit (SPE) is low. Whenever SPE is low, the
following occurs:
• The SPTE flag is set.
• Any transmission currently in progress is aborted.
• The shift register is cleared.
• The SPI state counter is cleared, making it ready for a new
complete transmission.
• All the SPI port logic is defaulted back to being general-purpose
I/O.
These items are reset only by a system reset:
• All control bits in the SPCR register
• All control bits in the SPSCR register (MODFEN, ERRIE, SPR1,
and SPR0)
• The status flags SPRF, OVRF, and MODF
By not resetting the control bits when SPE is low, the user can clear SPE
between transmissions without having to set all control bits again when
SPE is set back high for the next transmission.
Data Sheet
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MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Low-Power Modes
By not resetting the SPRF, OVRF, and MODF flags, the user can still
service these interrupts after the SPI has been disabled. The user can
disable the SPI by writing 0 to the SPE bit. The SPI can also be disabled
by a mode fault occurring in an SPI that was configured as a master with
the MODFEN bit set.
14.11 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
14.11.1 Wait Mode
The SPI module remains active after the execution of a WAIT instruction.
In wait mode the SPI module registers are not accessible by the CPU.
Any enabled CPU interrupt request from the SPI module can bring the
MCU out of wait mode.
If SPI module functions are not required during wait mode, reduce power
consumption by disabling the SPI module before executing the WAIT
instruction.
To exit wait mode when an overflow condition occurs, enable the OVRF
bit to generate CPU interrupt requests by setting the error interrupt
enable bit (ERRIE). (See 14.9 Interrupts.)
14.11.2 Stop Mode
The SPI module is inactive after the execution of a STOP instruction.
The STOP instruction does not affect register conditions. SPI operation
resumes after an external interrupt. If stop mode is exited by reset, any
transfer in progress is aborted, and the SPI is reset.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
307
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
14.12 SPI During Break Interrupts
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state. (See Section 9. System Integration
Module (SIM).)
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
I/O registers during the break state without affecting status bits. Some
status bits have a 2-step read/write clearing procedure. If software does
the first step on such a bit before the break, the bit cannot change during
the break state as long as BCFE is at logic 0. After the break, doing the
second step clears the status bit.
Since the SPTE bit cannot be cleared during a break with the BCFE bit
cleared, a write to the transmit data register in break mode does not
initiate a transmission nor is this data transferred into the shift register.
Therefore, a write to the SPDR in break mode with the BCFE bit cleared
has no effect.
14.13 I/O Signals
The SPI module has five I/O pins and shares four of them with a parallel
I/O port. They are:
• MISO — Data received
• MOSI — Data transmitted
• SPSCK — Serial clock
• SS — Slave select
• CGND — Clock ground (internally connected to V )
SS
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MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
I/O Signals
2
The SPI has limited inter-integrated circuit (I C) capability (requiring
software support) as a master in a single-master environment. To
2
communicate with I C peripherals, MOSI becomes an open-drain output
2
when the SPWOM bit in the SPI control register is set. In I C
communication, the MOSI and MISO pins are connected to a
2
bidirectional pin from the I C peripheral and through a pullup resistor to
V .
DD
14.13.1 MISO (Master In/Slave Out)
MISO is one of the two SPI module pins that transmits serial data. In full
duplex operation, the MISO pin of the master SPI module is connected
to the MISO pin of the slave SPI module. The master SPI simultaneously
receives data on its MISO pin and transmits data from its MOSI pin.
Slave output data on the MISO pin is enabled only when the SPI is
configured as a slave. The SPI is configured as a slave when its
SPMSTR bit is logic 0 and its SS pin is at logic 0. To support a multiple-
slave system, a logic 1 on the SS pin puts the MISO pin in a high-
impedance state.
When enabled, the SPI controls data direction of the MISO pin
regardless of the state of the data direction register of the shared I/O
port.
14.13.2 MOSI (Master Out/Slave In)
MOSI is one of the two SPI module pins that transmits serial data. In full-
duplex operation, the MOSI pin of the master SPI module is connected
to the MOSI pin of the slave SPI module. The master SPI simultaneously
transmits data from its MOSI pin and receives data on its MISO pin.
When enabled, the SPI controls data direction of the MOSI pin
regardless of the state of the data direction register of the shared I/O
port.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
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Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
14.13.3 SPSCK (Serial Clock)
The serial clock synchronizes data transmission between master and
slave devices. In a master MCU, the SPSCK pin is the clock output. In a
slave MCU, the SPSCK pin is the clock input. In full-duplex operation,
the master and slave MCUs exchange a byte of data in eight serial clock
cycles.
When enabled, the SPI controls data direction of the SPSCK pin
regardless of the state of the data direction register of the shared I/O
port.
14.13.4 SS (Slave Select)
The SS pin has various functions depending on the current state of the
SPI. For an SPI configured as a slave, the SS is used to select a slave.
For CPHA = 0, the SS is used to define the start of a transmission. (See
14.6 Transmission Formats.) Since it is used to indicate the start of a
transmission, the SS must be toggled high and low between each byte
transmitted for the CPHA = 0 format. However, it can remain low
between transmissions for the CPHA = 1 format. See Figure 14-12.
MISO/MOSI
MASTER SS
BYTE 1
BYTE 2
BYTE 3
SLAVE SS
CPHA = 0
SLAVE SS
CPHA = 1
Figure 14-12. CPHA/SS Timing
When an SPI is configured as a slave, the SS pin is always configured
as an input. It cannot be used as a general-purpose I/O regardless of the
state of the MODFEN control bit. However, the MODFEN bit can still
prevent the state of the SS from creating a MODF error. (See 14.14.2
SPI Status and Control Register.)
NOTE: A logic 1 voltage on the SS pin of a slave SPI puts the MISO pin in a high-
impedance state. The slave SPI ignores all incoming SPSCK clocks,
even if it was already in the middle of a transmission.
Data Sheet
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Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
I/O Signals
When an SPI is configured as a master, the SS input can be used in
conjunction with the MODF flag to prevent multiple masters from driving
MOSI and SPSCK. (See 14.8.2 Mode Fault Error.) For the state of the
SS pin to set the MODF flag, the MODFEN bit in the SPSCK register
must be set. If the MODFEN bit is low for an SPI master, the SS pin can
be used as a general-purpose I/O under the control of the data direction
register of the shared I/O port. With MODFEN high, it is an input-only pin
to the SPI regardless of the state of the data direction register of the
shared I/O port.
The CPU can always read the state of the SS pin by configuring the
appropriate pin as an input and reading the port data register. (See
Table 14-3.)
Table 14-3. SPI Configuration
SPE SPMSTR
MODFEN
SPI Configuration
Not enabled
State of SS Logic
General-purpose I/O;
SS ignored by SPI
(1)
0
1
1
1
X
X
0
X
0
Slave
Input-only to SPI
General-purpose I/O;
SS ignored by SPI
1
1
Master without MODF
Master with MODF
1
Input-only to SPI
Note 1. X = Don’t care
14.13.5 CGND (Clock Ground)
CGND is the ground return for the serial clock pin, SPSCK, and the
ground for the port output buffers. It is internally connected to V as
SS
shown in Table 14-1.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
311
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
14.14 I/O Registers
Three registers control and monitor SPI operation:
• SPI control register (SPCR)
• SPI status and control register (SPSCR)
• SPI data register (SPDR)
14.14.1 SPI Control Register
The SPI control register:
• Enables SPI module interrupt requests
• Configures the SPI module as master or slave
• Selects serial clock polarity and phase
• Configures the SPSCK, MOSI, and MISO pins as open-drain
outputs
• Enables the SPI module
Address: $0010
Bit 7
SPRIE
0
6
R
0
5
SPMSTR
1
4
CPOL
0
3
2
1
SPE
0
Bit 0
SPTIE
0
Read:
Write:
Reset:
CPHA
SPWOM
1
0
= Unimplemented
R
= Reserved
Figure 14-13. SPI Control Register (SPCR)
SPRIE — SPI Receiver Interrupt Enable Bit
This read/write bit enables CPU interrupt requests generated by the
SPRF bit. The SPRF bit is set when a byte transfers from the shift
register to the receive data register. Reset clears the SPRIE bit.
1 = SPRF CPU interrupt requests enabled
0 = SPRF CPU interrupt requests disabled
Data Sheet
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Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
I/O Registers
SPMSTR — SPI Master Bit
This read/write bit selects master mode operation or slave mode
operation. Reset sets the SPMSTR bit.
1 = Master mode
0 = Slave mode
CPOL — Clock Polarity Bit
This read/write bit determines the logic state of the SPSCK pin
between transmissions. (See Figure 14-4 and Figure 14-6.) To
transmit data between SPI modules, the SPI modules must have
identical CPOL values. Reset clears the CPOL bit.
CPHA — Clock Phase Bit
This read/write bit controls the timing relationship between the serial
clock and SPI data. (See Figure 14-4 and Figure 14-6.) To transmit
data between SPI modules, the SPI modules must have identical
CPHA values. When CPHA = 0, the SS pin of the slave SPI module
must be set to logic 1 between bytes. (See Figure 14-12.) Reset sets
the CPHA bit.
SPWOM — SPI Wired-OR Mode Bit
This read/write bit disables the pullup devices on pins SPSCK, MOSI,
and MISO so that those pins become open-drain outputs.
1 = Wired-OR SPSCK, MOSI, and MISO pins
0 = Normal push-pull SPSCK, MOSI, and MISO pins
SPE — SPI Enable
This read/write bit enables the SPI module. Clearing SPE causes a
partial reset of the SPI. (See 14.10 Resetting the SPI.) Reset clears
the SPE bit.
1 = SPI module enabled
0 = SPI module disabled
SPTIE— SPI Transmit Interrupt Enable
This read/write bit enables CPU interrupt requests generated by the
SPTE bit. SPTE is set when a byte transfers from the transmit data
register to the shift register. Reset clears the SPTIE bit.
1 = SPTE CPU interrupt requests enabled
0 = SPTE CPU interrupt requests disabled
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
313
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
14.14.2 SPI Status and Control Register
The SPI status and control register contains flags to signal these
conditions:
• Receive data register full
• Failure to clear SPRF bit before next byte is received (overflow
error)
• Inconsistent logic level on SS pin (mode fault error)
• Transmit data register empty
The SPI status and control register also contains bits that perform these
functions:
• Enable error interrupts
• Enable mode fault error detection
• Select master SPI baud rate
Address: $0011
Bit 7
Read: SPRF
Write:
6
ERRIE
0
5
4
3
2
1
Bit 0
SPR0
0
OVRF
MODF
SPTE
MODFEN SPR1
Reset:
0
0
0
1
0
0
= Unimplemented
Figure 14-14. SPI Status and Control Register (SPSCR)
SPRF — SPI Receiver Full Bit
This clearable, read-only flag is set each time a byte transfers from
the shift register to the receive data register. SPRF generates a CPU
interrupt request if the SPRIE bit in the SPI control register is set also.
During an SPRF CPU interrupt, the CPU clears SPRF by reading the
SPI status and control register with SPRF set and then reading the
SPI data register. Reset clears the SPRF bit.
1 = Receive data register full
0 = Receive data register not full
Data Sheet
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Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
I/O Registers
ERRIE — Error Interrupt Enable Bit
This read/write bit enables the MODF and OVRF bits to generate
CPU interrupt requests. Reset clears the ERRIE bit.
1 = MODF and OVRF can generate CPU interrupt requests
0 = MODF and OVRF cannot generate CPU interrupt requests
OVRF — Overflow Bit
This clearable, read-only flag is set if software does not read the byte
in the receive data register before the next full byte enters the shift
register. In an overflow condition, the byte already in the receive data
register is unaffected, and the byte that shifted in last is lost. Clear the
OVRF bit by reading the SPI status and control register with OVRF set
and then reading the receive data register. Reset clears the OVRF bit.
1 = Overflow
0 = No overflow
MODF — Mode Fault Bit
This clearable, read-only flag is set in a slave SPI if the SS pin goes
high during a transmission with the MODFEN bit set. In a master SPI,
the MODF flag is set if the SS pin goes low at any time with the
MODFEN bit set. Clear the MODF bit by reading the SPI status and
control register (SPSCR) with MODF set and then writing to the SPI
control register (SPCR). Reset clears the MODF bit.
1 = SS pin at inappropriate logic level
0 = SS pin at appropriate logic level
SPTE — SPI Transmitter Empty Bit
This clearable, read-only flag is set each time the transmit data
register transfers a byte into the shift register. SPTE generates an
SPTE CPU interrupt request if the SPTIE bit in the SPI control register
is set also.
NOTE: Do not write to the SPI data register unless the SPTE bit is high.
During an SPTE CPU interrupt, the CPU clears the SPTE bit by
writing to the transmit data register.
Reset sets the SPTE bit.
1 = Transmit data register empty
0 = Transmit data register not empty
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
315
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
MODFEN — Mode Fault Enable Bit
This read/write bit, when set to 1, allows the MODF flag to be set. If
the MODF flag is set, clearing the MODFEN does not clear the MODF
flag. If the SPI is enabled as a master and the MODFEN bit is low,
then the SS pin is available as a general-purpose I/O.
If the MODFEN bit is set, then this pin is not available as a general-
purpose I/O. When the SPI is enabled as a slave, the SS pin is not
available as a general-purpose I/O regardless of the value of
MODFEN. (See 14.13.4 SS (Slave Select).)
If the MODFEN bit is low, the level of the SS pin does not affect the
operation of an enabled SPI configured as a master. For an enabled
SPI configured as a slave, having MODFEN low only prevents the
MODF flag from being set. It does not affect any other part of SPI
operation. (See 14.8.2 Mode Fault Error.)
SPR1 and SPR0 — SPI Baud Rate Select Bits
In master mode, these read/write bits select one of four baud rates as
shown in Table 14-4. SPR1 and SPR0 have no effect in slave mode.
Reset clears SPR1 and SPR0.
Table 14-4. SPI Master Baud Rate Selection
SPR1 and SPR0
Baud Rate Divisor (BD)
00
01
10
11
2
8
32
128
Use this formula to calculate the SPI baud rate:
CGMOUT
Baud rate = --------------------------
2 × BD
where:
CGMOUT = base clock output of the clock generator module (CGM)
BD = baud rate divisor
Data Sheet
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MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI)
Freescale Semiconductor
Serial Peripheral Interface Module (SPI)
I/O Registers
14.14.3 SPI Data Register
The SPI data register consists of the read-only receive data register and
the write-only transmit data register. Writing to the SPI data register
writes data into the transmit data register. Reading the SPI data register
reads data from the receive data register. The transmit data and receive
data registers are separate registers that can contain different values.
(See Figure 14-2.)
Address: $0012
Bit 7
R7
6
5
4
3
2
1
Bit 0
R0
Read:
Write:
Reset:
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
T7
T0
Unaffected by reset
Figure 14-15. SPI Data Register (SPDR)
R7–R0/T7–T0 — Receive/Transmit Data Bits
NOTE: Do not use read-modify-write instructions on the SPI data register since
the register read is not the same as the register written.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
317
Serial Peripheral Interface Module (SPI)
Serial Peripheral Interface Module (SPI)
Data Sheet
MC68HC908LJ24/LK24 — Rev. 2.1
Serial Peripheral Interface Module (SPI) Freescale Semiconductor
318
Data Sheet — MC68HC908LJ24
Section 15. Multi-Master IIC Interface (MMIIC)
15.1 Contents
15.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .319
15.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320
15.4 I/O Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320
15.5 Multi-Master IIC Registers . . . . . . . . . . . . . . . . . . . . . . . . . . .321
15.5.1 Multi-Master IIC Address Register (MMADR) . . . . . . . . . .321
15.5.2 Multi-Master IIC Control Register (MMCR) . . . . . . . . . . . .323
15.5.3 Multi-Master IIC Master Control Register (MIMCR) . . . . . .324
15.5.4 Multi-Master IIC Status Register (MMSR) . . . . . . . . . . . . .326
15.5.5 Multi-Master IIC Data Transmit Register (MMDTR) . . . . . .328
15.5.6 Multi-Master IIC Data Receive Register (MMDRR) . . . . . .329
15.6 Programming Considerations . . . . . . . . . . . . . . . . . . . . . . . . .330
15.2 Introduction
This Multi-master IIC (MMIIC) Interface is designed for internal serial
communication between the MCU and other IIC devices. A hardware
circuit generates "start" and "stop" signal, while byte by byte data
transfer is interrupt driven by the software algorithm. Therefore, it can
greatly help the software in dealing with other devices to have higher
system efficiency in a typical digital monitor system.
This module not only can be applied in internal communications, but can
also be used as a typical command reception serial bus for factory setup
and alignment purposes. It also provides the flexibility of hooking
additional devices to an existing system for future expansion without
adding extra hardware.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
319
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Interface (MMIIC)
This Multi-master IIC module uses the SCL clock line and the SDA data
line to communicate with external DDC host or IIC interface. These two
pins are shared with port pins PTD6/KBI6 and PTD7/KBI7 respectively.
The outputs of SCL and SDA pins are open-drain type — no clamping
diode is connected between the pin and internal V . The maximum
DD
data rate typically is 750k-bps. The maximum communication length and
the number of devices that can be connected are limited by a maximum
bus capacitance of 400pF.
15.3 Features
• Compatibility with multi-master IIC bus standard
• Software controllable acknowledge bit generation
• Interrupt driven byte by byte data transfer
• Calling address identification interrupt
• Auto detection of R/W bit and switching of transmit or receive
mode
• Detection of START, repeated START, and STOP signals
• Auto generation of START and STOP condition in master mode
• Arbitration loss detection and No-ACK awareness in master mode
• 8 selectable baud rate master clocks
• Automatic recognition of the received acknowledge bit
15.4 I/O Pins
The MMIIC module uses two I/O pins, shared with standard port I/O pins.
The full name of the MMIIC I/O pins are listed in Table 15-1. The generic
pin name appear in the text that follows.
Table 15-1. Pin Name Conventions
MMIIC
Generic Pin Names:
Pin Selected for
IIC Function By:
Full MCU Pin Names:
(1)
(1)
SDA
SCL
PTD7/KBI7/SDA
PTD6/KBI6/SCL
MMEN bit in MMCR ($006C)
MMEN bit in MMCR ($006C)
Notes:
1. Do not enable the MMIIC function if the pin is used for KBI.
Data Sheet
320
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Registers
Addr.
Register Name
Multi-Master IIC
Bit 7
6
5
4
3
2
1
Bit 0
Read: MMALIF MMNAKIF MMBB
MMAST MMRW MMBR2 MMBR1 MMBR0
$006A Master Control Register Write:
0
0
0
0
(MIMCR)
Reset:
0
0
0
0
0
0
Read:
Multi-Master IIC Address
MMAD7 MMAD6 MMAD5 MMAD4 MMAD3 MMAD2 MMAD1 MMEXTAD
$006B
$006C
$006D
$006E
$006F
Register Write:
(MMADR)
Reset:
1
MMEN
0
0
MMIEN
0
1
0
0
0
0
0
0
0
0
0
Read:
Multi-Master IIC Control
MMTXAK REPSEN
Register Write:
(MMCR)
Reset:
0
0
0
0
0
0
0
Read: MMRXIF MMTXIF MMATCH MMSRW MMRXAK
MMTXBE MMRXBF
Multi-Master IIC
Status Register Write:
0
0
0
0
(MMSR)
Reset:
0
0
1
0
1
0
Read:
Multi-Master IIC
MMTD7 MMTD6 MMTD5 MMTD4 MMTD3 MMTD2 MMTD1 MMTD0
Data Transmit Register Write:
(MMDTR)
Reset:
1
1
1
1
1
1
1
1
Multi-Master IIC Read: MMRD7 MMRD6 MMRD5 MMRD4 MMRD3 MMRD2 MMRD1 MMRD0
Data Receive Register
Write:
(MMDRR)
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 15-1. MMIIC I/O Register Summary
15.5 Multi-Master IIC Registers
Six registers are associated with the Multi-master IIC module, they are
outlined in the following sections.
15.5.1 Multi-Master IIC Address Register (MMADR)
Address: $006B
Bit 7
6
5
4
3
2
1
Bit 0
Read:
MMAD7 MMAD6 MMAD5 MMAD4 MMAD3 MMAD2 MMAD1 MMEXTAD
Write:
Reset:
1
0
1
0
0
0
0
0
Figure 15-2. Multi-Master IIC Address Register (MMADR)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
321
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Interface (MMIIC)
MMAD[7:1] — Multi-Master Address
These seven bits represent the MMIIC interface’s own specific slave
address when in slave mode, and the calling address when in master
mode. Software must update MMAD[7:1] as the calling address while
entering master mode and restore its own slave address after master
mode is relinquished. This register is cleared as $A0 upon reset.
MMEXTAD — Multi-Master Expanded Address
This bit is set to expand the address of the MMIIC in slave mode.
When set, the MMIIC will acknowledge the following addresses from
a calling master: $MMAD[7:1], 0000000, and 0001100.
Reset clears this bit.
1 = MMIIC responds to the following calling addresses:
$MMAD[7:1], 0000000, and 0001100.
0 = MMIIC responds to address $MMAD[7:1]
For example, when MMADR is configured as:
MMAD7 MMAD6 MMAD5 MMAD4 MMAD3 MMAD2 MMAD1 MMEXTAD
1
1
0
1
0
1
0
1
The MMIIC module will respond to the calling address:
Bit 7
1
6
1
5
0
4
1
3
0
2
1
Bit 1
0
or the general calling address:
0
0
0
0
0
0
0
or the calling address:
0
0
0
1
1
0
0
NOTE: bit-0 of the 8-bit calling address is the MMRW bit from the calling master.
Data Sheet
322
MC68HC908LJ24/LK24 — Rev. 2.1
Multi-Master IIC Interface (MMIIC)
Freescale Semiconductor
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Registers
15.5.2 Multi-Master IIC Control Register (MMCR)
Address: $006C
Bit 7
MMEN
0
6
MMIEN
0
5
0
4
0
3
2
1
0
Bit 0
0
Read:
Write:
Reset:
MMTXAK REPSEN
0
0
0
0
0
0
= Unimplemented
Figure 15-3. Multi-Master IIC Control Register (MMCR)
MMEN — Multi-Master IIC Enable
This bit is set to enable the Multi-master IIC module. When
MMEN = 0, module is disabled and all flags will restore to its power-
on default states. Reset clears this bit.
1 = MMIIC module enabled
0 = MMIIC module disabled
MMIEN — Multi-Master IIC Interrupt Enable
When this bit is set, the MMTXIF, MMRXIF, MMALIF, and MMNAKIF
flags are enabled to generate an interrupt request to the CPU. When
MMIEN is cleared, the these flags are prevented from generating an
interrupt request. Reset clears this bit.
1 = MMTXIF, MMRXIF, MMALIF, and/or MMNAKIF bit set will
generate interrupt request to CPU
0 = MMTXIF, MMRXIF, MMALIF, and/or MMNAKIF bit set will not
generate interrupt request to CPU
MMTXAK — Transmit Acknowledge Enable
This bit is set to disable the MMIIC from sending out an acknowledge
signal to the bus at the 9th clock bit after receiving 8 data bits. When
MMTXAK is cleared, an acknowledge signal will be sent at the 9th
clock bit. Reset clears this bit.
1 = MMIIC does not send acknowledge signals at 9th clock bit
0 = MMIIC sends acknowledge signal at 9th clock bit
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
323
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Interface (MMIIC)
REPSEN — Repeated Start Enable
This bit is set to enable repeated START signal to be generated when
in master mode transfer (MMAST = 1). The REPSEN bit is cleared by
hardware after the completion of repeated START signal or when the
MMAST bit is cleared. Reset clears this bit.
1 = Repeated START signal will be generated if MMAST bit is set
0 = No repeated START signal will be generated
15.5.3 Multi-Master IIC Master Control Register (MIMCR)
Address: $006A
Bit 7
6
5
4
3
2
1
Bit 0
Read: MMALIF MMNAKIF MMBB
MMAST MMRW MMBR2 MMBR1 MMBR0
Write:
0
0
0
0
Reset:
0
0
0
0
0
0
= Unimplemented
Figure 15-4. Multi-Master IIC Master Control Register (MIMCR)
MMALIF — Multi-Master Arbitration Lost Interrupt Flag
This flag is set when software attempt to set MMAST but the MMBB
has been set by detecting the start condition on the lines or when the
MMIIC is transmitting a "1" to SDA line but detected a "0" from SDA
line in master mode – an arbitration loss. This bit generates an
interrupt request to the CPU if the MMIEN bit in MMCR is also set.
This bit is cleared by writing "0" to it or by reset.
1 = Lost arbitration in master mode
0 = No arbitration lost
MMNAKIF — No Acknowledge Interrupt Flag
This flag is only set in master mode (MMAST = 1) when there is no
acknowledge bit detected after one data byte or calling address is
transferred. This flag also clears MMAST. MMNAKIF generates an
interrupt request to CPU if the MMIEN bit in MMCR is also set. This
bit is cleared by writing "0" to it or by reset.
1 = No acknowledge bit detected
0 = Acknowledge bit detected
Data Sheet
324
MC68HC908LJ24/LK24 — Rev. 2.1
Multi-Master IIC Interface (MMIIC)
Freescale Semiconductor
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Registers
MMBB — Bus Busy Flag
This flag is set after a start condition is detected (bus busy), and is
cleared when a stop condition (bus idle) is detected.
Reset clears this bit.
1 = Start condition detected
0 = Stop condition detected or MMIIC is disabled
MMAST — Master Control Bit
This bit is set to initiate a master mode transfer. In master mode, the
module generates a start condition to the SDA and SCL lines,
followed by sending the calling address stored in MMADR.
When the MMAST bit is cleared by MMNAKIF set (no acknowledge)
or by software, the module generates the stop condition to the lines
after the current byte is transmitted.
If an arbitration loss occurs (MMALIF = 1), the module reverts to slave
mode by clearing MMAST, and releasing SDA and SCL lines
immediately.
This bit is cleared by writing "0" to it or by reset.
1 = Master mode operation
0 = Slave mode operation
MMRW — Master Read/Write
This bit will be transmitted out as bit 0 of the calling address when the
module sets the MMAST bit to enter master mode. The MMRW bit
determines the transfer direction of the data bytes that follows. When
it is "1", the module is in master receive mode. When it is "0", the
module is in master transmit mode. Reset clears this bit.
1 = Master mode receive
0 = Master mode transmit
MMBR2–MMBR0 — Baud Rate Select
These three bits select one of eight clock rates as the master clock
when the module is in master mode.
Since this master clock is derived the CPU bus clock, the user
program should not execute the WAIT instruction when the MMIIC
module in master mode. This will cause the SDA and SCL lines to
hang, as the WAIT instruction places the MCU in wait mode, with CPU
clock is halted. These bits are cleared upon reset.
(See Table 15-2 . Baud Rate Select.)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
325
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Interface (MMIIC)
Table 15-2. Baud Rate Select
MMBR2
MMBR1
MMBR0
Baud Rate
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Internal bus clock ÷ 8
Internal bus clock ÷ 16
Internal bus clock ÷ 32
Internal bus clock ÷ 64
Internal bus clock ÷ 128
Internal bus clock ÷ 256
Internal bus clock ÷ 512
Internal bus clock ÷ 1024
15.5.4 Multi-Master IIC Status Register (MMSR)
Address: $006D
Bit 7
6
5
4
3
2
0
1
Bit 0
Read: MMRXIF MMTXIF MMATCH MMSRW MMRXAK
MMTXBE MMRXBF
Write:
0
0
0
0
Reset:
0
0
1
0
1
0
= Unimplemented
Figure 15-5. Multi-Master IIC Status Register (MMSR)
MMRXIF — Multi-Master IIC Receive Interrupt Flag
This flag is set after the data receive register (MMDRR) is loaded with
a new received data. Once the MMDRR is loaded with received data,
no more received data can be loaded to the MMDRR register until the
CPU reads the data from the MMDRR to clear MMRXBF flag.
MMRXIF generates an interrupt request to CPU if the MMIEN bit in
MMCR is also set. This bit is cleared by writing "0" to it or by reset; or
when the MMEN = 0.
1 = New data in data receive register (MMDRR)
0 = No data received
Data Sheet
326
MC68HC908LJ24/LK24 — Rev. 2.1
Multi-Master IIC Interface (MMIIC)
Freescale Semiconductor
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Registers
MMTXIF — Multi-Master Transmit Interrupt Flag
This flag is set when data in the data transmit register (MMDTR) is
downloaded to the output circuit, and that new data can be written to
the MMDTR. MMTXIF generates an interrupt request to CPU if the
MMIEN bit in MMCR is also set. This bit is cleared by writing "0" to it
or when the MMEN = 0.
1 = Data transfer completed
0 = Data transfer in progress
MMATCH — Multi-Master Address Match
This flag is set when the received data in the data receive register
(MMDRR) is an calling address which matches with the address or its
extended addresses (MMEXTAD=1) specified in the MMADR
register.
1 = Received address matches MMADR
0 = Received address does not match
MMSRW — Multi-Master Slave Read/Write
This bit indicates the data direction when the module is in slave mode.
It is updated after the calling address is received from a master
device. MMSRW = 1 when the calling master is reading data from the
module (slave transmit mode). MMSRW = 0 when the master is
writing data to the module (receive mode).
1 = Slave mode transmit
0 = Slave mode receive
MMRXAK — Multi-Master Receive Acknowledge
When this bit is cleared, it indicates an acknowledge signal has been
received after the completion of 8 data bits transmission on the bus.
When MMRXAK is set, it indicates no acknowledge signal has been
detected at the 9th clock; the module will release the SDA line for the
master to generate "stop" or "repeated start" condition. Reset sets this
bit.
1 = No acknowledge signal received at 9th clock bit
0 = Acknowledge signal received at 9th clock bit
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
327
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Interface (MMIIC)
MMTXBE — Multi-Master Transmit Buffer Empty
This flag indicates the status of the data transmit register (MMDTR).
When the CPU writes the data to the MMDTR, the MMTXBE flag will
be cleared. MMTXBE is set when MMDTR is emptied by a transfer of
its data to the output circuit. Reset sets this bit.
1 = Data transmit register empty
0 = Data transmit register full
MMRXBF — Multi-Master Receive Buffer Full
This flag indicates the status of the data receive register (MMDRR).
When the CPU reads the data from the MMDRR, the MMRXBF flag
will be cleared. MMRXBF is set when MMDRR is full by a transfer of
data from the input circuit to the MMDRR. Reset clears this bit.
1 = Data receive register full
0 = Data receive register empty
15.5.5 Multi-Master IIC Data Transmit Register (MMDTR)
Address: $006E
Bit 7
6
5
4
3
2
1
Bit 0
Read:
MMTD7 MMTD6 MMTD5 MMTD4 MMTD3 MMTD2 MMTD1 MMTD0
Write:
Reset:
1
1
1
1
1
1
1
1
Figure 15-6. Multi-Master IIC Data Transmit Register (MMDTR)
When the MMIIC module is enabled, MMEN = 1, data written into this
register depends on whether module is in master or slave mode.
In slave mode, the data in MMDTR will be transferred to the output circuit
when:
• the module detects a matched calling address (MMATCH = 1),
with the calling master requesting data (MMSRW = 1); or
• the previous data in the output circuit has be transmitted and the
receiving master returns an acknowledge bit, indicated by a
received acknowledge bit (MMRXAK = 0).
Data Sheet
328
MC68HC908LJ24/LK24 — Rev. 2.1
Multi-Master IIC Interface (MMIIC)
Freescale Semiconductor
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Registers
If the calling master does not return an acknowledge bit (MMRXAK = 1),
the module will release the SDA line for master to generate a "stop" or
"repeated start" condition. The data in the MMDTR will not be transferred
to the output circuit until the next calling from a master. The transmit
buffer empty flag remains cleared (MMTXBE = 0).
In master mode, the data in MMDTR will be transferred to the output
circuit when:
• the module receives an acknowledge bit (MMRXAK = 0), after
setting master transmit mode (MMRW = 0), and the calling
address has been transmitted; or
• the previous data in the output circuit has be transmitted and the
receiving slave returns an acknowledge bit, indicated by a
received acknowledge bit (MMRXAK = 0).
If the slave does not return an acknowledge bit (MMRXAK = 1), the
master will generate a "stop" or "repeated start" condition. The data in
the MMDTR will not be transferred to the output circuit. The transmit
buffer empty flag remains cleared (MMTXBE = 0).
The sequence of events for slave transmit and master transmit are
illustrated in Figure 15-8.
15.5.6 Multi-Master IIC Data Receive Register (MMDRR)
Address: $006F
Bit 7
6
5
4
3
2
1
Bit 0
Read: MMRD7 MMRD6 MMRD5 MMRD4 MMRD3 MMRD2 MMRD1 MMRD0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 15-7. Multi-Master IIC Data Receive Register (MMDRR)
When the MMIIC module is enabled, MMEN = 1, data in this read-only
register depends on whether module is in master or slave mode.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
329
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Interface (MMIIC)
In slave mode, the data in MMDRR is:
• the calling address from the master when the address match flag
is set (MMATCH = 1); or
• the last data received when MMATCH = 0.
In master mode, the data in the MMDRR is:
• the last data received.
When the MMDRR is read by the CPU, the receive buffer full flag is
cleared (MMRXBF = 0), and the next received data is loaded to the
MMDRR. Each time when new data is loaded to the MMDRR, the
MMRXIF interrupt flag is set, indicating that new data is available in
MMDRR.
The sequence of events for slave receive and master receive are
illustrated in Figure 15-8.
15.6 Programming Considerations
When the MMIIC module detects an arbitration loss in master mode, it
will release both SDA and SCL lines immediately. But if there are no
further STOP conditions detected, the module will hang up. Therefore, it
is recommended to have time-out software to recover from such ill
condition. The software can start the time-out counter by looking at the
MMBB (Bus Busy) flag in the MIMCR and reset the counter on the
completion of one byte transmission. If a time-out occur, software can
clear the MMEN bit (disable MMIIC module) to release the bus, and
hence clearing the MMBB flag. This is the only way to clear the MMBB
flag by software if the module hangs up due to a no STOP condition
received. The MMIIC can resume operation again by setting the MMEN
bit.
Data Sheet
330
MC68HC908LJ24/LK24 — Rev. 2.1
Multi-Master IIC Interface (MMIIC)
Freescale Semiconductor
Multi-Master IIC Interface (MMIIC)
Programming Considerations
(a) Master Transmit Mode
TX Data1
START
Address
0
ACK
ACK
TX DataN
ACK
STOP
MMTXBE=0
MMTXBE=1
MMTXIF=1
MMTXBE=1
MMNAKIF=1
MMAST=0
MMTXBE=1
MMRW=0
MMTXIF=1
MMTXIF=1
MMAST=1
Data2 → MMDTR
Data3 → MMDTR
MMTXBE=0
DataN+2 → MMDTR
Data1 → MMDTR
(b) Master Receive Mode
RX Data1
START
Address
1
ACK
ACK
RX DataN
NAK
STOP
MMRXBF=0
MMRW=1
MMNAKIF=1
MMAST=0
Data1 → MMDRR
MMRXIF=1
MMRXBF=1
DataN → MMDRR
MMRXIF=1
MMAST=1
MMTXBE=0
MMRXBF=1
(dummy data → MMDTR)
(c) Slave Transmit Mode
TX Data1
START
Address
1
ACK
ACK
TX DataN
NAK
STOP
MMTXBE=1
MMRXIF=1
MMNAKIF=1
MMTXBE=0
MMTXBE=1
MMTXBE=1
MMRXBF=0
MMRXBF=1
MMATCH=1
MMSRW=1
MMTXIF=1
MMTXIF=1
Data2 → MMDTR
DataN+2 → MMDTR
Data1 → MMDTR
(d) Slave Receive Mode
RX Data1
START
Address
0
ACK
ACK
RX DataN
ACK
STOP
Data1 → MMDRR
MMRXIF=1
MMRXBF=1
DataN → MMDRR
MMRXIF=1
MMTXBE=0
MMRXBF=0
MMRXIF=1
MMRXBF=1
MMATCH=1
MMSRW=0
MMRXBF=1
Shaded data packets indicate transmissions by the MCU
Figure 15-8. Data Transfer Sequences for Master/Slave Transmit/Receive Modes
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
331
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Interface (MMIIC)
Data Sheet
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
332
Multi-Master IIC Interface (MMIIC)
Data Sheet — MC68HC908LJ24
Section 16. Analog-to-Digital Converter (ADC)
16.1 Contents
16.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .334
16.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .334
16.4 Functional Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .335
16.4.1 ADC Port I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .335
16.4.2 Voltage Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .337
16.4.3 Conversion Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .337
16.4.4 Continuous Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . .338
16.4.5 Result Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .338
16.4.6 Monotonicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .339
16.5 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.7 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
16.7.1 ADC Voltage In (V
) . . . . . . . . . . . . . . . . . . . . . . . . . . .341
ADIN
16.7.2 ADC Analog Power Pin (V
) . . . . . . . . . . . . . . . . . . . . .341
DDA
16.7.3 ADC Analog Ground Pin (V
). . . . . . . . . . . . . . . . . . . . .341
SSA
16.7.4 ADC Voltage Reference High Pin (V
). . . . . . . . . . . . .341
REFH
16.7.5 ADC Voltage Reference Low Pin (V
) . . . . . . . . . . . . .341
REFL
16.8 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .342
16.8.1 ADC Status and Control Register. . . . . . . . . . . . . . . . . . . .342
16.8.2 ADC Data Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .344
16.8.3 ADC Clock Control Register. . . . . . . . . . . . . . . . . . . . . . . .346
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
333
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
16.2 Introduction
This section describes the analog-to-digital convert (ADC). The ADC is
a 6-channel 10-bit linear successive approximation ADC.
16.3 Features
Features of the ADC module include:
• Six channels with multiplexed input
• High impedance buffered input
• Linear successive approximation with monotonicity
• 10-Bit resolution
• Single or continuous conversion
• Conversion complete flag or conversion complete interrupt
• Selectable ADC clock
• Conversion result justification
– 8-bit truncated mode
– Right justified mode
– Left justified mode
– Left justified sign mode
Data Sheet
334
MC68HC908LJ24/LK24 — Rev. 2.1
Analog-to-Digital Converter (ADC)
Freescale Semiconductor
Analog-to-Digital Converter (ADC)
Functional Descriptions
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read: COCO
ADC Status and Control
AIEN
ADCO
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
$003C
Register Write:
(ADSCR)
Reset:
Read:
Write:
Reset:
Read:
0
ADx
R
0
ADx
R
0
ADx
R
1
ADx
R
1
ADx
R
1
ADx
R
1
ADx
R
1
ADx
R
ADC Data Register High
(ADRH)
$003D
$003E
$003F
0
0
0
0
0
0
0
0
ADx
R
ADx
R
ADx
R
ADx
R
ADx
R
ADx
R
ADx
R
ADx
R
ADC Data Register Low
(ADRL) Write:
Reset:
0
0
0
0
0
0
0
0
Read:
0
0
ADC Clock Register
ADIV2
0
ADIV1
0
ADIV0
0
ADICLK MODE1 MODE0
(ADCLK) Write:
Reset:
R
0
0
1
0
0
= Unimplemented
R
= Reserved
Figure 16-1. ADC I/O Register Summary
16.4 Functional Descriptions
The ADC provides six pins for sampling external sources at pins
PTA4/ADC0–PTA7/ADC3 and PTB6/ADC4–PTB7/ADC5. An analog
multiplexer allows the single ADC converter to select one of ten ADC
channels as ADC voltage in (V
). V
is converted by the
ADIN
ADIN
successive approximation register-based analog-to-digital converter.
When the conversion is completed, ADC places the result in the ADC
data register, high and low byte (ADRH and ADRL), and sets a flag or
generates an interrupt.
Figure 16-2 shows the structure of the ADC module.
16.4.1 ADC Port I/O Pins
PTA4–PTA7 and PTB6–PTB7 are general-purpose I/O pins that are
shared with the ADC channels. The channel select bits, ADCH[4:0],
define which ADC channel/port pin will be used as the input signal. The
ADC overrides the port I/O logic by forcing that pin as input to the ADC.
The remaining ADC channels/port pins are controlled by the port I/O
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
335
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
logic and can be used as general-purpose I/O pins. Writes to the port
data register or data direction register will not have any affect on the port
pin that is selected by the ADC. Read of a port pin which is in use by the
ADC will return the pin condition if the corresponding DDR bit is at
logic 0. If the DDR bit is at logic 1, the value in the port data latch is read.
INTERNAL
DATA BUS
READ DDRAx/DDRBx
WRITE DDRAx/DDRBx
DISABLE
DDRAx/DDRBx
PTAx/PTBx
RESET
WRITE PTAx/PTBx
PTAx/PTBx
READ PTAx/PTBx
ADC0–ADC5
(6 CHANNELS)
DISABLE
ADC DATA REGISTERS
VLCD
VREFH
VREFL
ADRH
ADRL
1.2V
BANDGAP
REFERENCE
ADC
VOLTAGE IN
CONVERSION
COMPLETE
(VADIN
)
CHANNEL
SELECT
INTERRUPT
LOGIC
ADC
ADC CLOCK
AIEN
COCO
ADCH[4:0]
CGMXCLK
CLOCK
GENERATOR
BUS CLOCK
ADIV[2:0] ADICLK
Figure 16-2. ADC Block Diagram
Data Sheet
336
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
Functional Descriptions
16.4.2 Voltage Conversion
When the input voltage to the ADC equals V
, the ADC converts the
REFH
signal to $3FF (full scale). If the input voltage equals V
, the ADC
REFL
converts it to $000. Input voltages between V
and V
are
REFH
REFL
straight-line linear conversions. All other input voltages will result in
$3FF if greater than V and $000 if less than V
.
REFL
REFH
NOTE: Input voltage should not exceed the analog supply voltages.
16.4.3 Conversion Time
Conversion starts after a write to the ADSCR. A conversion is between
16 and 17 ADC clock cycles, therefore:
16 to17 ADC cycles
Conversion time =
ADC frequency
Number of bus cycles = conversion time × bus frequency
The ADC conversion time is determined by the clock source chosen and
the divide ratio selected. The clock source is either the bus clock or
CGMXCLK and is selectable by the ADICLK bit located in the ADC clock
control register. The divide ratio is selected by the ADIV[2:0] bits.
For example, if a 4MHz CGMXCLK is selected as the ADC input clock
source, with a divide-by-2 prescale, and the bus speed is set at 8MHz:
16 to 17 ADC cycles
Conversion time =
= 8 to 8.5 µs
4MHz ÷ 2
Number of bus cycles = 8µs x 8MHz = 64 to 68 cycles
NOTE: The ADC frequency must be between f minimum and f
ADIC
ADIC
maximum to meet ADC specifications. See 24.12 5V ADC Electrical
Characteristics and 24.13 3.3V ADC Electrical Characteristics.
Since an ADC cycle may be comprised of several bus cycles (eight in the
previous example) and the start of a conversion is initiated by a bus cycle
write to the ADSCR, from zero to four additional bus cycles may occur
before the start of the initial ADC cycle. This results in a fractional ADC
cycle and is represented as the 17th cycle.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
337
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
16.4.4 Continuous Conversion
In the continuous conversion mode, the ADC continuously converts the
selected channel, filling the ADC data register (ADRH:ADRL) with new
data after each conversion. Data from the previous conversion will be
overwritten whether that data has been read or not. Conversions will
continue until the ADCO bit is cleared. The COCO bit is set after each
conversion and can be cleared by writing to the ADC status and control
register or reading of the ADRL data register.
16.4.5 Result Justification
The conversion result may be formatted in four different ways.
• Left justified
• Right justified
• Left justified sign data mode
• 8-bit truncation
All four of these modes are controlled using MODE0 and MODE1 bits
located in the ADC clock control register (ADCLK).
Left justification will place the eight most significant bits (MSB) in the
ADC data register high (ADRH). This may be useful if the result is to be
treated as an 8-bit result where the least significant two bits, located in
the ADC data register low (ADRL) can be ignored. However, ADRL must
be read after ADRH or else the interlocking will prevent all new
conversions from being stored.
Right justification will place only the two MSBs in the corresponding ADC
data register high (ADRH) and the eight LSB bits in ADC data register
low (ADRL). This mode of operation typically is used when a 10-bit
unsigned result is desired.
Left justified sign data mode is similar to left justified mode with one
exception. The MSB of the 10-bit result, AD9 located in ADRH is
complemented. This mode of operation is useful when a result,
represented as a signed magnitude from mid-scale, is needed.
Data Sheet
338
MC68HC908LJ24/LK24 — Rev. 2.1
Analog-to-Digital Converter (ADC)
Freescale Semiconductor
Analog-to-Digital Converter (ADC)
Functional Descriptions
Finally, 8-bit truncation mode will place the eight MSBs in ADC data
register low (ADRL). The two LSBs are dropped. This mode of operation
is used when compatibility with 8-bit ADC designs are required. No
interlocking between ADRH and ADRL is present.
NOTE: Quantization error is affected when only the most significant eight bits
are used as a result. See Figure 16-3.
8-BIT 10-BIT
RESULT RESULT
IDEAL 8-BIT CHARACTERISTIC
WITH QUANTIZATION = ±1/2
10-BIT TRUNCATED
TO 8-BIT RESULT
003
00B
00A
009
IDEAL 10-BIT CHARACTERISTIC
WITH QUANTIZATION = ±1/2
002
001
000
008
007
006
005
004
003
002
001
000
WHEN TRUNCATION IS USED,
ERROR FROM IDEAL 8-BIT = 3/8 LSB
DUE TO NON-IDEAL QUANTIZATION.
INPUT VOLTAGE
1/2
2 1/2
4 1/2
6 1/2
8 1/2
REPRESENTED AS 10-BIT
INPUT VOLTAGE
REPRESENTED AS 8-BIT
1 1/2
3 1/2
5 1/2
7 1/2
9 1/2
1/2
1 1/2
2 1/2
Figure 16-3. 8-Bit Truncation Mode Error
16.4.6 Monotonicity
The conversion process is monotonic and has no missing codes.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
339
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
16.5 Interrupts
When the AIEN bit is set, the ADC module is capable of generating a
CPU interrupt after each ADC conversion. A CPU interrupt is generated
if the COCO bit is at logic 0. The COCO bit is not used as a conversion
complete flag when interrupts are enabled. The interrupt vector is
defined in Table 2-1 . Vector Addresses.
16.6 Low-Power Modes
The STOP and WAIT instructions put the MCU in low power-
consumption standby modes.
16.6.1 Wait Mode
The ADC continues normal operation in wait mode. Any enabled CPU
interrupt request from the ADC can bring the MCU out of wait mode. If
the ADC is not required to bring the MCU out of wait mode, power down
the ADC by setting the ADCH[4:0] bits to logic 1’s before executing the
WAIT instruction.
16.6.2 Stop Mode
The ADC module is inactive after the execution of a STOP instruction.
Any pending conversion is aborted. ADC conversions resume when the
MCU exits stop mode. Allow one conversion cycle to stabilize the analog
circuitry before attempting a new ADC conversion after exiting stop
mode.
16.7 I/O Signals
The ADC module has ten channels, six channels are shared with port A
and port B I/O pins; two channels are the ADC voltage reference inputs,
V
and V
; one channel is the V
input; and one channel is the
LCD
REFH
REFL
1.2V bandgap reference voltage.
Data Sheet
340
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
I/O Signals
16.7.1 ADC Voltage In (V
)
ADIN
V
is the input voltage signal from one of the ten channels to the ADC
ADIN
module.
16.7.2 ADC Analog Power Pin (V
)
DDA
The ADC analog portion uses V
as its power pin. Connect the V
DDA
DDA
pin to the same voltage potential as V . External filtering may be
DD
necessary to ensure clean V
for good results.
DDA
NOTE: Route V
carefully for maximum noise immunity and place bypass
DDA
capacitors as close as possible to the package.
16.7.3 ADC Analog Ground Pin (V
)
SSA
The ADC analog portion uses V
as its ground pin. Connect the V
SSA
SSA
pin to the same voltage potential as V .
SS
NOTE: On the 64-pin and 80-pin MC68HC908LJ24, V
is internally bonded
SSA
to V .
SS
16.7.4 ADC Voltage Reference High Pin (V
)
REFH
V
is the power supply for setting the reference voltage V
.
REFH
REFH
Connect the V
pin to the same voltage potential as V
. There will
REFH
DDA
be a finite current associated with V
(see 24.12 5V ADC Electrical
REFH
Characteristics).
NOTE: Route V
carefully for maximum noise immunity and place bypass
REFH
capacitors as close as possible to the package.
16.7.5 ADC Voltage Reference Low Pin (V
)
REFL
V
is the lower reference supply for the ADC. Connect the V
pin
REFL
REFL
to the same voltage potential as V
. There will be a finite current
SSA
associated with V
(see 24.12 5V ADC Electrical Characteristics).
REFL
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
Analog-to-Digital Converter (ADC)
341
Analog-to-Digital Converter (ADC)
16.8 I/O Registers
These I/O registers control and monitor operation of the ADC:
• ADC status and control register, (ADSCR)
• ADC data register (ADRH:ADRL)
• ADC clock control register (ADCLK)
16.8.1 ADC Status and Control Register
This section describes the function of the ADC status and control
register (ADSCR). Writing ADSCR aborts the current conversion and
initiates a new conversion.
Address: $003C
Read: COCO
AIEN
0
ADCO
0
ADCH4
1
ADCH3
1
ADCH2
1
ADCH1
1
ADCH0
1
Write:
Reset:
0
= Unimplemented
Figure 16-4. ADC Status and Control Register (ADSCR)
COCO — Conversions Complete Bit
When the AIEN bit is a logic 0, the COCO is a read-only bit which is
set each time a conversion is completed. This bit is cleared whenever
the ADSCR is written, or whenever the ADC clock control register is
written, or whenever the ADC data register low, ADRL, is read.
If the AIEN bit is logic 1, the COCO bit always read as logic 0, CPU to
service the ADC interrupt will be generated at the end if an ADC
conversion. Reset clears the COCO bit.
1 = Conversion completed (AIEN = 0)
0 = Conversion not completed (AIEN = 0)/CPU interrupt (AIEN=1)
AIEN — ADC Interrupt Enable Bit
When this bit is set, an interrupt is generated at the end of an ADC
conversion. The interrupt signal is cleared when the data register,
ADR0, is read or the ADSCR is written. Reset clears the AIEN bit.
1 = ADC interrupt enabled
0 = ADC interrupt disabled
Data Sheet
342
MC68HC908LJ24/LK24 — Rev. 2.1
Analog-to-Digital Converter (ADC)
Freescale Semiconductor
Analog-to-Digital Converter (ADC)
I/O Registers
ADCO — ADC Continuous Conversion Bit
When set, the ADC will convert samples continuously and update the
ADC data register at the end of each conversion. Only one conversion
is allowed when this bit is cleared. Reset clears the ADCO bit.
1 = Continuous ADC conversion
0 = One ADC conversion
ADCH[4:0] — ADC Channel Select Bits
ADCH[4:0] form a 5-bit field which is used to select one of the ADC
channels when not in auto-scan mode. The five channel select bits
are detailed in Table 16-1.
NOTE: Care should be taken when using a port pin as both an analog and a
digital input simultaneously to prevent switching noise from corrupting
the analog signal.
Recovery from the disabled state requires one conversion cycle to
stabilize.
Table 16-1. MUX Channel Select
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
ADC Channel
ADC0
ADC1
ADC2
ADC3
ADC4
ADC5
ADC6
ADC7
ADC8
↓
Input Select
0
0
0
0
0
0
0
0
0
↓
1
1
0
0
0
0
0
0
0
0
1
↓
1
1
0
0
0
0
1
1
1
1
0
↓
1
1
0
0
1
1
0
0
1
1
0
↓
0
0
0
1
0
1
0
1
0
1
0
↓
0
1
PTA4
PTA5
PTA6
PTA7
PTB6
PTB7
1.2V Bandgap reference
V
LCD
Reserved
ADC28
ADC29
V
(see Note 2)
(see Note 2)
—
REFH
V
1
1
1
1
1
1
1
0
1
ADC30
REFL
1
ADC powered-off
NOTES:
1. If any reserved channels are selected, the resulting ADC conversion will be unknown.
2. The voltage levels supplied from internal reference nodes as specified in the table are used to verify the operation of
the ADC converter both in production test and for user applications.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
343
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
16.8.2 ADC Data Register
The ADC data register consist of a pair of 8-bit registers: high byte
(ADRH), and low byte (ADRL). This pair form a 16-bit register to store
the 10-bit ADC result for the selected ADC result justification mode.
In 8-bit truncated mode, the ADRL holds the eight most significant bits
(MSBs) of the 10-bit result. The ADRL is updated each time an ADC
conversion completes. In 8-bit truncated mode, ADRL contains no
interlocking with ADRH. (See Figure 16-5 . ADRH and ADRL in 8-Bit
Truncated Mode.)
Addr.
Register Name
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
Read:
Write:
Reset:
Read:
Write:
Reset:
ADC Data Register High
(ADRH)
$003D
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
AD9
R
AD8
R
AD7
R
AD6
R
AD5
R
AD4
R
AD3
R
AD2
R
ADC Data Register Low
(ADRL)
$003E
0
0
0
0
0
0
0
0
Figure 16-5. ADRH and ADRL in 8-Bit Truncated Mode
In right justified mode the ADRH holds the two MSBs, and the ADRL
holds the eight least significant bits (LSBs), of the 10-bit result. ADRH
and ADRL are updated each time a single channel ADC conversion
completes. Reading ADRH latches the contents of ADRL. Until ADRL is
read all subsequent ADC results will be lost.
(See Figure 16-6 . ADRH and ADRL in Right Justified Mode.)
Addr.
Register Name
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
AD9
R
Bit 0
AD8
R
Read:
Write:
Reset:
Read:
Write:
Reset:
ADC Data Register High
(ADRH)
$003D
R
R
R
R
R
R
0
0
0
0
0
0
0
0
AD7
R
AD6
R
AD5
R
AD4
R
AD3
R
AD2
R
AD1
R
AD0
R
ADC Data Register Low
(ADRL)
$003E
0
0
0
0
0
0
0
0
Figure 16-6. ADRH and ADRL in Right Justified Mode
Data Sheet
344
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
I/O Registers
In left justified mode the ADRH holds the eight most significant bits
(MSBs), and the ADRL holds the two least significant bits (LSBs), of the
10-bit result. The ADRH and ADRL are updated each time a single
channel ADC conversion completes. Reading ADRH latches the
contents of ADRL. Until ADRL is read all subsequent ADC results will be
lost. (See Figure 16-7 . ADRH and ADRL in Left Justified Mode.)
Addr.
Register Name
Bit 7
AD9
R
6
AD8
R
5
AD7
R
4
AD6
R
3
AD5
R
2
AD4
R
1
AD3
R
Bit 0
AD2
R
Read:
Write:
Reset:
Read:
Write:
Reset:
ADC Data Register High
(ADRH)
$003D
0
0
0
0
0
0
0
0
AD1
R
AD0
R
0
0
0
0
0
0
ADC Data Register Low
(ADRL)
$003E
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Figure 16-7. ADRH and ADRL in Left Justified Mode
In left justified sign mode the ADRH holds the eight MSBs with the MSB
complemented, and the ADRL holds the two least significant bits (LSBs),
of the 10-bit result. The ADRH and ADRL are updated each time a single
channel ADC conversion completes. Reading ADRH latches the
contents of ADRL. Until ADRL is read all subsequent ADC results will be
lost. (See Figure 16-8 . ADRH and ADRL in Left Justified Sign Data
Mode.)
Addr.
Register Name
Bit 7
AD9
R
6
AD8
R
5
AD7
R
4
AD6
R
3
AD5
R
2
AD4
R
1
AD3
R
Bit 0
AD2
R
Read:
Write:
Reset:
Read:
Write:
Reset:
ADC Data Register High
(ADRH)
$003D
0
0
0
0
0
0
0
0
AD1
R
AD0
R
0
0
0
0
0
0
ADC Data Register Low
(ADRL)
$003E
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Figure 16-8. ADRH and ADRL in Left Justified Sign Data Mode
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
345
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
16.8.3 ADC Clock Control Register
The ADC clock control register (ADCLK) selects the clock frequency for
the ADC.
Address: $003F
Read:
ADIV2
Write:
0
0
0
R
0
ADIV1
0
ADIV0
0
ADICLK MODE1 MODE0
Reset:
0
0
0
1
= Unimplemented
R
= Reserved
Figure 16-9. ADC Clock Control Register (ADCLK)
ADIV[2:0] — ADC Clock Prescaler Bits
ADIV2, ADIV1, and ADIV0 form a 3-bit field which selects the divide
ratio used by the ADC to generate the internal ADC clock.
Table 16-2 shows the available clock configurations. The ADC clock
should be set to between 32kHz and 2MHz.
Table 16-2. ADC Clock Divide Ratio
ADIV2
ADIV1
ADIV0
ADC Clock Rate
ADC input clock ÷ 1
ADC input clock ÷ 2
ADC input clock ÷ 4
ADC input clock ÷ 8
ADC input clock ÷ 16
0
0
0
0
1
0
0
1
1
X
0
1
0
1
X
X = don’t care
ADICLK — ADC Input Clock Select Bit
ADICLK selects either bus clock or CGMXCLK as the input clock
source to generate the internal ADC clock. Reset selects CGMXCLK
as the ADC clock source.
Data Sheet
346
MC68HC908LJ24/LK24 — Rev. 2.1
Analog-to-Digital Converter (ADC)
Freescale Semiconductor
Analog-to-Digital Converter (ADC)
I/O Registers
If the external clock (CGMXCLK) is equal to or greater than 1MHz,
CGMXCLK can be used as the clock source for the ADC. If
CGMXCLK is less than 1MHz, use the PLL-generated bus clock as
the clock source. As long as the internal ADC clock is at f
, correct
ADIC
operation can be guaranteed.
1 = Internal bus clock
0 = External clock, CGMXCLK
CGMXCLK or bus frequency
f
=
ADIC
ADIV[2:0]
MODE1 and MODE0 — Modes of Result Justification
MODE1 and MODE0 selects between four modes of operation. The
manner in which the ADC conversion results will be placed in the ADC
data registers is controlled by these modes of operation. Reset
returns right-justified mode.
Table 16-3. ADC Mode Select
MODE1
MODE0
ADC Clock Rate
8-bit truncated mode
Right justified mode
0
0
1
1
0
1
0
1
Left justified mode
Left justified sign data mode
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
347
Analog-to-Digital Converter (ADC)
Analog-to-Digital Converter (ADC)
Data Sheet
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
348
Analog-to-Digital Converter (ADC)
Data Sheet — MC68HC908LJ24
Section 17. Liquid Crystal Display (LCD) Driver
17.1 Contents
17.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .350
17.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .350
17.4 Pin Name Conventions and I/O Register Addresses . . . . . . .350
17.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .354
17.5.1 LCD Duty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .356
17.5.2 LCD Voltages (V
, V
, V
, V
) . . . . . . . . . . .356
LCD3
LCD
LCD1
LCD2
17.5.3 LCD Cycle Frame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .356
17.5.4 Fast Charge and Low Current . . . . . . . . . . . . . . . . . . . . . .357
17.5.5 Contrast Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .358
17.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .358
17.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .359
17.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .359
17.7 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .359
17.7.1 BP0–BP3 (Backplane Drivers) . . . . . . . . . . . . . . . . . . . . . .360
17.7.2 FP0–FP32 (Frontplane Drivers) . . . . . . . . . . . . . . . . . . . . .362
17.8 Seven Segment Display Connection . . . . . . . . . . . . . . . . . . .366
17.9 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .369
17.9.1 LCD Control Register (LCDCR) . . . . . . . . . . . . . . . . . . . . .369
17.9.2 LCD Clock Register (LCDCLK) . . . . . . . . . . . . . . . . . . . . .371
17.9.3 LCD Data Registers (LDAT1–LDAT17) . . . . . . . . . . . . . . .373
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
349
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
17.2 Introduction
This section describes the liquid crystal display (LCD) driver module.
The LCD driver module can drive a maximum of 33 frontplanes and 4
backplanes, depending on the LCD duty selected.
17.3 Features
Features of the LCD driver module include the following:
• Software programmable driver segment configurations:
– 32 frontplanes × 4 backplanes (128 segments)
– 33 frontplanes × 3 backplanes (99 segments)
– 33 frontplanes × 1 backplane (33 segments)
• LCD bias voltages generated by internal resistor ladder
• Software programmable contrast control
17.4 Pin Name Conventions and I/O Register Addresses
Three dedicated I/O pins are for the backplanes, BP0–BP2; sixteen
dedicated I/O pins are for the frontplanes, FP1–FP10 and FP27–FP32;
and the sixteen frontplanes, FP11–FP26, are shared with port C and E
pins. FP0 and BP3 shares the same pin and configured by the
DUTY[1:0] bits in the LCD clock register.
The full names of the LCD output pins are shown in Table 17-1. The
generic pin names appear in the text that follows.
Table 17-1. Pin Name Conventions
LCD Generic Pin Name
FP0/BP3
Full MCU Pin Name
FP0/BP3
Pin Selected for LCD Function by:
—
BP0–BP2
BP0–BP2
—
FP1–FP10
FP1–FP10
—
PEE in CONFIG2
PCEL:PCEH in CONFIG2
—
FP11–FP18
FP19–FP26
FP27–FP32
PTE0/FP11–PTE7/FP18
PTC0/FP19–PTC7/FP26
FP27–FP32
Data Sheet
350
MC68HC908LJ24/LK24 — Rev. 2.1
Liquid Crystal Display (LCD) Driver
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Pin Name Conventions and I/O Register Addresses
Addr.
Register Name
Bit 7
6
5
4
3
DUTY0
0
2
LCLK2
0
1
LCLK1
0
Bit 0
LCLK0
0
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
0
FCCTL1 FCCTL0 DUTY1
LCD Clock Register
(LCDCLK)
$004F
0
LCDE
0
0
0
0
FC
0
LC
LCCON3 LCCON2 LCCON1 LCCON0
LCD Control Register
(LCDCR)
$0051
$0052
$0053
$0054
$0055
$0056
$0057
$0058
$0059
0
F1B2
U
0
0
0
F0B3
U
0
F0B2
U
0
F0B1
U
0
F0B0
U
F1B3
U
F1B1
U
F1B0
U
LCD Data Register 1
(LDAT1)
F3B3
U
F3B2
U
F3B1
U
F3B0
U
F2B3
U
F2B2
U
F2B1
U
F2B0
U
LCD Data Register 2
(LDAT2)
F5B3
U
F5B2
U
F5B1
U
F5B0
U
F4B3
U
F4B2
U
F4B1
U
F4B0
U
LCD Data Register 3
(LDAT3)
F7B3
U
F7B2
U
F7B1
U
F7B0
U
F6B3
U
F6B2
U
F6B1
U
F6B0
U
LCD Data Register 4
(LDAT4)
F9B3
U
F9B2
U
F9B1
U
F9B0
U
F8B3
U
F8B2
U
F8B1
U
F8B0
U
LCD Data Register 5
(LDAT5)
F11B3
U
F11B2
U
F11B1
U
F11B0
U
F10B3
U
F10B2
U
F10B1
U
F10B0
U
LCD Data Register 6
(LDAT6)
F13B3
U
F13B2
U
F13B1
U
F13B0
U
F12B3
U
F12B2
U
F12B1
U
F12B0
U
LCD Data Register 7
(LDAT7)
F15B3
U
F15B2
U
F15B1
U
F15B0
U
F14B3
U
F14B2
U
F14B1
U
F14B0
U
LCD Data Register 8
(LDAT8)
U = Unaffected
= Unimplemented
Figure 17-1. LCD I/O Register Summary
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
351
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
Read:
F17B3
U
F17B2
U
F17B1
U
F17B0
U
F16B3
U
F16B2
U
F16B1
U
F16B0
U
LCD Data Register 9
(LDAT9)
$005A
$005B
$005C
$005D
$005E
$005F
$0060
$0061
$0062
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
F19B3
U
F19B2
U
F19B1
U
F19B0
U
F18B3
U
F18B2
U
F18B1
U
F18B0
U
LCD Data Register 10
(LDAT10)
F21B3
U
F21B2
U
F21B1
U
F21B0
U
F20B3
U
F20B2
U
F20B1
U
F20B0
U
LCD Data Register 11
(LDAT11)
F23B3
U
F23B2
U
F23B1
U
F23B0
U
F22B3
U
F22B2
U
F22B1
U
F22B0
U
LCD Data Register 12
(LDAT12)
F25B3
U
F25B2
U
F25B1
U
F25B0
U
F24B3
U
F24B2
U
F24B1
U
F24B0
U
LCD Data Register 13
(LDAT13)
F27B3
U
F27B2
U
F27B1
U
F27B0
U
F26B3
U
F26B2
U
F26B1
U
F26B0
U
LCD Data Register 14
(LDAT14)
F29B3
U
F29B2
U
F29B1
U
F29B0
U
F28B3
U
F28B2
U
F28B1
U
F28B0
U
LCD Data Register 15
(LDAT15)
F31B3
U
F31B2
U
F31B1
U
F31B0
U
F30B3
U
F30B2
U
F30B1
U
F30B0
U
LCD Data Register 16
(LDAT16)
F32B3
U
F32B2
U
F32B1
U
F32B0
U
LCD Data Register 17
(LDAT17)
U = Unaffected
= Unimplemented
Figure 17-1. LCD I/O Register Summary
Data Sheet
352
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
Functional Description
17.5 Functional Description
Figure 17-2 shows a block diagram of the LCD driver module, and
Figure 17-3 shows a simplified schematic of the LCD system.
The LCD driver module uses a 1/3 biasing method. The LCD power is
supplied by the V
pin. Voltages V
, V
, and V
are
LCD
LCD1
LCD2
LCD3
generated by an internal resistor ladder.
The LCD data registers, LDAT1–LDAT17, control the LCD segments’
ON/OFF, with each data register controlling two frontplanes. When a
logic 1 is written to a FxBx bit in the data register, the corresponding
frontplane-backplane segment will turn ON. When a logic 0 is written, the
the segment will turn OFF.
When the LCD driver module is disabled (LCDE = 0), the LCD display
will be OFF, all backplane and frontplane drivers have the same
potential as V . The resistor ladder is disconnected from V to reduce
DD
DD
power consumption.
PORT-E LOGIC
LCD FRONTPLANE DRIVER AND DATA LATCH
PTC0/FP19
PTC1/FP20
PTC2/FP21
PTC3/FP22
PTC4/FP23
PTC5/FP24
PTC6/FP25
PTC7/FP26
FP27
FP4
FP3
FP2
FP1
1/3
1/4
FP0/BP3
BP2
LCDE (LCDC)
BP1
STATE
CONTROL
FP28
BP0
FP29
1/1 1/3 1/4
FP30
FP31
FP32
Figure 17-2. LCD Block Diagram
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
353
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
LCD
FP0
FP1
FP24
BP0
BP1
BP2
R
R
R
R
R
R
FP
FP
FP
BP
BP
BP
V
LCD
V
LCD
R
LCD
V
V
LCD1
LCD2
R
R
LCD
LCD
V
V
LCD3
bias
BIAS
CONTROL
V
R
LCCON[3:0]
Figure 17-3. Simplified LCD Schematic (1/3 Duty, 1/3 Bias)
Data Sheet
354
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
Functional Description
17.5.1 LCD Duty
The setting of the LCD output waveform duty is dependent on the
number of backplane drivers required. Three LCD duties are available:
• Static duty — BP0 is used only
• 1/3 duty — BP0, BP1, and BP3 are used
• 1/4 duty — BP0, BP1, BP2, and BP3 are used
When the LCD driver module is enabled the backplane waveforms for
the selected duty are driven out of the backplane pins. The backplane
waveforms are periodic and are shown are shown in Figure 17-5,
Figure 17-6, and Figure 17-7.
17.5.2 LCD Voltages (V
V
V
, V
)
LCD3
LCD, LCD1, LCD2
The voltage V
is from the V
pin and must not exceed V . V
,
LCD
LCD
DD LCD1
V
, and V
are internal bias voltages for the LCD driver
LCD3
LCD2
waveforms. They are derived from V
using a resistor ladder (see
LCD
Figure 17-3).
The relative potential of the LCD voltages are:
• V
• V
• V
• V
= V
DD
LCD
= 2/3 × (V
= 1/3 × (V
– V
– V
)
)
LCD1
LCD2
LCD3
LCD
LCD
bias
bias
= V
bias
The V
bias voltage, V , is controlled by the LCD contrast control
bias
LCD3
bits, LCCON[2:0].
17.5.3 LCD Cycle Frame
The LCD driver module uses the CGMXCLK (see Section 7. Oscillator
(OSC))as the input reference clock. This clock is divided to produce the
LCD waveform base clock, LCDCLK, by configuring the LCLK[2:0] bits
in the LCD clock register. The LCDCLK clocks the backplane and the
frontplane output waveforms.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
355
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
The LCD cycle frame is determined by the equation:
1
LCD CYCLE FRAME =
LCD WAVEFORM BASE CLOCK × DUTY
For example, for 1/3 duty and 256Hz waveform base clock:
1
LCD CYCLE FRAME =
256 × (1/3)
= 11.72 ms
17.5.4 Fast Charge and Low Current
The default value for each of the bias resistors (see Figure 17-3), R
,
LCD
in the resistor ladder is approximately 37kΩ at V
= 3V. The relatively
LCD
high current drain through the 37kΩ resistor ladder may not be suitable
for some LCD panel connections. Lowering this current is possible by
setting the LC bit in the LCD control register, switching the R
value
LCD
to 146kΩ.
Although the lower current drain is desirable, but in some LCD panel
connections, the higher current is required to drive the capacitive load of
the LCD panel. In most cases, the higher current is only required when
the LCD waveforms change state (the rising and falling edges in the LCD
output waveforms). The fast charge option is designed to have the high
current for the switching and the low current for the steady state. Setting
the FC bit in the LCD control register selects the fast charge option. The
R
value is set to 37kΩ (for high current) for a fraction of time for each
LCD
LCD waveform switching edge, and then back to 146kΩ for the steady
state period. The duration of the fast charge time is set by configuring the
FCCTL[1:0] bits in the LCD clock register, and can be LCDCLK/32,
LCDCLK/64, or LCDCLK/128. Figure 17-4 shows the fast charge clock
relative to the BP0 waveform.
Data Sheet
356
MC68HC908LJ24/LK24 — Rev. 2.1
Liquid Crystal Display (LCD) Driver
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Low-Power Modes
LCDCLK
LCD WAVEFORM
EXAMPLE: BP0
FAST CHARGE CLOCK
HIGH CURRENT SELECTED BEFORE SWITCHING EDGE,
PERIOD IS DEFINED BY FCCTL[1:0]
Figure 17-4. Fast Charge Timing
17.5.5 Contrast Control
The contrast of the connected LCD panel can be adjusted by configuring
the LCCON[3:0] bits in the LCD control register. The LCCON[3:0] bits
provide a 16-step contrast control, which adjusts the bias voltage in the
resistor ladder for LCD voltage, V
. The relative voltages, V
and
LCD1
LCD3
V
, are altered accordingly. For example, setting LCCON[3:0] = $F,
LCD2
the relative panel potential voltage (V
– V
) is reduced from
LCD
LCD3
maximum 3.3V to approximate 2.45V.
The V voltage can be monitored by the ADC channel, ADC7, and
LCD
then adjustments to the bias voltage by the user software to provide
automatic contrast control.
17.6 Low-Power Modes
The STOP and WAIT instructions put the MCU in low power-
consumption standby modes.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
357
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
17.6.1 Wait Mode
The LCD driver module continues normal operation in wait mode. If the
LCD is not required in wait mode, power down the LCD module by
clearing the LCDE bit before executing the WAIT instruction.
17.6.2 Stop Mode
For continuous LCD module operation in stop mode, the oscillator stop
mode enable bit (STOP_XCLKEN in CONFIG2 register) must be set
before executing the STOP instruction. When STOP_XCLKEN is set,
CGMXCLK continues to drive the LCD module.
If STOP_XCLKEN bit is cleared, the LCD module is inactive after the
execution of a STOP instruction. The STOP instruction does not affect
LCD register states. LCD module operation resumes after an external
interrupt. To further reduce power consumption, the LCD module should
be powered-down by clearing the LCDE bit before executing the STOP
instruction.
17.7 I/O Signals
The LCD driver module has thirty-six (36) output pins and shares eight
of them with port C I/O pins and eight with port E I/O pins.
• FP0/BP3 (multiplexed; selected as FP0 or BP3 by DUTY[1:0])
• BP0–BP2
• FP1–FP10
• FP11–FP18 (shared with port E)
• FP19–FP26 (shared with port C)
• FP27–FP32
Data Sheet
358
MC68HC908LJ24/LK24 — Rev. 2.1
Liquid Crystal Display (LCD) Driver
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
I/O Signals
17.7.1 BP0–BP3 (Backplane Drivers)
BP0–BP3 are the backplane driver output pins. These are connected to
the backplane of the LCD panel. Depending on the LCD duty selected,
the voltage waveforms in Figure 17-5, Figure 17-6, and Figure 17-7
appear on the backplane pins.
BP3 pin is only used when 1/4 duty is selected. The pin becomes FP0
for static and 1/3 duty operations.
DUTY = STATIC
BP0
1FRAME
V
V
V
LCD
LCD1
LCD2
V
LCD3
NOTES:
1. BP1, BP2, and BP3 are not used.
2. At static duty, 1FRAME is equal to the cycle of LCD waveform base clock.
Figure 17-5. Static LCD Backplane Driver Waveform
DUTY = 1/3
BP0
1FRAME
V
V
V
LCD
LCD1
LCD2
V
LCD3
V
V
V
V
LCD
LCD1
LCD2
LCD3
BP1
BP2
V
V
V
V
LCD
LCD1
LCD2
LCD3
NOTES:
1. BP3 is not used.
2. At 1/3 duty, 1FRAME has three times the cycle of LCD waveform base clock.
Figure 17-6. 1/3 Duty LCD Backplane Driver Waveforms
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
359
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
DUTY = 1/4
BP0
1FRAME
V
V
V
LCD
LCD1
LCD2
V
LCD3
V
V
V
V
LCD
LCD1
LCD2
LCD3
BP1
BP2
V
V
V
V
LCD
LCD1
LCD2
LCD3
V
LCD
V
V
LCD1
LCD2
BP3
V
LCD3
Figure 17-7. 1/4 Duty LCD Backplane Driver Waveforms
Data Sheet
360
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
I/O Signals
17.7.2 FP0–FP32 (Frontplane Drivers)
FP0–FP32 are the frontplane driver output pins. These are connected to
the frontplane of the LCD panel. Depending on LCD duty selected and
the contents in the LCD data registers, the voltage waveforms in Figure
17-8, Figure 17-9, Figure 17-10 and Figure 17-11 appear on the
frontplane pins.
FP11–FP18 are shared with port E I/O pins. These pins are configured
for standard I/O or LCD use by the PEE bit in CONFIG2 register.
FP19–FP26 are shared with port C I/O pins. These pins are configured
for standard I/O or LCD use by the PCEL and PCEH bits in CONFIG2
register.
DUTY = STATIC
DATA LATCH: 1 = ON, 0 = OFF
FPx OUTPUT
1FRAME
V
V
V
LCD
FxB0
LCD1
LCD2
—
—
—
—
—
—
0
V
LCD3
V
V
V
V
LCD
FxB0
1
LCD1
LCD2
LCD3
Figure 17-8. Static LCD Frontplane Driver Waveforms
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
361
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
DUTY = 1/3
DATA LATCH: 1 = ON, 0 = OFF
FPx OUTPUT
1FRAME
V
V
V
LCD
FxB2
0
FxB1
0
FxB0
0
LCD1
LCD2
—
—
—
—
—
—
—
—
V
LCD3
V
V
V
V
LCD
FxB2
0
FxB1
0
FxB0
1
LCD1
LCD2
LCD3
V
V
V
V
LCD
FxB2
0
FxB1
1
FxB0
0
LCD1
LCD2
LCD3
V
V
V
V
LCD
FxB2
1
FxB1
0
FxB0
0
LCD1
LCD2
LCD3
V
V
V
V
LCD
FxB2
0
FxB1
1
FxB0
1
LCD1
LCD2
LCD3
V
V
V
V
LCD
FxB2
1
FxB1
1
FxB0
0
LCD1
LCD2
LCD3
V
V
V
V
LCD
FxB2
1
FxB1
0
FxB0
1
LCD1
LCD2
LCD3
V
V
V
V
LCD
FxB2
1
FxB1
1
FxB0
1
LCD1
LCD2
LCD3
Figure 17-9. 1/3 Duty LCD Frontplane Driver Waveforms
Data Sheet
362
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
I/O Signals
FPx OUTPUT
DUTY = 1/4
DATA LATCH: 1 = ON, 0 = OFF
1FRAME
V
V
V
LCD
FxB3
0
FxB2
0
FxB1
0
FxB0
0
LCD1
LCD2
V
LCD3
FxB3
0
FxB2
0
FxB1
0
FxB0
1
FxB3
0
FxB2
0
FxB1
1
FxB0
0
FxB3
0
FxB2
0
FxB1
1
FxB0
1
FxB3
0
FxB2
1
FxB1
0
FxB0
0
FxB3
0
FxB2
1
FxB1
0
FxB0
1
FxB3
0
FxB2
1
FxB1
1
FxB0
0
FxB3
0
FxB2
1
FxB1
1
FxB0
1
Figure 17-10. 1/4 Duty LCD Frontplane Driver Waveforms
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
363
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
FPx OUTPUT
DUTY = 1/4
DATA LATCH: 1 = ON, 0 = OFF
1FRAME
V
V
V
LCD
FxB3
1
FxB2
0
FxB1
0
FxB0
0
LCD1
LCD2
V
LCD3
FxB3
1
FxB2
0
FxB1
0
FxB0
1
FxB3
1
FxB2
0
FxB1
1
FxB0
0
FxB3
1
FxB2
0
FxB1
1
FxB0
1
FxB3
1
FxB2
1
FxB1
0
FxB0
0
FxB3
1
FxB2
1
FxB1
0
FxB0
1
FxB3
1
FxB2
1
FxB1
1
FxB0
0
FxB3
1
FxB2
1
FxB1
1
FxB0
1
Figure 17-11. 1/4 Duty LCD Frontplane Driver Waveforms (continued)
Data Sheet
364
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
Seven Segment Display Connection
17.8 Seven Segment Display Connection
The following shows an example for connecting a 7-segment LCD
display to the LCD driver.
The example uses 1/3 duty cycle, with pins BP0, BP1, BP2, FP0, FP1,
and FP2 connected as shown in Figure 17-12. The output waveforms
are shown in Figure 17-13.
FP CONNECTION
BP CONNECTION
a
a
BP0 (a, b COMMONED)
f
b
f
b
g
g
BP1 (c, f, g COMMONED)
BP2 (d, e COMMONED)
e
c
e
c
d
d
FP2 (b, c COMMONED)
FP1 (a, d, g COMMONED)
FP0 (e, f COMMONED)
The segment assignments for each bit in the data registers are:
F1B3
F1B2
F1B1
F1B0
F0B3
F0B2
F0B1
F0B0
LDAT1
$0052
—
d
g
a
—
e
f
—
FP1
FP0
F3B3
F3B2
F3B1
F3B0
F2B3
F2B2
F2B1
F2B0
LDAT2
$0053
—
—
—
—
—
—
c
b
FP2
To display the character "4": LDAT1 = X010X01X, LDAT2 = XXXXXX11
a
g
LDAT1
$0052
X
0
1
0
X
X
0
1
1
X
1
f
b
c
e
LDAT2
$0053
d
X
X
X
X
X
X = don’t care
Figure 17-12. 7-Segment Display Example
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
365
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
DUTY = 1/3
1FRAME
V
V
V
LCD
LCD1
LCD2
BP0
BP1
V
LCD3
V
V
V
V
LCD
LCD1
LCD2
LCD3
V
V
V
V
LCD
LCD1
LCD2
LCD3
BP2
V
V
V
V
LCD
F0B2 F0B1 F0B0
LCD1
LCD2
LCD3
—
0
1
0
FP0
V
V
V
V
LCD
F1B2 F1B1 F1B0
LCD1
LCD2
LCD3
—
—
0
1
0
FP1
FP2
V
V
V
V
LCD
F2B2 F2B1 F2B0
LCD1
LCD2
LCD3
0
1
1
Figure 17-13. BP0–BP2 and FP0–FP2 Output Waveforms for
7-Segment Display Example
Data Sheet
366
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
Seven Segment Display Connection
The voltage waveform across the "f" segment of the LCD (between BP1
and FP0) is illustrated in Figure 17-14. As shown in the waveform, the
voltage peaks reach the LCD-ON voltage, V
will be ON.
, therefore, the segment
LCD
+V
+V
+V
LCD
LCD1
LCD2
BP1–FP0
0
–V
–V
–V
LCD2
LCD1
LCD
Figure 17-14. "f" Segment Voltage Waveform
The voltage waveform across the "e" segment of the LCD (between BP2
and FP0) is illustrated in Figure 17-15. As shown in the waveform, the
voltage peaks do not reach the LCD-ON voltage, V
segment will be OFF.
, therefore, the
LCD
+V
LCD
+V
+V
0
LCD1
LCD2
BP2–FP0
–V
–V
–V
LCD2
LCD1
LCD
Figure 17-15. "e" Segment Voltage Waveform
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
367
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
17.9 I/O Registers
Nineteen (19) registers control LCD driver module operation:
• LCD control register (LCDCR)
• LCD clock register (LCDCLK)
• LCD data registers (LDAT1–LDAT17)
17.9.1 LCD Control Register (LCDCR)
The LCD control register (LCDCR):
• Enables the LCD driver module
• Selects bias resistor value and fast-charge control
• Selects LCD contrast
Address: $0051
Bit 7
LCDE
0
6
0
5
FC
0
4
LC
0
3
2
1
Bit 0
Read:
Write:
Reset:
LCCON3 LCCON2 LCCON1 LCCON0
0
0
0
0
0
= Unimplemented
Figure 17-16. LCD Control Register (LCDCR)
LCDE — LCD Enable
This read/write bit enables the LCD driver module; the backplane and
frontplane drive LCD waveforms out of BPx and FPx pins. Reset
clears the LCDE bit.
1 = LCD driver module enabled
0 = LCD driver module disabled
FC — Fast Charge
LC — Low Current
These read/write bits are used to select the value of the resistors in
resistor ladder for LCD voltages. Reset clears the FC and LC bits.
Data Sheet
368
MC68HC908LJ24/LK24 — Rev. 2.1
Liquid Crystal Display (LCD) Driver
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
I/O Registers
Table 17-2. Resistor Ladder Selection
FC
X
LC
0
Action
Each resistor is approximately 37 kΩ (default)
Each resistor is approximately 146 kΩ
Fast charge mode
0
1
1
1
LCCON[3:0] — LCD Contrast Control
These read/write bits select the bias voltage, V . This voltage
bias
controls the contrast of the LCD.
Maximum contrast is set when LCCON[3:0] =%0000;
minimum contrast is set when LCCON[3:0] =%1111.
Table 17-3. LCD Bias Voltage Control
Bias Voltage
LCCON3
LCCON2
LCCON1
LCCON0
(% of V
)
DD
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0.6
2.9
5.2
7.4
9.6
11.6
13.5
15.3
17.2
18.8
20.5
22.0
23.6
25.0
26.4
27.7
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
369
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
17.9.2 LCD Clock Register (LCDCLK)
The LCD clock register (LCDCLK):
• Selects the fast charge duty cycle
• Selects LCD driver duty cycle
• Selects LCD waveform base clock
Address: $004F
Bit 7
6
5
4
3
DUTY0
0
2
LCLK2
0
1
LCLK1
0
Bit 0
LCLK0
0
Read:
Write:
Reset:
0
FCCTL1 FCCTL0 DUTY1
0
0
0
0
= Unimplemented
Figure 17-17. LCD Clock Register (LCDCLK)
FCCTL[1:0] — Fast Charge Duty Cycle Select
These read/write bits select the duty cycle of the fast charge duration.
Reset clears these bits. (See 17.5.4 Fast Charge and Low Current)
Table 17-4. Fast Charge Duty Cycle Selection
FCCTL1:FCCTL0
Fast Charge Duty Cycle
In each LCDCLK/2 period, each bias resistor is reduced to
37 kΩ for a duration of LCDCLK/32.
00
In each LCDCLK/2 period, each bias resistor is reduced to
37 kΩ for a duration of LCDCLK/64.
01
In each LCDCLK/2 period, each bias resistor is reduced to
37 kΩ for a duration of LCDCLK/128.
10
11
Not used
Data Sheet
370
MC68HC908LJ24/LK24 — Rev. 2.1
Liquid Crystal Display (LCD) Driver
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
I/O Registers
DUTY[1:0] — Duty Cycle Select
These read/write bits select the duty cycle of the LCD driver output
waveforms. The multiplexed FP0/BP3 pin is controlled by the duty
cycle selected. Reset clears these bits.
Table 17-5. LCD Duty Cycle Selection
DUTY1:DUTY0
Description
00
01
10
11
Static selected; FP0/BP3 pin function as FP0.
1/3 duty cycle selected; FP0/BP3 pin functions as FP0.
1/4 duty cycle selected; FP0/BP3 pin functions as BP3.
Not used
LCLK[2:0] — LCD Waveform Base Clock Select
These read/write bits selects the LCD waveform base clock. Reset
clears these bits.
Table 17-6. LCD Waveform Base Clock Selection
LCD Frame Rate
LCD Frame Rate
LCD Waveform Base
Clock Frequency
LCDCLK (Hz)
(1)
f
=
f
=
XTAL
4.9152MHz
XTAL
Divide
Ratio
32.768kHz
LCLK2 LCLK1 LCLK0
f
=
f
=
1/3
1/4
1/3
1/4
XTAL
XTAL
duty
85.3
42.7
21.3
10.7
—
duty
duty
duty
32.768kHz 4.9152MHz
0
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
128
256
256
128
64
32
—
—
—
64
32
16
8
—
—
—
0
—
0
512
—
—
—
0
1024
16384
32768
65536
—
—
—
1
300
150
75
—
—
—
100
50
75
1
1
—
—
37.5
18.75
—
—
25
1
Reserved
Notes:
1. fXTAL is the same as CGMXCLK (see Section 7. Oscillator (OSC)).
MC68HC908LJ24/LK24 — Rev. 2.1
Data Sheet
371
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
17.9.3 LCD Data Registers (LDAT1–LDAT17)
The seventeen (17) LCD data registers enable and disable the drive to
the corresponding LCD segments.
Addr.
Register Name
Bit 7
F1B3
U
6
F1B2
U
5
F1B1
U
4
F1B0
U
3
F0B3
U
2
F0B2
U
1
F0B1
U
Bit 0
F0B0
U
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
LCD Data Register 1
(LDAT1)
$0052
F3B3
U
F3B2
U
F3B1
U
F3B0
U
F2B3
U
F2B2
U
F2B1
U
F2B0
U
LCD Data Register 2
(LDAT2)
$0053
$0054
$0055
$0056
$0057
$0058
$0059
$005A
F5B3
U
F5B2
U
F5B1
U
F5B0
U
F4B3
U
F4B2
U
F4B1
U
F4B0
U
LCD Data Register 3
(LDAT3)
F7B3
U
F7B2
U
F7B1
U
F7B0
U
F6B3
U
F6B2
U
F6B1
U
F6B0
U
LCD Data Register 4
(LDAT4)
F9B3
U
F9B2
U
F9B1
U
F9B0
U
F8B3
U
F8B2
U
F8B1
U
F8B0
U
LCD Data Register 5
(LDAT5)
F11B3
U
F11B2
U
F11B1
U
F11B0
U
F10B3
U
F10B2
U
F10B1
U
F10B0
U
LCD Data Register 6
(LDAT6)
F13B3
U
F13B2
U
F13B1
U
F13B0
U
F12B3
U
F12B2
U
F12B1
U
F12B0
U
LCD Data Register 7
(LDAT7)
F15B3
U
F15B2
U
F15B1
U
F15B0
U
F14B3
U
F14B2
U
F14B1
U
F14B0
U
LCD Data Register 8
(LDAT8)
F17B3
F17B2
F17B1
U
F17B0
F16B3
F16B2
U
F16B1
U
F16B0
U
LCD Data Register 9
(LDAT9)
U
U
U
U
U = Unaffected
= Unimplemented
Figure 17-18. LCD Data Registers 1–17 (LDAT1–LDAT17)
Data Sheet
372
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
I/O Registers
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
F19B3
U
F19B2
U
F19B1
U
F19B0
U
F18B3
U
F18B2
U
F18B1
U
F18B0
U
LCD Data Register 10
(LDAT10)
$005B
$005C
$005D
$005E
$005F
$0060
$0061
$0062
F21B3
U
F21B2
U
F21B1
U
F21B0
U
F20B3
U
F20B2
U
F20B1
U
F20B0
U
LCD Data Register 11
(LDAT11)
F23B3
U
F23B2
U
F23B1
U
F23B0
U
F22B3
U
F22B2
U
F22B1
U
F22B0
U
LCD Data Register 12
(LDAT12)
F25B3
U
F25B2
U
F25B1
U
F25B0
U
F24B3
U
F24B2
U
F24B1
U
F24B0
U
LCD Data Register 13
(LDAT13)
F27B3
U
F27B2
U
F27B1
U
F27B0
U
F26B3
U
F26B2
U
F26B1
U
F26B0
U
LCD Data Register 14
(LDAT14)
F29B3
U
F29B2
U
F29B1
U
F29B0
U
F28B3
U
F28B2
U
F28B1
U
F28B0
U
LCD Data Register 15
(LDAT15)
F31B3
U
F31B2
U
F31B1
U
F31B0
U
F30B3
U
F30B2
U
F30B1
U
F30B0
U
LCD Data Register 16
(LDAT16)
F32B3
F32B2
U
F32B1
U
F32B0
U
LCD Data Register 17
(LDAT17)
U
U = Unaffected
= Unimplemented
Figure 17-18. LCD Data Registers 1–17 (LDAT1–LDAT17)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
373
Liquid Crystal Display (LCD) Driver
Liquid Crystal Display (LCD) Driver
Data Sheet
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
374
Liquid Crystal Display (LCD) Driver
Data Sheet — MC68HC908LJ24
Section 18. Input/Output (I/O) Ports
18.1 Contents
18.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .376
18.3 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .380
18.3.1 Port A Data Register (PTA) . . . . . . . . . . . . . . . . . . . . . . . .380
18.3.2 Data Direction Register A (DDRA) . . . . . . . . . . . . . . . . . . .381
18.4 Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .383
18.4.1 Port B Data Register (PTB) . . . . . . . . . . . . . . . . . . . . . . . .383
18.4.2 Data Direction Register B (DDRB) . . . . . . . . . . . . . . . . . . .385
18.4.3 Port B LED Control Register (LEDB) . . . . . . . . . . . . . . . . .386
18.5 Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .387
18.5.1 Port C Data Register (PTC) . . . . . . . . . . . . . . . . . . . . . . . .387
18.5.2 Data Direction Register C (DDRC). . . . . . . . . . . . . . . . . . .388
18.5.3 Port C LED Control Register (LEDC) . . . . . . . . . . . . . . . . .389
18.6 Port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .390
18.6.1 Port D Data Register (PTD) . . . . . . . . . . . . . . . . . . . . . . . .390
18.6.2 Data Direction Register D (DDRD). . . . . . . . . . . . . . . . . . .392
18.7 Port E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .394
18.7.1 Port E Data Register (PTE) . . . . . . . . . . . . . . . . . . . . . . . .394
18.7.2 Data Direction Register E (DDRE) . . . . . . . . . . . . . . . . . . .395
18.7.3 Port E LED Control Register (LEDE) . . . . . . . . . . . . . . . . .396
18.8 Port F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .397
18.8.1 Port F Data Register (PTF) . . . . . . . . . . . . . . . . . . . . . . . .397
18.8.2 Data Direction Register F (DDRF) . . . . . . . . . . . . . . . . . . .398
18.8.3 Port F LED Control Register (LEDF) . . . . . . . . . . . . . . . . .399
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
375
Input/Output (I/O) Ports
Input/Output (I/O) Ports
18.2 Introduction
Forty-eight (48) bidirectional input-output (I/O) pins form six parallel
ports. All I/O pins are programmable as inputs or outputs.
NOTE: Connect any unused I/O pins to an appropriate logic level, either VDD or
VSS. Although the I/O ports do not require termination for proper
operation, termination reduces excess current consumption and the
possibility of electrostatic damage.
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
Port A Data Register
(PTA)
$0000
Unaffected by reset
PTB4 PTB3
Unaffected by reset
PTC4 PTC3
Unaffected by reset
PTD4 PTD3
Unaffected by reset
PTB7
PTC7
PTD7
PTB6
PTC6
PTD6
PTB5
PTC5
PTD5
PTB2
PTC2
PTD2
PTB1
PTC1
PTD1
PTB0
PTC0
PTD0
Port B Data Register
(PTB)
$0001
$0002
$0003
$0004
$0005
$0006
$0007
Port C Data Register
(PTC)
Port D Data Register
(PTD)
DDRA7
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
Data Direction Register A
(DDRA)
0
0
0
0
0
0
0
0
DDRB7
DDRB6
DDRB5
DDRB4
DDRB3
DDRB2
DDRB1
DDRB0
Data Direction Register B
(DDRB)
0
DDRC7
0
0
DDRC6
0
0
DDRC5
0
0
DDRC4
0
0
DDRC3
0
0
DDRC2
0
0
DDRC1
0
0
DDRC0
0
Data Direction Register C
(DDRC)
DDRD7
0
DDRD6
0
DDRD5
0
DDRD4
0
DDRD3
0
DDRD2
0
DDRD1
0
DDRD0
0
Data Direction Register D
(DDRD)
Figure 18-1. I/O Port Register Summary
Data Sheet
376
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Introduction
Addr.
Register Name
Bit 7
PTE7
U
6
PTE6
U
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
Read:
PTE5
PTE4
PTE3
PTE2
PTE1
PTE0
Port E Data Register
(PTE)
$0008
U
U
U
U
U
U
DDRE7
0
DDRE6
0
DDRE5
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
Data Direction Register E
(DDRE)
$0009
$000A
$000B
$000C
$000D
$000E
$000F
0
0
0
0
0
0
PTF7
U
PTF6
U
PTF5
PTF4
PTF3
PTF2
PTF1
PTF0
Port F Data Register
(PTF)
U
U
U
U
U
U
DDRF7
DDRF6
DDRF5
DDRF4
DDRF3
DDRF2
DDRF1
DDRF0
Data Direction Register F
(DDRF)
0
0
0
0
0
0
0
0
0
0
Port-B LED Control
LEDB5
LEDB4
LEDB3
LEDB2
LEDB1
LEDB0
Register Write:
(LEDB)
Reset:
0
LEDC7
0
0
LEDC6
0
0
LEDC5
0
0
LEDC4
0
0
LEDC3
0
0
LEDC2
0
0
LEDC1
0
0
LEDC0
0
Read:
Port-C LED Control
Register Write:
(LEDC)
Reset:
Read:
Port-E LED Control
LEDE7
0
LEDE6
0
LEDE5
0
LEDE4
0
LEDE3
0
LEDE2
0
LEDE1
0
LEDE0
0
Register Write:
(LEDE)
Reset:
Read:
Port-F LED Control
LEDF7
0
LEDF6
0
LEDF5
0
LEDF4
0
LEDF3
0
LEDF2
0
LEDF1
0
LEDF0
0
Register Write:
(LEDF)
Reset:
Figure 18-1. I/O Port Register Summary
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
377
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Table 18-1. Port Control Register Bits Summary (Sheet 1 of 2)
Module Control
Register
Port
Bit
DDR
Pin
Module
Control Bit
KBIE0
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
DDRA0
DDRA1
DDRA2
DDRA3
DDRA4
DDRA5
DDRA6
DDRA7
DDRB0
DDRB1
DDRB2
DDRB3
DDRB4
DDRB5
DDRB6
DDRB7
DDRC0
DDRC1
DDRC2
DDRC3
DDRC4
DDRC5
DDRC6
DDRC7
PTA0/KBI0
PTA1/KBI1
PTA2/KBI2
PTA3/KBI3
PTA4/ADC0
PTA5/ADC1
PTA6/ADC2
PTA7/ADC3
PTB0/TxD
KBIE1
KBI
KBIER ($001C)
KBIE2
KBIE3
A
ADC
ADSCR ($003C)
SCC1 ($0013)
ADCH[4:0]
SCI
TIM1
TIM2
ADC
ENSCI
PTB1/RxD
T1SC0 ($0025) ELS0B:ELS0A
T1SC1 ($0028) ELS1B:ELS1A
T2SC0 ($0030) ELS0B:ELS0A
T2SC1 ($0033) ELS1B:ELS1A
PTB2/T1CH0
PTB3/T1CH1
PTB4/T2CH0
PTB5/T2CH1
PTB6/ADC4
PTB7/ADC5
PTC0/FP19
PTC1/FP20
PTC2/FP21
PTC3/FP22
PTC4/FP23
PTC5/FP24
PTC6/FP25
PTC7/FP26
B
ADSCR ($003C)
ADCH[4:0]
PCEL
C
LCD
CONFIG2 ($001D)
PCEH
Data Sheet
378
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Introduction
Table 18-1. Port Control Register Bits Summary (Sheet 2 of 2)
Module Control
Register
Port
Bit
DDR
Pin
Module
Control Bit
SPE
SPCR ($0010)
RTCCOMR ($0040)
0
DDRD0
PTD0/SS/CALIN
CAL
1
2
DDRD1
DDRD2
PTD1/MISO
PTD2/MOSI
SPI
RTC
SPCR ($0010)
SPE
SPCR ($0010)
RTCCOMR ($0040)
KBIER ($001C)
T1SC ($0020)
SPE
CAL
3
4
5
6
7
DDRD3
DDRD4
DDRD5
DDRD6
DDRD7
PTD3/SPSCK/CALOUT
PTD4/KBI4/T1CLK
PTD5/KBI5/T2CLK
PTD6/KBI6/SCL
KBIE4
PS[2:0]
KBIE5
PS[2:0]
KBIE6
MMEN
KBIE7
MMEN
(1)
D
KBI
TIM
KBIER ($001C)
T2SC ($002B)
KBIER ($001C)
MMCR ($006C)
KBIER ($001C)
MMCR ($006C)
KBI
MMIIC
PTD7/KBI7/SDA
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
DDRE0
DDRE1
DDRE2
DDRE3
DDRE4
DDRE5
DDRE6
DDRE7
DDRF0
DDRF1
DDRF2
DDRF3
DDRF4
DDRF5
DDRF6
DDRF7
PTE0/FP11
PTE1/FP12
PTE2/FP13
PTE3/FP14
PTE4/FP15
PTE5/FP16
PTE6/FP17
PTE7/FP18
PTF0
E
LCD
CONFIG2 ($001D)
PEE
PTF1
PTF2
PTF3
F
—
—
—
PTF4
PTF5
PTF6
PTF7
Notes:
1. In addition to the standard I/O function on PTD0 and PTD3–PTD7 pins, these pins are shared with two other modules.
For each of the pins, ONLY enable ONE module at any one time to avoid pin contention.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
379
Input/Output (I/O) Ports
Input/Output (I/O) Ports
18.3 Port A
Port A is an 8-bit special function port that shares four of its port pins with
the analog-to-digital converter (ADC) module and four of its port pins
with the keyboard interrupt module (KBI).
18.3.1 Port A Data Register (PTA)
The port A data register contains a data latch for each of the eight port A
pins.
Address: $0000
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
Unaffected by Reset
ADC0 KBI3
Alternative Function: ADC3
ADC2
ADC1
KBI2
KBI1
KBI0
Figure 18-2. Port A Data Register (PTA)
PTA[7:0] — Port A Data Bits
These read/write bits are software programmable. Data direction of
each port A pin is under the control of the corresponding bit in data
direction register A. Reset has no effect on port A data.
KBI[3:0] — Keyboard Interrupt Channels 3 to 0
KBI[3:0] are pins used for the keyboard interrupt input. The
corresponding input, KBI[3:0], can be enabled in the keyboard
interrupt enable register, KBIER. Port pins used as KBI input will
override any control from the port I/O logic. See Section 20.
Keyboard Interrupt Module (KBI).
Data Sheet
380
MC68HC908LJ24/LK24 — Rev. 2.1
Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
Port A
ADC[3:0] — ADC channels 0 to 3
ADC[3:0] are pins used for the input channels to the analog-to-digital
converter module. The channel select bits, ADCH[4:0], in the ADC
status and control register define which port pin will be used as an
ADC input and overrides any control from the port I/O logic. See
Section 16. Analog-to-Digital Converter (ADC).
NOTE: Care must be taken when reading port A while applying analog voltages
to ADC[3:0] pins. If the appropriate ADC channel is not enabled,
excessive current drain may occur if analog voltages are applied to the
PTAx/ADCx pin, while PTA is read as a digital input. Those ports not
selected as analog input channels are considered digital I/O ports.
18.3.2 Data Direction Register A (DDRA)
Data direction register A determines whether each port A pin is an input
or an output. Writing a logic 1 to a DDRA bit enables the output buffer for
the corresponding port A pin; a logic 0 disables the output buffer.
Address: $0004
Bit 7
DDRA7
0
6
DDRA6
0
5
DDRA5
0
4
DDRA4
0
3
DDRA3
0
2
DDRA2
0
1
DDRA1
0
Bit 0
DDRA0
0
Read:
Write:
Reset:
Figure 18-3. Data Direction Register A (DDRA)
DDRA[7:0] — Data Direction Register A Bits
These read/write bits control port A data direction. Reset clears
DDRA[7:0], configuring all port A pins as inputs.
1 = Corresponding port A pin configured as output
0 = Corresponding port A pin configured as input
NOTE: Avoid glitches on port A pins by writing to the port A data register before
changing data direction register A bits from 0 to 1. Figure 18-4 shows
the port A I/O logic.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
381
Input/Output (I/O) Ports
Input/Output (I/O) Ports
READ DDRA ($0004)
WRITE DDRA ($0004)
DDRAx
PTAx
RESET
WRITE PTA ($0000)
READ PTA ($0000)
PTAx
Figure 18-4. Port A I/O Circuit
When DDRAx is a logic 1, reading address $0000 reads the PTAx data
latch. When DDRAx is a logic 0, reading address $0000 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-2 summarizes the operation of the port A pins.
Table 18-2. Port A Pin Functions
Accesses to DDRA
Read/Write
Accesses to PTA
DDRA
Bit
PTA Bit
I/O Pin Mode
Read
Pin
Write
(1)
(2)
(3)
0
1
X
Input, Hi-Z
DDRA[7:0]
PTA[7:0]
X
Output
DDRA[7:0]
PTA[7:0]
PTA[7:0]
Notes:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
Data Sheet
382
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Port B
18.4 Port B
Port B is a 8-bit special function port that shares two of its port pins with
the infrared serial communication interface (IRSCI) module, two of its
port pins with the timer interface module 1 (TIM1) module, two of its port
pins with the timer interface module 2 (TIM2), and two of its port pins with
the ADC module.
Port pins PTB0–PTB5 can be configured for direct LED drive.
18.4.1 Port B Data Register (PTB)
The port B data register contains a data latch for each of the eight port B
pins.
Address: $0001
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTB7
Write:
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Reset:
Unaffected by reset
T2CH0 T1CH1
Alternative Function: ADC5
Additional Function:
ADC4
T2CH1
T1CH0
RxD
TxD
LED drive LED drive LED drive LED drive LED drive LED drive
Figure 18-5. Port B Data Register (PTB)
PTB[7:0] — Port B Data Bits
These read/write bits are software programmable. Data direction of
each port B pin is under the control of the corresponding bit in data
direction register B. Reset has no effect on port B data.
TxD, RxD — SCI Data I/O Pins
The TxD and RxD pins are the transmit data output and receive data
input for the IRSCI module. The enable SCI bit, ENSCI, in the SCI
control register 1 enables the PTB0/TxD and PTB1/RxD pins as SCI
TxD and RxD pins and overrides any control from the port I/O. See
Section 13. Infrared Serial Communications Interface Module
(IRSCI).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
383
Input/Output (I/O) Ports
Input/Output (I/O) Ports
T1CH[1:0] — Timer 1 Channel I/O Bits
The T1CH1 and T1CH0 pins are the TIM1 input capture/output
compare pins. The edge/level select bits, ELSxB:ELSxA, determine
whether the PTB2/T1CH0 and PTB3/T1CH1 pins are timer channel
I/O pins or general-purpose I/O pins. See Section 11. Timer
Interface Module (TIM).
T2CH[1:0] — Timer 2 Channel I/O Bits
The T2CH1 and T2CH0 pins are the TIM1 input capture/output
compare pins. The edge/level select bits, ELSxB:ELSxA, determine
whether the PTB4/T2CH0 and PTB5/T2CH1 pins are timer channel
I/O pins or general-purpose I/O pins. See Section 11. Timer
Interface Module (TIM).
ADC[5:4] — ADC Channels 5 and 4
ADC[5:4] are pins used for the input channels to the analog-to-digital
converter module. The channel select bits, ADCH[4:0], in the ADC
status and control register define which port pin will be used as an
ADC input and overrides any control from the port I/O logic. See
Section 16. Analog-to-Digital Converter (ADC).
NOTE: Care must be taken when reading port B while applying analog voltages
to ADC[5:4] pins. If the appropriate ADC channel is not enabled,
excessive current drain may occur if analog voltages are applied to the
PTBx/ADCx pin, while PTB is read as a digital input. Those ports not
selected as analog input channels are considered digital I/O ports.
LED Drive — Direct LED Drive Pins
PTB0–PTB5 pins can be configured for direct LED drive. See 18.4.3
Port B LED Control Register (LEDB).
Data Sheet
384
MC68HC908LJ24/LK24 — Rev. 2.1
Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
Port B
18.4.2 Data Direction Register B (DDRB)
Data direction register B determines whether each port B pin is an input
or an output. Writing a logic 1 to a DDRB bit enables the output buffer for
the corresponding port B pin; a logic 0 disables the output buffer.
Address: $0005
Bit 7
DDRB7
0
6
DDRB6
0
5
DDRB5
0
4
DDRB4
0
3
DDRB3
0
2
DDRB2
0
1
DDRB1
0
Bit 0
DDRB0
0
Read:
Write:
Reset:
Figure 18-6. Data Direction Register B (DDRB)
DDRB[7:0] — Data Direction Register B Bits
These read/write bits control port B data direction. Reset clears
DDRB[7:0], configuring all port B pins as inputs.
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
NOTE: Avoid glitches on port B pins by writing to the port B data register before
changing data direction register B bits from 0 to 1. Figure 18-7 shows
the port B I/O logic.
READ DDRB ($0005)
WRITE DDRB ($0005)
DDRBx
RESET
WRITE PTB ($0001)
PTBx
PTBx
READ PTB ($0001)
Figure 18-7. Port B I/O Circuit
When DDRBx is a logic 1, reading address $0001 reads the PTBx data
latch. When DDRBx is a logic 0, reading address $0001 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
385
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Table 18-3 summarizes the operation of the port B pins.
Table 18-3. Port B Pin Functions
Accesses to DDRB
I/O Pin Mode
Accesses to PTB
DDRB
Bit
PTB Bit
Read/Write
DDRB[7:0]
DDRB[7:0]
Read
Write
(1)
(2)
(3)
0
1
X
Input, Hi-Z
Output
Pin
PTB[7:0]
X
PTB[7:0]
PTB[7:0]
Notes:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
18.4.3 Port B LED Control Register (LEDB)
The port-B LED control register (LEDB) controls the direct LED drive
capability on PTB5–PTB0 pins. Each bit is individually configurable and
requires that the data direction register, DDRB, bit be configured as an
output.
When the IRSCI is enabled, setting the LEDB0 bit also enables high
current (15mA) sink capability for the TxD pin.
Address: $000C
Bit 7
0
6
0
5
LEDB5
0
4
LEDB4
0
3
LEDB3
0
2
LEDB2
0
1
LEDB1
0
Bit 0
LEDB0
0
Read:
Write:
Reset:
0
0
Figure 18-8. Port B LED Control Register (LEDB)
LEDB[5:0] — Port B LED Drive Enable Bits
These read/write bits are software programmable to enable the direct
LED drive on an output port pin.
1 = Corresponding port B pin is configured for direct LED drive,
with 15mA current sinking capability
0 = Corresponding port B pin is configured for standard drive
Data Sheet
386
MC68HC908LJ24/LK24 — Rev. 2.1
Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
Port C
18.5 Port C
Port C is an 8-bit special function port that shares all of its port pins with
the liquid crystal display (LCD) driver module.
Port pins PTC0–PTC7 can be configured for direct LED drive.
18.5.1 Port C Data Register (PTC)
The port C data register contains a data latch for each of the eight port C
pins.
Address: $0002
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTC7
Write:
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
Reset:
Unaffected by reset
FP23 FP22
Alternative Function: FP26
FP25
FP24
FP21
FP20
FP19
Additional Function: LED drive LED drive LED drive LED drive LED drive LED drive LED drive LED drive
Figure 18-9. Port C Data Register (PTC)
PTC[7:0] — Port C Data Bits
These read/write bits are software programmable. Data direction of
each port C pin is under the control of the corresponding bit in data
direction register C. Reset has no effect on port C data.
FP[26:19] — LCD Driver Frontplanes 26–19
FP[26:19] are pins used for the frontplane output of the LCD driver
module. The enable bits, PCEH and PCEL, in the CONFIG2 register,
determine whether the PTC7/FP26–PTC4/FP23 and
PTC3/FP22–PTC0/FP19 pins are LCD frontplane driver pins or
general-purpose I/O pins. See Section 17. Liquid Crystal Display
(LCD) Driver.
LED drive — Direct LED Drive Pins
PTC0–PTC7 pins can be configured for direct LED drive. See 18.5.3
Port C LED Control Register (LEDC).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
387
Input/Output (I/O) Ports
Input/Output (I/O) Ports
18.5.2 Data Direction Register C (DDRC)
Data direction register C determines whether each port C pin is an input
or an output. Writing a logic 1 to a DDRC bit enables the output buffer for
the corresponding port C pin; a logic 0 disables the output buffer.
Address: $0006
Bit 7
DDRC7
0
6
DDRC6
0
5
DDRC5
0
4
DDRC4
0
3
DDRC3
0
2
DDRC2
0
1
DDRC1
0
Bit 0
DDRC0
0
Read:
Write:
Reset:
Figure 18-10. Data Direction Register C (DDRC)
DDRC[7:0] — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears
DDRC[7:0], configuring all port C pins as inputs.
1 = Corresponding port C pin configured as output
0 = Corresponding port C pin configured as input
NOTE: Avoid glitches on port C pins by writing to the port C data register before
changing data direction register C bits from 0 to 1. Figure 18-11 shows
the port C I/O logic.
READ DDRC ($0006)
WRITE DDRC ($0006)
DDRCx
RESET
WRITE PTC ($0002)
PTCx
PTCx
READ PTC ($0002)
Figure 18-11. Port C I/O Circuit
Data Sheet
388
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Port C
When DDRCx is a logic 1, reading address $0002 reads the PTCx data
latch. When DDRCx is a logic 0, reading address $0002 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-4 summarizes the operation of the port C pins.
Table 18-4. Port C Pin Functions
Accesses to DDRC
Read/Write
Accesses to PTC
DDRC
Bit
PTC Bit
I/O Pin Mode
Read
Pin
Write
(1)
(2)
(3)
0
1
X
Input, Hi-Z
DDRC[7:0]
PTC[7:0]
X
Output
DDRC[7:0]
PTC[7:0]
PTC[7:0]
Notes:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
18.5.3 Port C LED Control Register (LEDC)
Port-C LED control register (LEDC) controls the direct LED drive
capability on PTC7–PTC0 pins. Each bit is individually configurable and
requires that the data direction register, DDRC, bit be configured as an
output.
Address: $000D
Bit 7
LEDC7
0
6
LEDC6
0
5
LEDC5
0
4
LEDC4
0
3
LEDC3
0
2
LEDC2
0
1
LEDC1
0
Bit 0
LEDC0
0
Read:
Write:
Reset:
Figure 18-12. Port C LED Control Register (LEDC)
LEDC[7:0] — Port C LED Drive Enable Bits
These read/write bits are software programmable to enable the direct
LED drive on an output port pin.
1 = Corresponding port C pin is configured for direct LED drive,
with 15mA current sinking capability
0 = Corresponding port C pin is configured for standard drive
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
389
Input/Output (I/O) Ports
Input/Output (I/O) Ports
18.6 Port D
Port D is an 8-bit special function port that shares its pins with the serial
peripheral interface (SPI) module, keyboard interrupt module, RTC
module, MMIIC module, and timer modules.
18.6.1 Port D Data Register (PTD)
The port D data register contains a data latch for each of the eight port D
pins.
Address: $0003
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTD7
PTD6
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
Unaffected by reset
KBI4/ SPSCK/
KBI7/
SDA*
KBI6/
SCL*
KBI5/
SS/
CALIN*
Alternative Function:
MOSI
MISO
T2CLK* T1CLK* CALOUT*
* These port pins are shared with two other modules. For each of the pins, ONLY enable ONE module at any one
time to avoid pin contention.
Figure 18-13. Port D Data Register (PTD)
PTD[7:0] — Port D Data Bits
These read/write bits are software programmable. Data direction of
each port D pin is under the control of the corresponding bit in data
direction register D. Reset has no effect on port D data.
KBI[7:4] — Keyboard Interrupt Channels 7 to 4
KBI[7:4] are pins used for the keyboard interrupt input. The
corresponding input, KBI[7:4], can be enabled in the keyboard
interrupt enable register, KBIER. Port pins used as KBI input will
override any control from the port I/O logic. See Section 20.
Keyboard Interrupt Module (KBI).
Data Sheet
390
MC68HC908LJ24/LK24 — Rev. 2.1
Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
Port D
SDA, SCL — Multi-Master IIC Data and Clock Pins
The SDA and SCL pins are multi-master IIC data and clock open-
drain pins, enabled by setting the MMEN bit in the MMIIC control
register (MMCR). Port pins used as MMIIC will override any control
from the port I/O logic. See Section 15. Multi-Master IIC Interface
(MMIIC).
T2CLK — TIM2 Clock Input Pin
The T2CLK pin is the external clock input for TIM2, enabled by setting
the prescaler select bits, PS[2:0] to %111, in the TIM2 status and
control register (T2SC). Port pin used as T2CLK will override any
control from the port I/O logic. See Section 11. Timer Interface
Module (TIM).
T1CLK — TIM1 Clock Input Pin
The T1CLK pin is the external clock input for TIM1, enabled by setting
the prescaler select bits, PS[2:0] to %111, in the TIM1 status and
control register (T1SC). Port pin used as T1CLK will override any
control from the port I/O logic. See Section 11. Timer Interface
Module (TIM).
SPSCK, MOSI, MISO, and SS — SPI Functional Pins
These four pins are the SPI clock, master-output-slave-input, master-
input-slave-output, and slave select pins; enabled by setting the SPI
enable bit, SPE, in the SPI control register (SPCR). Port pins used as
SPI will override any control from the port I/O logic. See Section 14.
Serial Peripheral Interface Module (SPI).
CALOUT, CALIN — RTC Calibration Pins
The CALOUT and CALIN pins are RTC calibration pins, enabled by
setting the CAL bit in the RTC calibration register (RTCCOMR). Port
pins used for RTC calibration will override any control from the port
I/O logic. See Section 12. Real Time Clock (RTC).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
391
Input/Output (I/O) Ports
Input/Output (I/O) Ports
18.6.2 Data Direction Register D (DDRD)
Data direction register D determines whether each port D pin is an input
or an output. Writing a logic 1 to a DDRD bit enables the output buffer for
the corresponding port D pin; a logic 0 disables the output buffer.
Address: $0007
Bit 7
DDRD7
0
6
DDRD6
0
5
DDRD5
0
4
DDRD4
0
3
DDRD3
0
2
DDRD2
0
1
DDRD1
0
Bit 0
DDRD0
0
Read:
Write:
Reset:
Figure 18-14. Data Direction Register D (DDRD)
DDRD[7:0] — Data Direction Register D Bits
These read/write bits control port D data direction. Reset clears
DDRD[7:0], configuring all port D pins as inputs.
1 = Corresponding port D pin configured as output
0 = Corresponding port D pin configured as input
NOTE: Avoid glitches on port D pins by writing to the port D data register before
changing data direction register D bits from 0 to 1. Figure 18-15 shows
the port D I/O logic.
READ DDRD ($0007)
WRITE DDRD ($0007)
DDRDx
RESET
WRITE PTD ($0003)
PTDx
PTDx
READ PTD ($0003)
Figure 18-15. Port D I/O Circuit
Data Sheet
392
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Port D
When DDRDx is a logic 1, reading address $0003 reads the PTDx data
latch. When DDRDx is a logic 0, reading address $0003 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-5 summarizes the operation of the port D pins.
Table 18-5. Port D Pin Functions
Accesses to DDRD
Read/Write
Accesses to PTD
DDRD
Bit
PTD Bit
I/O Pin Mode
Read
Pin
Write
(1)
(2)
(3)
0
1
X
Input, Hi-Z
DDRD[7:0]
PTD[7:0]
X
Output
DDRD[7:0]
PTD[7:0]
PTD[7:0]
Notes:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
393
Input/Output (I/O) Ports
Input/Output (I/O) Ports
18.7 Port E
Port E is an 8-bit special function port that shares all of its port pins with
the liquid crystal display (LCD) driver module.
Port pins PTE0–PTE7 can be configured for direct LED drive.
18.7.1 Port E Data Register (PTE)
The port E data register contains a data latch for each of the eight port E
pins.
Address: $0008
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTE7
PTE6
PTE5
PTE4
PTE3
PTE2
PTE1
PTE0
Unaffected by reset
FP15 FP14
Alternative Function: FP18
FP17
FP16
FP13
FP12
FP11
Additional Function: LED drive LED drive LED drive LED drive LED drive LED drive LED drive LED drive
Figure 18-16. Port E Data Register (PTE)
PTE[7:0] — Port E Data Bits
These read/write bits are software programmable. Data direction of
each port E pin is under the control of the corresponding bit in data
direction register E. Reset has no effect on port E data.
FP[18:11] — LCD Driver Frontplanes 18–11
FP[18:11] are pins used for the frontplane output of the LCD driver
module. The enable bit, PEE, in the CONFIG2 register, determines
whether the PTE7/FP18–PTE0/FP11 pins are LCD frontplane driver
pins or general-purpose I/O pins. See Section 17. Liquid Crystal
Display (LCD) Driver.
LED drive — Direct LED Drive Pins
PTE0–PTE7 pins can be configured for direct LED drive. See 18.7.3
Port E LED Control Register (LEDE).
Data Sheet
394
MC68HC908LJ24/LK24 — Rev. 2.1
Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
Port E
18.7.2 Data Direction Register E (DDRE)
Data direction register E determines whether each port E pin is an input
or an output. Writing a logic 1 to a DDRE bit enables the output buffer for
the corresponding port E pin; a logic 0 disables the output buffer.
Address: $0009
Bit 7
DDRE7
0
6
DDRE6
0
5
DDRE5
0
4
DDRE4
0
3
DDRE3
0
2
DDRE2
0
1
DDRE1
0
Bit 0
DDRE0
0
Read:
Write:
Reset:
Figure 18-17. Data Direction Register E (DDRE)
DDRE[7:0] — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears
DDRE[7:0], configuring all port E pins as inputs.
1 = Corresponding port E pin configured as output
0 = Corresponding port E pin configured as input
NOTE: Avoid glitches on port E pins by writing to the port E data register before
changing data direction register E bits from 0 to 1. Figure 18-18 shows
the port E I/O logic.
READ DDRE ($0009)
WRITE DDRE ($0009)
DDREx
RESET
WRITE PTE ($0008)
PTEx
PTEx
READ PTE ($0008)
Figure 18-18. Port E I/O Circuit
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
395
Input/Output (I/O) Ports
Input/Output (I/O) Ports
When DDREx is a logic 1, reading address $0008 reads the PTEx data
latch. When DDREx is a logic 0, reading address $0008 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-6 summarizes the operation of the port E pins.
Table 18-6. Port E Pin Functions
Accesses to DDRE
Read/Write
Accesses to PTE
DDRE
Bit
PTE Bit
I/O Pin Mode
Read
Pin
Write
(1)
(2)
(3)
0
1
X
Input, Hi-Z
DDRE[7:0]
PTE[7:0]
X
Output
DDRE[7:0]
PTE[7:0]
PTE[7:0]
Notes:
1. X = don’t care; except.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
18.7.3 Port E LED Control Register (LEDE)
The port-E LED control register (LEDE) controls the direct LED drive
capability on PTE7–PTE0 pins. Each bit is individually configurable and
requires that the data direction register, DDRE, bit be configured as an
output.
Address: $000E
Bit 7
LEDE7
0
6
LEDE6
0
5
LEDE5
0
4
LEDE4
0
3
LEDE3
0
2
LEDE2
0
1
LEDE1
0
Bit 0
LEDE0
0
Read:
Write:
Reset:
Figure 18-19. Port E LED Control Register (LEDE)
LEDE[7:0] — Port E LED Drive Enable Bits
These read/write bits are software programmable to enable the direct
LED drive on an output port pin.
1 = Corresponding port E pin is configured for direct LED drive,
with 15mA current sinking capability
0 = Corresponding port E pin is configured for standard drive
Data Sheet
396
MC68HC908LJ24/LK24 — Rev. 2.1
Input/Output (I/O) Ports
Freescale Semiconductor
Input/Output (I/O) Ports
Port F
18.8 Port F
Port F is an 8-bit general-purpose I/O port.
Port pins PTF0–PTF7 can be configured for direct LED drive.
NOTE: PTF0–PTF7 are not available in the 64-pin packages.
18.8.1 Port F Data Register (PTF)
The port F data register contains a data latch for each of the eight port F
pins.
Address: $000A
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTF7
PTF6
PTF5
PTF4
PTF3
PTF2
PTF1
PTF0
Unaffected by Reset
Additional Function: LED drive LED drive LED drive LED drive LED drive LED drive LED drive LED drive
Figure 18-20. Port F Data Register (PTF)
PTF[7:0] — Port F Data Bits
These read/write bits are software programmable. Data direction of
each port F pin is under the control of the corresponding bit in data
direction register F. Reset has no effect on port F data.
LED drive — Direct LED Drive Pins
PTF0–PTF7 pins can be configured for direct LED drive. See 18.8.3
Port F LED Control Register (LEDF).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
397
Input/Output (I/O) Ports
Input/Output (I/O) Ports
18.8.2 Data Direction Register F (DDRF)
Data direction register F determines whether each port F pin is an input
or an output. Writing a logic 1 to a DDRF bit enables the output buffer for
the corresponding port F pin; a logic 0 disables the output buffer.
NOTE: For those devices packaged in a 64-pin package, PTF0–PTF7 are
connected to ground internally. DDRF0–DDRF7 should be set to a 0 to
configure PTF0–PTF7 as inputs.
Address: $000B
Bit 7
DDRF7
0
6
DDRF6
0
5
DDRF5
0
4
DDRF4
0
3
DDRF3
0
2
DDRF2
0
1
DDRF1
0
Bit 0
DDRF0
0
Read:
Write:
Reset:
Figure 18-21. Data Direction Register F (DDRF)
DDRF[7:0] — Data Direction Register F Bits
These read/write bits control port F data direction. Reset clears
DDRF[7:0], configuring all port F pins as inputs.
1 = Corresponding port F pin configured as output
0 = Corresponding port F pin configured as input
NOTE: Avoid glitches on port F pins by writing to the port F data register before
changing data direction register F bits from 0 to 1. Figure 18-22 shows
the port F I/O logic.
READ DDRF ($000B)
WRITE DDRF ($000B)
DDRFx
RESET
WRITE PTF ($000A)
PTFx
PTFx
READ PTF ($000A)
Figure 18-22. Port F I/O Circuit
Data Sheet
398
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Port F
When DDRFx is a logic 1, reading address $000A reads the PTFx data
latch. When DDRFx is a logic 0, reading address $000A reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-7 summarizes the operation of the port F pins.
Table 18-7. Port F Pin Functions
Accesses to DDRF
Read/Write
Accesses to PTF
Read Write
DDRF
Bit
PTF Bit
I/O Pin Mode
(1)
(2)
(3)
0
1
X
Input, Hi-Z
DDRF[7:0]
Pin
PTF[7:0]
PTF[7:0]
X
Output
DDRF[7:0]
PTF[7:0]
Notes:
1. X = don’t care; except.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
18.8.3 Port F LED Control Register (LEDF)
Port-F LED control register (LEDF) controls the direct LED drive
capability on PTF7–PTF0 pins. Each bit is individually configurable and
requires that the data direction register, DDRF, bit be configured as an
output.
Address: $000F
Bit 7
LEDF7
0
6
LEDF6
0
5
LEDF5
0
4
LEDF4
0
3
LEDF3
0
2
LEDF2
0
1
LEDF1
0
Bit 0
LEDF0
0
Read:
Write:
Reset:
Figure 18-23. Port F LED Control Register (LEDF)
LEDF[7:0] — Port F LED Drive Enable Bits
These read/write bits are software programmable to enable the direct
LED drive on an output port pin.
1 = Corresponding port F pin is configured for direct LED drive,
with 15mA current sinking capability
0 = Corresponding port F pin is configured for standard drive
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
399
Input/Output (I/O) Ports
Input/Output (I/O) Ports
Data Sheet
400
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Input/Output (I/O) Ports
Data Sheet — MC68HC908LJ24
Section 19. External Interrupt (IRQ)
19.1 Contents
19.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .401
19.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .401
19.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .402
19.4.1 IRQ Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .404
19.5 IRQ Module During Break Interrupts . . . . . . . . . . . . . . . . . . .405
19.6 IRQ Status and Control Register (INTSCR) . . . . . . . . . . . . . .405
19.2 Introduction
19.3 Features
The external interrupt (IRQ) module provides a maskable interrupt input.
Features of the IRQ module include the following:
• A dedicated external interrupt pin (IRQ)
• IRQ interrupt control bits
• Hysteresis buffer
• Programmable edge-only or edge and level interrupt sensitivity
• Automatic interrupt acknowledge
• Internal pullup resistor
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
401
External Interrupt (IRQ)
External Interrupt (IRQ)
19.4 Functional Description
A logic 0 applied to the external interrupt pin can latch a CPU interrupt
request. Figure 19-1 shows the structure of the IRQ module.
Interrupt signals on the IRQ pin are latched into the IRQ latch. An
interrupt latch remains set until one of the following actions occurs:
• Vector fetch — A vector fetch automatically generates an interrupt
acknowledge signal that clears the IRQ latch.
• Software clear — Software can clear the interrupt latch by writing
to the acknowledge bit in the interrupt status and control register
(INTSCR). Writing a logic 1 to the ACK bit clears the IRQ latch.
• Reset — A reset automatically clears the interrupt latch.
The external interrupt pin is falling-edge-triggered and is software-
configurable to be either falling-edge or low-level-triggered. The MODE
bit in the INTSCR controls the triggering sensitivity of the IRQ pin.
When the interrupt pin is edge-triggered only, the CPU interrupt request
remains set until a vector fetch, software clear, or reset occurs.
When the interrupt pin is both falling-edge and low-level-triggered, the
CPU interrupt request remains set until both of the following occur:
• Vector fetch or software clear
• Return of the interrupt pin to logic 1
The vector fetch or software clear may occur before or after the interrupt
pin returns to logic 1. As long as the pin is low, the interrupt request
remains pending. A reset will clear the latch and the MODE control bit,
thereby clearing the interrupt even if the pin stays low.
When set, the IMASK bit in the INTSCR mask all external interrupt
requests. A latched interrupt request is not presented to the interrupt
priority logic unless the IMASK bit is clear.
NOTE: The interrupt mask (I) in the condition code register (CCR) masks all
interrupt requests, including external interrupt requests.
Data Sheet
402
MC68HC908LJ24/LK24 — Rev. 2.1
External Interrupt (IRQ)
Freescale Semiconductor
External Interrupt (IRQ)
Functional Description
RESET
ACK
TO CPU FOR
BIL/BIH
VECTOR
FETCH
INSTRUCTIONS
DECODER
VDD
VDD
INTERNAL
PULLUP
DEVICE
IRQF
CLR
D
Q
IRQ
SYNCHRONIZER
INTERRUPT
REQUEST
CK
IRQ
IMASK
MODE
TO MODE
SELECT
LOGIC
HIGH
VOLTAGE
DETECT
Figure 19-1. IRQ Module Block Diagram
Addr.
Register Name
Bit 7
6
5
4
3
2
0
1
Bit 0
Read:
Write:
Reset:
0
0
0
0
IRQF
IRQ Status and Control
Register
IMASK MODE
$001E
ACK
0
(INTSCR)
0
0
0
0
0
0
0
= Unimplemented
Figure 19-2. IRQ I/O Port Register Summary
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
403
External Interrupt (IRQ)
External Interrupt (IRQ)
19.4.1 IRQ Pin
A logic 0 on the IRQ pin can latch an interrupt request into the IRQ latch.
A vector fetch, software clear, or reset clears the IRQ latch.
If the MODE bit is set, the IRQ pin is both falling-edge-sensitive and low-
level-sensitive. With MODE set, both of the following actions must occur
to clear IRQ:
• Vector fetch or software clear — A vector fetch generates an
interrupt acknowledge signal to clear the latch. Software may
generate the interrupt acknowledge signal by writing a logic 1 to
the ACK bit in the interrupt status and control register (INTSCR).
The ACK bit is useful in applications that poll the IRQ pin and
require software to clear the IRQ latch. Writing to the ACK bit prior
to leaving an interrupt service routine can also prevent spurious
interrupts due to noise. Setting ACK does not affect subsequent
transitions on the IRQ pin. A falling edge that occurs after writing
to the ACK bit latches another interrupt request. If the IRQ mask
bit, IMASK, is clear, the CPU loads the program counter with the
vector address at locations $FFFA and $FFFB.
• Return of the IRQ pin to logic 1 — As long as the IRQ pin is at
logic 0, IRQ remains active.
The vector fetch or software clear and the return of the IRQ pin to logic 1
may occur in any order. The interrupt request remains pending as long
as the IRQ pin is at logic 0. A reset will clear the latch and the MODE
control bit, thereby clearing the interrupt even if the pin stays low.
If the MODE bit is clear, the IRQ pin is falling-edge-sensitive only. With
MODE clear, a vector fetch or software clear immediately clears the IRQ
latch.
The IRQF bit in the INTSCR register can be used to check for pending
interrupts. The IRQF bit is not affected by the IMASK bit, which makes it
useful in applications where polling is preferred.
Use the BIH of BIL instruction to read the logic level on the IRQ pin.
NOTE: When using the level-sensitive interrupt trigger, avoid false interrupts by
masking interrupt requests in the interrupt routine.
Data Sheet
404
MC68HC908LJ24/LK24 — Rev. 2.1
External Interrupt (IRQ)
Freescale Semiconductor
External Interrupt (IRQ)
IRQ Module During Break Interrupts
19.5 IRQ Module During Break Interrupts
The system integration module (SIM) controls whether the IRQ latch can
be cleared during the break state. The BCFE bit in the break flag control
register (BFCR) enables software to clear the latches during the break
state. (See Section 23. Break Module (BRK).)
To allow software to clear the IRQ latch during a break interrupt, write a
logic 1 to the BCFE bit. If a latch is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect the latches during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), writing to the ACK bit in the
IRQ status and control register during the break state has no effect on
the IRQ latch.
19.6 IRQ Status and Control Register (INTSCR)
The IRQ status and control register (INTSCR) controls and monitors
operation of the IRQ module. The INTSCR has the following functions:
• Shows the state of the IRQ flag
• Clears the IRQ latch
• Masks IRQ and interrupt request
• Controls triggering sensitivity of the IRQ interrupt pin
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
405
External Interrupt (IRQ)
External Interrupt (IRQ)
Address: $001E
Bit 7
0
6
0
5
0
4
0
3
2
0
1
IMASK
0
Bit 0
MODE
0
Read:
Write:
Reset:
IRQF
ACK
0
0
0
0
0
0
= Unimplemented
Figure 19-3. IRQ Status and Control Register (INTSCR)
IRQF — IRQ Flag Bit
This read-only status bit is high when the IRQ interrupt is pending.
1 = IRQ interrupt pending
0 = IRQ interrupt not pending
ACK — IRQ Interrupt Request Acknowledge Bit
Writing a logic 1 to this write-only bit clears the IRQ latch. ACK always
reads as logic 0. Reset clears ACK.
IMASK — IRQ Interrupt Mask Bit
Writing a logic 1 to this read/write bit disables IRQ interrupt requests.
Reset clears IMASK.
1 = IRQ interrupt requests disabled
0 = IRQ interrupt requests enabled
MODE — IRQ Edge/Level Select Bit
This read/write bit controls the triggering sensitivity of the IRQ pin.
Reset clears MODE.
1 = IRQ interrupt requests on falling edges and low levels
0 = IRQ interrupt requests on falling edges only
Data Sheet
406
MC68HC908LJ24/LK24 — Rev. 2.1
External Interrupt (IRQ)
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 20. Keyboard Interrupt Module (KBI)
20.1 Contents
20.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .407
20.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .408
20.4 I/O Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .408
20.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .409
20.5.1 Keyboard Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . .411
20.6 Keyboard Interrupt Registers . . . . . . . . . . . . . . . . . . . . . . . . .412
20.6.1 Keyboard Status and Control Register. . . . . . . . . . . . . . . .412
20.6.2 Keyboard Interrupt Enable Register. . . . . . . . . . . . . . . . . .413
20.7 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414
20.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414
20.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414
20.8 Keyboard Module During Break Interrupts . . . . . . . . . . . . . . .414
20.2 Introduction
The keyboard interrupt module (KBI) provides eight independently
maskable external interrupts which are accessible via PTA0–PTA3 and
PTD4–PTD7. When a port pin is enabled for keyboard interrupt function
(except PTD6 and PTD7), an internal 30kΩ pullup device is also enabled
on the pin.
NOTE: PTD6/KBI6/SCL–PTD7/KBI7/SDA pins do not have internal pullup
devices. These two pins are open-drain when configured as outputs.
User should connect pullup devices when using these two pins for KBI
function.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
407
Keyboard Interrupt Module (KBI)
Keyboard Interrupt Module (KBI)
20.3 Features
Features of the keyboard interrupt module include the following:
• Eight keyboard interrupt pins with pullup devices
• Separate keyboard interrupt enable bits and one keyboard
interrupt mask
• Programmable edge-only or edge- and level- interrupt sensitivity
• Exit from low-lower modes
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
KEYF
0
ACKK
0
Keyboard Status and
IMASKK MODEK
$001B
Control Register Write:
(KBSCR)
Reset:
0
KBIE7
0
0
KBIE6
0
0
KBIE5
0
0
KBIE4
0
0
KBIE3
0
0
KBIE1
0
0
KBIE0
0
Read:
Keyboard Interrupt
KBIE2
0
$001C
Enable Register Write:
(KBIER)
Reset:
= Unimplemented
Figure 20-1. KBI I/O Register Summary
20.4 I/O Pins
The eight keyboard interrupt pins are shared with standard port I/O pins.
The full name of the KBI pins are listed in Table 20-1. The generic pin
name appear in the text that follows.
Table 20-1. Pin Name Conventions
KBI
Pin Selected for KBI Function by
Full MCU Pin Name
Generic Pin Name
KBIEx Bit in KBIER
KBIE0–KBIE3
KBIE4
KBI0–KBI3
KBI4
PTA0/KBI0–PTA3/KBI3
(1)
PTD4/KBI4/T1CLK
(1)
KBI5
PTD5/KBI5/T2CLK
KBIE5
(1)
KBI6
PTD6/KBI6/SCL
KBIE6
(1)
KBI7
PTD7/KBI7/SDA
KBIE7
Notes:
1. Do not enable the KBI function if the pin is used for TIM / MMIIC function.
Data Sheet
408
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Keyboard Interrupt Module (KBI)
Keyboard Interrupt Module (KBI)
Functional Description
20.5 Functional Description
INTERNAL BUS
VECTOR FETCH
DECODER
KBI0
ACKK
VDD
KEYF
RESET
CLR
.
D
Q
KEYBOARD
INTERRUPT
REQUEST
SYNCHRONIZER
KBIE0
.
CK
TO PULLUP ENABLE
.
KEYBOARD
INTERRUPT FF
IMASKK
KBI7
MODEK
KBIE7
TO PULLUP ENABLE
Figure 20-2. Keyboard Interrupt Block Diagram
Writing to the KBIE7–KBIE0 bits in the keyboard interrupt enable register
independently enables or disables a port A or port D pin as a keyboard
interrupt pin. Enabling a keyboard interrupt pin in port A or port D also
enables its internal pullup device. A logic 0 applied to an enabled
keyboard interrupt pin latches a keyboard interrupt request.
A keyboard interrupt is latched when one or more keyboard pins goes
low after all were high. The MODEK bit in the keyboard status and
control register controls the triggering mode of the keyboard interrupt.
• If the keyboard interrupt is edge-sensitive only, a falling edge on a
keyboard pin does not latch an interrupt request if another
keyboard pin is already low. To prevent losing an interrupt request
on one pin because another pin is still low, software can disable
the latter pin while it is low.
• If the keyboard interrupt is falling edge- and low level-sensitive, an
interrupt request is present as long as any keyboard pin is low.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
409
Keyboard Interrupt Module (KBI)
Keyboard Interrupt Module (KBI)
If the MODEK bit is set, the keyboard interrupt pins are both falling edge-
and low level-sensitive, and both of the following actions must occur to
clear a keyboard interrupt request:
• Vector fetch or software clear — A vector fetch generates an
interrupt acknowledge signal to clear the interrupt request.
Software may generate the interrupt acknowledge signal by
writing a logic 1 to the ACKK bit in the keyboard status and control
register KBSCR. The ACKK bit is useful in applications that poll
the keyboard interrupt pins and require software to clear the
keyboard interrupt request. Writing to the ACKK bit prior to leaving
an interrupt service routine can also prevent spurious interrupts
due to noise. Setting ACKK does not affect subsequent transitions
on the keyboard interrupt pins. A falling edge that occurs after
writing to the ACKK bit latches another interrupt request. If the
keyboard interrupt mask bit, IMASKK, is clear, the CPU loads the
program counter with the vector address at locations $FFDC and
$FFDD.
• Return of all enabled keyboard interrupt pins to logic 1 — As long
as any enabled keyboard interrupt pin is at logic 0, the keyboard
interrupt remains set.
The vector fetch or software clear and the return of all enabled keyboard
interrupt pins to logic 1 may occur in any order.
If the MODEK bit is clear, the keyboard interrupt pin is falling-edge-
sensitive only. With MODEK clear, a vector fetch or software clear
immediately clears the keyboard interrupt request.
Reset clears the keyboard interrupt request and the MODEK bit, clearing
the interrupt request even if a keyboard interrupt pin stays at logic 0.
The keyboard flag bit (KEYF) in the keyboard status and control register
can be used to see if a pending interrupt exists. The KEYF bit is not
affected by the keyboard interrupt mask bit (IMASKK) which makes it
useful in applications where polling is preferred.
To determine the logic level on a keyboard interrupt pin, use the data
direction register to configure the pin as an input and read the data
register.
Data Sheet
410
MC68HC908LJ24/LK24 — Rev. 2.1
Keyboard Interrupt Module (KBI)
Freescale Semiconductor
Keyboard Interrupt Module (KBI)
Functional Description
NOTE: Setting a keyboard interrupt enable bit (KBIEx) forces the corresponding
keyboard interrupt pin to be an input, overriding the data direction
register. However, the data direction register bit must be a logic 0 for
software to read the pin.
20.5.1 Keyboard Initialization
When a keyboard interrupt pin is enabled, it takes time for the internal
pullup to reach a logic 1. Therefore a false interrupt can occur as soon
as the pin is enabled.
To prevent a false interrupt on keyboard initialization:
1. Mask keyboard interrupts by setting the IMASKK bit in the
keyboard status and control register.
2. Enable the KBI pins by setting the appropriate KBIEx bits in the
keyboard interrupt enable register.
3. Write to the ACKK bit in the keyboard status and control register
to clear any false interrupts.
4. Clear the IMASKK bit.
An interrupt signal on an edge-triggered pin can be acknowledged
immediately after enabling the pin. An interrupt signal on an edge- and
level-triggered interrupt pin must be acknowledged after a delay that
depends on the external load.
Another way to avoid a false interrupt:
1. Configure the keyboard pins as outputs by setting the appropriate
DDR bits in data direction register.
2. Write logic 1s to the appropriate data register bits.
3. Enable the KBI pins by setting the appropriate KBIEx bits in the
keyboard interrupt enable register.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
411
Keyboard Interrupt Module (KBI)
Keyboard Interrupt Module (KBI)
20.6 Keyboard Interrupt Registers
Two registers control the operation of the keyboard interrupt module:
• Keyboard status and control register (KBSCR)
• Keyboard interrupt enable register (KBIER)
20.6.1 Keyboard Status and Control Register
• Flags keyboard interrupt requests
• Acknowledges keyboard interrupt requests
• Masks keyboard interrupt requests
• Controls keyboard interrupt triggering sensitivity
Address: $001B
Bit 7
6
0
5
0
4
0
3
2
1
Bit 0
Read:
Write:
Reset:
0
KEYF
0
ACKK
0
IMASKK MODEK
0
0
0
0
0
0
0
= Unimplemented
Figure 20-3. Keyboard Status and Control Register (KBSCR)
KEYF — Keyboard Flag Bit
This read-only bit is set when a keyboard interrupt is pending.
Reset clears the KEYF bit.
1 = Keyboard interrupt pending
0 = No keyboard interrupt pending
ACKK — Keyboard Acknowledge Bit
Writing a logic 1 to this write-only bit clears the keyboard interrupt
request. ACKK always reads as logic 0. Reset clears ACKK.
Data Sheet
412
MC68HC908LJ24/LK24 — Rev. 2.1
Keyboard Interrupt Module (KBI)
Freescale Semiconductor
Keyboard Interrupt Module (KBI)
Keyboard Interrupt Registers
IMASKK — Keyboard Interrupt Mask Bit
Writing a logic 1 to this read/write bit prevents the output of the
keyboard interrupt mask from generating interrupt requests. Reset
clears the IMASKK bit.
1 = Keyboard interrupt requests masked
0 = Keyboard interrupt requests not masked
MODEK — Keyboard Triggering Sensitivity Bit
This read/write bit controls the triggering sensitivity of the keyboard
interrupt pins. Reset clears MODEK.
1 = Keyboard interrupt requests on falling edges and low levels
0 = Keyboard interrupt requests on falling edges only
20.6.2 Keyboard Interrupt Enable Register
The keyboard interrupt enable register individually enables or disables
the PTA0/KBI0–PTA3/KBI3 and PTD4/KBI4–PTD7/KBI7 pins to operate
as a keyboard interrupt pin.
Address: $001C
Bit 7
KBIE7
0
6
KBIE6
0
5
KBIE5
0
4
KBIE4
0
3
KBIE3
0
2
KBIE2
0
1
KBIE1
0
Bit 0
KBIE0
0
Read:
Write:
Reset:
Figure 20-4. Keyboard Interrupt Enable Register (KBIER)
KBIE7–KBIE0 — Keyboard Interrupt Enable Bits
Each of these read/write bits enables the corresponding keyboard
interrupt pin to latch interrupt requests. Reset clears the keyboard
interrupt enable register.
1 = KBIx pin enabled as keyboard interrupt pin
0 = KBIx pin not enabled as keyboard interrupt pin
NOTE: KBI5–KBI0 pin has an internal pullup device when KBIEx is set.
KBI7–KBI6 pin does not have an internal pullup device.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
413
Keyboard Interrupt Module (KBI)
Keyboard Interrupt Module (KBI)
20.7 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
20.7.1 Wait Mode
20.7.2 Stop Mode
The keyboard interrupt module remains active in wait mode. Clearing the
IMASKK bit in the keyboard status and control register enables keyboard
interrupt requests to bring the MCU out of wait mode.
The keyboard interrupt module remains active in stop mode. Clearing
the IMASKK bit in the keyboard status and control register enables
keyboard interrupt requests to bring the MCU out of stop mode.
20.8 Keyboard Module During Break Interrupts
The system integration module (SIM) controls whether the keyboard
interrupt latch can be cleared during the break state. The BCFE bit in the
SIM break flag control register (BFCR) enables software to clear status
bits during the break state.
To allow software to clear the keyboard interrupt latch during a break
interrupt, write a logic 1 to the BCFE bit. If a latch is cleared during the
break state, it remains cleared when the MCU exits the break state.
To protect the latch during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), writing to the keyboard
acknowledge bit (ACKK) in the keyboard status and control register
during the break state has no effect.
Data Sheet
414
MC68HC908LJ24/LK24 — Rev. 2.1
Keyboard Interrupt Module (KBI)
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 21. Computer Operating Properly (COP)
21.1 Contents
21.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .415
21.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .416
21.4 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.1 ICLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.2 STOP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.3 COPCTL Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.4 Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
21.4.5 Internal Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .418
21.4.6 Reset Vector Fetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .418
21.4.7 COPD (COP Disable). . . . . . . . . . . . . . . . . . . . . . . . . . . . .418
21.4.8 COPRS (COP Rate Select) . . . . . . . . . . . . . . . . . . . . . . . .418
21.5 COP Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .419
21.6 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .419
21.7 Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .419
21.8 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .419
21.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .420
21.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .420
21.9 COP Module During Break Mode . . . . . . . . . . . . . . . . . . . . . .420
21.2 Introduction
The computer operating properly (COP) module contains a free-running
counter that generates a reset if allowed to overflow. The COP module
helps software recover from runaway code. Prevent a COP reset by
clearing the COP counter periodically. The COP module can be disabled
through the COPD bit in the configuration register 1 (CONFIG1).
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
415
Computer Operating Properly (COP)
Computer Operating Properly (COP)
21.3 Functional Description
Figure 21-1 shows the structure of the COP module.
RESET CIRCUIT
12-BIT COP PRESCALER
ICLK
RESET STATUS REGISTER
STOP INSTRUCTION
INTERNAL RESET SOURCES
RESET VECTOR FETCH
COPCTL WRITE
COP CLOCK
6-BIT COP COUNTER
COPEN (FROM SIM)
COP DISABLE
(COPD FROM CONFIG1)
RESET
CLEAR
COPCTL WRITE
COP COUNTER
COP RATE SEL
(COPRS FROM CONFIG1)
Figure 21-1. COP Block Diagram
The COP counter is a free-running 6-bit counter preceded by a 12-bit
prescaler counter. If not cleared by software, the COP counter overflows
18
4
13
4
and generates an asynchronous reset after 2 – 2 or 2 – 2 ICLK
cycles, depending on the state of the COP rate select bit, COPRS, in the
13
4
CONFIG1 register. With a 2 – 2 ICLK cycle overflow option, a 47-kHz
ICLK gives a COP timeout period of 174ms. Writing any value to location
$FFFF before an overflow occurs prevents a COP reset by clearing the
COP counter and stages 12 through 5 of the prescaler.
NOTE: Service the COP immediately after reset and before entering or after
exiting STOP Mode to guarantee the maximum time before the first COP
counter overflow.
Data Sheet
416
MC68HC908LJ24/LK24 — Rev. 2.1
Computer Operating Properly (COP)
Freescale Semiconductor
Computer Operating Properly (COP)
I/O Signals
A COP reset pulls the RST pin low for 32 ICLK cycles and sets the COP
bit in the SIM reset status register (SRSR).
In monitor mode, the COP is disabled if the RST pin or the IRQ is held
at V
. During the break state, V
on the RST pin disables the COP.
TST
TST
NOTE: Place COP clearing instructions in the main program and not in an
interrupt subroutine. Such an interrupt subroutine could keep the COP
from generating a reset even while the main program is not working
properly.
21.4 I/O Signals
The following paragraphs describe the signals shown in Figure 21-1.
21.4.1 ICLK
ICLK is the internal oscillator output signal. ICLK frequency is
approximately equal to 47-kHz. See Section 24. Electrical
Specifications for ICLK parameters.
21.4.2 STOP Instruction
The STOP instruction clears the COP prescaler.
21.4.3 COPCTL Write
Writing any value to the COP control register (COPCTL) (see 21.5 COP
Control Register) clears the COP counter and clears bits 12 through 5
of the prescaler. Reading the COP control register returns the low byte
of the reset vector.
21.4.4 Power-On Reset
The power-on reset (POR) circuit clears the COP prescaler 4096 ICLK
cycles after power-up.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
417
Computer Operating Properly (COP)
Computer Operating Properly (COP)
21.4.5 Internal Reset
An internal reset clears the COP prescaler and the COP counter.
21.4.6 Reset Vector Fetch
A reset vector fetch occurs when the vector address appears on the data
bus. A reset vector fetch clears the COP prescaler.
21.4.7 COPD (COP Disable)
The COPD signal reflects the state of the COP disable bit (COPD) in the
CONFIG1 register. (See Figure 21-2 and Section 5. Configuration
Registers (CONFIG).)
21.4.8 COPRS (COP Rate Select)
The COPRS signal reflects the state of the COP rate select bit (COPRS)
in the CONFIG1 register.
Address: $001F
Bit 7
6
5
4
3
2
SSREC
0
1
STOP
0
Bit 0
COPD
0
Read:
Write:
Reset:
0
COPRS LVISTOP LVIRSTD LVIPWRD
††
0
0
0
0
0
†† Reset by POR only.
= Unimplemented
Figure 21-2. Configuration Register 1 (CONFIG1)
COPRS — COP Rate Select
COPRS selects the COP time-out period. Reset clears COPRS.
13
4
1 = COP time out period = 2 – 2 ICLK cycles
18
4
0 = COP time out period = 2 – 2 ICLK cycles
COPD — COP Disable Bit
COPD disables the COP module.
1 = COP module disabled
0 = COP module enabled
Data Sheet
418
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Computer Operating Properly (COP)
Computer Operating Properly (COP)
COP Control Register
21.5 COP Control Register
The COP control register is located at address $FFFF and overlaps the
reset vector. Writing any value to $FFFF clears the COP counter and
starts a new timeout period. Reading location $FFFF returns the low
byte of the reset vector.
Address: $FFFF
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
Low byte of reset vector
Clear COP counter
Unaffected by reset
Figure 21-3. COP Control Register (COPCTL)
21.6 Interrupts
The COP does not generate CPU interrupt requests.
21.7 Monitor Mode
When monitor mode is entered with V
on the IRQ pin, the COP is
TST
disabled as long as V
remains on the IRQ pin or the RST pin. When
TST
monitor mode is entered by having blank reset vectors and not having
on the IRQ pin, the COP is automatically disabled until a POR
V
TST
occurs.
21.8 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
419
Computer Operating Properly (COP)
Computer Operating Properly (COP)
21.8.1 Wait Mode
The COP remains active during wait mode. To prevent a COP reset
during wait mode, periodically clear the COP counter in a CPU interrupt
routine.
21.8.2 Stop Mode
Stop mode turns off the ICLK input to the COP and clears the COP
prescaler. Service the COP immediately before entering or after exiting
stop mode to ensure a full COP timeout period after entering or exiting
stop mode.
To prevent inadvertently turning off the COP with a STOP instruction, a
configuration option is available that disables the STOP instruction.
When the STOP bit in the configuration register has the STOP
instruction is disabled, execution of a STOP instruction results in an
illegal opcode reset.
21.9 COP Module During Break Mode
The COP is disabled during a break interrupt when V
is present on
TST
the RST pin.
Data Sheet
420
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Computer Operating Properly (COP)
Data Sheet — MC68HC908LJ24
Section 22. Low-Voltage Inhibit (LVI)
22.1 Contents
22.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421
22.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421
22.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .422
22.4.1 Polled LVI Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .424
22.4.2 Forced Reset Operation. . . . . . . . . . . . . . . . . . . . . . . . . . .424
22.4.3 Voltage Hysteresis Protection . . . . . . . . . . . . . . . . . . . . . .424
22.4.4 LVI Trip Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425
22.5 LVI Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425
22.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
22.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
22.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
22.2 Introduction
22.3 Features
This section describes the low-voltage inhibit (LVI) module, which
monitors the voltage on the V pin and can force a reset when the V
DD
DD
voltage falls below the LVI trip falling voltage, V
.
TRIPF
Features of the LVI module include:
• Programmable LVI interrupt and reset
• Selectable LVI trip voltage
• Programmable stop mode operation
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
421
Low-Voltage Inhibit (LVI)
Low-Voltage Inhibit (LVI)
Addr.
Register Name
Bit 7
6
LVIIE
0
5
4
3
2
1
Bit 0
Read: LVIOUT
LVIIF
0
LVIIACK
0
0
0
0
0
Low-Voltage Inhibit Status
$FE0F
Register Write:
(LVISR)
Reset:
0
0
0
0
0
0
= Unimplemented
Figure 22-1. LVI I/O Register Summary
22.4 Functional Description
Figure 22-2 shows the structure of the LVI module.
VDD
STOP INSTRUCTION
LVISTOP
FROM CONFIG1
DEFAULT
FROM CONFIG1
LVIRSTD
ENABLED
LVIPWRD
FROM CONFIG1
V
V
DD > VTRIPR = 0
LVI RESET
LOW VDD
DETECTOR
DD ≤ VTRIPF = 1
FROM LVISR
LVIIE
LVISEL[1:0]
FROM CONFIG2
LVI
INTERRUPT
REQUEST
EDGE
DETECT
LATCH
CLR
LVIOUT
LVIIACK
LVIIF
TO LVISR
FROM LVISR TO LVISR
Figure 22-2. LVI Module Block Diagram
The LVI is enabled out of reset. The LVI module contains a bandgap
reference circuit and comparator. Clearing the LVI power disable bit,
LVIPWRD, enables the LVI to monitor V voltage. Clearing the LVI
DD
reset disable bit, LVIRSTD, enables the LVI module to generate a reset
when V falls below a voltage, V
. Setting the LVI enable in stop
TRIPF
DD
mode bit, LVISTOP, enables the LVI to operate in stop mode.
Data Sheet
422
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Low-Voltage Inhibit (LVI)
Low-Voltage Inhibit (LVI)
Functional Description
The LVI trip point selection bits, LVISEL[1:0], select the trip point
voltage, V , to be configured for 5V or 3V operation. The actual trip
TRIPF
points are shown in Section 24. Electrical Specifications.
Setting LVI interrupt enable bit, LVIIE, enables LVI interrupts whenever
the LVIOUT bit toggles (from logic 0 to logic 1, or from logic 1 to logic 0).
NOTE: After a power-on reset (POR) the LVI’s default mode of operation is 3V.
If a 5V system is used, the user must modified the LVISEL[1:0] bits to
raise the trip point to 5V operation. Note that this must be done after
every power-on reset since the default will revert back to 3V mode after
each power-on reset. If the V supply is below the 3V mode trip voltage
DD
when POR is released, the MCU will immediately go into reset. The LVI
in this case will hold the MCU in reset until either V goes above the
DD
rising 3V trip point, V
, which will release reset or V decreases to
DD
TRIPR
approximately 0V which will re-trigger the power-on reset.
LVISTOP, LVIPWRD, LVIRSTD, and LVISEL[1:0] are in the
configuration registers. See Section 5. Configuration Registers
(CONFIG) for details of the LVI’s configuration bits. Once an LVI reset
occurs, the MCU remains in reset until V rises above a voltage,
DD
V
, which causes the MCU to exit reset. See 9.4.2.5 Low-Voltage
TRIPR
Inhibit (LVI) Reset for details of the interaction between the SIM and the
LVI. The output of the comparator controls the state of the LVIOUT flag
in the LVI status register (LVISR). The LVIIE, LVIIF, and LVIIACK bits in
the LVISR control LVI interrupt functions.
An LVI reset also drives the RST pin low to provide low-voltage
protection to external peripheral devices.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
423
Low-Voltage Inhibit (LVI)
Low-Voltage Inhibit (LVI)
22.4.1 Polled LVI Operation
In applications that can operate at V levels below the V
level,
TRIPF
DD
software can monitor V by polling the LVIOUT bit, or by setting the LVI
DD
interrupt enable bit, LVIIE, to enable interrupt requests. In the
configuration register 1 (CONFIG1), the LVIPWRD bit must be at logic 0
to enable the LVI module, and the LVIRSTD bit must be at logic 1 to
disable LVI resets.
The LVI interrupt flag, LVIIF, is set whenever the LVIOUT bit changes
state (toggles). When LVIF is set, a CPU interrupt request is generated
if the LVIIE is also set. In the LVI interrupt service subroutine, LVIIF bit
can be cleared by writing a logic 1 to the LVI interrupt acknowledge bit,
LVIIACK.
22.4.2 Forced Reset Operation
In applications that require V to remain above the V
level,
TRIPF
DD
enabling LVI resets allows the LVI module to reset the MCU when V
DD
falls below the V
level. In the configuration register 1 (CONFIG1),
TRIPF
the LVIPWRD and LVIRSTD bits must be at logic 0 to enable the LVI
module and to enable LVI resets.
If LVIIE is set to enable LVI interrupts when LVIRSTD is cleared, LVI
reset has a higher priority over LVI interrupt. In this case, when V falls
DD
below the V
cleared.
level, an LVI reset will occur, and the LVIIE bit will be
TRIPF
22.4.3 Voltage Hysteresis Protection
Once the LVI has triggered (by having V fall below V
), the LVI
TRIPF
DD
will maintain a reset condition until V rises above the rising trip point
DD
voltage, V
. This prevents a condition in which the MCU is
TRIPR
continually entering and exiting reset if V is approximately equal to
DD
V
. V
is greater than V
by the hysteresis voltage, V
.
TRIPF
TRIPR
TRIPF
HYS
Data Sheet
424
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Low-Voltage Inhibit (LVI)
Low-Voltage Inhibit (LVI)
LVI Status Register
22.4.4 LVI Trip Selection
The trip point selection bits, LVISEL[1:0], in the CONFIG2 register select
whether the LVI is configured for 5V or 3V operation. (See Section 5.
Configuration Registers (CONFIG).)
NOTE: The MCU is guaranteed to operate at a minimum supply voltage. The trip
point (V
[5V] or V
[3V]) may be lower than this. (See
TRIPF
TRIPF
Section 24. Electrical Specifications for the actual trip point voltages.)
22.5 LVI Status Register
The LVI status register (LVISR) controls LVI interrupt functions and
indicates if the V voltage was detected below the V
level.
TRIPF
DD
Address: $FE0F
Bit 7
Read: LVIOUT
Write:
6
LVIIE
0
5
4
3
0
2
0
1
Bit 0
0
LVIIF
0
LVIIACK
0
0
Reset:
0
0
0
0
0
0
= Unimplemented
Table 22-1. LVI Status Register (LVISR)
LVIOUT — LVI Output Bit
This read-only flag becomes set when the V voltage falls below the
DD
V
trip voltage (see Table 22-2). Reset clears the LVIOUT bit.
TRIPF
Table 22-2. LVIOUT Bit Indication
V
LVIOUT
DD
V
> V
< V
0
DD
TRIPR
V
1
DD
TRIPF
V
< V < V
DD TRIPR
Previous value
TRIPF
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
425
Low-Voltage Inhibit (LVI)
Low-Voltage Inhibit (LVI)
LVIIE — LVI Interrupt Enable Bit
This read/write bit enables the LVIIF bit to generate CPU interrupt
requests. Reset clears the LVIIE bit.
1 = LVIIF can generate CPU interrupt requests
0 = LVIIF cannot generate CPU interrupt requests
LVIIF — LVI Interrupt Flag
This clearable, read-only flag is set whenever the LVIOUT bit toggles.
Reset clears the LVIIF bit.
1 = LVIOUT has toggled
0 = LVIOUT has not toggled
LVIIACK — LVI Interrupt Acknowledge Bit
Writing a logic 1 to this write-only bit clears the LVI interrupt flag,
LVIIF. LVIIACK always reads as logic 0.
1 = Clears LVIIF bit
0 = No effect
22.6 Low-Power Modes
The STOP and WAIT instructions put the MCU in low power-
consumption standby modes.
22.6.1 Wait Mode
22.6.2 Stop Mode
If enabled, the LVI module remains active in wait mode. If enabled to
generate resets or interrupts, the LVI module can generate a reset or an
interrupt and bring the MCU out of wait mode.
If enabled in stop mode (LVISTOP = 1), the LVI module remains active
in stop mode. If enabled to generate resets or interrupts, the LVI module
can generate a reset or an interrupt and bring the MCU out of stop mode.
NOTE: If enabled to generate both resets and interrupts, there will be no LVI
interrupts, as resets have a higher priority.
Data Sheet
426
MC68HC908LJ24/LK24 — Rev. 2.1
Low-Voltage Inhibit (LVI)
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 23. Break Module (BRK)
23.1 Contents
23.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .427
23.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .428
23.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .428
23.4.1 Flag Protection During Break Interrupts. . . . . . . . . . . . . . .430
23.4.2 CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . .430
23.4.3 TIM1 and TIM2 During Break Interrupts. . . . . . . . . . . . . . .430
23.4.4 COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . .430
23.5 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .430
23.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .430
23.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .431
23.6 Break Module Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .431
23.6.1 Break Status and Control Register. . . . . . . . . . . . . . . . . . .431
23.6.2 Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . .432
23.6.3 SIM Break Status Register. . . . . . . . . . . . . . . . . . . . . . . . .432
23.6.4 SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . .434
23.2 Introduction
This section describes the break module. The break module can
generate a break interrupt that stops normal program flow at a defined
address to enter a background program.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
427
Break Module (BRK)
Break Module (BRK)
23.3 Features
Features of the break module include:
• Accessible input/output (I/O) registers during the break interrupt
• CPU-generated break interrupts
• Software-generated break interrupts
• COP disabling during break interrupts
23.4 Functional Description
When the internal address bus matches the value written in the break
address registers, the break module issues a breakpoint signal to the
CPU. The CPU then loads the instruction register with a software
interrupt instruction (SWI) after completion of the current CPU
instruction. The program counter vectors to $FFFC and $FFFD ($FEFC
and $FEFD in monitor mode).
The following events can cause a break interrupt to occur:
• A CPU-generated address (the address in the program counter)
matches the contents of the break address registers.
• Software writes a logic 1 to the BRKA bit in the break status and
control register.
When a CPU-generated address matches the contents of the break
address registers, the break interrupt begins after the CPU completes its
current instruction. A return-from-interrupt instruction (RTI) in the break
routine ends the break interrupt and returns the MCU to normal
operation. Figure 23-1 shows the structure of the break module.
Data Sheet
428
MC68HC908LJ24/LK24 — Rev. 2.1
Break Module (BRK)
Freescale Semiconductor
Break Module (BRK)
Functional Description
IAB15–IAB8
BREAK ADDRESS REGISTER HIGH
8-BIT COMPARATOR
IAB15–IAB0
CONTROL
BREAK
8-BIT COMPARATOR
BREAK ADDRESS REGISTER LOW
IAB7–IAB0
Figure 23-1. Break Module Block Diagram
Addr.
Register Name
Bit 7
6
5
4
3
2
1
SBSW
Note
0
Bit 0
Read:
R
R
R
R
R
R
R
SIM Break Status Register
(SBSR)
$FE00
Write:
Reset:
Read:
SIM Break Flag Control
BCFE
R
R
R
R
R
R
R
$FE03
$FE0C
$FE0D
$FE0E
Register Write:
(SBFCR)
Reset:
0
Bit 15
0
Read:
Break Address
14
13
0
12
0
11
0
10
0
9
0
1
Bit 8
0
Register High Write:
(BRKH)
Reset:
0
Read:
Break Address
Bit 7
0
6
5
4
3
2
Bit 0
Register Low Write:
(BRKL)
Reset:
0
BRKA
0
0
0
0
0
0
0
0
0
0
0
0
0
Read:
Break Status and Control
BRKE
0
Register Write:
(BRKSCR)
Reset:
0
0
0
0
0
0
Note: Writing a logic 0 clears SBSW.
= Unimplemented
R
= Reserved
Figure 23-2. Break Module I/O Register Summary
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
429
Break Module (BRK)
Break Module (BRK)
23.4.1 Flag Protection During Break Interrupts
The BCFE bit in the SIM break flag control register (SBFCR) enables
software to clear status bits during the break state.
23.4.2 CPU During Break Interrupts
The CPU starts a break interrupt by:
• Loading the instruction register with the SWI instruction
• Loading the program counter with $FFFC and $FFFD
($FEFC and $FEFD in monitor mode)
The break interrupt begins after completion of the CPU instruction in
progress. If the break address register match occurs on the last cycle of
a CPU instruction, the break interrupt begins immediately.
23.4.3 TIM1 and TIM2 During Break Interrupts
A break interrupt stops the timer counters.
23.4.4 COP During Break Interrupts
The COP is disabled during a break interrupt when V
the RST pin.
is present on
TST
23.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
23.5.1 Wait Mode
If enabled, the break module is active in wait mode. In the break routine,
the user can subtract one from the return address on the stack if SBSW
is set (see Section 9. System Integration Module (SIM)). Clear the
SBSW bit by writing logic 0 to it.
Data Sheet
430
MC68HC908LJ24/LK24 — Rev. 2.1
Break Module (BRK)
Freescale Semiconductor
Break Module (BRK)
Break Module Registers
23.5.2 Stop Mode
A break interrupt causes exit from stop mode and sets the SBSW bit in
the break status register.
23.6 Break Module Registers
These registers control and monitor operation of the break module:
• Break status and control register (BRKSCR)
• Break address register high (BRKH)
• Break address register low (BRKL)
• SIM break status register (SBSR)
• SIM break flag control register (SBFCR)
23.6.1 Break Status and Control Register
The break status and control register (BRKSCR) contains break module
enable and status bits.
Address: $FE0E
Bit 7
BRKE
0
6
BRKA
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
Read:
Write:
Reset:
0
0
0
0
0
0
= Unimplemented
Figure 23-3. Break Status and Control Register (BRKSCR)
BRKE — Break Enable Bit
This read/write bit enables breaks on break address register matches.
Clear BRKE by writing a logic 0 to bit 7. Reset clears the BRKE bit.
1 = Breaks enabled on 16-bit address match
0 = Breaks disabled on 16-bit address match
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
431
Break Module (BRK)
Break Module (BRK)
BRKA — Break Active Bit
This read/write status and control bit is set when a break address
match occurs. Writing a logic 1 to BRKA generates a break interrupt.
Clear BRKA by writing a logic 0 to it before exiting the break routine.
Reset clears the BRKA bit.
1 = (When read) Break address match
0 = (When read) No break address match
23.6.2 Break Address Registers
The break address registers (BRKH and BRKL) contain the high and low
bytes of the desired breakpoint address. Reset clears the break address
registers.
Address: $FE0C
Bit 7
Bit 15
0
6
14
0
5
13
0
4
12
0
3
11
0
2
10
0
1
9
0
Bit 0
Bit 8
0
Read:
Write:
Reset:
Figure 23-4. Break Address Register High (BRKH)
Address: $FE0D
Bit 7
6
6
0
5
5
0
4
4
0
3
3
0
2
2
0
1
1
0
Bit 0
Bit 0
0
Read:
Bit 7
Write:
Reset:
0
Figure 23-5. Break Address Register Low (BRKL)
23.6.3 SIM Break Status Register
The SIM break status register (SBSR) contains a flag to indicate that a
break caused an exit from wait mode. The flag is useful in applications
requiring a return to wait mode after exiting from a break interrupt.
Data Sheet
432
MC68HC908LJ24/LK24 — Rev. 2.1
Break Module (BRK)
Freescale Semiconductor
Break Module (BRK)
Break Module Registers
Address: $FE00
Bit 7
6
R
0
5
4
3
R
0
2
R
0
1
SBSW
Note
0
Bit 0
R
Read:
R
R
R
Write:
Reset:
0
0
0
0
Note: Writing a logic 0 clears SBSW.
R
= Reserved
Figure 23-6. SIM Break Status Register (SBSR)
SBSW — Break Wait Bit
This status bit is set when a break interrupt causes an exit from wait
mode or stop mode. Clear SBSW by writing a logic 0 to it. Reset clears
SBSW.
1 = Stop mode or wait mode was exited by break interrupt
0 = Stop mode or wait mode was not exited by break interrupt
SBSW can be read within the break interrupt routine. The user can
modify the return address on the stack by subtracting 1 from it. The
following code is an example.
;This code works if the H register has been pushed onto the stack in the break
;service routine software. This code should be executed at the end of the break
;service routine software.
HIBYTE
LOBYTE
EQU
EQU
5
6
;
If not SBSW, do RTI
BRCLR
SBSW,SBSR, RETURN
;See if wait mode or stop mode was exited by
;break.
TST
BNE
DEC
DEC
LOBYTE,SP
DOLO
;If RETURNLO is not zero,
;then just decrement low byte.
;Else deal with high byte, too.
;Point to WAIT/STOP opcode.
;Restore H register.
HIBYTE,SP
LOBYTE,SP
DOLO
RETURN
PULH
RTI
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
Break Module (BRK)
433
Break Module (BRK)
23.6.4 SIM Break Flag Control Register
The SIM break flag control register (SBFCR) contains a bit that enables
software to clear status bits while the MCU is in a break state.
Address: $FE03
Bit 7
6
5
4
3
2
1
Bit 0
R
Read:
Write:
Reset:
BCFE
R
R
R
R
R
R
0
R
= Reserved
Figure 23-7. SIM Break Flag Control Register (SBFCR)
BCFE — Break Clear Flag Enable Bit
This read/write bit enables software to clear status bits by accessing
status registers while the MCU is in a break state. To clear status bits
during the break state, the BCFE bit must be set.
1 = Status bits clearable during break
0 = Status bits not clearable during break
Data Sheet
434
MC68HC908LJ24/LK24 — Rev. 2.1
Break Module (BRK)
Freescale Semiconductor
Data Sheet — MC68HC908LJ24
Section 24. Electrical Specifications
24.1 Contents
24.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .435
24.3 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . .436
24.4 Functional Operating Range. . . . . . . . . . . . . . . . . . . . . . . . . .437
24.5 Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . .437
24.6 5V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . .438
24.7 3.3V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . .439
24.8 5V Control Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .440
24.9 3.3V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .441
24.10 5V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . .441
24.11 3.3V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . .442
24.12 5V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . .443
24.13 3.3V ADC Electrical Characteristics. . . . . . . . . . . . . . . . . . . .444
24.14 Timer Interface Module Characteristics . . . . . . . . . . . . . . . . .445
24.15 CGM Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . .445
24.16 5V SPI Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .446
24.17 3.3V SPI Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . .447
24.18 FLASH Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . .450
24.2 Introduction
This section contains electrical and timing specifications.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
435
Electrical Specifications
Electrical Specifications
24.3 Absolute Maximum Ratings
Maximum ratings are the extreme limits to which the MCU can be
exposed without permanently damaging it.
NOTE: This device is not guaranteed to operate properly at the maximum
ratings. Refer to DC Electrical Characteristics for guaranteed
operating conditions.
Table 24-1. Absolute Maximum Ratings
(1)
Symbol
Value
Unit
Characteristic
Supply voltage
V
–0.3 to +6.0
V
DD
Input voltage
All pins (except IRQ)
IRQ pin
V
– 0.3 to V + 0.3
V
V
SS
DD
IN
V
– 0.3 to 8.5
SS
Maximum current per pin
I
±25
mA
excluding V and V
DD
SS
Maximum current out of V
Maximum current into V
I
100
100
mA
mA
°C
SS
MVSS
I
DD
MVDD
T
Storage temperature
–55 to +150
STG
Notes:
1. Voltages referenced to VSS
.
This device contains circuitry to protect the inputs against damage due
to high static voltages or electric fields; however, it is advised that normal
precautions be taken to avoid application of any voltage higher than
maximum-rated voltages to this high-impedance circuit. For proper
operation, it is recommended that V and V
be constrained to the
IN
OUT
range V ≤ (V or V
) ≤ V . Reliability of operation is enhanced if
DD
SS
IN
OUT
unused inputs are connected to an appropriate logic voltage level (for
example, either V or V .)
SS
DD
Data Sheet
436
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Electrical Specifications
Electrical Specifications
Functional Operating Range
24.4 Functional Operating Range
Table 24-2. Functional Operating Range
Characteristic
Symbol
Value
Unit
T
Operating temperature range
– 40 to +85
°C
A
3.3 ± 10%
5 ± 10%
V
Operating voltage range
V
DD
24.5 Thermal Characteristics
Table 24-3. Thermal Characteristics
Characteristic
Symbol
Value
Unit
Thermal resistance
64-pin LQFP
64-pin QFP
80-pin LQFP
80-pin QFP
72
67
85
75
θ
°C/W
JA
P
I/O pin power dissipation
User determined
W
W
I/O
P = (I × V ) + P =
I/O
D
DD
DD
(1)
P
Power dissipation
D
K/(T + 273 °C)
J
P x (T + 273 °C)
D
A
(2)
K
W/°C
°C
Constant
2
+ P × θ
D
JA
T
T + (P × θ )
A D JA
Average junction temperature
J
Notes:
1. Power dissipation is a function of temperature.
2. K constant unique to the device. K can be determined for a known TA and measured PD.
With this value of K, PD and TJ can be determined for any value of TA.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
437
Electrical Specifications
Electrical Specifications
24.6 5V DC Electrical Characteristics
Table 24-4. 5V DC Electrical Characteristics
(1)
(2)
Characteristic
Symbol
Min
–0.8
Typ
Max
Unit
Output high voltage (I
All ports
= –2.0 mA)
LOAD
V
V
—
—
—
V
OH
DD
Output low voltage
(I
= 1.6mA) All ports
LOAD
V
—
0.4
V
OL
(I
= 15.0 mA) PTB0–PTB5, PTC0–PTC7,
LOAD
PTE0–PTE7, PTF0–PTF7
Input high voltage
All ports, RST, IRQ, OSC1
V
0.7 × V
V
—
—
V
V
IH
DD
DD
Input low voltage
All ports, RST, IRQ, OSC1
V
V
0.3 × V
DD
IL
SS
V
supply current
DD
(3)
Run , f
= 8 MHz
OP
with all modules on
with ADC on
with ADC off
(4)
—
—
—
15
13
10.5
20
18
14
mA
mA
mA
I
DD
Wait , f = 8 MHz (all modules off)
—
5
8
mA
OP
(5)
Stop, f = 8 kHz
OP
(6)
with OSC, RTC, LCD , LVI on
—
—
—
—
300
20
7
400
30
12
1
µA
µA
µA
µA
(6)
with OSC, RTC, LCD on
with OSC, RTC on
all modules off
—
Digital I/O ports Hi-Z leakage current
All ports, RST
I
I
—
—
—
—
± 10
± 1
µA
µA
IL
Input current
IRQ
IN
C
Capacitance
Ports (as input or output)
—
—
—
—
12
8
OUT
pF
C
IN
(7)
V
0
—
—
—
100
—
8
mV
V/ms
V
POR re-arm voltage
POR
POR
(8)
R
0.035
POR rise-time ramp rate
V
1.5 × V
Monitor mode entry voltage (at IRQ pin)
TST
DD
(9)
Pullup resistors
R
R
21
21
30
30
39
39
kΩ
kΩ
PU1
PU2
PTA0–PTA3 and PTD4–PTD7 as KBI0–KBI7
RST, IRQ
V
V
Low-voltage inhibit, trip falling voltage
Low-voltage inhibit, trip rising voltage
3.6
3.7
—
—
4.6
4.7
V
V
TRIPF
TRIPR
Data Sheet
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
438
Electrical Specifications
Electrical Specifications
3.3V DC Electrical Characteristics
Notes:
1. VDD = 4.5 to 5.5 Vdc, VSS = 0 Vdc, TA = TL to TH, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25 °C only.
3. Run (operating) IDD measured using external square wave clock source. All inputs 0.2 V from rail. No dc loads. Less than
100 pF on all outputs. CL = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects run IDD
4. Wait IDD measured using external square wave clock source. All inputs 0.2 V from rail. No dc loads. Less than 100 pF on
all outputs. CL = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects wait IDD
.
.
5. The 8kHz clock is from a 32kHz external square wave clock input at OSC1, for the driving the RTC. Due to loading effects,
the IDD values will be larger when a 32kHz crystal circuit is connected.
6. LCD driver configured for low current mode.
7. Maximum is highest voltage that POR is guaranteed.
8. If minimum VDD is not reached before the internal POR reset is released, RST must be driven low externally until minimum
VDD is reached.
9. RPU1 and RPU2 are measured at VDD = 5.0V
24.7 3.3V DC Electrical Characteristics
Table 24-5. 3.3V DC Electrical Characteristics
(1)
(2)
Characteristic
Symbol
Min
–0.4
Typ
Max
Unit
Output high voltage (I
All ports
= –1.0 mA)
LOAD
V
V
—
—
—
V
OH
DD
Output low voltage
(I
= 0.8mA) All ports
LOAD
V
—
0.4
V
OL
(I
= 10.0 mA) PTB0–PTB5, PTC0–PTC7,
LOAD
PTE0–PTE7, PTF0–PTF7
Input high voltage
All ports, RST, IRQ, OSC1
V
0.7 × V
V
—
—
V
V
IH
DD
DD
Input low voltage
All ports, RST, IRQ, OSC1
V
V
0.3 × V
DD
IL
SS
V
supply current
DD
(3)
Run , f
= 4 MHz
OP
with all modules on
with ADC on
with ADC off
(4)
—
—
—
5.5
4.5
3
8
6
5
mA
mA
mA
I
DD
Wait , f = 4 MHz (all modules off)
—
1.5
2.5
mA
OP
(5)
Stop, f = 8 kHz
OP
(6)
with OSC, RTC, LCD , LVI on
—
—
—
—
180
15
2.5
—
250
20
4
µA
µA
µA
µA
(6)
with OSC, RTC, LCD on
with OSC, RTC on
all modules off
1
Digital I/O ports Hi-Z leakage current
All ports, RST
I
I
—
—
—
—
± 10
± 1
µA
µA
IL
Input current
IRQ
IN
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
439
Electrical Specifications
Electrical Specifications
Table 24-5. 3.3V DC Electrical Characteristics
(1)
(2)
Characteristic
Symbol
Min
Typ
Max
Unit
C
Capacitance
Ports (as input or output)
—
—
—
—
12
8
OUT
pF
C
IN
(7)
V
R
0
0.02
—
—
—
100
—
8
mV
V/ms
V
POR re-arm voltage
POR
POR
(8)
POR rise-time ramp rate
V
1.5 × V
Monitor mode entry voltage (at IRQ pin)
HI
DD
(9)
Pullup resistors
R
R
21
21
30
30
39
39
kΩ
kΩ
PU1
PU2
PTA0–PTA3 and PTD4–PTD7 as KBI0–KBI7
RST, IRQ
V
V
Low-voltage inhibit, trip falling voltage
Low-voltage inhibit, trip rising voltage
Notes:
2.1
2.2
—
—
2.8
2.9
V
V
TRIPF
TRIPR
1. VDD = 3.0 to 3.6 Vdc, VSS = 0 Vdc, TA = TL to TH, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25 °C only.
3. Run (operating) IDD measured using external square wave clock source. All inputs 0.2 V from rail. No dc loads. Less than
100 pF on all outputs. CL = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects run IDD
4. Wait IDD measured using external square wave clock source. All inputs 0.2 V from rail. No dc loads. Less than 100 pF on
all outputs. CL = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects wait IDD
.
.
5. The 8kHz clock is from a 32kHz external square wave clock input at OSC1, for the driving the RTC. Due to loading effects,
the IDD values will be larger when a 32kHz crystal circuit is connected.
6. LCD driver configured for low current mode.
7. Maximum is highest voltage that POR is guaranteed.
8. If minimum VDD is not reached before the internal POR reset is released, RST must be driven low externally until minimum
VDD is reached.
9. RPU1 and RPU2 are measured at VDD = 3.3V.
24.8 5V Control Timing
Table 24-6. 5V Control Timing
(1)
Characteristic
Symbol
Min
—
Max
8
Unit
MHz
ns
(2)
f
Internal operating frequency
OP
(3)
t
750
—
RST input pulse width low
IRL
Notes:
1. VSS = 0 Vdc; timing shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
2. Some modules may require a minimum frequency greater than dc for proper operation; see appropriate table for this
information.
3. Minimum pulse width reset is guaranteed to be recognized. It is possible for a smaller pulse width to cause a reset.
Data Sheet
440
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Electrical Specifications
Electrical Specifications
3.3V Control Timing
24.9 3.3V Control Timing
Table 24-7. 3.3V Control Timing
(1)
Characteristic
Symbol
Min
—
Max
4
Unit
MHz
µs
(2)
f
Internal operating frequency
OP
(3)
t
1.5
—
RST input pulse width low
IRL
Notes:
1. VSS = 0 Vdc; timing shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
2. Some modules may require a minimum frequency greater than dc for proper operation; see appropriate table for this
information.
3. Minimum pulse width reset is guaranteed to be recognized. It is possible for a smaller pulse width to cause a reset.
24.10 5V Oscillator Characteristics
Table 24-8. 5V Oscillator Specifications
Characteristic
Symbol
Min
Typ
Max
Unit
(1)
f
Internal oscillator clock frequency
Hz
50k
ICLK
(2)
f
dc
—
20M
Hz
Hz
External reference clock to OSC1
OSC
(3)
f
—
—
—
—
—
—
32.768k
—
4.9152M
Crystal reference frequency
XCLK
(4)
C
—
—
—
—
—
Crystal load capacitance
L
C
2 × C (27p)
Crystal fixed capacitance
Crystal tuning capacitance
Feedback bias resistor
F
F
1
L
C
2 × C (33p)
2
L
R
20M
Ω
Ω
B
(5)
R
100k
Series resistor
S
Notes:
1. Typical value reflect average measurements at midpoint of voltage range, 25 ×C only. See Figure 24-1 for plot.
2. No more than 10% duty cycle deviation from 50%.
3. Fundamental mode crystals only.
4. Consult crystal manufacturer’s data.
5. Not Required for high frequency crystals.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
441
Electrical Specifications
Electrical Specifications
24.11 3.3V Oscillator Characteristics
Table 24-9. 3.3V Oscillator Specifications
Characteristic
Symbol
Min
Typ
Max
Unit
(1)
f
Internal oscillator clock frequency
Hz
47k
ICLK
(2)
f
dc
—
16M
Hz
Hz
External reference clock to OSC1
OSC
(3)
f
—
—
—
—
—
—
32.768k
—
4.9152M
Crystal reference frequency
XCLK
(4)
C
—
—
—
—
—
Crystal load capacitance
L
C
2 × C (27p)
Crystal fixed capacitance
Crystal tuning capacitance
Feedback bias resistor
F
F
1
L
C
2 × C (33p)
2
L
R
20M
Ω
Ω
B
(5)
R
100k
Series resistor
S
Notes:
1. Typical value reflect average measurements at midpoint of voltage range, 25 ×C only. See Figure 24-1 for plot.
2. No more than 10% duty cycle deviation from 50%.
3. Fundamental mode crystals only.
4. Consult crystal manufacturer’s data.
5. Not Required for high frequency crystals.
65
–40
°
C
60
55
50
45
40
35
+25
+85
°
°
C
C
2
3
4
5
6
Supply Voltage, VDD (V)
Figure 24-1. Typical Internal Oscillator Frequency
Data Sheet
442
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Electrical Specifications
Electrical Specifications
5V ADC Electrical Characteristics
24.12 5V ADC Electrical Characteristics
Table 24-10. 5V ADC Electrical Characteristics
Characteristic
Symbol
Min
Max
Unit
Notes
V
V
is an dedicated pin and
DDA
V
Supply voltage
4.5
5.5
V
should be tied to V on the
DDA
DD
PCB with proper decoupling.
V
V
≤ V
DDA
Input range
Resolution
0
V
ADIN
DDA
ADIN
B
10
10
bits
AD
Includes quantization.
±0.5 LSB = ±1 ADC count.
A
Absolute accuracy
—
± 1.5
LSB
AD
f
t
= 1/f
ADC internal clock
Conversion range
32 k
2 M
Hz
V
ADIC
ADIC ADIC
R
V
V
REFH
AD
REFL
ADC voltage
reference high
V
V
+ 0.1
DDA
—
V
V
REFH
ADC voltage
reference low
V
V
– 0.1
V
is tied to V internally.
—
17
—
REFL
SSA
SSA
SS
t
ADIC
t
Conversion time
Sample time
16
5
ADC
cycles
t
ADIC
t
ADS
cycles
M
Monotonically
Guaranteed
AD
Z
V
= V
Zero input reading
Full-scale reading
Input capacitance
Input impedance
000
3FC
—
001
3FF
20
HEX
HEX
pF
ADI
ADIN
REFL
F
V
= V
ADI
ADIN
REFH
C
Not tested.
ADI
R
20M
—
—
Ω
ADI
V
/V
I
1.6
mA
Not tested.
REFH REFL
VREF
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
443
Electrical Specifications
Electrical Specifications
24.13 3.3V ADC Electrical Characteristics
Table 24-11. 3.3V ADC Electrical Characteristics
Characteristic
Symbol
Min
Max
Unit
Notes
V
V
is an dedicated pin and
DDA
V
Supply voltage
3.0
3.6
V
should be tied to V on the
DDA
DD
PCB with proper decoupling.
V
V
≤ V
DDA
Input range
Resolution
0
V
ADIN
DDA
ADIN
B
10
10
bits
AD
Includes quantization.
±0.5 LSB = ±1 ADC count.
A
Absolute accuracy
—
± 1.5
LSB
AD
f
t
= 1/f
ADC internal clock
Conversion range
32 k
2 M
Hz
V
ADIC
ADIC ADIC
R
V
V
REFH
AD
REFL
ADC voltage
reference high
V
V
+ 0.1
DDA
—
V
V
REFH
ADC voltage
reference low
V
V
– 0.1
V
is tied to V internally.
—
17
—
REFL
SSA
SSA
SS
t
ADIC
t
Conversion time
Sample time
16
5
ADC
cycles
t
ADIC
t
ADS
cycles
M
Monotonically
Guaranteed
AD
Z
V
= V
Zero input reading
Full-scale reading
Input capacitance
Input impedance
000
3FC
—
001
3FF
20
HEX
HEX
pF
ADI
ADIN
REFL
F
V
= V
ADI
ADIN
REFH
C
Not tested.
ADI
R
20M
—
—
Ω
Measured at 5V
Not tested.
ADI
V
/V
I
1.6
mA
REFH REFL
VREF
Data Sheet
444
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Electrical Specifications
Electrical Specifications
Timer Interface Module Characteristics
24.14 Timer Interface Module Characteristics
Table 24-12. Timer Interface Module Characteristics
Characteristic
Input capture pulse width
Symbol
, t
Min
Max
Unit
t
t
1
—
TIH TIL
CYC
24.15 CGM Electrical Specifications
Table 24-13. CGM Electrical Specifications
Characteristic
Reference frequency
Symbol
Min
30
—
Typ
Max
100
—
Unit
kHz
kHz
Hz
f
32.768
38.4
—
RDV
f
Range nominal multiplies
VCO center-of-range frequency
VCO range linear range multiplier
VCO power-of-two-range multiplier
VCO multiply factor
NOM
f
38.4k
1
40.0M
255
4
VRS
L
—
E
1
—
2
N
1
—
4095
8
P
VCO prescale multiplier
Reference divider factor
VCO operating frequency
Manual acquisition time
1
—
2
R
1
1
15
f
38.4k
—
—
40.0M
50
Hz
ms
ms
VCLK
t
—
LOCK
t
Automatic lock time
—
—
50
LOCK
f
×
RCLK
(1)
f
0.025% ×
0
—
Hz
PLL jitter
J
P
2 N/4
Notes:
1. Deviation of average bus frequency over 2ms. N = VCO multiplier.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
445
Electrical Specifications
Electrical Specifications
24.16 5V SPI Characteristics
Table 24-14. 5V SPI Characteristics
Diagram
Number
(2)
Symbol
Min
Max
Unit
Characteristic
Operating frequency
(1)
Master
Slave
f
f
f
/128
dc
f /2
OP
MHz
MHz
OP(M)
OP
f
OP(S)
OP
Cycle time
Master
Slave
1
t
t
2
1
128
—
t
t
CYC(M)
CYC
CYC
CYC(S)
2
3
Enable lead time
Enable lag time
t
1
1
—
—
t
t
Lead(S)
CYC
CYC
t
Lag(S)
Clock (SPSCK) high time
4
5
6
7
Master
Slave
t
t
t
–25
64 t
ns
ns
SCKH(M)
CYC
CYC
1/2 t
–25
—
SCKH(S)
CYC
Clock (SPSCK) low time
Master
Slave
t
t
t
–25
64 t
ns
ns
SCKL(M)
CYC
CYC
1/2 t
–25
—
SCKL(S)
CYC
Data setup time (inputs)
Master
Slave
t
30
30
—
—
ns
ns
SU(M)
t
SU(S)
Data hold time (inputs)
Master
Slave
t
30
30
—
—
ns
ns
H(M)
t
H(S)
(3)
Access time, slave
8
9
CPHA = 0
CPHA = 1
t
t
0
0
40
40
ns
ns
A(CP0)
A(CP1)
(4)
Disable time, slave
t
—
40
ns
DIS(S)
Data valid time, after enable edge
Master
Slave
10
t
t
—
—
50
50
ns
ns
V(M)
(5)
V(S)
Data hold time, outputs, after enable edge
11
Master
Slave
t
t
0
0
—
—
ns
ns
HO(M)
HO(S)
Notes:
1. Numbers refer to dimensions in Figure 24-2 and Figure 24-3.
2. All timing is shown with respect to 20% V and 70% V , unless noted; 100 pF load on all SPI pins.
DD
DD
3. Time to data active from high-impedance state
4. Hold time to high-impedance state
5. With 100 pF on all SPI pins
Data Sheet
446
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Electrical Specifications
Electrical Specifications
3.3V SPI Characteristics
24.17 3.3V SPI Characteristics
Table 24-15. 3.3V SPI Characteristics
Diagram
Number
(2)
Symbol
Min
Max
Unit
Characteristic
(1)
Operating frequency
Master
Slave
f
f
f
/128
dc
f /2
OP
MHz
MHz
OP(M)
OP
f
OP(S)
OP
Cycle time
Master
Slave
1
t
t
2
1
128
—
t
t
CYC(M)
CYC
CYC
CYC(S)
2
3
Enable lead time
Enable lag time
t
1
1
—
—
t
t
Lead(s)
CYC
CYC
t
Lag(s)
Clock (SPSCK) high time
4
5
6
7
Master
Slave
t
t
t
–35
64 t
ns
ns
SCKH(M)
CYC
CYC
1/2 t
–35
—
SCKH(S)
CYC
Clock (SPSCK) low time
Master
Slave
t
t
t
–35
64 t
ns
ns
SCKL(M)
CYC
CYC
1/2 t
–35
—
SCKL(S)
CYC
Data setup time (inputs)
Master
Slave
t
40
40
—
—
ns
ns
SU(M)
t
SU(S)
Data hold time (inputs)
Master
Slave
t
40
40
—
—
ns
ns
H(M)
t
H(S)
(3)
Access time, slave
8
9
CPHA = 0
CPHA = 1
t
t
0
0
50
50
ns
ns
A(CP0)
A(CP1)
(4)
Disable time, slave
t
—
50
ns
DIS(S)
Data valid time, after enable edge
Master
Slave
10
t
t
—
—
60
60
ns
ns
V(M)
(5)
V(S)
Data hold time, outputs, after enable edge
11
Master
Slave
t
t
0
0
—
—
ns
ns
HO(M)
HO(S)
Notes:
1. Numbers refer to dimensions in Figure 24-2 and Figure 24-3.
2. All timing is shown with respect to 20% V
and 70% V , unless noted; 100 pF load on all SPI pins.
DD
DD
3. Time to data active from high-impedance state
4. Hold time to high-impedance state
5. With 100 pF on all SPI pins
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
447
Electrical Specifications
Electrical Specifications
SS
SS PIN OF MASTER HELD HIGH
INPUT
1
5
4
SPSCK OUTPUT
CPOL = 0
NOTE
NOTE
4
5
SPSCK OUTPUT
CPOL = 1
6
7
MISO
MSB IN
BITS 6–1
BITS 6–1
LSB IN
INPUT
11
MASTER MSB OUT
10
11
MOSI
MASTER LSB OUT
OUTPUT
Note: This first clock edge is generated internally, but is not seen at the SPSCK pin.
a) SPI Master Timing (CPHA = 0)
SS
SS PIN OF MASTER HELD HIGH
1
INPUT
SPSCK OUTPUT
CPOL = 0
5
NOTE
NOTE
4
SPSCK OUTPUT
CPOL = 1
5
4
6
7
MISO
MSB IN
11
BITS 6–1
BITS 6–1
LSB IN
INPUT
10
10
MOSI
MASTER MSB OUT
MASTER LSB OUT
OUTPUT
Note: This last clock edge is generated internally, but is not seen at the SPSCK pin.
b) SPI Master Timing (CPHA = 1)
Figure 24-2. SPI Master Timing
Data Sheet
448
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Electrical Specifications
Electrical Specifications
3.3V SPI Characteristics
SS
INPUT
3
1
SPSCK INPUT
CPOL = 0
5
4
4
5
2
SPSCK INPUT
CPOL = 1
9
8
MISO
SLAVE MSB OUT
BITS 6–1
BITS 6–1
SLAVE LSB OUT
11
NOTE
INPUT
11
6
7
10
MOSI
MSB IN
LSB IN
OUTPUT
Note: Not defined but normally MSB of character just received
a) SPI Slave Timing (CPHA = 0)
SS
INPUT
1
SPSCK INPUT
CPOL = 0
5
4
5
2
3
SPSCK INPUT
CPOL = 1
4
10
9
8
MISO
NOTE
SLAVE MSB OUT
BITS 6–1
BITS 6–1
SLAVE LSB OUT
OUTPUT
11
6
7
10
MOSI
MSB IN
LSB IN
INPUT
Note: Not defined but normally LSB of character previously transmitted
b) SPI Slave Timing (CPHA = 1)
Figure 24-3. SPI Slave Timing
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
449
Electrical Specifications
Electrical Specifications
24.18 FLASH Memory Characteristics
Table 24-16. FLASH Memory Electrical Characteristics
Characteristic
RAM data retention voltage
Symbol
Min.
Max.
Unit
V
V
1.3
—
RDR
Number of rows per page
Number of bytes per page
2
Rows
Bytes
128
(1)
Read bus clock frequency
Page erase time
32k
1
8M
—
Hz
ms
f
read
(2)
t
erase
(3)
Mass erase time
4
10
5
—
—
—
—
—
40
30
30
—
ms
µs
µs
µs
µs
µs
ns
ns
µs
t
merase
t
PGM/ERASE to HVEN setup time
High-voltage hold time
High-voltage hold time (mass erase)
Program hold time
nvs
t
nvh
t
100
5
nvhl
t
pgs
t
Program time
30
—
—
1
prog
t
Address/data setup time
Address/data hold time
Recovery time
ads
t
adh
(4)
t
rcv
(5)
Cumulative HV period
—
10k
10k
10
25
—
—
—
ms
t
hv
(6)
—
Cycles
Cycles
Years
Row erase endurance
(7)
—
—
Row program endurance
(8)
Data retention time
Notes:
1. fread is defined as the frequency range for which the FLASH memory can be read.
2. If the page erase time is longer than terase (Min.), there is no erase-disturb, but it reduces the endurance of the FLASH
memory.
3. If the mass erase time is longer than tmerase (Min.), there is no erase-disturb, but is reduces the endurance of the FLASH
memory.
4. It is defined as the time it needs before the FLASH can be read after turning off the high voltage charge pump, by clearing
HVEN to logic 0.
5. thv is the cumulative high voltage programming time to the same row before next erase, and the same address can not be
programmed twice before next erase.
6. The minimum row endurance value specifies each row of the FLASH memory is guaranteed to work for at least this many
erase/program cycles.
7. The minimum row endurance value specifies each row of the FLASH memory is guaranteed to work for at least this many
erase/program cycle.
8. The FLASH is guaranteed to retain data over the entire operating temperature range for at least the minimum time
specified.
Data Sheet
450
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Electrical Specifications
Data Sheet — MC68HC908LJ24
Section 25. Mechanical Specifications
25.1 Contents
25.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .451
25.3 64-Pin Low-Profile Quad Flat Pack (LQFP) . . . . . . . . . . . . . .452
25.4 64-Pin Quad Flat Pack (QFP). . . . . . . . . . . . . . . . . . . . . . . . .453
25.5 80-Pin Low-Profile Quad Flat Pack (LQFP) . . . . . . . . . . . . . .454
25.6 80-Pin Quad Flat Pack (QFP). . . . . . . . . . . . . . . . . . . . . . . . .455
25.2 Introduction
This section gives the dimensions for:
• 64-pin low-profile quad flat pack (case no. 840F)
• 64-pin quad flat pack (case no. 840B)
• 80-pin low-profile quad flat pack (case no. 917)
• 80-pin quad flat pack (case no. 841B)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
451
Mechanical Specifications
Mechanical Specifications
25.3 64-Pin Low-Profile Quad Flat Pack (LQFP)
4X
4X 16 TIPS
0.2
H
A–B
D
0.2
C
A–B D
A2
S
0.05
64
49
(S)
1
48
2X R R1
θ
1
0.25
A
B
GAGE PLANE
θ
E
E1
(L2)
A1
L
(L)
3X
E1/2
VIEW Y
E/2
VIEW AA
16
33
NOTES:
17
32
1. ALL DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE H IS COINCIDENT WITH THE
BOTTOM OF THE LEAD WHERE THE LEAD EXITS
THE PLASTIC BODY AT THE BOTTOM OF THE
PARTING LINE.
D
D1/2
D/2
4. DATUMS A, B AND D TO BE DETERMINED AT
DATUM PLANE H.
D1
5. DIMENSIONS D AND E TO BE DETERMINED AT
SEATING PLANE C.
D
6. DIMENSIONS D1 AND E1 DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS 0.25
PER SIDE. DIMENSIONS D1 AND E1 DO INCLUDE
MOLD MISMATCH AND ARE DETERMINED AT
DATUM PLANE H.
7. DIMENSION b DOES NOT INCLUDE DAMBAR
PROTRUSION. THE DAMBAR PROTRUSION
SHALL NOT CAUSE THE b DIMENSION TO
EXCEED 0.35. MINIMUM SPACE BETWEEN
PROTRUSION AND ADJACENT LEAD OR
PROTRUSION 0.07.
4X (θ2)
4X (θ3)
H
C
A
0.08
C
MILLIMETERS
SEATING
PLANE
DIM
A
A1
A2
b
b1
c
c1
D
MIN
—
MAX
1.60
0.15
1.45
0.27
0.23
0.20
0.16
VIEW AA
0.05
1.35
0.17
0.17
0.09
0.09
BASE METAL
12.00 BSC
b1
D1
e
E
E1
L
10.00 BSC
0.50 BSC
12.00 BSC
10.00 BSC
X
X=A, B OR D
c
c1
0.45
0.75
L1
L2
R1
S
1.00 REF
0.50 REF
C
L
0.10
0.20
0.20 REF
AB
AB
e/2
PLATING
θ
0
0
°
°
7°
—
b
θ
θ
θ
1
2
3
60X e
12
12
°
°
REF
REF
M
0.08
C A–B D
VIEW Y
SECTION AB–AB
ROTATED 90° CLOCKWISE
Figure 25-1. 64-Pin Low-Profile Quad Flat Pack (Case No. 840F)
Data Sheet
452
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Mechanical Specifications
Mechanical Specifications
64-Pin Quad Flat Pack (QFP)
25.4 64-Pin Quad Flat Pack (QFP)
L
48
33
49
32
B
P
B
–A–
–B–
L
V
B
–A–, –B–, –D–
DETAIL A
DETAIL A
64
17
F
1
16
–D–
A
M
S
S
S
0.20 (0.008)
H
A–B
D
D
J
N
0.05 (0.002) A–B
S
BASE
METAL
M
S
0.20 (0.008)
C
A–B
E
C
D
DETAIL C
M
M
S
S
D
0.20 (0.008)
C
A–B
SECTION B–B
VIEW ROTATED 90°
DATUM
PLANE
–H–
–C–
SEATING
PLANE
0.10 (0.004)
M
H
G
U
NOTES:
MILLIMETERS
INCHES
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
DIM
A
B
C
D
E
MIN
13.90
13.90
2.15
0.30
2.00
0.30
0.80 BSC
—
0.13
0.65
12.00 REF
MAX
14.10
14.10
2.45
0.45
2.40
MIN
MAX
0.555
0.555
0.096
0.018
0.094
0.016
0.547
0.547
0.085
0.012
0.079
0.012
0.031 BSC
—
0.005
0.026
0.472 REF
5 °
0.005
0.016 BSC
0°
0.005
0.667
0.005
0°
0.667
0.014
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE –H– IS LOCATED AT BOTTOM OF
LEAD AND IS COINCIDENT WITH THE LEAD
WHERE THE LEAD EXITS THE PLASTIC BODY AT
THE BOTTOM OF THE PARTING LINE.
4. DATUMS –A–, –B– AND –D– TO BE DETERMINED
AT DATUM PLANE –H–.
5. DIMENSIONS S AND V TO BE DETERMINED AT
SEATING PLANE –C–.
6. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS 0.25
(0.010) PER SIDE. DIMENSIONS A AND B DO
INCLUDE MOLD MISMATCH AND ARE
DETERMINED AT DATUM PLANE –H–.
7. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
T
R
F
0.40
G
H
J
K
L
M
N
P
Q
R
S
T
U
V
W
X
DATUM
PLANE
–H–
0.25
0.23
0.95
0.010
0.009
0.037
Q
5°
0.13
0.40 BSC
10°
0.17
10°
0.007
K
0°
0.13
16.95
0.13
0°
16.95
0.35
1.6 REF
7°
0.30
17.45
—
—
17.45
0.45
7°
0.012
0.687
—
—
0.687
0.018
W
PROTRUSION SHALL BE 0.08 (0.003) TOTAL IN
EXCESS OF THE D DIMENSION AT MAXIMUM
MATERIAL CONDITION. DAMBAR CANNOT BE
LOCATED ON THE LOWER RADIUS OR THE FOOT.
X
DETAIL C
0.063 REF
Figure 25-2. 64-Pin Quad Flat Pack (Case No. 840B)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
453
Mechanical Specifications
Mechanical Specifications
25.5 80-Pin Low-Profile Quad Flat Pack (LQFP)
B
B
D
D/2
D1
D1/2
VIEW Y
e/2
PIN 1
IDEx
80
61
X
X=A, B, or D
1
60
VIEW Y
3 PLACES
E/2
b1
PLATING
E
c
c1
E1
A
B
BASE
METAL
E1/2
b
M
0.08
C
A–B
D
20
41
SECTION B–B
80 PLACES
21
40
ROTATED 90° CLOCKWISE
NOTES:
D
0.200
H
A–B
D
4X
1. ALL DIMENSIONS AND TOLERANCES TO
CONFORM TO ASME Y14.5M, 1994.
4X
0.200
C
A–B
D
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE H IS COINCIDENT WITH THE
BOTTOM OF THE LEAD WHERE THE LEAD
EXITS THE PLASTIC BODY AT THE BOTTOM OF
THE PARTING LINE.
4. DATUMS A, B AND D TO BE DETERMINED AT
DATUM PLANE H.
5. DIMENSIONS D AND E TO BE DETERMINED AT
SEATING PLANE C.
6. DIMENSIONS D1 AND E1 DO NOT INCLUDE
MOLD PROTRUSION. ALLOWABLE
PROTRUSION IS 0.25 PER SIDE. DIMENSIONS
D1 AND E1 DO INCLUDE MOLD MISMATCH AND
ARE DETERMINED AT DATUM PLANE H.
7. DIMENSION b DOES NOT INCLUDE DAMBAR
PROTRUSION. THE DAMBAR PROTRUSION
SHALL NOT CAUSE THE b DIMENSION TO
EXCEED 0.35.
θ2
8X
VIEW P
A2
A1
H
0.1
C
A
e
76X
SEATING
PLANE
C
MILLIMETERS
DIM
A
A1
A2
D
MIN
—
0.05
1.35
MAX
1.60
0.15
1.45
S
14.00 BSC
D1
E
E1
L
12.00 BSC
14.00 BSC
12.00 BSC
0.45
0.75
θ1
L1
L2
R1
R2
S
b
b1
c
1.00 REF
0.50 REF
0.20 REF
0.20 REF
0.17 REF
R (R1)
R (R2)
0.17
0.27
0.23
0.20
0.16
GAGE
PLANE
θ
0.17
0.12
0.12
c1
e
θ
0.50 BSC
(L2)
0
°
7°
0.25
L
θ
θ
1
2
0
10
°
°
—
14°
(L1)
VIEW P
Figure 25-3. 80-Pin Low-Profile Quad Flat Pack (Case No. 917)
Data Sheet
454
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Mechanical Specifications
Mechanical Specifications
80-Pin Quad Flat Pack (QFP)
25.6 80-Pin Quad Flat Pack (QFP)
L
60
61
41
40
B
P
B
–B–
–A–
L
B
V
–A–,–B–,–D–
DETAIL A
DEATIL A
21
80
F
1
20
–D–
A
S
M
S
S
S
0.20
H
A–B
D
0.05 A–B
J
N
M
S
0.20
C
A–B
D
D
M
E
DETAIL C
M
S
S
0.20
C
A–B
D
SECTION B–B
VIEW ROTATED 90°
C
DATUM
PLANE
–H–
–C–
0.10
H
SEATING
PLANE
M
G
NOTES:
MILLIMETERS
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE –H– IS LOCATED AT BOTTOM OF
LEAD AND IS COINCIDENT WITH THE LEAD WHERE
THE LEAD EXITS THE PLASTIC BODY AT THE
BOTTOM OF THE PARTING LINE.
4. DATUMS –A–, –B– AND –D– TO BE DETERMINED AT
DATUM PLANE –H–.
5. DIMENSIONS S AND V TO BE DETERMINED AT
SEATING PLANE –C–.
6. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS 0.25
PER SIDE. DIMENSIONS A AND B DO INCLUDE
MOLD MISMATCH AND ARE DETERMINED AT
DATUM PLANE –H–.
7. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR PROTRUSION
SHALL BE 0.08 TOTAL IN EXCESS OF THE D
DIMENSION AT MAXIMUM MATERIAL CONDITION.
DAMBAR CANNOT BE LOCATED ON THE LOWER
RADIUS OR THE FOOT.
DIM
A
B
C
D
E
MIN
13.90
13.90
2.15
0.22
2.00
0.22
MAX
14.10
14.10
2.45
0.38
2.40
U
T
F
0.33
G
H
J
K
L
M
N
P
Q
R
S
T
U
V
W
X
0.65 BSC
DATUM –H–
—
0.13
0.65
0.25
0.23
0.95
PLANE
R
12.35 REF
5°
10°
0.13
0.17
0.325 BSC
K
0°
0.13
16.95
0.13
0°
7°
0.30
17.45
—
Q
W
X
DETAIL C
—
16.95
0.35
17.45
0.45
1.6 REF
Figure 25-4. 80-Pin Quad Flat Pack (Case No. 841B)
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
455
Mechanical Specifications
Mechanical Specifications
Data Sheet
456
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Mechanical Specifications
Data Sheet — MC68HC908LJ24
Section 26. Ordering Information
26.1 Contents
26.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457
26.3 MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457
26.2 Introduction
This section contains ordering numbers for the MC68HC908LJ24.
26.3 MC Order Numbers
Table 26-1. MC Order Numbers
Operating
MC Order Number
MC68HC908LJ24CPB
Package
Temperature Range
64-pin LQFP
64-pin QFP
80-pin LQFP
80-pin QFP
–40 to +85 °C
–40 to +85 °C
–40 to +85 °C
–40 to +85 °C
MC68HC908LJ24CFU
MC68HC908LJ24CPK
MC68HC908LJ24CFQ
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
457
Ordering Information
Ordering Information
Data Sheet
458
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Ordering Information
Data Sheet — MC68HC908LJ24
Appendix A. MC68HC908LK24
A.1 Contents
A.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .459
A.3 Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .460
A.4 Low-Voltage Inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .460
A.5 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . .461
A.5.1
A.5.2
A.5.3
A.5.4
5V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . .461
3.3V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . .461
5V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . .462
3.3V Oscillator Characteristics. . . . . . . . . . . . . . . . . . . . . .462
A.6 MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .462
A.2 Introduction
The MC68HC908LK24 is a MC68HC908LJ24 with a low-power
oscillator that supports a 32.768kHz crystal only.
The entire data book apply to the MC68HC908LK24 device, with
exceptions outlined in this appendix.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
459
A.3 Oscillator
The low-power oscillator supports a reference frequency of 32.768kHz
only; either from a crystal oscillator circuit (Figure A-1) or a direct clock
input to the OSC1 pin.
MCU
OSC1
OSC2
RB
RS
32.768kHz
X1
C1
C2
Figure A-1. MC68HC908LK24 Crystal Oscillator Connection
A.4 Low-Voltage Inhibit
The LVIPWRD bit in CONFIG1 register is logic 1 after any reset.
Address: $001F
Bit 7
6
5
4
3
0
2
1
Bit 0
Read:
COPRS LVISTOP LVIRSTD LVIPWRD
SSREC
STOP
COPD
Write:
Reset:
Reset:
MC68HC908LK24
MC68HC908LJ24
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
††
0
†† Reset by POR only.
= Unimplemented
Figure A-2. MC68HC908LK24 Configuration Register 1 (CONFIG1)
LVIPWRD — LVI Power Disable Bit
LVIPWRD disables the LVI module.
1 = LVI module power disabled
0 = LVI module power enabled
Data Sheet
460
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
A.5 Electrical Specifications
Electrical specifications for the MC68HC908LJ24 apply to the
MC68HC908LK24, except for the parameters indicated below.
A.5.1 5V DC Electrical Characteristics
Table A-1. 5V DC Electrical Characteristics
(1)
(2)
Characteristic
supply current
Symbol
Min
Typ
Max
Unit
V
DD
(3)
I
DD
Stop, f = 8 kHz
OP
with OSC, RTC on
—
5.5
µA
7.5
Low-voltage inhibit, trip rising voltage
LVI reset disabled (LVIRSTD = 1)
LVI reset enabled (LVIRSTD = 0)
V
3.7
3.62
—
—
4.7
4.62
V
V
TRIPR
Notes:
1. VDD = 4.5 to 5.5 Vdc, VSS = 0 Vdc, TA = TL to TH, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25 °C only.
3. The 8kHz clock is from a 32kHz external square wave clock input at OSC1, for the driving the RTC. Due to loading effects,
the IDD values will be larger when a 32kHz crystal circuit is connected.
A.5.2 3.3V DC Electrical Characteristics
Table A-2. 3.3V DC Electrical Characteristics
(1)
(2)
Characteristic
Symbol
Min
Typ
Max
Unit
Low-voltage inhibit, trip rising voltage
LVI disabled (LVIRSTD = 1)
LVI enabled (LVIRSTD = 0)
V
2.2
2.12
—
—
2.9
2.82
V
V
TRIPR
Notes:
1. VDD = 3.0 to 3.6 Vdc, VSS = 0 Vdc, TA = TL to TH, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25 °C only.
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
Data Sheet
461
A.5.3 5V Oscillator Characteristics
Table A-3. 5V Oscillator Specifications
Characteristic
Symbol
Min
dc
Typ
Max
—
Unit
Hz
(1)
f
32.768k
32.768k
External reference clock to OSC1
OSC
(2)
f
—
—
Hz
Crystal reference frequency
XCLK
Notes:
1. No more than 10% duty cycle deviation from 50%.
2. Fundamental mode crystals only.
A.5.4 3.3V Oscillator Characteristics
Table A-4. 3.3V Oscillator Specifications
Characteristic
Symbol
Min
dc
Typ
Max
—
Unit
Hz
(1)
f
32.768k
32.768k
External reference clock to OSC1
OSC
(2)
f
—
—
Hz
Crystal reference frequency
XCLK
Notes:
1. No more than 10% duty cycle deviation from 50%.
2. Fundamental mode crystals only.
A.6 MC Order Numbers
Table A-5 shows the ordering numbers for the MC68HC908LK24.
Table A-5. MC68HC908LK24 Order Numbers
Operating
Temperature Range
MC Order Number
Package
MC68HC908LK24CPB
MC68HC908LK24CFU
MC68HC908LK24CPK
MC68HC908LK24CFQ
64-pin LQFP
64-pin QFP
80-pin LQFP
80-pin QFP
–40 to +85 °C
–40 to +85 °C
–40 to +85 °C
–40 to +85 °C
Data Sheet
462
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
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Rev. 2.1
MC68HC908LJ24/D
August 16, 2005
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