MC908GR60ACFAE [NXP]
8 BIT MCU WITH 60K FLASH;
| 型号： | MC908GR60ACFAE |
| 厂家： | 
NXP |
| 描述： | 8 BIT MCU WITH 60K FLASH 时钟 外围集成电路 |
| 文件： | 总314页 (文件大小：2891K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MC68HC908GR60A
MC68HC908GR48A
MC68HC908GR32A
Data Sheet
M68HC08
Microcontrollers
MC68HC908GR60A
Rev. 5
04/2007
freescale.com
MC68HC908GR60A
MC68HC908GR48A
MC68HC908GR32A
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/
Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
This product incorporates SuperFlash® technology licensed from SST.
© Freescale Semiconductor, Inc., 2004, 2006, 2007. All rights reserved.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Revision History
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.
Revision History
Revision
Level
Page
Number(s)
Date
Description
April, 2004
July, 2004
N/A
Initial release
N/A
9.7.3 Keyboard Interrupt Polarity Register — Corrected description of
KBIP7–KBIP0.
1
2
3
119
Table 13-6. ESCI LIN Control Bits — Corrected Functionality definitions
13.9.1 ESCI Arbiter Control Register — Corrected definition for ACLK bit.
13.9.3 Bit Time Measurement — Corrected description of ACLK bit.
174
179
180
June, 2005
10.5 Clock Generator Module (CGM) — Updated description to remove
erroneous information.
March, 2006
122
Added 1.5.15 Unused Pin Termination
28
12.1 Introduction — Replaced note
131
174
Table 13-6. ESCI LIN Control Bits — Corrected functionality column.
The following sections were updated to show that a break interrupt inhibits
input captures:
17.6 TIM1 During Break Interrupts
18.6 TIM2 During Break Interrupts
19.2.1.2 TIM During Break Interrupts
233
251
264
July, 2006
4
Figure 19-10. Normal Monitor Mode Circuit and Figure 19-11. Forced Monitor
Mode — Changed capacitor values
269
279
284
20.5 5.0-Vdc Electrical Characteristics — Updated minimum value for
low-voltage inhibit, trip rising voltage (VTRIPR).
20.9.1 CGM Component Specifications — Updated values for feedback bias
resistor
Figure 2-2. Control, Status, and Data Registers — Replaced TBMCLKSEL
with TMBCLKSEL to be compatible with development tool nomenclature
33
90
Chapter 5 Configuration Register (CONFIG) — Replaced COPCLK with
CGMXCLK
89
91
10.6.2 Stop Mode — Replaced COPCLK with CGMXCLK
122
154
156
Figure 13-3. ESCI Module Block Diagram — Changed BUS_CLK to Bus
Clock and deleted reference to 4x BUSCLK
13.4.2 Transmitter — Changed ESCIBDSRC to SCIBDSRC
13.9.1 ESCI Arbiter Control Register and 13.9.3 Bit Time Measurement —
Replaced one quarter with one half in the definition for ACLK = 1
179
180
April, 2007
5
Chapter 16 Timebase Module (TBM) — Replaced TBMCLKSEL with
TMBCLKSEL to be compatible with development tool nomenclature
222
223
20.5 5.0-Vdc Electrical Characteristics and 20.6 3.3-Vdc Electrical
Characteristics — Updated tables
279
281
20.9 Clock Generation Module (CGM) Characteristics — Updated section to
include the following:
20.9.1 CGM Operating Conditions
20.9.2 CGM Component Information
20.9.3 CGM Acquisition/Lock Time Information
284
284
285
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List of Chapters
Chapter 1 General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Chapter 2 Memory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Chapter 3 Analog-to-Digital Converter (ADC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
Chapter 4 Clock Generator Module (CGM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
Chapter 5 Configuration Register (CONFIG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
Chapter 6 Computer Operating Properly (COP) Module . . . . . . . . . . . . . . . . . . . . . . . . . . .93
Chapter 7 Central Processor Unit (CPU). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
Chapter 8 External Interrupt (IRQ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109
Chapter 9 Keyboard Interrupt Module (KBI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113
Chapter 10 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121
Chapter 11 Low-Voltage Inhibit (LVI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127
Chapter 12 Input/Output (I/O) Ports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131
Chapter 13 Enhanced Serial Communications Interface (ESCI) Module . . . . . . . . . . . . .151
Chapter 14 System Integration Module (SIM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183
Chapter 15 Serial Peripheral Interface (SPI) Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . .201
Chapter 16 Timebase Module (TBM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
Chapter 17 Timer Interface Module (TIM1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225
Chapter 18 Timer Interface Module (TIM2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .241
Chapter 19 Development Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
Chapter 20 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .277
Chapter 21 Ordering Information and Mechanical Specifications . . . . . . . . . . . . . . . . . .295
Appendix A MC68HC908GR48A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .305
Appendix B MC68HC908GR32A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .309
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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List of Chapters
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
6
Table of Contents
Chapter 1
General Description
1.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.2
1.2.1
1.2.2
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Standard Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Features of the CPU08 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.3
1.4
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.5
Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Power Supply Pins (VDD and VSS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Oscillator Pins (OSC1 and OSC2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
External Reset Pin (RST). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
External Interrupt Pin (IRQ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
CGM Power Supply Pins (VDDA and VSSA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
ADC Power Supply/Reference Pins (VDDAD/VREFH and VSSAD/VREFL). . . . . . . . . . . . . . . . 26
Port A Input/Output (I/O) Pins (PTA7/KBD7/AD15–PTA0/KBD0/AD8) . . . . . . . . . . . . . . . . 27
Port B I/O Pins (PTB7/AD7–PTB0/AD0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Port C I/O Pins (PTC6–PTC0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Port D I/O Pins (PTD7/T2CH1–PTD0/SS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Port E I/O Pins (PTE5–PTE2, PTE1/RxD, and PTE0/TxD) . . . . . . . . . . . . . . . . . . . . . . . . . 27
Port F I/O Pins (PTF7/T2CH5–PTF0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Port G I/O Pins (PTG7/AD23–PTBG0/AD16) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Unused Pin Termination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.5.1
1.5.2
1.5.3
1.5.4
1.5.5
1.5.6
1.5.7
1.5.8
1.5.9
1.5.10
1.5.11
1.5.12
1.5.13
1.5.14
1.5.15
Chapter 2
Memory
2.1
2.2
2.3
2.4
2.5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Unimplemented Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Reserved Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Input/Output (I/O) Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Random-Access Memory (RAM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.6
FLASH-1 Memory (FLASH-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
FLASH-1 Control and Block Protect Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
FLASH-1 Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
FLASH-1 Block Protect Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
FLASH-1 Block Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
FLASH-1 Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
FLASH-1 Page Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.6.1
2.6.2
2.6.2.1
2.6.2.2
2.6.3
2.6.4
2.6.5
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Table of Contents
2.6.6
FLASH-1 Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.6.7
2.6.7.1
2.6.7.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.7
FLASH-2 Memory (FLASH-2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
FLASH-2 Control and Block Protect Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
FLASH-2 Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
FLASH-2 Block Protect Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
FLASH-2 Block Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
FLASH-2 Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
FLASH-2 Page Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
FLASH-2 Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
2.7.1
2.7.2
2.7.2.1
2.7.2.2
2.7.3
2.7.4
2.7.5
2.7.6
2.7.7
2.7.7.1
2.7.7.2
Chapter 3
Analog-to-Digital Converter (ADC)
3.1
3.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
ADC Port I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Voltage Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Conversion Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Conversion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Accuracy and Precision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Result Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.3.6
3.4
3.5
Monotonicity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
3.6
3.6.1
3.6.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.7
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
ADC Analog Power Pin (VDDAD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
ADC Analog Ground Pin (VSSAD). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
ADC Voltage Reference High Pin (VREFH). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
ADC Voltage Reference Low Pin (VREFL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
ADC Voltage In (VADIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3.7.1
3.7.2
3.7.3
3.7.4
3.7.5
3.8
3.8.1
3.8.2
3.8.2.1
3.8.2.2
3.8.2.3
3.8.2.4
3.8.3
I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
ADC Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
ADC Data Register High and Data Register Low. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Left Justified Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Right Justified Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Left Justified Signed Data Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Eight Bit Truncation Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
ADC Clock Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Chapter 4
Clock Generator Module (CGM)
4.1
4.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Crystal Oscillator Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Phase-Locked Loop Circuit (PLL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
PLL Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Acquisition and Tracking Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Manual and Automatic PLL Bandwidth Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Programming the PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Special Programming Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Base Clock Selector Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.3.6
4.3.7
4.3.8
4.3.9
4.4
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Crystal Amplifier Output Pin (OSC2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
PLL Analog Power Pin (VDDA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
PLL Analog Ground Pin (VSSA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Oscillator Enable Signal (SIMOSCEN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Oscillator Enable in Stop Mode Bit (OSCENINSTOP). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Crystal Output Frequency Signal (CGMXCLK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
CGM Base Clock Output (CGMOUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
CGM CPU Interrupt (CGMINT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5
4.4.6
4.4.7
4.4.8
4.4.9
4.4.10
4.5
CGM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
PLL Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
PLL Bandwidth Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
PLL Multiplier Select Register High . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
PLL Multiplier Select Register Low . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
PLL VCO Range Select Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.5.1
4.5.2
4.5.3
4.5.4
4.5.5
4.6
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
4.7
Special Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
CGM During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
4.7.1
4.7.2
4.7.3
4.8
Acquisition/Lock Time Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Acquisition/Lock Time Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Parametric Influences on Reaction Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Choosing a Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.8.1
4.8.2
4.8.3
Chapter 5
Configuration Register (CONFIG)
5.1
5.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
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Chapter 6
Computer Operating Properly (COP) Module
6.1
6.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.3
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
CGMXCLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
STOP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
COPCTL Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Internal Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
COPD (COP Disable). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
COPRS (COP Rate Select) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.3.1
6.3.2
6.3.3
6.3.4
6.3.5
6.3.6
6.3.7
6.4
6.5
6.6
COP Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Monitor Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.7
6.7.1
6.7.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.8
COP Module During Break Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Chapter 7
Central Processor Unit (CPU)
7.1
7.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
7.3
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
7.3.1
7.3.2
7.3.3
7.3.4
7.3.5
7.4
Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.5
7.5.1
7.5.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.6
7.7
7.8
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Chapter 8
External Interrupt (IRQ)
8.1
8.2
8.3
8.4
8.5
8.6
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
IRQ Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
IRQ Module During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
IRQ Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
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Keyboard Interrupt Module (KBI)
9.1
9.2
9.3
9.4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Keyboard Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
9.5
9.5.1
9.5.2
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
9.6
Keyboard Module During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
9.7
I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Keyboard Status and Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Keyboard Interrupt Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Keyboard Interrupt Polarity Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
9.7.1
9.7.2
9.7.3
Chapter 10
Low-Power Modes
10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
10.1.1
10.1.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
10.2 Analog-to-Digital Converter (ADC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
10.2.1
10.2.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
10.3 Break Module (BRK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
10.3.1
10.3.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
10.4 Central Processor Unit (CPU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10.4.1
10.4.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10.5 Clock Generator Module (CGM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10.5.1
10.5.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10.6 Computer Operating Properly Module (COP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10.6.1
10.6.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10.7 External Interrupt Module (IRQ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.7.1
10.7.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.8 Keyboard Interrupt Module (KBI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.8.1
10.8.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.9 Low-Voltage Inhibit Module (LVI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.9.1
10.9.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
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10.10 Enhanced Serial Communications Interface Module (ESCI) . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.10.1
10.10.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.11 Serial Peripheral Interface Module (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
10.11.1
10.11.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
10.12 Timer Interface Module (TIM1 and TIM2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
10.12.1
10.12.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
10.13 Timebase Module (TBM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
10.13.1
10.13.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
10.14 Exiting Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
10.15 Exiting Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Chapter 11
Low-Voltage Inhibit (LVI)
11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
11.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
11.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
11.3.1
11.3.2
11.3.3
11.3.4
Polled LVI Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Forced Reset Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Voltage Hysteresis Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
LVI Trip Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
11.4 LVI Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
11.5 LVI Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
11.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
11.6.1
11.6.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Chapter 12
Input/Output (I/O) Ports
12.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
12.2 Unused Pin Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
12.3 Port A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
12.3.1
12.3.2
12.3.3
Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Data Direction Register A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Port A Input Pullup Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
12.4 Port B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
12.4.1
12.4.2
Port B Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Data Direction Register B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
12.5 Port C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
12.5.1
12.5.2
12.5.3
Port C Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Data Direction Register C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Port C Input Pullup Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
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12.6 Port D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
12.6.1
12.6.2
12.6.3
Port D Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Data Direction Register D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Port D Input Pullup Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
12.7 Port E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
12.7.1
12.7.2
Port E Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Data Direction Register E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
12.8 Port F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
12.8.1
12.8.2
Port F Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Data Direction Register F. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
12.9 Port G. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
12.9.1
12.9.2
Port G Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Data Direction Register G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Chapter 13
Enhanced Serial Communications Interface (ESCI) Module
13.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
13.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
13.3 Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
13.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
13.4.1
13.4.2
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Character Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Break Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Idle Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Inversion of Transmitted Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Transmitter Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Receiver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Character Reception. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Framing Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Baud Rate Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Receiver Wakeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Receiver Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Error Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
13.4.2.1
13.4.2.2
13.4.2.3
13.4.2.4
13.4.2.5
13.4.2.6
13.4.3
13.4.3.1
13.4.3.2
13.4.3.3
13.4.3.4
13.4.3.5
13.4.3.6
13.4.3.7
13.4.3.8
13.5 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
13.5.1
13.5.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
13.6 ESCI During Break Module Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
13.7 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
13.7.1
13.7.2
PTE0/TxD (Transmit Data). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
PTE1/RxD (Receive Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
13.8 I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
13.8.1
13.8.2
ESCI Control Register 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
ESCI Control Register 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
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13.8.3
13.8.4
13.8.5
13.8.6
13.8.7
13.8.8
ESCI Control Register 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
ESCI Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
ESCI Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
ESCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
ESCI Baud Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
ESCI Prescaler Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
13.9 ESCI Arbiter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
13.9.1
13.9.2
13.9.3
13.9.4
ESCI Arbiter Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
ESCI Arbiter Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Bit Time Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Arbitration Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Chapter 14
System Integration Module (SIM)
14.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
14.2 SIM Bus Clock Control and Generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
14.2.1
14.2.2
14.2.3
Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Clock Startup from POR or LVI Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Clocks in Stop Mode and Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
14.3 Reset and System Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
14.3.1
14.3.2
External Pin Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Active Resets from Internal Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Computer Operating Properly (COP) Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Monitor Mode Entry Module Reset (MODRST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
14.3.2.1
14.3.2.2
14.3.2.3
14.3.2.4
14.3.2.5
14.3.2.6
14.4 SIM Counter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
14.4.1
14.4.2
14.4.3
SIM Counter During Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
SIM Counter During Stop Mode Recovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
SIM Counter and Reset States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
14.5 Exception Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
14.5.1
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
SWI Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Interrupt Status Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Status Flag Protection in Break Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
14.5.1.1
14.5.1.2
14.5.1.3
14.5.2
14.5.3
14.5.4
14.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
14.6.1
14.6.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
14.7 SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
14.7.1
14.7.2
14.7.3
Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
SIM Reset Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Break Flag Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
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Chapter 15
Serial Peripheral Interface (SPI) Module
15.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
15.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
15.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
15.3.1
15.3.2
Master Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
Slave Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
15.4 Transmission Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
15.4.1
15.4.2
15.4.3
15.4.4
Clock Phase and Polarity Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Transmission Format When CPHA = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Transmission Format When CPHA = 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Transmission Initiation Latency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
15.5 Queuing Transmission Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
15.6 Error Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
15.6.1
15.6.2
Overflow Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Mode Fault Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
15.7 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
15.8 Resetting the SPI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
15.9 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
15.9.1
15.9.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
15.10 SPI During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
15.11 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
15.11.1
15.11.2
15.11.3
15.11.4
MISO (Master In/Slave Out). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
MOSI (Master Out/Slave In). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
SPSCK (Serial Clock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
SS (Slave Select). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
15.12 I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
15.12.1
15.12.2
15.12.3
SPI Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
SPI Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
SPI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Chapter 16
Timebase Module (TBM)
16.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
16.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
16.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
16.4 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
16.5 TBM Interrupt Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
16.6 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
16.6.1
16.6.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
16.7 Timebase Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
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Table of Contents
Chapter 17
Timer Interface Module (TIM1)
17.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
17.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
17.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
17.3.1
17.3.2
17.3.3
17.3.3.1
17.3.3.2
17.3.4
17.3.4.1
17.3.4.2
17.3.4.3
TIM1 Counter Prescaler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Pulse Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Unbuffered PWM Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
PWM Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
17.4 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
17.5 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
17.6 TIM1 During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
17.7 Input/Output Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
17.8 Input/Output Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
17.8.1
17.8.2
17.8.3
17.8.4
17.8.5
TIM1 Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
TIM1 Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
TIM1 Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
TIM1 Channel Status and Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
TIM1 Channel Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Chapter 18
Timer Interface Module (TIM2)
18.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
18.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
18.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
18.3.1
18.3.2
18.3.3
18.3.3.1
18.3.3.2
18.3.4
18.3.4.1
18.3.4.2
18.3.4.3
TIM2 Counter Prescaler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
Pulse Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Unbuffered PWM Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
PWM Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
18.4 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
18.5 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
18.5.1
18.5.2
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
18.6 TIM2 During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
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18.7 I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
18.7.1
18.7.2
TIM2 Clock Pin (T2CH0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
TIM2 Channel I/O Pins (T2CH5:T2CH2 and T2CH1:T2CH0) . . . . . . . . . . . . . . . . . . . . . . 252
18.8 I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
18.8.1
18.8.2
18.8.3
18.8.4
18.8.5
TIM2 Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
TIM2 Counter Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
TIM2 Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
TIM2 Channel Status and Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
TIM2 Channel Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Chapter 19
Development Support
19.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
19.2 Break Module (BRK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
19.2.1
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
Flag Protection During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Break Module Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Break Status and Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Break Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Break Flag Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
19.2.1.1
19.2.1.2
19.2.1.3
19.2.2
19.2.2.1
19.2.2.2
19.2.2.3
19.2.2.4
19.2.3
19.3 Monitor Module (MON) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
19.3.1
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
Normal Monitor Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Forced Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Monitor Vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Break Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Baud Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
19.3.1.1
19.3.1.2
19.3.1.3
19.3.1.4
19.3.1.5
19.3.1.6
19.3.1.7
19.3.2
Chapter 20
Electrical Specifications
20.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
20.2 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
20.3 Functional Operating Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
20.4 Thermal Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
20.5 5.0-Vdc Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
20.6 3.3-Vdc Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
20.7 5.0-Volt Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
20.8 3.3-Volt Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
17
Table of Contents
20.9 Clock Generation Module (CGM) Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
20.9.1
20.9.2
20.9.3
CGM Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
CGM Component Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
CGM Acquisition/Lock Time Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
20.10 5.0-Volt ADC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286
20.11 3.3-Volt ADC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
20.12 5.0-Volt SPI Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
20.13 3.3-Volt SPI Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
20.14 Timer Interface Module Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
20.15 Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
Chapter 21
Ordering Information and Mechanical Specifications
21.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
21.2 MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
21.3 Package Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
Appendix A
MC68HC908GR48A
A.1
A.2
A.3
A.4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
Appendix B
MC68HC908GR32A
B.1
B.2
B.3
B.4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
18
Freescale Semiconductor
Chapter 1
General Description
1.1 Introduction
The MC68HC908GR60A, MC68HC908GR48A, and MC68HC908GR32A are members of the low-cost,
high-performance M68HC08 Family of 8-bit microcontroller units (MCUs). 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.
The information contained in this document pertains to all three devices with the exceptions noted in
Appendix A MC68HC908GR48A and Appendix B MC68HC908GR32A.
1.2 Features
For convenience, features have been organized to reflect:
•
•
Standard features
Features of the CPU08
1.2.1 Standard Features
Features of the MC68HC908GR60A include:
•
•
•
•
•
•
High-performance M68HC08 architecture optimized for C-compilers
Fully upward-compatible object code with M6805, M146805, and M68HC05 Families
8-MHz internal bus frequency
Clock generation module supporting 1-MHz to 8-MHz crystals
FLASH program memory security(1)
On-chip programming firmware for use with host personal computer which does not require high
voltage for entry
•
•
In-system programming (ISP)
System protection features:
–
–
Optional computer operating properly (COP) reset
Low-voltage detection with optional reset and selectable trip points for 3.3-V and 5.0-V
operation
–
–
Illegal opcode detection with reset
Illegal address detection with reset
•
•
Low-power design; fully static with stop and wait modes
Standard low-power modes of operation:
–
–
Wait mode
Stop mode
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for
unauthorized users.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
19
General Description
•
•
Master reset pin and power-on reset (POR)
On-chip FLASH memory:
–
–
–
MC68HC908GR60A — 60 Kbytes
MC68HC908GR48A — 48 Kbytes
MC68HC908GR32A — 32 Kbytes
•
Random-access memory (RAM):
–
–
–
MC68HC908GR60A — 2048 bytes
MC68HC908GR48A — 1536 bytes
MC68HC908GR32A — 1536 bytes
•
•
•
Serial peripheral interface (SPI) module
Enhanced serial communications interface (ESCI) module
One 16-bit, 2-channel timer interface module (TIM1) with selectable input capture, output compare,
and pulse-width modulation (PWM) capability on each channel
One 16-bit, 6-channel timer interface module (TIM2) with selectable input capture, output compare,
and pulse-width modulation (PWM) capability on each channel
Timebase module with clock prescaler circuitry for eight user selectable periodic real-time
interrupts with optional active clock source during stop mode for periodic wakeup from stop using
an external crystal
•
•
•
•
24-channel, 10-bit successive approximation analog-to-digital converter (ADC)
8-bit keyboard wakeup port with software selectable rising or falling edge detect, as well as high or
low level detection
•
•
Up to 53 general-purpose input/output (I/O) pins, including:
–
–
40 shared-function I/O pins, depending on package choice
Up to 13 dedicated I/O pins, depending on package choice
Selectable pullups on inputs only on ports A, C, and D. Selection is on an individual port bit basis.
During output mode, pullups are disengaged.
•
•
•
•
•
•
Internal pullups on IRQ and RST to reduce customer system cost
High current 10-mA sink/source capability on all port pins
Higher current 20-mA sink/source capability on PTC0–PTC4 and PTF0–PTF3
User selectable clockout feature with divide by 1, 2, and 4 of the bus or crystal frequency
User selection of having the oscillator enabled or disabled during stop mode
BREAK module (BRK) to allow single breakpoint setting during
in-circuit debugging
•
Available packages:
–
–
–
32-pin low-profile quad flat pack (LQFP)
48-pin low-profile quad flat pack (LQFP)
64-pin quad flat pack (QFP)
•
Specific features in 32-pin LQFP are:
–
–
–
–
–
Port A is only 4 bits: PTA0–PTA3; shared with ADC and KBI modules
Port B is only 6 bits: PTB0–PTB5; shared with ADC module
Port C is only 2 bits: PTC0–PTC1
Port D is only 7 bits: PTD0–PTD6; shared with SPI, TIM1 and TIM2 modules
Port E is only 2 bits: PTE0–PTE1; shared with ESCI module
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
20
Freescale Semiconductor
MCU Block Diagram
•
•
Specific features in 48-pin LQFP are:
–
–
–
–
–
Port A is 8 bits: PTA0–PTA7; shared with ADC and KBI modules
Port B is 8 bits: PTB0–PTB7; shared with ADC module
Port C is only 7 bits: PTC0–PTC6
Port D is 8 bits: PTD0–PTD7; shared with SPI, TIM1, and TIM2 modules
Port E is only 6 bits: PTE0–PTE5; shared with ESCI module
Specific features in 64-pin QFP are:
–
–
–
–
–
–
–
Port A is 8 bits: PTA0–PTA7; shared with ADC and KBI modules
Port B is 8 bits: PTB0–PTB7; shared with ADC module
Port C is only 7 bits: PTC0–PTC6
Port D is 8 bits: PTD0–PTD7; shared with SPI, TIM1, andTIM2 modules
Port E is only 6 bits: PTE0–PTE5; shared with ESCI module
Port F is 8 bits: PTF0–PTF7; shared with TIM2 module
Port G is 8 bits; PTG0–PTG7; shared with ADC module
1.2.2 Features of the CPU08
Features of the CPU08 include:
•
•
•
•
•
•
•
•
•
•
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
1.3 MCU Block Diagram
Figure 1-1 shows the structure of the MC68HC908GR60A. Refer to Appendix A MC68HC908GR48A and
Appendix B MC68HC908GR32A.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
21
General Description
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 62,078 BYTES
USER RAM — 2048 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
MONITOR ROM
2-CHANNEL TIMER INTERFACE
MODULE
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure 1-1. MC68HC908GR60A Block Diagram
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
22
Freescale Semiconductor
Pin Assignments
1.4 Pin Assignments
Figure 1-2, Figure 1-3, and Figure 1-4 illustrate the pin assignments for the 32-pin LQFP, 48-pin LQFP,
and 64-pin QFP respectively.
RST
PTE0/TxD
24
23
22
21
20
19
18
17
1
PTA2/KBD2/AD10
PTA1/KBD1/AD9
PTA0/KBD0/AD8
VSSAD/VREFL
VDDAD/VREFH
PTB5/AD5
2
3
4
5
6
7
8
PTE1/RxD
IRQ
PTD0/SS/MCLK
PTD1/MISO
PTD2/MOSI
PTD3/SPSCK
PTB4/AD4
PTB3/AD3
Figure 1-2. 32-Pin LQFP Pin Assignments
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
23
General Description
PTA2/KBD2/AD10
36
RST
PTE0/TxD
PTE1/RxD
PTE2
1
PTA1/KBD1/AD9
PTA0/KBD0/AD8
35
34
33
32
31
30
29
28
27
26
2
3
4
5
6
7
8
9
PTC6
PTC5
PTE3
VSSAD/VREFL
VDDAD/VREFH
PTB7/AD7
PTE4
PTE5
IRQ
PTD0/SS/MCLK
PTD1/MISO
PTB6/AD6
PTB5/AD5
PTB4/AD4
PTB3/AD3
10
11
PTD2/MOSI
25
PTD3/SPSCK
12
Figure 1-3. 48-Pin LQFP Pin Assignments
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
24
Pin Functions
64
49
63 62 61 60 59 58 57 56 55 54 53 52 51 50
RST
PTA2/KBD2/AD10
48
1
PTA1/KBD1/AD9
PTA0/KBD0/AD8
PTC6
47
46
45
PTE0/TxD
PTE1/RxD
PTE2
2
3
4
5
6
7
8
9
PTE3
44
43
42
41
40
39
38
37
PTC5
PTE4
PTG3/AD19
PTG2/AD18
PTG1/AD17
PTG0/AD16
VSSAD/VREFL
PTE5
PTF0
PTF1
PTF2
10
11
12
13
14
15
PTF3
VDDAD/VREFH
PTB7/AD7
PTB6/AD6
IRQ
PTD0/SS/MCLK
PTD1/MISO
36
35
34
PTB5/AD5
PTB4/AD4
PTB3/AD3
PTD2/MOSI
PTD3/SPSCK
16
33
23 24 25 26 27 28 29 30 31
18 19 20 21 22
17
32
Figure 1-4. 64-Pin QFP Pin Assignments
1.5 Pin Functions
Descriptions of the pin functions are provided here.
1.5.1 Power Supply Pins (V and V )
DD
SS
VDD and VSS are the power supply and ground pins. The MCU operates 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 1-5
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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
25
General Description
MCU
VDD
VSS
C1
0.1 μF
+
C2
VDD
Note: Component values shown represent typical applications.
Figure 1-5. Power Supply Bypassing
1.5.2 Oscillator Pins (OSC1 and OSC2)
OSC1 and OSC2 are the connections for an external crystal, resonator, or clock circuit. See Chapter 4
Clock Generator Module (CGM).
1.5.3 External Reset Pin (RST)
A low on the RST pin forces the MCU to a known startup state. RST is bidirectional, allowing a reset of
the entire system. It is driven low when any internal reset source is asserted. This pin contains an internal
pullup resistor. See Chapter 14 System Integration Module (SIM).
1.5.4 External Interrupt Pin (IRQ)
IRQ is an asynchronous external interrupt pin. This pin contains an internal pullup resistor. See Chapter
8 External Interrupt (IRQ).
1.5.5 CGM Power Supply Pins (V
and V
)
DDA
SSA
VDDA and VSSA are the power supply pins for the analog portion of the clock generator module (CGM).
Decoupling of these pins should be as per the digital supply. See Chapter 4 Clock Generator Module
(CGM).
1.5.6 External Filter Capacitor Pin (CGMXFC)
CGMXFC is an external filter capacitor connection for the CGM. See Chapter 4 Clock Generator Module
(CGM).
1.5.7 ADC Power Supply/Reference Pins (V
/V
and V
/V
)
DDAD REFH
SSAD REFL
VDDAD and VSSAD are the power supply pins to the analog-to-digital converter (ADC). VREFH and VREFL
are the reference voltage pins for the ADC. VREFH is the high reference supply for the ADC, and by default
the VDDAD/VREFH pin should be externally filtered and connected to the same voltage potential as VDD
.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
26
Freescale Semiconductor
Pin Functions
VREFL is the low reference supply for the ADC, and by default the VSSAD/VREFL pin should be connected
to the same voltage potential as VSS. See Chapter 3 Analog-to-Digital Converter (ADC).
1.5.8 Port A Input/Output (I/O) Pins (PTA7/KBD7/AD15–PTA0/KBD0/AD8)
PTA7–PTA0 are general-purpose, bidirectional I/O port pins. Any or all of the port A pins can be
programmed to serve as keyboard interrupt pins or used as analog-to-digital inputs. PTA7–PTA4 are only
available on the 48-pin LQFP and 64-pin QFP packages. See Chapter 12 Input/Output (I/O) Ports,
Chapter 9 Keyboard Interrupt Module (KBI), and Chapter 3 Analog-to-Digital Converter (ADC).
These port pins also have selectable pullups when configured for input mode. The pullups are disengaged
when configured for output mode. The pullups are selectable on an individual port bit basis.
1.5.9 Port B I/O Pins (PTB7/AD7–PTB0/AD0)
PTB7–PTB0 are general-purpose, bidirectional I/O port pins that can also be used for analog-to-digital
converter (ADC) inputs. PTB7–PTB6 are only available on the 48-pin LQFP and 64-pin QFP packages.
See Chapter 12 Input/Output (I/O) Ports and Chapter 3 Analog-to-Digital Converter (ADC).
1.5.10 Port C I/O Pins (PTC6–PTC0)
PTC6 and PTC5 are general-purpose, bidirectional I/O port pins.
PTC4–PTC0 are general-purpose, bidirectional I/O port pins that contain higher current sink/source
capability. PTC6–PTC2 are only available on the 48-pin LQFP and 64-pin QFP packages. See Chapter
12 Input/Output (I/O) Ports.
These port pins also have selectable pullups when configured for input mode. The pullups are disengaged
when configured for output mode. The pullups are selectable on an individual port bit basis.
1.5.11 Port D I/O Pins (PTD7/T2CH1–PTD0/SS)
PTD7–PTD0 are special-function, bidirectional I/O port pins. PTD3–PTD0 can be programmed to be
serial peripheral interface (SPI) pins, while PTD7–PTD4 can be individually programmed to be timer
interface module (TIM1 and TIM2) pins. PTD0 can be used to output a clock, MCLK. PTD7 is only
available on the 48-pin LQFP and 64-pin QFP packages. See Chapter 17 Timer Interface Module (TIM1),
Chapter 18 Timer Interface Module (TIM2), Chapter 15 Serial Peripheral Interface (SPI) Module, Chapter
12 Input/Output (I/O) Ports, and Chapter 5 Configuration Register (CONFIG).
These port pins also have selectable pullups when configured for input mode. The pullups are disengaged
when configured for output mode. The pullups are selectable on an individual port bit basis.
1.5.12 Port E I/O Pins (PTE5–PTE2, PTE1/RxD, and PTE0/TxD)
PTE5–PTE0 are general-purpose, bidirectional I/O port pins. PTE1 and PTE0 can also be programmed
to be enhanced serial communications interface (ESCI) pins. PTE5–PTE2 are only available on the
48-pin LQFP and 64-pin QFP packages. See Chapter 13 Enhanced Serial Communications Interface
(ESCI) Module and Chapter 12 Input/Output (I/O) Ports.
1.5.13 Port F I/O Pins (PTF7/T2CH5–PTF0)
PTF7–PTF4 are special-function, bidirectional I/O port pins that can be individually programmed to be
timer interface module (TIM2) pins.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
27
General Description
PTF3–PTF0 are general-purpose, bidirectional I/O port pins that contain higher current sink/source
capability.
PTF7–PTF0 are only available on the 64-pin QFP package. See Chapter 17 Timer Interface Module
(TIM1), Chapter 18 Timer Interface Module (TIM2), and Chapter 12 Input/Output (I/O) Ports.
1.5.14 Port G I/O Pins (PTG7/AD23–PTBG0/AD16)
PTG7–PTG0 are general-purpose, bidirectional I/O port pins that can also be used for analog-to-digital
converter (ADC) inputs. PTG7–PTG0 are only available on the 64-pin QFP package. See Chapter 12
Input/Output (I/O) Ports and Chapter 3 Analog-to-Digital Converter (ADC).
1.5.15 Unused Pin Termination
Input pins and I/O port pins that are not used in the application must be terminated. This prevents excess
current caused by floating inputs, and enhances immunity during noise or transient events. Termination
methods include:
1. Configuring unused pins as outputs and driving high or low;
2. Configuring unused pins as inputs and enabling internal pull-ups;
3. Configuring unused pins as inputs and using external pull-up or pull-down resistors.
Never connect unused pins directly to VDD or VSS
.
Since some general-purpose I/O pins are not available on all packages, these pins must be terminated
as well. Either method 1 or 2 above are appropriate.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
28
Freescale Semiconductor
Chapter 2
Memory
2.1 Introduction
The CPU08 can address 64 Kbytes of memory space. The memory map, shown in Figure 2-1, includes:
•
•
•
62,078 bytes of user FLASH memory
2048 bytes of random-access memory (RAM)
52 bytes of user-defined vectors
2.2 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.
2.3 Reserved Memory Locations
Accessing a reserved location can have unpredictable effects on microcontroller (MCU) operation. In the
Figure 2-1 and in register figures in this document, reserved locations are marked with the word Reserved
or with the letter R.
2.4 Input/Output (I/O) Section
Most of the control, status, and data registers are in the zero page area of $0000–$003F, or at
$0440–$0461. Additional I/O registers have these addresses:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
$FE00; SIM break status register, BSR
$FE01; SIM reset status register, SRSR
$FE02; reserved
$FE03; SIM break flag control register, BFCR
$FE04; interrupt status register 1, INT1
$FE05; interrupt status register 2, INT2
$FE06; interrupt status register 3, INT3
$FE07; interrupt status register 4, INT4
$FE08; FLASH-2 control register, FL2CR
$FE09; break address register high, BRKH
$FE0A; break address register low, BRKL
$FE0B; break status and control register, BRKSCR
$FE0C; LVI status register, LVISR
$FE0D; FLASH-2 test control register, FLTCR2
$FE0E; FLASH-1 test control register, FLTCR1
$FF80; FLASH-1 block protect register, FL1BPR
$FF81; FLASH-2 block protect register, FL2BPR
$FF88; FLASH-1 control register, FL1CR
Data registers are shown in Figure 2-2. Table 2-1 is a list of vector locations.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
29
Memory
$FE00
$FE01
$FE02
$FE03
$FE04
$FE05
$FE06
$FE07
$FE08
$FE09
$FE0A
$FE0B
$FE0C
$FE0D
$FE0E
$FE0F
SIM BREAK STATUS REGISTER (BSR)
SIM RESET STATUS REGISTER (SRSR)
RESERVED
$0000
↓
$003F
I/O REGISTERS
64 BYTES
SIM BREAK FLAG CONTROL REGISTER (BFCR)
INTERRUPT STATUS REGISTER 1 (INT1)
INTERRUPT STATUS REGISTER 2 (INT2)
INTERRUPT STATUS REGISTER 3 (INT3)
INTERRUPT STATUS REGISTER 4 (INT4)
FLASH-2 CONTROL REGISTER (FL2CR)
BREAK ADDRESS REGISTER HIGH (BRKH)
BREAK ADDRESS REGISTER LOW (BRKL)
BREAK STATUS AND CONTROL REGISTER (BRKSCR)
LVI STATUS REGISTER (LVISR)
$0040
↓
$043F
RAM-1
1024 BYTES
$0440
↓
$0461
I/O REGISTERS
34 BYTES
$0462
↓
$04FF
FLASH-2
158 BYTES
$0500
↓
$057F
RESERVED
128 BYTES
FLASH-2 TEST CONTROL REGISTER (FLTCR2)
FLASH-1 TEST CONTROL REGISTER (FLTCR1)
UNIMPLEMENTED
$0580
↓
$097F
RAM-2
1024 BYTES
UNIMPLEMENTED
16 BYTES
RESERVED FOR COMPATIBILITY WITH MONITOR CODE
FOR A-FAMILY PART
$FE10
↓
$FE1F
$0980
↓
$1B7F
FLASH-2
4608 BYTES
$FE20
↓
$FF7F
MONITOR ROM
352 BYTES
$1B80
↓
$1DFF
RESERVED
640 BYTES
$FF80
$FF81
FLASH-1 BLOCK PROTECT REGISTER (FL1BPR)
FLASH-2 BLOCK PROTECT REGISTER (FL2BPR)
$1E00
↓
$1E0F
MONITOR ROM
16 BYTES
$FF82
↓
$FF87
RESERVED
6 BYTES
$1E10
↓
$1E1F
RESERVED
16 BYTES
$FF88
FLASH-1 CONTROL REGISTER (FL1CR)
$1E20
↓
$7FFF
$FF89
↓
$FFCB
FLASH-2
25,056 BYTES
RESERVED
67 BYTES
$8000
↓
$FDFF
$FFCC
↓
FLASH-1
32,256 BYTES
FLASH-1 VECTORS
52 BYTES
$FFFF(1)
1. $FFF6–$FFFD used for eight security bytes
Figure 2-1. MC68HC908GR60A Memory Map
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
30
Freescale Semiconductor
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Port A Data Register
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
$0000
(PTA) Write:
See page 135.
Reset:
Read:
Unaffected by reset
PTB4 PTB3
Unaffected by reset
PTC4 PTC3
Unaffected by reset
PTD4 PTD3
Unaffected by reset
Port B Data Register
PTB7
1
PTB6
PTC6
PTD6
PTB5
PTC5
PTD5
PTB2
PTC2
PTD2
PTB1
PTC1
PTD1
PTB0
PTC0
PTD0
$0001
$0002
$0003
$0004
$0005
$0006
$0007
$0008
$0009
$000A
$000B
(PTB) Write:
See page 138.
Reset:
Read:
Port C Data Register
(PTC) Write:
See page 140.
Reset:
Read:
Port D Data Register
PTD7
(PTD) Write:
See page 142.
Reset:
Read:
Data Direction Register A
DDRA7
0
DDRA6
0
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
(DDRA) Write:
See page 136.
Reset:
Read:
0
DDRB5
0
0
DDRB4
0
0
DDRB3
0
0
DDRB2
0
0
DDRB1
0
0
DDRB0
0
Data Direction Register B
DDRB7
DDRB6
0
(DDRB) Write:
See page 138.
Reset:
Read:
0
0
Data Direction Register C
DDRC6
0
DDRC5
0
DDRC4
0
DDRC3
0
DDRC2
0
DDRC1
0
DDRC0
0
(DDRC) Write:
See page 140.
Reset:
Read:
0
Data Direction Register D
DDRD7
DDRD6
DDRD5
0
DDRD4
0
DDRD3
0
DDRD2
0
DDRD1
0
DDRD0
0
(DDRD) Write:
See page 143.
Reset:
Read:
0
0
0
0
Port E Data Register
PTE5
PTE4
PTE3
PTE2
PTE1
PTE0
(PTE) Write:
See page 145.
Reset:
Read:
Unaffected by reset
ESCI Prescaler Register
PDS2
0
PDS1
PDS0
0
PSSB4
0
PSSB3
PSSB2
PSSB1
PSSB0
(SCPSC) Write:
See page 175.
Reset:
Read:
0
0
0
0
0
ALOST
AFIN
ARUN
AROVFL
ARD8
ESCI Arbiter Control
Register (SCIACTL) Write:
AM1
AM0
ACLK
See page 179.
Reset:
0
0
0
0
0
0
0
0
Read:
ARD7
ARD6
ARD5
ARD4
ARD3
ARD2
ARD1
ARD0
ESCI Arbiter Data
Register (SCIADAT) Write:
See page 180.
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R = Reserved
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 1 of 9)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
31
Memory
Addr.
Register Name
Bit 7
6
5
DDRE5
0
4
DDRE4
0
3
DDRE3
0
2
DDRE2
0
1
DDRE1
0
Bit 0
DDRE0
0
Read:
0
0
Data Direction Register E
$000C
$000D
$000E
$000F
$0010
$0011
$0012
$0013
$0014
$0015
$0016
$0017
(DDRE) Write:
See page 146.
Reset:
Read:
0
0
Port A Input Pullup Enable
PTAPUE7 PTAPUE6 PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE1 PTAPUE0
Register (PTAPUE) Write:
See page 137.
Reset:
0
0
0
0
0
0
0
0
0
Read:
Port C Input Pullup Enable
PTCPUE6 PTCPUE5 PTCPUE4 PTCPUE3 PTCPUE2 PTCPUE1 PTCPUE0
Register (PTCPUE) Write:
See page 142.
Reset:
0
0
0
0
0
0
0
0
Read:
Port D Input Pullup Enable
PTDPUE7 PTDPUE6 PTDPUE5 PTDPUE4 PTDPUE3 PTDPUE2 PTDPUE1 PTDPUE0
Register (PTDPUE) Write:
See page 145.
Reset:
0
0
0
0
0
0
0
SPE
0
0
Read:
SPI Control Register
SPRIE
R
0
SPMSTR
CPOL
CPHA
SPWOM
0
SPTIE
0
(SPCR) Write:
See page 217.
Reset:
0
1
0
1
Read:
SPRF
OVRF
MODF
SPTE
SPI Status and Control
ERRIE
MODFEN
SPR1
SPR0
Register (SPSCR) Write:
See page 218.
Reset:
0
0
0
0
1
0
0
0
Read:
R7
T7
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
R0
T0
SPI Data Register
(SPDR) Write:
See page 220.
Reset:
Unaffected by reset
Read:
ESCI Control Register 1
LOOPS
0
ENSCI
TXINV
M
0
WAKE
0
ILTY
0
PEN
0
PTY
0
(SCC1) Write:
See page 166.
Reset:
0
TCIE
0
0
Read:
ESCI Control Register 2
SCTIE
SCRIE
ILIE
0
TE
RE
0
RWU
0
SBK
0
(SCC2) Write:
See page 168.
Reset:
0
0
0
Read:
R8
ESCI Control Register 3
T8
R
R
ORIE
NEIE
FEIE
PEIE
(SCC3) Write:
See page 169.
Reset:
U
0
0
0
0
0
0
0
Read:
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
ESCI Status Register 1
(SCS1) Write:
See page 170.
Reset:
1
0
1
0
0
0
0
0
0
0
0
0
0
0
Read:
BKF
RPF
ESCI Status Register 2
(SCS2) Write:
See page 173.
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R = Reserved
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 2 of 9)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
32
Freescale Semiconductor
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
R7
6
5
4
3
2
1
Bit 0
R0
Read:
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
ESCI Data Register
$0018
(SCDR) Write:
T7
T0
See page 173.
Reset:
Read:
Unaffected by reset
ESCI Baud Rate Register
LINT
LINR
SCP1
SCP0
R
SCR2
SCR1
SCR0
$0019
$001A
$001B
$001C
$001D
(SCBR) Write:
See page 174.
Reset:
Read:
0
0
0
0
0
0
0
0
0
0
0
0
KEYF
0
ACKK
0
Keyboard Status and Control
IMASKK
MODEK
Register (INTKBSCR) Write:
See page 118.
Reset:
0
0
0
0
0
0
KBIE1
0
0
Read:
Keyboard Interrupt Enable
KBIE7
KBIE6
0
KBIE5
0
KBIE4
0
KBIE3
KBIE2
0
KBIE0
Register (INTKBIER) Write:
See page 119.
Reset:
0
0
0
0
Read:
TBIF
Timebase Module Control
TBR2
TBR1
TBR0
TBIE
TBON
0
R
Register (TBCR) Write:
See page 224.
TACK
0
Reset:
0
0
0
0
0
0
0
0
0
0
0
MODE
0
Read:
IRQF
IRQ Status and Control
IMASK
0
Register (INTSCR) Write:
ACK
0
See page 112.
Reset:
0
0
0
0
0
0
Configuration Register 2 Read:
TMBCLK- OSCENIN-
SEL
(CONFIG2)(1)
MCLKSEL
MCLK1
MCLK0
R
SCIBDSRC
STOP
Write:
$001E
$001F
See page 90.
Reset:
0
0
0
0
0
0
0
1
Read:
COPRS
0
LVISTOP LVIRSTD LVIPWRD LVI5OR3†
SSREC
0
STOP
0
COPD
0
Configuration Register 1
(CONFIG1)(1) Write:
See page 91.
Reset:
0
0
0
0
1. One-time writable register after each reset, except LVI5OR3 bit. LVI5OR3 bit is only reset via POR (power-on reset).
Read:
TOF
0
0
TRST
0
0
TIM1 Status and Control
TOIE
TSTOP
PS2
PS1
PS0
$0020
$0021
$0022
$0023
Register (T1SC) Write:
See page 234.
Reset:
0
0
1
0
0
0
9
0
Read:
Bit 15
14
13
12
11
10
Bit 8
TIM1 Counter
Register High (T1CNTH) Write:
See page 235.
Reset:
0
0
6
0
5
0
4
0
3
0
2
0
1
0
Read:
Bit 7
Bit 0
TIM1 Counter
Register Low (T1CNTL) Write:
See page 235.
Reset:
0
Bit 15
1
0
14
1
0
13
1
0
0
11
1
0
0
9
1
0
Bit 8
1
Read:
TIM1 Counter Modulo
12
10
Register High (T1MODH) Write:
See page 236.
Reset:
1
1
= Unimplemented
R = Reserved
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 3 of 9)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
33
Memory
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Bit 0
1
Read:
TIM1 Counter Modulo
Register Low (T1MODL) Write:
Bit 7
6
1
5
1
4
1
3
2
1
$0024
$0025
$0026
$0027
$0028
$0029
$002A
$002B
$002C
$002D
$002E
$002F
See page 236.
Reset:
1
CH0F
0
1
ELS0B
0
1
ELS0A
0
1
TOV0
0
Read:
TIM1 Channel 0 Status and
Control Register (T1SC0) Write:
CH0IE
0
MS0B
0
MS0A
0
CH0MAX
0
See page 237.
Reset:
0
Read:
TIM1 Channel 0
Register High (T1CH0H) Write:
Bit 15
Bit 7
14
13
12
11
10
9
Bit 8
See page 240.
Reset:
Indeterminate after reset
Read:
TIM1 Channel 0
Register Low (T1CH0L) Write:
6
5
0
4
3
2
1
Bit 0
See page 240.
Reset:
Indeterminate after reset
Read:
CH1F
TIM1 Channel 1 Status and
Control Register (T1SC1) Write:
CH1IE
MS1A
0
ELS1B
ELS1A
TOV1
CH1MAX
0
0
See page 237.
Reset:
0
0
0
0
0
9
0
Read:
TIM1 Channel 1
Register High (T1CH1H) Write:
Bit 15
14
13
12
11
10
Bit 8
See page 240.
Reset:
Indeterminate after reset
Read:
TIM1 Channel 1
Register Low (T1CH1L) Write:
Bit 7
6
5
4
3
2
1
Bit 0
PS0
See page 240.
Reset:
Indeterminate after reset
Read:
TOF
0
0
TRST
0
0
TIM2 Status and Control
TOIE
TSTOP
PS2
PS1
Register (T2SC) Write:
See page 237.
Reset:
0
0
1
0
0
0
9
0
Read:
Bit 15
14
13
12
11
10
Bit 8
TIM2 Counter
Register High (T2CNTH) Write:
See page 235.
Reset:
0
0
6
0
5
0
4
0
3
0
2
0
1
0
Read:
Bit 7
Bit 0
TIM2 Counter
Register Low (T2CNTL) Write:
See page 235.
Reset:
0
Bit 15
1
0
14
1
0
13
1
0
12
1
0
11
1
0
10
1
0
9
1
1
1
0
Bit 8
1
Read:
TIM2 Counter Modulo
Register High (T2MODH) Write:
See page 236.
Reset:
Read:
TIM2 Counter Modulo
Register Low (T2MODL) Write:
Bit 7
1
6
5
4
3
2
Bit 0
1
See page 236.
Reset:
1
1
1
1
1
= Unimplemented
R = Reserved
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 4 of 9)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
34
Freescale Semiconductor
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
CH0F
0
6
CH0IE
0
5
MS0B
0
4
MS0A
0
3
ELS0B
0
2
ELS0A
0
1
TOV0
0
Bit 0
CH0MAX
0
Read:
TIM2 Channel 0 Status and
Control Register (T2SC0) Write:
$0030
See page 237.
Reset:
0
Read:
TIM2 Channel 0
Bit 15
Bit 7
14
13
12
11
10
9
Bit 8
$0031
$0032
$0033
$0034
$0035
$0036
$0037
$0038
$0039
$003A
$003B
Register High (T2CH0H) Write:
See page 240.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 0
6
5
0
4
3
2
1
Bit 0
Register Low (T2CH0L) Write:
See page 240.
Reset:
Indeterminate after reset
Read:
CH1F
TIM2 Channel 1 Status and
CH1IE
MS1A
0
ELS1B
ELS1A
TOV1
CH1MAX
Control Register (T2SC1) Write:
0
0
See page 237.
Reset:
0
0
0
0
0
9
0
Read:
TIM2 Channel 1
Bit 15
14
13
12
11
10
Bit 8
Register High (T2CH1H) Write:
See page 240.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 1
Register Low (T2CH1L) Write:
Bit 7
6
5
4
3
2
1
Bit 0
See page 240.
Reset:
Indeterminate after reset
Read:
PLLF
PLL Control Register
PLLIE
0
PLLON
1
BCS
R
R
VPR1
VPR0
(PCTL) Write:
See page 81.
Reset:
0
0
0
0
0
0
0
0
0
0
Read:
LOCK
PLL Bandwidth Control
AUTO
ACQ
R
Register (PBWC) Write:
See page 82.
Reset:
0
0
0
0
0
0
0
0
0
0
MUL10
0
0
0
Read:
PLL Multiplier Select High
MUL11
MUL9
MUL8
Register (PMSH) Write:
See page 83.
Reset:
0
0
0
0
0
0
0
Read:
PLL Multiplier Select Low
MUL7
0
MUL6
1
MUL5
0
MUL4
0
MUL3
MUL2
U
MUL1
MUL0
Register (PMSL) Write:
See page 84.
Reset:
U
U
U
Read:
PLL VCO Select Range
VRS7
VRS6
VRS5
VRS4
VRS3
VRS2
0
VRS1
VRS0
Register (PMRS) Write:
See page 84.
Reset:
0
0
1
0
0
0
0
0
0
R
0
0
R
0
0
R
1
Read:
Reserved Write:
Reset:
R
0
0
0
0
0
= Unimplemented
R = Reserved
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 5 of 9)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
35
Memory
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
$003D
$003E
$003F
$0440
$0441
$0444
$0445
Register (ADSCR) Write:
R
0
See page 65.
Reset:
0
0
0
0
1
0
1
0
1
0
1
1
Read:
0
AD9
AD8
ADC Data High Register
(ADRH) Write:
See page 67.
Reset:
Unaffected by reset
AD4 A3
Read:
AD7
AD6
AD5
AD2
AD1
AD0
0
ADC Data Low Register
(ADRL) Write:
See page 67.
Reset:
Unaffected by reset
Read:
ADC Clock Register
ADIV2
0
ADIV1
0
ADIV0
0
ADICLK
0
MODE1
0
MODE0
1
R
0
(ADCLK) Write:
See page 69.
Reset:
0
Read:
Port F Data Register
PTF7
PTF6
PTF5
PTF4
PTAF3
PTF2
PTF1
PTF0
(PTF) Write:
See page 147.
Reset:
Unaffected by reset
PTG4 PTG3
Unaffected by reset
Read:
Port G Data Register
PTG7
PTG6
PTG5
PTG2
PTG1
PTG0
(PTG) Write:
See page 149.
Reset:
Read:
Data Direction Register F
DDRF7
0
DDRF6
0
DDRF5
0
DDRF4
0
DDRF3
0
DDRF2
0
DDRF1
0
DDRF0
0
(DDRF) Write:
See page 148.
Reset:
Read:
Data Direction Register G
DDRG7
0
DDRG6
0
DDRG5
0
DDRG4
0
DDRG3
0
DDRG2
0
DDRG1
0
DDRG0
0
(DDRG) Write:
See page 150.
Reset:
Keyboard Interrupt Read:
KBIP7
KBIP6
KBIP5
KBIP4
KBIP3
KBIP2
KBIP1
KBIP0
Polarity Register
Write:
$0448
(INTKBIPR)
Reset:
Read:
0
0
0
0
0
0
0
0
See page 119.
CH2F
TIM2 Channel 2 Status and
CH2IE
MS2B
0
MS2A
0
ELS2B
ELS2A
TOV2
CH2MAX
$0456
$0457
$0458
Control Register (T2SC2) Write:
0
0
See page 255.
Reset:
0
0
0
0
9
0
Read:
TIM2 Channel 2
Bit 15
14
13
12
11
10
Bit 8
Register High (T2CH2H) Write:
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 2
Register Low (T2CH2L) Write:
Bit 7
6
5
4
3
2
1
Bit 0
See page 258.
Reset:
Indeterminate after reset
R = Reserved
= Unimplemented
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 6 of 9)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
36
Freescale Semiconductor
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
CH3F
0
6
CH3IE
0
5
4
MS3A
0
3
ELS3B
0
2
ELS3A
0
1
TOV3
0
Bit 0
CH3MAX
0
Read:
0
TIM2 Channel 3 Status and
Control Register (T2SC3) Write:
$0459
See page 255.
Reset:
0
0
Read:
TIM2 Channel 3
Bit 15
Bit 7
14
13
12
11
10
9
Bit 8
$045A
$045B
$045C
$045D
$045E
$045F
$0460
$0461
$FE00
Register High (T2CH3H) Write:
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 3
6
5
4
3
2
1
Bit 0
Register Low (T2CH3L) Write:
See page 258.
Reset:
Indeterminate after reset
Read:
CH4F
TIM2 Channel 4 Status and
Control Register (T2SC4) Write:
CH4IE
MS4B
0
MS4A
0
ELS4B
ELS4A
TOV4
CH4MAX
0
0
See page 255.
Reset:
0
0
0
0
9
0
Read:
TIM2 Channel 4
Register High (T2CH4H) Write:
Bit 15
14
13
12
11
10
Bit 8
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 4
Register Low (T2CH4L) Write:
Bit 7
6
5
0
4
3
2
1
Bit 0
See page 258.
Reset:
Indeterminate after reset
Read:
CH5F
TIM2 Channel 5 Status and
Control Register (T2SC5) Write:
CH5IE
MS5A
0
ELS5B
ELS5A
TOV 5
CH5MAX
0
0
See page 255.
Reset:
0
0
0
0
0
9
0
Read:
TIM2 Channel 5
Register High (T2CH5H) Write:
Bit 15
14
13
12
11
10
Bit 8
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 5
Register Low (T2CH5L) Write:
Bit 7
6
5
4
3
2
1
Bit 0
See page 258.
Reset:
Indeterminate after reset
Read:
SBSW
NOTE 1
0
Break Status Register
R
0
R
0
R
0
R
0
R
0
R
0
R
0
(BSR) Write:
See page 199.
Reset:
1. Writing a 0 clears SBSW.
Read:
POR
PIN
COP
ILOP
ILAD
MODRST
LVI
0
SIM Reset Status Register
$FE01
$FE02
(SRSR) Write:
See page 199.
POR:
Read:
1
R
0
0
R
0
0
R
0
0
0
R
0
0
0
R
0
0
R
0
R
R
Reserved Write:
Reset:
0
0
= Unimplemented
R = Reserved
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 7 of 9)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
37
Memory
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Break Flag Control Register
BCFE
R
R
R
R
R
R
R
$FE03
$FE04
$FE05
$FE06
$FE07
$FE08
$FE09
$FE0A
$FE0B
$FE0C
$FE0D
$FE0E
(BFCR) Write:
See page 200.
Reset:
Read:
0
IF6
R
0
IF5
R
0
IF4
R
0
IF3
R
0
IF2
R
0
IF1
R
0
0
0
0
Interrupt Status Register 1
(INT1) Write:
See page 195.
R
R
Reset:
Read:
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) Write:
See page 195.
Reset:
Read:
0
0
0
0
0
0
0
0
IF22
R
IF21
R
IF20
R
IF19
R
IF18
R
IF17
R
IF16
R
IF15
R
Interrupt Status Register 3
(INT3) Write:
See page 195.
Reset:
Read:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
IF24
R
IF23
R
Interrupt Status Register 4
(INT4) Write:
See page 196.
R
R
R
R
R
R
Reset:
Read:
0
0
0
0
0
0
0
0
0
0
0
0
FLASH-2 Control Register
HVEN
MASS
ERASE
PGM
0
(FL2CR) Write:
See page 50.
Reset:
Read:
0
Bit 15
0
0
0
13
0
0
12
0
0
11
0
0
10
0
0
9
0
1
Break Address Register High
14
Bit 8
0
(BRKH) Write:
See page 265.
Reset:
Read:
0
Break Address Register Low
Bit 7
0
6
0
5
4
3
2
Bit 0
(BRKL) Write:
See page 265.
Reset:
Read:
0
0
0
0
0
0
0
0
0
0
0
0
Break Status and Control
BRKE
BRKA
Register (BRKSCR) Write:
See page 265.
Reset:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Read: LVIOUT
LVI Status Register
(LVISR) Write:
See page 129.
Reset:
Read:
Write:
Reset:
Read:
Write:
Reset:
0
R
0
0
R
0
0
R
0
0
R
0
0
R
0
0
R
0
0
R
0
0
R
0
FLASH-2 Test Control
Register (FLTCR2)
R
0
R
0
R
0
R
R
0
R
R
0
R
0
FLASH-1 Test Control
Register (FLTCR1)
0
0
= Unimplemented
R = Reserved
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 8 of 9)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
38
Freescale Semiconductor
Input/Output (I/O) Section
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
Read:
Write:
Reset:
FLASH-1 Block Protect
Register (FL1BPR)
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
(1)
$FF80
See page 43.
Unaffected by reset
BPR4 BPR3
FLASH-2 Block Protect
BPR7
BPR6
BPR5
BPR2
BPR1
BPR0
(1)
$FF81
Register (FL2BPR)
See page 51.
Unaffected by reset
1. Non-volatile FLASH register
Read:
0
0
0
0
0
0
0
FLASH-1 Control Register
HVEN
MASS
0
ERASE
0
PGM
0
$FF88
$FFFF
(FL1CR) Write:
See page 42.
Reset:
0
0
Read:
Low byte of reset vector
COP Control Register
(COPCTL) Write:
Writing clears COP counter (any value)
Unaffected by reset
See page 95.
Reset:
= Unimplemented
R = Reserved
U = Unaffected
Figure 2-2. Control, Status, and Data Registers (Sheet 9 of 9)
Table 2-1. Vec.tor Addresses
Vector Priority
Vector
Address
$FFCC
$FFCD
$FFCE
$FFCF
$FFD0
$FFD1
$FFD2
$FFD3
Vector
TIM2 Channel 5 Vector (High)
TIM2 Channel 5 Vector (Low)
TIM2 Channel 4 Vector (High)
TIM2 Channel 4 Vector (Low)
TIM2 Channel 3 Vector (High)
TIM2 Channel 3 Vector (Low)
TIM2 Channel 2 Vector (High)
TIM2 Channel 2 Vector (Low)
Lowest
IF24
IF23
IF22
IF21
IF20
↓
IF17
$FFD4
↓
$FFDB
Reserved
$FFDC
$FFDD
$FFDE
$FFDF
Timebase Vector (High)
IF16
IF15
Timebase Vector (Low)
ADC Conversion Complete Vector (High)
ADC Conversion Complete Vector (Low)
Continued on next page
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
39
Memory
Table 2-1. Vector Addresses (Continued)
Vector Priority
Vector
Address
$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
Vector
Keyboard Vector (High)
IF14
Keyboard Vector (Low)
ESCI Transmit Vector (High)
ESCI Transmit Vector (Low)
ESCI Receive Vector (High)
ESCI Receive Vector (Low)
ESCI Error Vector (High)
ESCI Error Vector (Low)
SPI Transmit Vector (High)
SPI Transmit Vector (Low)
SPI Receive Vector (High)
SPI Receive 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)
IF13
IF12
IF11
IF10
IF9
IF8
IF7
IF6
IF5
IF4
IF3
IF2
IF1
—
PLL Vector (Low)
IRQ Vector (High)
IRQ Vector (Low)
SWI Vector (High)
SWI Vector (Low)
Reset Vector (High)
—
Highest
Reset Vector (Low)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
40
Random-Access Memory (RAM)
2.5 Random-Access Memory (RAM)
The RAM locations are broken into two non-continuous memory blocks. The RAM addresses locations
are $0040–$043F and $0580–$097F. The location of the stack RAM is programmable. The 16-bit stack
pointer allows the stack to be anywhere in the 64-Kbyte memory space.
NOTE
For correct operation, the stack pointer must point only to RAM locations.
Within page zero are 192 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.
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.
2.6 FLASH-1 Memory (FLASH-1)
This subsection describes the operation of the embedded FLASH-1 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.
2.6.1 Functional Description
The FLASH-1 memory is an array of 32,256 bytes with two bytes of block protection (one byte for
protecting areas within FLASH-1 array and one byte for protecting areas within FLASH-2 array) and an
additional 52 bytes of user vectors. An erased bit reads as a 1 and a programmed bit reads as a 0.
Memory in the FLASH-1 array is organized into rows within pages. There are two rows of memory per
page with 64 bytes per row. The minimum erase block size is a single page,128 bytes. Programming is
performed on a per-row basis, 64 bytes at a time. Program and erase operations are facilitated through
control bits in the FLASH-1 control register (FL1CR). Details for these operations appear later in this
subsection.
The FLASH-1 memory map consists of:
•
•
•
•
•
$8000–$FDFF: user memory (32,256 bytes)
$FF80: FLASH-1 block protect register (FL1BPR)
$FF81: FLASH-2 block protect register (FL2BPR)
$FF88: FLASH-1 control register (FL1CR)
$FFCC–$FFFF: these locations are reserved for user-defined interrupt and reset vectors (see
Table 2-1 for details)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
41
Memory
Programming tools are available from Freescale Semiconductor. Contact your local representative for
more information.
NOTE
A security feature prevents viewing of the FLASH contents.(1)
2.6.2 FLASH-1 Control and Block Protect Registers
The FLASH-1 array has two registers that control its operation, the FLASH-1 control register (FL1CR) and
the FLASH-1 block protect register (FL1BPR).
2.6.2.1 FLASH-1 Control Register
The FLASH-1 control register (FL1CR) 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
= Unimplemented
Figure 2-3. FLASH-1 Control Register (FL1CR)
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
Setting this read/write bit configures the FLASH-1 array for mass erase operation.
1 = MASS erase operation selected
0 = MASS erase operation unselected
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 unselected
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 unselected
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for
unauthorized users.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
42
Freescale Semiconductor
FLASH-1 Memory (FLASH-1)
2.6.2.2 FLASH-1 Block Protect Register
The FLASH-1 block protect register (FL1BPR) is implemented as a byte within the FLASH-1 memory;
therefore, it can only be written during a FLASH programming sequence. The value in this register
determines the starting location of the protected range within the FLASH-1 memory.
Address: $FF80
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
Unaffected by reset
Figure 2-4. FLASH-1 Block Protect Register (FL1BPR)
FL1BPR[7:0] — Block Protect Register Bits 7 to 0
These eight bits represent bits [14:7] of a 16-bit memory address. Bit 15 is a 1 and bits [6:0] are 0s.
The resultant 16-bit address is used for specifying the start address of the FLASH-1 memory for block
protection. FLASH-1 is protected from this start address to the end of FLASH-1 memory at $FFFF.
With this mechanism, the protect start address can be $XX00 and $XX80 (128 byte page boundaries)
within the FLASH-1 array.
16-BIT MEMORY ADDRESS
START ADDRESS OF FLASH
0
0
0
0
0
0
0
FLBPR VALUE
1
BLOCK PROTECT
Figure 2-5. FLASH-1 Block Protect Start Address
Table 2-2. FLASH-1 Protected Ranges
FL1BPR[7:0]
$FF
Protected Range
No protection
$FE
$FF00–$FFFF
$FD
↓
$0B
$FE80–$FFFF
↓
$8580–$FFFF
$0A
$09
$8500–$FFFF
$8480–$FFFF
$08
↓
$8400–$FFFF
↓
$04
$8200–$FFFF
$03
$02
$01
$00
$8180–$FFFF
$8100–$FFFF
$8080–$FFFF
$8000–$FFFF
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
43
Memory
Decreasing the value in FL1BPR by one increases the protected range by one page (128 bytes).
However, programming the block protect register with $FE protects a range twice that size, 256 bytes, in
the corresponding array. $FE means that locations $FF00–$FFFF are protected in FLASH-1.
The FLASH memory does not exist at some locations. The block protection range configuration is
unaffected if FLASH memory does not exist in that range. Refer to Figure 2-1 and make sure that the
desired locations are protected.
2.6.3 FLASH-1 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 for protecting blocks of memory from unintentional erase or program
operations due to system malfunction. This protection is done by using the FLASH-1 block protection
register (FL1BPR). FL1BPR determines the range of the FLASH-1 memory which is to be protected. The
range of the protected area starts from a location defined by FL1BPR and ends at the bottom of the
FLASH-1 memory ($FFFF). When the memory is protected, the HVEN bit can not be set in either ERASE
or PROGRAM operations.
NOTE
In performing a program or erase operation, the FLASH-1 block protect
register must be read after setting the PGM or ERASE bit and before
asserting the HVEN bit.
When the FLASH-1 block protect register is programmed with all 0’s, the entire memory is protected from
being programmed and erased. When all the bits are erased (all 1’s), the entire memory is accessible for
program and erase.
When bits within FL1BPR are programmed (0), they lock a block of memory address ranges as shown in
Figure 2-4. If FL1BPR is programmed with any value other than $FF, the protected block of FLASH
memory can not be erased or programmed.
NOTE
The vector locations and the FLASH block protect registers are located in
the same page. FL1BPR and FL2BPR are not protected with special
hardware or software. Therefore, if this page is not protected by FL1BPR
and the vector locations are erased by either a page or a mass erase
operation, then both FL1BPR and FL2BPR will also get erased.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
44
Freescale Semiconductor
FLASH-1 Memory (FLASH-1)
2.6.4 FLASH-1 Mass Erase Operation
Use this step-by-step procedure to erase the entire FLASH-1 memory:
1. Set both the ERASE bit and the MASS bit in the FLASH-1 control register (FL1CR).
2. Read the FLASH-1 block protect register (FL1BPR).
NOTE
Mass erase is disabled whenever any block is protected (FL1BPR does not
equal $FF).
3. Write to any FLASH-1 address within the FLASH-1 array with any data.
4. Wait for a time, tNVS (minimum 10 μs).
5. Set the HVEN bit.
6. Wait for a time, tMERASE (minimum 4 ms).
7. Clear the ERASE and MASS bits.
8. Wait for a time, tNVHL (minimum 100 μs).
9. Clear the HVEN bit.
10. Wait for a time, tRCV, (typically 1 μs) after which the memory can be accessed in normal read mode.
NOTE
A. Programming and erasing of FLASH locations can not be performed by code being executed from the
same FLASH array.
B. While these operations must be performed in the order shown, other unrelated operations may occur
between the steps. However, care must be taken to ensure that these operations do not access any
address within the FLASH array memory space such as the COP control register (COPCTL) at
$FFFF.
C. It is highly recommended that interrupts be disabled during program/erase operations.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
45
Memory
2.6.5 FLASH-1 Page Erase Operation
Use this step-by-step procedure to erase a page (128 bytes) of FLASH-1 memory:
1. Set the ERASE bit and clear the MASS bit in the FLASH-1 control register (FL1CR).
2. Read the FLASH-1 block protect register (FL1BPR).
3. Write any data to any FLASH-1 address within the address range of the page (128 byte block) to
be erased.
4. Wait for time, tNVS (minimum 10 μs).
5. Set the HVEN bit.
6. Wait for time, tERASE (minimum 1 ms or 4 ms).
7. Clear the ERASE bit.
8. Wait for time, tNVH (minimum 5 μs).
9. Clear the HVEN bit.
10. Wait for a time, tRCV, (typically 1 μs) after which the memory can be accessed in normal read mode.
NOTE
A. Programming and erasing of FLASH locations can not be performed by code being executed from the
same FLASH array.
B. While these operations must be performed in the order shown, other unrelated operations may occur
between the steps. However, care must be taken to ensure that these operations do not access any
address within the FLASH array memory space such as the COP control register (COPCTL) at
$FFFF.
C. It is highly recommended that interrupts be disabled during program/erase operations.
In applications that require more than 1000 program/erase cycles, use the 4 ms page erase specification
to get improved long-term reliability. Any application can use this 4 ms page erase specification. However,
in applications where a FLASH location will be erased and reprogrammed less than 1000 times, and
speed is important, use the 1 ms page erase specification to get a shorter cycle time.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
46
Freescale Semiconductor
FLASH-1 Memory (FLASH-1)
2.6.6 FLASH-1 Program Operation
Programming of the FLASH-1 memory is done on a row basis. A row consists of 64 consecutive bytes
with address ranges as follows:
•
•
•
•
$XX00 to $XX3F
$XX40 to $XX7F
$XX80 to $XXBF
$XXC0 to $XXFF
During the programming cycle, make sure that all addresses being written to fit within one of the ranges
specified above. Attempts to program addresses in different row ranges in one programming cycle will fail.
Use this step-by-step procedure to program a row of FLASH-1 memory.
NOTE
Only bytes which are currently $FF may be programmed.
1. Set the PGM bit in the FLASH-1 control register (FL1CR). This configures the memory for program
operation and enables the latching of address and data programming.
2. Read the FLASH-1 block protect register (FL1BPR).
3. Write to any FLASH-1 address within the row address range desired with any data.
4. Wait for time, tNVS (minimum 10 μs).
5. Set the HVEN bit.
6. Wait for time, tPGS (minimum 5 μs).
7. Write data byte to the FLASH-1 address to be programmed.
8. Wait for time, tPROG (minimum 30 μs).
9. Repeat steps 7 and 8 until all the bytes within the row are programmed.
10. Clear the PGM bit.
11. Wait for time, tNVH (minimum 5 μs)
12. Clear the HVEN bit.
13. Wait for a time, tRCV, (typically 1 μs) after which the memory can be accessed in normal read mode.
The FLASH programming algorithm flowchart is shown in Figure 2-6.
NOTE
A. Programming and erasing of FLASH locations can not be performed by code being executed from the
same FLASH array.
B. While these operations must be performed in the order shown, other unrelated operations may occur
between the steps. However, care must be taken to ensure that these operations do not access any
address within the FLASH array memory space such as the COP control register (COPCTL) at
$FFFF.
C. It is highly recommended that interrupts be disabled during program/erase operations.
D. Do not exceed tPROG maximum or tHV maximum. tHV is defined as the cumulative high voltage
programming time to the same row before next erase. tHV must satisfy this condition:
t
NVS+ tNVH + tPGS + (tPROG X 64) ≤ tHV maximum
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
47
Memory
E. The time between each FLASH address change (step 7 to step 7), or the time between the last FLASH
address programmed to clearing the PGM bit (step 7 to step 10) must not exceed the maximum
programming time, tPROG maximum.
F. Be cautious when programming the FLASH-1 array to ensure that non-FLASH locations are not used
as the address that is written to when selecting either the desired row address range in step 3 of the
algorithm or the byte to be programmed in step 7 of the algorithm.
2.6.7 Low-Power Modes
The WAIT and STOP instructions will place the MCU in low power-consumption standby modes.
2.6.7.1 Wait Mode
Putting the MCU into wait mode while the FLASH is in read mode does not affect the operation of the
FLASH memory directly; however, no memory activity will take place since the CPU is inactive.
The WAIT instruction should not be executed while performing a program or erase operation on the
FLASH. Wait mode will suspend any FLASH program/erase operations and leave the memory in a
standby mode.
2.6.7.2 Stop Mode
Putting the MCU into stop mode while the FLASH is in read mode does not affect the operation of the
FLASH memory directly; however, no memory activity will take place since the CPU is inactive.
The STOP instruction should not be executed while performing a program or erase operation on the
FLASH. Stop mode will suspend any FLASH program/erase operations and leave the memory in a
standby mode.
NOTE
Standby mode is the power saving mode of the FLASH module, in which all
internal control signals to the FLASH are inactive and the current
consumption of the FLASH is minimum.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
48
Freescale Semiconductor
FLASH-1 Memory (FLASH-1)
Algorithm for programming
a row (64 bytes) of FLASH memory
1
2
3
SET PGM BIT
READ THE FLASH BLOCK
PROTECT REGISTER
WRITE ANY DATA TO ANY FLASH
ADDRESS WITHIN THE ROW
ADDRESS RANGE DESIRED
4
5
6
WAIT FOR A TIME, t
SET HVEN BIT
NVS
WAIT FOR A TIME, t
PGS
7
8
WRITE DATA TO THE FLASH
ADDRESS TO BE PROGRAMMED
WAIT FOR A TIME, t
PROG
COMPLETED
PROGRAMMING
THIS ROW?
YES
NO
10
CLEAR PGM BIT
11
12
13
WAIT FOR A TIME, t
NVH
NOTES:
CLEAR HVEN BIT
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 step10) must not exceed the maximum
programming time, tPROG, maximum.
WAIT FOR A TIME, t
RCV
This row program algorithm assumes the row/s to be
programmed are initially erased.
END OF PROGRAMMING
Figure 2-6. FLASH-1 Programming Algorithm Flowchart
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
49
Memory
2.7 FLASH-2 Memory (FLASH-2)
This subsection describes the operation of the embedded FLASH-2 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.
2.7.1 Functional Description
The FLASH-2 memory is a non-continuous array consisting of a total of 29,822 bytes. An erased bit reads
as a 1 and a programmed bit reads as a 0.
Memory in the FLASH-2 array is organized into rows within pages. There are two rows of memory per
page with 64 bytes per row. The minimum erase block size is a single page,128 bytes. Programming is
performed on a per-row basis, 64 bytes at a time. Program and erase operations are facilitated through
control bits in the FLASH-2 control register (FL2CR). Details for these operations appear later in this
subsection.
The FLASH-2 memory map consists of:
•
•
•
•
$0462–$04FF: user memory (158 bytes)
$0980–$1B7F: user memory (4608 bytes)
$1E20–$7FFF: user memory (25056 bytes)
$FF81: FLASH-2 block protect register (FL2BPR)
NOTE
FL2BPR physically resides within FLASH-1 memory addressing space
•
$FE08: FLASH-2 control register (FL2CR)
Programming tools are available from Freescale Semiconductor. Contact your local representative for
more information.
NOTE
A security feature prevents viewing of the FLASH contents.(1)
2.7.2 FLASH-2 Control and Block Protect Registers
The FLASH-2 array has two registers that control its operation, the FLASH-2 control register (FL2CR) and
the FLASH-2 block protect register (FL2BPR).
2.7.2.1 FLASH-2 Control Register
The FLASH-2 control register (FL2CR) controls FLASH-2 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
= Unimplemented
Figure 2-7. FLASH-2 Control Register (FL2CR)
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for
unauthorized users.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
50
Freescale Semiconductor
FLASH-2 Memory (FLASH-2)
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
Setting this read/write bit configures the FLASH-2 array for mass or page erase operation.
1 = Mass erase operation selected
0 = Page 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 set at the same time.
1 = Erase operation selected
0 = Erase operation unselected
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 unselected
2.7.2.2 FLASH-2 Block Protect Register
The FLASH-2 block protect register (FL2BPR) is implemented as a byte within the FLASH-1 memory;
therefore, can only be written during a FLASH-1 programming sequence. The value in this register
determines the starting location of the protected range within the FLASH-2 memory.
Address:
$FF81
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
Unaffected by reset
Figure 2-8. FLASH-2 Block Protect Register (FL2BPR)
NOTE
The FLASH-2 block protect register (FL2BPR) controls the block protection
for the FLASH-2 array. However, FL2BPR is implemented within the
FLASH-1 memory array and therefore, the FLASH-1 control register
(FL1CR) must be used to program/erase FL2BPR.
FL2BPR[7:0] — Block Protect Register Bits 7 to 0
These eight bits represent bits [14:7] of a 16-bit memory address. Bit 15 is a 0 and bits [6:0] are 0s.
The resultant 16-bit address is used for specifying the start address of the FLASH-2 memory for block
protection. FLASH-2 is protected from this start address to the end of FLASH-2 memory at $7FFF.
With this mechanism, the protect start address can be $XX00 and $XX80 (128 byte page boundaries)
within the FLASH-2 array.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
51
Memory
16-BIT MEMORY ADDRESS
START ADDRESS OF FLASH
BLOCK PROTECT
0
0
0
0
0
0
0
FLBPR VALUE
0
Figure 2-9. FLASH-2 Block Protect Start Address
Table 2-3. FLASH-2 Protected Ranges
FL2BPR[7:0]
$FF
Protected Range
No Protection
$FE
$7F00–$7FFF
$FD
↓
$7E80–$7FFF
↓
$0B
$0580–$7FFF
$0A
$09
$0500–$7FFF
$0480–$7FFF
$08
↓
$04
$0462–$7FFF
↓
$0462–$7FFF
$03
$02
$01
$00
$0462–$7FFF
$0462–$7FFF
$0462–$7FFF
$0462–$7FFF
Decreasing the value in FL2BPR by one increases the protected range by one page (128 bytes).
However, programming the block protect register with $FE protects a range twice that size, 256 bytes, in
the corresponding array. $FE means that locations $7F00–$7FFF are protected in FLASH-2.
The FLASH memory does not exist at some locations. The block protection range configuration is
unaffected if FLASH memory does not exist in that range. Refer to Figure 2-1 and make sure that the
desired locations are protected.
2.7.3 FLASH-2 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 for protecting blocks of memory from unintentional erase or program
operations due to system malfunction. This protection is done by using the FLASH-2 block protection
register (FL2BPR). FL2BPR determines the range of the FLASH-2 memory which is to be protected. The
range of the protected area starts from a location defined by FL2BPR and ends at the bottom of the
FLASH-2 memory ($7FFF). When the memory is protected, the HVEN bit can not be set in either ERASE
or PROGRAM operations.
NOTE
In performing a program or erase operation, the FLASH-2 block protect
register must be read after setting the PGM or ERASE bit and before
asserting the HVEN bit.
When the FLASH-2 block protect register is programmed with all 0’s, the entire memory is protected from
being programmed and erased. When all the bits are erased (all 1’s), the entire memory is accessible for
program and erase.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
FLASH-2 Memory (FLASH-2)
When bits within FL2BPR are programmed (0), they lock a block of memory address ranges as shown in
2.7.2.2 FLASH-2 Block Protect Register. If FL2BPR is programmed with any value other than $FF, the
protected block of FLASH memory can not be erased or programmed.
NOTE
The vector locations and the FLASH block protect registers are located in
the same page. FL1BPR and FL2BPR are not protected with special
hardware or software. Therefore, if this page is not protected by FL1BPR
and the vector locations are erased by either a page or a mass erase
operation, both FL1BPR and FL2BPR will also get erased.
2.7.4 FLASH-2 Mass Erase Operation
Use this step-by-step procedure to erase the entire FLASH-2 memory:
1. Set both the ERASE bit and the MASS bit in the FLASH-2 control register (FL2CR).
2. Read the FLASH-2 block protect register (FL2BPR).
NOTE
Mass erase is disabled whenever any block is protected (FL2BPR does not
equal $FF).
3. Write to any FLASH-2 address within the FLASH-2 array with any data.
4. Wait for a time, tNVS (minimum 10 μs).
5. Set the HVEN bit.
6. Wait for a time, tMERASE (minimum 4 ms).
7. Clear the ERASE and MASS bits.
8. Wait for a time, tNVHL (minimum 100 μs).
9. Clear the HVEN bit.
10. Wait for a time, tRCV, (typically 1 μs) after which the memory can be accessed in normal read mode.
NOTE
A. Programming and erasing of FLASH locations can not be performed by code being executed from the
same FLASH array.
B. While these operations must be performed in the order shown, other unrelated operations may occur
between the steps. However, care must be taken to ensure that these operations do not access any
address within the FLASH array memory space such as the COP control register (COPCTL) at
$FFFF.
C. It is highly recommended that interrupts be disabled during program/erase operations.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
53
Memory
2.7.5 FLASH-2 Page Erase Operation
Use this step-by-step procedure to erase a page (128 bytes) of FLASH-2 memory:
1. Set the ERASE bit and clear the MASS bit in the FLASH-2 control register (FL2CR).
2. Read the FLASH-2 block protect register (FL2BPR).
3. Write any data to any FLASH-2 address within the address range of the page (128 byte block) to
be erased.
4. Wait for time, tNVS (minimum 10 μs).
5. Set the HVEN bit.
6. Wait for time, tERASE (minimum 1 ms or 4 ms).
7. Clear the ERASE bit.
8. Wait for time, tNVH (minimum 5 μs).
9. Clear the HVEN bit.
10. Wait for a time, tRCV, (typically 1 μs) after which the memory can be accessed in normal read mode.
NOTE
A. Programming and erasing of FLASH locations can not be performed by code being executed from the
same FLASH array.
B. While these operations must be performed in the order shown, other unrelated operations may occur
between the steps. However, care must be taken to ensure that these operations do not access any
address within the FLASH array memory space such as the COP control register (COPCTL) at
$FFFF.
C. It is highly recommended that interrupts be disabled during program/erase operations.
In applications that require more than 1000 program/erase cycles, use the 4 ms page erase specification
to get improved long-term reliability. Any application can use this 4 ms page erase specification. However,
in applications where a FLASH location will be erased and reprogrammed less than 1000 times, and
speed is important, use the 1 ms page erase specification to get a shorter cycle time.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
54
Freescale Semiconductor
FLASH-2 Memory (FLASH-2)
2.7.6 FLASH-2 Program Operation
Programming of the FLASH memory is done on a row basis. A row consists of 64 consecutive bytes with
address ranges as follows:
•
•
•
•
$XX00 to $XX3F
$XX40 to $XX7F
$XX80 to $XXBF
$XXC0 to $XXFF
During the programming cycle, make sure that all addresses being written to fit within one of the ranges
specified above. Attempts to program addresses in different row ranges in one programming cycle will fail.
NOTE
Only bytes which are currently $FF may be programmed.
Use this step-by-step procedure to program a row of FLASH-2 memory:
1. Set the PGM bit in the FLASH-2 control register (FL2CR). This configures the memory for program
operation and enables the latching of address and data programming.
2. Read the FLASH-2 block protect register (FL2BPR).
3. Write to any FLASH-2 address within the row address range desired with any data.
4. Wait for time, tNVS (minimum 10 μs).
5. Set the HVEN bit.
6. Wait for time, tPGS (minimum 5 μs).
7. Write data byte to the FLASH-2 address to be programmed.
8. Wait for time, t PROG (minimum 30 μs).
9. Repeat step 7 and 8 until all the bytes within the row are programmed.
10. Clear the PGM bit.
11. Wait for time, tNVH (minimum 5 μs).
12. Clear the HVEN bit.
13. Wait for a time, tRCV, (typically 1 μs) after which the memory can be accessed in normal read mode.
The FLASH programming algorithm flowchart is shown in Figure 2-10.
NOTE
A. Programming and erasing of FLASH locations can not be performed by code being executed from the
same FLASH array.
B. While these operations must be performed in the order shown, other unrelated operations may occur
between the steps. However, care must be taken to ensure that these operations do not access any
address within the FLASH array memory space such as the COP control register (COPCTL) at
$FFFF.
C. It is highly recommended that interrupts be disabled during program/erase operations.
D. Do not exceed t PROG maximum or tHV maximum. tHV is defined as the cumulative high voltage
programming time to the same row before next erase. tHV must satisfy this condition:
t
NVS+ tNVH + tPGS + (tPROG X 64) ≤ tHV maximum
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
55
Memory
E. The time between each FLASH address change (step 7 to step 7), or the time between the last FLASH
address programmed to clearing the PGM bit (step 7 to step 10) must not exceed the maximum
programming time, tPROG maximum.
F. Be cautious when programming the FLASH-2 array to ensure that non-FLASH locations are not used
as the address that is written to when selecting either the desired row address range in step 3 of the
algorithm or the byte to be programmed in step 7 of the algorithm.
2.7.7 Low-Power Modes
The WAIT and STOP instructions will place the MCU in low power-consumption standby modes.
2.7.7.1 Wait Mode
Putting the MCU into wait mode while the FLASH is in read mode does not affect the operation of the
FLASH memory directly; however, no memory activity will take place since the CPU is inactive.
The WAIT instruction should not be executed while performing a program or erase operation on the
FLASH. Wait mode will suspend any FLASH program/erase operations and leave the memory in a
standby mode.
2.7.7.2 Stop Mode
Putting the MCU into stop mode while the FLASH is in read mode does not affect the operation of the
FLASH memory directly; however, no memory activity will take place since the CPU is inactive.
The STOP instruction should not be executed while performing a program or erase operation on the
FLASH. Stop mode will suspend any FLASH program/erase operations and leave the memory in a
standby mode.
NOTE
Standby mode is the power saving mode of the FLASH module, in which all
internal control signals to the FLASH are inactive and the current
consumption of the FLASH is minimum.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
56
Freescale Semiconductor
FLASH-2 Memory (FLASH-2)
Algorithm for programming
a row (64 bytes) of FLASH memory
1
2
3
SET PGM BIT
READ THE FLASH BLOCK
PROTECT REGISTER
WRITE ANY DATA TO ANY FLASH
ADDRESS WITHIN THE ROW
ADDRESS RANGE DESIRED
4
5
6
WAIT FOR A TIME, t
SET HVEN BIT
NVS
WAIT FOR A TIME, t
PGS
7
8
WRITE DATA TO THE FLASH
ADDRESS TO BE PROGRAMMED
WAIT FOR A TIME, t
PROG
COMPLETED
PROGRAMMING
THIS ROW?
YES
NO
10
CLEAR PGM BIT
11
12
13
WAIT FOR A TIME, t
NVH
NOTES:
CLEAR HVEN BIT
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 step10) must not exceed the maximum
programming time, tPROG, maximum.
WAIT FOR A TIME, t
RCV
This row program algorithm assumes the row/s to be
programmed are initially erased.
END OF PROGRAMMING
Figure 2-10. FLASH-2 Programming Algorithm Flowchart
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
57
Memory
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
58
Chapter 3
Analog-to-Digital Converter (ADC)
3.1 Introduction
This section describes the 10-bit analog-to-digital converter (ADC).
3.2 Features
Features of the ADC module include:
•
•
•
•
•
•
•
•
24 channels with multiplexed input
Linear successive approximation with monotonicity
10-bit resolution
Single or continuous conversion
Conversion complete flag or conversion complete interrupt
Selectable ADC clock
Left or right justified result
Left justified sign data mode
3.3 Functional Description
The ADC provides 24 pins for sampling external sources at pins PTG7/AD23–PTG0/AD16,
PTA7/KBD7/AD15–PTA0/KBD0/AD8, and PTB7/AD7–PTB0/AD0. An analog multiplexer allows the
single ADC converter to select one of 24 ADC channels as ADC voltage in (VADIN). VADIN is converted by
the successive approximation register-based analog-to-digital converter. When the conversion is
completed, ADC places the result in the ADC data register and sets a flag or generates an interrupt. See
Figure 3-2.
3.3.1 ADC Port I/O Pins
PTG7/AD23–PTG0/AD16, PTA7/KBD7/AD15–PTA0/KBD0/AD8, and PTB7/AD7–PTB0/AD0 are
general-purpose I/O (input/output) pins that share with the ADC channels. The channel select bits 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
logic and can be used as general-purpose I/O. Writes to the port register or data direction register (DDR)
will not have any affect on the port pin that is selected by the ADC. A read of a port pin in use by the ADC
will return a 0.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
59
Analog-to-Digital Converter (ADC)
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 62,078 BYTES
USER RAM — 2048 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
MONITOR ROM
2-CHANNEL TIMER INTERFACE
MODULE
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure 3-1. Block Diagram Highlighting ADC Block and Pins
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
60
Freescale Semiconductor
Functional Description
INTERNAL
DATA BUS
READ DDRx
WRITE DDRx
DISABLE
DDRx
PTx
RESET
WRITE PTx
READ PTx
PTx
ADC CHANNEL x
DISABLE
ADC DATA REGISTER
ADC
VOLTAGE IN
(VADIN
CONVERSION
COMPLETE
ADCH4–ADCH0
)
CHANNEL
SELECT
INTERRUPT
LOGIC
ADC
ADC CLOCK
AIEN COCO
CGMXCLK
CLOCK
GENERATOR
BUS CLOCK
ADIV2–ADIV0 ADICLK
Figure 3-2. ADC Block Diagram
3.3.2 Voltage Conversion
When the input voltage to the ADC equals VREFH, the ADC converts the signal to $3FF (full scale). If the
input voltage equals VREFL, the ADC converts it to $000. Input voltages between VREFH and VREFL are a
straight-line linear conversion.
NOTE
The ADC input voltage must always be greater than VSSAD and less than
VDDAD
.
Connect the VDDAD pin to the same voltage potential as the VDD pin, and
connect the VSSAD pin to the same voltage potential as the VSS pin.
The VDDAD pin should be routed carefully for maximum noise immunity.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
61
Analog-to-Digital Converter (ADC)
3.3.3 Conversion Time
Conversion starts after a write to the ADC status and control register (ADSCR). One conversion will take
between 16 and 17 ADC clock cycles. The ADIVx and ADICLK bits should be set to provide a 1-MHz ADC
clock frequency.
16 to 17 ADC cycles
Conversion time =
ADC frequency
Number of bus cycles = conversion time × bus frequency
3.3.4 Conversion
In continuous conversion mode, the ADC data register will be filled 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
will stay set until the next read of the ADC data register.
In single conversion mode, conversion begins with a write to the ADSCR. Only one conversion occurs
between writes to the ADSCR.
When a conversion is in process and the ADSCR is written, the current conversion data should be
discarded to prevent an incorrect reading.
3.3.5 Accuracy and Precision
The conversion process is monotonic and has no missing codes.
3.3.6 Result Justification
The conversion result may be formatted in four different ways:
1. Left justified
2. Right justified
3. Left Justified sign data mode
4. 8-bit truncation mode
All four of these modes are controlled using MODE0 and MODE1 bits located in the ADC clock register
(ADCLK).
Left justification will place the eight most significant bits (MSB) in the corresponding ADC data register
high, ADRH. This may be useful if the result is to be treated as an 8-bit result where the two least
significant bits (LSB), 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 LSBs 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. Finally, 8-bit truncation mode will place
the eight MSBs in the 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Monotonicity
NOTE
Quantization error is affected when only the most significant eight bits are
used as a result. See Figure 3-3.
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
1 1/2
3 1/2
5 1/2
7 1/2
9 1/2
INPUT VOLTAGE
REPRESENTED AS 8-BIT
1/2
1 1/2
2 1/2
Figure 3-3. Bit Truncation Mode Error
3.4 Monotonicity
The conversion process is monotonic and has no missing codes.
3.5 Interrupts
When the AIEN bit is set, the ADC module is capable of generating CPU interrupts after each ADC
conversion. A CPU interrupt is generated if the COCO bit is a 0. The COCO bit is not used as a conversion
complete flag when interrupts are enabled.
3.6 Low-Power Modes
The WAIT and STOP instruction can put the MCU in low power- consumption standby modes.
3.6.1 Wait Mode
The ADC continues normal operation during 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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
63
Analog-to-Digital Converter (ADC)
down the ADC by setting ADCH4–ADCH0 bits in the ADC status and control register before executing the
WAIT instruction.
3.6.2 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 after an external interrupt. Allow one
conversion cycle to stabilize the analog circuitry.
3.7 I/O Signals
The ADC module has eight pins shared with port A and the KBI module:
PTA7/KBD7/AD15–PTA0/KBD0/AD8
The ADC module has eight pins shared with port B:
PTB7/AD7–PTB0/AD0
The ADC module has eight pins shared with port G:
PTG7/AD23–PTG0/AD16
3.7.1 ADC Analog Power Pin (V
)
DDAD
The ADC analog portion uses VDDAD as its power pin. Connect the VDDAD pin to the same voltage
potential as VDD. External filtering may be necessary to ensure clean VDDAD for good results.
NOTE
For maximum noise immunity, route VDDAD carefully and place bypass
capacitors as close as possible to the package.
VDDAD and VREFH are bonded internally.
3.7.2 ADC Analog Ground Pin (V
)
SSAD
The ADC analog portion uses VSSAD as its ground pin. Connect the VSSAD pin to the same voltage
potential as VSS
.
NOTE
Route VSSAD cleanly to avoid any offset errors.
VSSAD and VREFL are bonded internally.
3.7.3 ADC Voltage Reference High Pin (V
)
REFH
The ADC analog portion uses VREFH as its upper voltage reference pin. By default, connect the VREFH
pin to the same voltage potential as VDD. External filtering is often necessary to ensure a clean VREFH for
good results. Any noise present on this pin will be reflected and possibly magnified in A/D conversion
values.
NOTE
For maximum noise immunity, route VREFH carefully and place bypass
capacitors as close as possible to the package. Routing VREFH close and
parallel to VREFL may improve common mode noise rejection.
VDDAD and VREFH are bonded internally.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
64
Freescale Semiconductor
I/O Registers
3.7.4 ADC Voltage Reference Low Pin (V
)
REFL
The ADC analog portion uses VREFL as its lower voltage reference pin. By default, connect the VREFL pin
to the same voltage potential as VSS. External filtering is often necessary to ensure a clean VREFL for good
results. Any noise present on this pin will be reflected and possibly magnified in A/D conversion values.
NOTE
For maximum noise immunity, route VREFL carefully and, if not connected
to VSS, place bypass capacitors as close as possible to the package.
Routing VREFH close and parallel to VREFL may improve common mode
noise rejection.
VSSAD and VREFL are bonded internally.
3.7.5 ADC Voltage In (V
)
ADIN
VADIN is the input voltage signal from one of the 24 ADC channels to the ADC module.
3.8 I/O Registers
These I/O registers control and monitor ADC operation:
•
•
•
ADC status and control register (ADSCR)
ADC data register (ADRH and ADRL)
ADC clock register (ADCLK)
3.8.1 ADC Status and Control Register
Function of the ADC status and control register (ADSCR) is described here.
Address:
$003C
Bit 7
COCO
R
6
5
ADCO
0
4
ADCH4
1
3
ADCH3
1
2
ADCH2
1
1
ADCH1
1
Bit 0
ADCH0
1
Read:
Write:
Reset:
AIEN
0
0
R
= Reserved
Figure 3-4. ADC Status and Control Register (ADSCR)
COCO — Conversions Complete Bit
In non-interrupt mode (AIEN = 0), COCO is a read-only bit that is set at the end of each conversion.
COCO will stay set until cleared by a read of the ADC data register. Reset clears this bit.
In interrupt mode (AIEN = 1), COCO is a read-only bit that is not set at the end of a conversion. It
always reads as a 0.
1 = Conversion completed (AIEN = 0)
0 = Conversion not completed (AIEN = 0) or CPU interrupt enabled (AIEN = 1)
NOTE
The write function of the COCO bit is reserved. When writing to the ADSCR
register, always have a 0 in the COCO bit position.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
65
Analog-to-Digital Converter (ADC)
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 is read or the status/control register is written. Reset clears the AIEN bit.
1 = ADC interrupt enabled
0 = ADC interrupt disabled
ADCO — ADC Continuous Conversion Bit
When set, the ADC will convert samples continuously and update the ADR register at the end of each
conversion. Only one conversion is completed between writes to the ADSCR when this bit is cleared.
Reset clears the ADCO bit.
1 = Continuous ADC conversion
0 = One ADC conversion
ADCH4–ADCH0 — ADC Channel Select Bits
ADCH4–ADCH0 form a 5-bit field which is used to select one of 32 ADC channels. Only 24 channels,
AD23–AD0, are available on this MCU. The channels are detailed in Table 3-1. Care should be taken
when using a port pin as both an analog and digital input simultaneously to prevent switching noise
from corrupting the analog signal. See Table 3-1.
The ADC subsystem is turned off when the channel select bits are all set to 1. This feature allows for
reduced power consumption for the MCU when the ADC is not being used.
NOTE
Recovery from the disabled state requires one conversion cycle to stabilize.
The voltage levels supplied from internal reference nodes, as specified in
Table 3-1, are used to verify the operation of the ADC converter both in production test and for user
applications.
Table 3-1. Mux Channel Select(1)
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
Input Select
PTB0/AD0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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
PTB1/AD1
PTB2/AD2
PTB3/AD3
PTB4/AD4
PTB5/AD5
PTB6/AD6
PTB7/AD7
PTA0/KBD0/AD8
PTA1/KBD1/AD9
PTA2/KBD2/AD10
PTA3/KBD3/AD11
PTA4/KBD4/AD12
PTA5/KBD5/AD13
PTA6/KBD6/AD14
PTA7/KBD7/AD15
Continued on next page
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
66
I/O Registers
Table 3-1. Mux Channel Select(1) (Continued)
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
Input Select
PTG0/AD16
PTG1/AD17
PTG2/AD18
PTG3/AD19
PTG4/AD20
PTG5/AD21
PTG6/AD22
PTG7/AD23
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1
↓
1
1
↓
1
0
↓
1
0
↓
0
0
↓
0
Unused
VREFH
VREFL
1
1
1
1
1
1
1
1
1
0
1
1
1
0
1
ADC power off
1. If any unused channels are selected, the resulting ADC conversion will be unknown or re-
served.
3.8.2 ADC Data Register High and Data Register Low
3.8.2.1 Left Justified Mode
In left justified mode, the ADRH register holds the eight MSBs of the
10-bit result. The ADRL register holds the two LSBs of the 10-bit result. All other bits read as 0. ADRH
and ADRL are updated each time an ADC single channel conversion completes. Reading ADRH latches
the contents of ADRL until ADRL is read. All subsequent results will be lost until the ADRH and ADRL
reads are completed.
Address:
$003D
Bit 7
ADRH
Bit 0
6
5
4
3
2
1
Read:
Write:
AD9
AD8
AD7
AD6
AD5
AD4
AD3
AD2
Reset:
Address:
Read:
Unaffected by reset
$003E
AD1
ADRL
0
AD0
0
0
0
0
0
Write:
Reset:
Unaffected by reset
= Unimplemented
Figure 3-5. ADC Data Register High (ADRH) and Low (ADRL)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
67
Analog-to-Digital Converter (ADC)
3.8.2.2 Right Justified Mode
In right justified mode, the ADRH register holds the two MSBs of the
10-bit result. All other bits read as 0. The ADRL register holds the eight LSBs of the 10-bit result. ADRH
and ADRL are updated each time an ADC single channel conversion completes. Reading ADRH latches
the contents of ADRL until ADRL is read. All subsequent results will be lost until the ADRH and ADRL
reads are completed.
Address:
$003D
Bit 7
0
ADRH
Bit 0
6
0
5
0
4
0
3
0
2
0
1
Read:
Write:
AD9
AD8
Reset:
Address:
Read:
Unaffected by reset
$003E
AD7
ADRL
AD0
AD6
AD5
AD4
AD3
AD2
AD1
Write:
Reset:
Unaffected by reset
= Unimplemented
Figure 3-6. ADC Data Register High (ADRH) and Low (ADRL)
3.8.2.3 Left Justified Signed Data Mode
In left justified signed data mode, the ADRH register holds the eight MSBs of the 10-bit result. The only
difference from left justified mode is that the AD9 is complemented. The ADRL register holds the two
LSBs of the 10-bit result. All other bits read as 0. ADRH and ADRL are updated each time an ADC single
channel conversion completes. Reading ADRH latches the contents of ADRL until ADRL is read. All
subsequent results will be lost until the ADRH and ADRL reads are completed.
Address:
$003D
Bit 7
6
5
4
3
2
1
Bit 0
AD2
Read:
Write:
AD9
AD8
AD7
AD6
AD5
AD4
AD3
Reset:
Address:
Read:
Unaffected by reset
$003E
AD1
AD0
0
0
0
0
0
0
Write:
Reset:
Unaffected by reset
= Unimplemented
Figure 3-7. ADC Data Register High (ADRH) and Low (ADRL)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
68
I/O Registers
3.8.2.4 Eight Bit Truncation Mode
In 8-bit truncation mode, the ADRL register holds the eight MSBs of the 10-bit result. The ADRH register
is unused and reads as 0. The ADRL register is updated each time an ADC single channel conversion
completes. In 8-bit mode, the ADRL register contains no interlocking with ADRH.
Address:
$003D
Bit 7
0
ADRH
Bit 0
0
6
0
5
0
4
0
3
0
2
0
1
0
Read:
Write:
Reset:
Address:
Read:
Unaffected by reset
$003E
AD9
ADRL
AD2
AD8
AD7
AD6
AD5
AD4
AD3
Write:
Reset:
Unaffected by reset
= Unimplemented
Figure 3-8. ADC Data Register High (ADRH) and Low (ADRL)
3.8.3 ADC Clock Register
The ADC clock register (ADCLK) selects the clock frequency for the ADC.
Address:
$003F
Bit 7
6
ADIV1
0
5
ADIV0
0
4
3
2
MODE0
1
1
R
0
Bit 0
0
Read:
Write:
Reset:
ADIV2
0
ADICLK
MODE1
0
0
0
= Unimplemented
R
= Reserved
Figure 3-9. ADC Clock Register (ADCLK)
ADIV2–ADIV0 — ADC Clock Prescaler Bits
ADIV2–ADIV0 form a 3-bit field which selects the divide ratio used by the ADC to generate the internal
ADC clock. Table 3-2 shows the available clock configurations. The ADC clock should be set to
approximately 1 MHz.
Table 3-2. 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
0
1
0
1
X(1)
X(1)
1. X = Don’t care
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
69
Analog-to-Digital Converter (ADC)
ADICLK — ADC Input Clock Select Bit
ADICLK selects either the bus clock or the oscillator output clock (CGMXCLK) as the input clock
source to generate the internal ADC clock. Reset selects CGMXCLK as the ADC clock source.
1 = Internal bus clock
0 = Oscillator output clock (CGMXCLK)
The ADC requires a clock rate of approximately 1 MHz for correct operation. If the selected clock source
is not fast enough, the ADC will generate incorrect conversions. See 20.10 5.0-Volt ADC Characteristics.
f
or bus frequency
CGMXCLK
≅ 1 MHz
f
=
ADIC
ADIV[2:0]
MODE1 and MODE0 — Modes of Result Justification Bits
MODE1 and MODE0 select among 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.
00 = 8-bit truncation mode
01 = Right justified mode
10 = Left justified mode
11 = Left justified signed data mode
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
70
Freescale Semiconductor
Chapter 4
Clock Generator Module (CGM)
4.1 Introduction
This section describes the clock generator module. The CGM generates the crystal clock signal,
CGMXCLK, which operates at the frequency of the crystal. The CGM also generates the base clock
signal, CGMOUT, which is based on either the crystal clock divided by two or the phase-locked loop (PLL)
clock, CGMVCLK, divided by two. In user mode, 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 fully functional
frequency generator designed for use with crystals or ceramic resonators. The PLL can generate a
maximum bus frequency of 8 MHz using a 1-8MHz crystal or external clock source.
4.2 Features
Features of the CGM include:
•
Phase-locked loop with output frequency in integer multiples of an integer dividend of the crystal
reference
•
•
•
•
•
•
High-frequency crystal operation with low-power operation and high-output frequency resolution
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
4.3 Functional Description
The CGM consists of three major submodules:
•
•
•
Crystal oscillator circuit — The crystal oscillator circuit generates the constant crystal frequency
clock, CGMXCLK.
Phase-locked loop (PLL) — The PLL generates the programmable VCO frequency clock,
CGMVCLK.
Base clock selector circuit — This software-controlled circuit selects either CGMXCLK divided by
two or the VCO clock, CGMVCLK, divided by two as the base clock, CGMOUT. The SIM derives
the system clocks from either CGMOUT or CGMXCLK.
Figure 4-1 shows the structure of the CGM.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
71
Clock Generator Module (CGM)
OSCILLATOR (OSC)
OSC2
CGMXCLK
(TO: SIM, TBM, ADC)
OSC1
SIMOSCEN (FROM SIM)
OSCENINSTOP
(FROM CONFIG)
PHASE-LOCKED LOOP (PLL)
CGMRCLK
CGMOUT
A
B
CLOCK
SELECT
CIRCUIT
÷
2
BCS
(TO SIM)
S*
SIMDIV2
*WHEN S = 1,
CGMOUT = B
VDDA
CGMXFC
VSSA
(FROM SIM)
VPR1–VPR0
VRS7–VRS0
VOLTAGE
PHASE
LOOP
CONTROLLED
OSCILLATOR
CGMVCLK
DETECTOR
FILTER
PLL ANALOG
CGMINT
(TO SIM)
AUTOMATIC
MODE
LOCK
INTERRUPT
CONTROL
DETECTOR
CONTROL
LOCK
AUTO
ACQ
PLLIE
PLLF
MUL11–MUL0
CGMVDV
FREQUENCY
DIVIDER
Figure 4-1. CGM Block Diagram
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
72
Functional Description
4.3.1 Crystal Oscillator Circuit
The crystal oscillator circuit consists of an inverting amplifier and an external crystal. The OSC1 pin is the
input to the amplifier and the OSC2 pin is the output. The SIMOSCEN signal from the system integration
module (SIM) or the OSCENINSTOP bit in the CONFIG register enable the crystal oscillator circuit.
The CGMXCLK signal is the output of the crystal oscillator circuit and runs at a rate equal to the crystal
frequency. CGMXCLK is then buffered to produce CGMRCLK, the PLL reference clock.
CGMXCLK can be used by other modules which require precise timing for operation. The duty cycle of
CGMXCLK is not guaranteed to be 50% and depends on external factors, including the crystal and related
external components. An externally generated clock also can feed the OSC1 pin of the crystal oscillator
circuit. Connect the external clock to the OSC1 pin and let the OSC2 pin float.
4.3.2 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.
4.3.3 PLL Circuits
The PLL consists of these circuits:
•
•
•
•
•
Voltage-controlled oscillator (VCO)
Modulo VCO frequency divider
Phase detector
Loop filter
Lock detector
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, fVRS. Modulating the voltage on the
CGMXFC pin changes the frequency within this range. By design, fVRS is equal to the nominal
center-of-range frequency, fNOM, (71.4 kHz) times a linear factor, L, and a power-of-two factor, E, or
(L × 2E)fNOM
.
CGMRCLK is the PLL reference clock, a buffered version of CGMXCLK. CGMRCLK runs at a frequency,
fRCLK. The VCO’s output clock, CGMVCLK, running at a frequency, fVCLK, is fed back through a
programmable modulo divider. The modulo divider reduces the VCO clock by a factor, N. The dividers
output is the VCO feedback clock, CGMVDV, running at a frequency, fVDV = fVCLK/(N). (For more
information, see 4.3.6 Programming the PLL.)
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 4.3.4 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 reference
clock, CGMRCLK. Therefore, the speed of the lock detector is directly proportional to the reference
frequency, fRCLK. The circuit determines the mode of the PLL and the lock condition based on this
comparison.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
73
Clock Generator Module (CGM)
4.3.4 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 4.5.2 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 4.3.8 Base Clock Selector Circuit.) The PLL is automatically in
tracking mode when not in acquisition mode or when the ACQ bit is set.
4.3.5 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 4.5.2 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 (for example, during PLL start up) 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 4.3.8 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 4.6 Interrupts for information and precautions on using interrupts.)
The following conditions apply when the PLL is in automatic bandwidth control mode:
•
The ACQ bit (See 4.5.2 PLL Bandwidth Control Register.) is a read-only indicator of the mode of
the filter. (See 4.3.4 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 4.8 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 4.8 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 4.5.1 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
fBUSMAX
.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
74
Functional Description
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 4.8
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.
4.3.6 Programming the PLL
Use the following procedure to program the PLL. For reference, the variables used and their meaning are
shown in Table 4-1.
Table 4-1. Variable Definitions
Variable
Definition
Desired bus clock frequency
fBUSDES
fVCLKDES
fRCLK
fVCLK
fBUS
Desired VCO clock frequency
Chosen reference crystal frequency
Calculated VCO clock frequency
Calculated bus clock frequency
Nominal VCO center frequency
Programmed VCO center frequency
fNOM
fVRS
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, fBUSDES
.
2. Calculate the desired VCO frequency (four times the desired bus frequency).
f
VCLKDES = 4 x fBUSDES
3. Choose a practical PLL (crystal) reference frequency, fRCLK. Typically, the reference crystal is 1–8
MHz.
Frequency errors to the PLL are corrected at a rate of fRCLK
.
For stability and lock time reduction, this rate must be as fast as possible. The VCO frequency must
be an integer multiple of this rate. The relationship between the VCO frequency, fVCLK, and the
reference frequency, fRCLK, is:
f
VCLK = (N) (fRCLK
)
N, the range multiplier, must be an integer.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
75
Clock Generator Module (CGM)
In cases where desired bus frequency has some tolerance, choose fRCLK to a value determined
either by other module requirements (such as modules which are clocked by CGMXCLK), cost
requirements, or ideally, as high as the specified range allows. See Chapter 20 Electrical
Specifications. After choosing N, the actual bus frequency can be determined using equation in 2
above.
4. Select a VCO frequency multiplier, N.
f
⎛
⎜
⎝
⎞
⎟
⎠
VCLKDES
-------------------------
N = round
f
RCLK
5. Calculate and verify the adequacy of the VCO and bus frequencies fVCLK and fBUS
.
f
= (N) × f
= (f
VCLK
RCLK
f
) ⁄ 4
VCLK
BUS
6. Select the VCO’s power-of-two range multiplier E, according to Table 4-2.
Table 4-2. Power-of-Two Range Selectors
Frequency Range
E
0
1
0 < fVCLK ≤ 8 MHz
8 MHz< fVCLK ≤ 16 MHz
16 MHz< fVCLK ≤ 32 MHz
2(1)
1. Do not program E to a value of 3.
7. Select a VCO linear range multiplier, L, where fNOM = 71.4 kHz
fVCLK
L = Round
2E x fNOM
8. Calculate and verify the adequacy of the VCO programmed center-of-range frequency, fVRS. The
center-of-range frequency is the midpoint between the minimum and maximum frequencies
attainable by the PLL.
f
VRS = (L x 2E) fNOM
9. For proper operation,
E
f
× 2
NOM
--------------------------
≤
VCLK
f
– f
VRS
2
10. Verify the choice of N, E, and L by comparing fVCLK to fVRS and fVCLKDES. For proper operation,
fVCLK must be within the application’s tolerance of fVCLKDES, and fVRS must be as close as possible
to fVCLK
.
NOTE
Exceeding the recommended maximum bus frequency or VCO frequency
can crash the MCU.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
76
Freescale Semiconductor
Functional Description
11. Program the PLL registers accordingly:
a. In the VPR bits of the PLL control register (PCTL), program the binary equivalent of E.
b. In the PLL multiplier select register low (PMSL) and the PLL multiplier select register high
(PMSH), program the binary equivalent of N. If using a 1–8 MHz reference, the PMSL register
must be reprogrammed from the reset value before enabling the PLL.
c. In the PLL VCO range select register (PMRS), program the binary coded equivalent of L.
Table 4-3 provides numeric examples (register values are in hexadecimal notation):
Table 4-3. Numeric Example
fBUS
fRCLK
N
E
0
0
0
1
1
1
2
2
2
L
500 kHz
1.25 MHz
2.0 MHz
2.5 MHz
3.0 MHz
4.0 MHz
5.0 MHz
7.0 MHz
8.0 MHz
1 MHz
1 MHz
1 MHz
1 MHz
1 MHz
1 MHz
1 MHz
1 MHz
1 MHz
002
005
008
00A
00C
010
014
01C
020
1B
45
70
45
53
70
46
62
70
4.3.7 Special Programming Exceptions
The programming method described in 4.3.6 Programming the PLL does not account for two possible
exceptions. A value of 0 for N or L is meaningless when used in the equations given. To account for these
exceptions:
•
•
A 0 value for 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 4.3.8 Base Clock Selector Circuit.
4.3.8 Base Clock Selector Circuit
This circuit is used to select either the crystal clock, CGMXCLK, or the VCO clock, CGMVCLK, 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 CGMVCLK 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 the base clock
frequency, is one-fourth the frequency of the selected clock (CGMXCLK or CGMVCLK).
The BCS bit in the PLL control register (PCTL) selects which clock drives CGMOUT. The 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 VCO clock is selected. The PLL cannot be turned on or off simultaneously with the selection or
deselection of the VCO clock. The 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 crystal clock would be forced as the source of the base
clock.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
77
Clock Generator Module (CGM)
4.3.9 CGM External Connections
In its typical configuration, the CGM requires external components. Five of these are for the crystal
oscillator and two or four are for the PLL.
The crystal oscillator is normally connected in a Pierce oscillator configuration, as shown in Figure 4-2.
Figure 4-2 shows only the logical representation of the internal components and may not represent actual
circuitry. The oscillator configuration uses five components:
•
•
•
•
•
Crystal, X1
Fixed capacitor, C1
Tuning capacitor, C2 (can also be a fixed capacitor)
Feedback resistor, RB
Series resistor, RS
The series resistor (RS) is included in the diagram to follow strict Pierce oscillator guidelines. Refer to the
crystal manufacturer’s data for more information regarding values for C1 and C2.
Figure 4-2 also shows the external components for the PLL:
•
•
Bypass capacitor, CBYP
Filter network
Routing should be done with great care to minimize signal cross talk and noise.
SIMOSCEN
OSCENINSTOP
(FROM CONFIG)
CGMXCLK
CGMXFC
VSSA
OSC1
OSC2
RS
VDDA
VDD
RB
X1
RF1
CF1
CBYP
CF2
C1
C2
Note: Filter network in box can be replaced with a single capacitor, but will degrade stability.
Figure 4-2. CGM External Connections
4.4 I/O Signals
The following paragraphs describe the CGM I/O signals.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
78
I/O Signals
4.4.1 Crystal Amplifier Input Pin (OSC1)
The OSC1 pin is an input to the crystal oscillator amplifier.
4.4.2 Crystal Amplifier Output Pin (OSC2)
The OSC2 pin is the output of the crystal oscillator inverting amplifier.
4.4.3 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 4-2.)
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.
4.4.4 PLL Analog Power Pin (V
)
DDA
VDDA is a power pin used by the analog portions of the PLL. Connect the VDDA pin to the same voltage
potential as the VDD pin.
NOTE
Route VDDA carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
4.4.5 PLL Analog Ground Pin (V
)
SSA
VSSA is a ground pin used by the analog portions of the PLL. Connect the VSSA pin to the same voltage
potential as the VSS pin.
NOTE
Route VSSA carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
4.4.6 Oscillator Enable Signal (SIMOSCEN)
The SIMOSCEN signal comes from the system integration module (SIM) and enables the oscillator and
PLL.
4.4.7 Oscillator Enable in Stop Mode Bit (OSCENINSTOP)
OSCENINSTOP is a bit in the CONFIG2 register that enables the oscillator to continue operating during
stop mode. If this bit is set, the oscillator continues running during stop mode. If this bit is not set (default),
the oscillator is controlled by the SIMOSCEN signal which will disable the oscillator during stop mode.
4.4.8 Crystal Output Frequency Signal (CGMXCLK)
CGMXCLK is the crystal oscillator output signal. It runs at the full speed of the crystal (fXCLK) and comes
directly from the crystal oscillator circuit. Figure 4-2 shows only the logical relation of CGMXCLK to OSC1
and OSC2 and may not represent the actual circuitry. The duty cycle of CGMXCLK is unknown and may
depend on the crystal and other external factors. Also, the frequency and amplitude of CGMXCLK can be
unstable at start up.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
79
Clock Generator Module (CGM)
4.4.9 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 either the oscillator output, CGMXCLK, divided by two or the VCO clock, CGMVCLK,
divided by two.
4.4.10 CGM CPU Interrupt (CGMINT)
CGMINT is the interrupt signal generated by the PLL lock detector.
4.5 CGM Registers
These registers control and monitor operation of the CGM:
•
•
•
•
•
PLL control register (PCTL) — see 4.5.1 PLL Control Register
PLL bandwidth control register (PBWC) — see 4.5.2 PLL Bandwidth Control Register
PLL multiplier select register high (PMSH) — see 4.5.3 PLL Multiplier Select Register High
PLL multiplier select register low (PMSL) — see 4.5.4 PLL Multiplier Select Register Low
PLL VCO range select register (PMRS) — see 4.5.5 PLL VCO Range Select Register
Figure 4-3 is a summary of the CGM registers.
Addr.
Register Name
Bit 7
PLLIE
0
6
5
PLLON
1
4
3
2
1
Bit 0
Read:
PLLF
PLL Control Register
BCS
R
R
VPR1
VPR0
$0036
(PCTL) Write:
See page 81.
Reset:
Read:
0
0
0
0
0
0
0
0
0
0
LOCK
PLL Bandwidth Control
AUTO
ACQ
R
$0037
$0038
Register (PBWC) Write:
See page 82.
Reset:
Read:
0
0
0
0
0
0
0
0
0
0
0
0
PLL Multiplier Select High
MUL11
MUL10
MUL9
MUL8
Register (PMSH) Write:
See page 83.
Reset:
Read:
0
0
0
0
0
MUL3
0
0
0
0
PLL Multiplier Select Low
MUL7
0
MUL6
1
MUL5
0
MUL4
0
MUL2
MUL1
MUL0
$0039
Register (PMSL) Write:
See page 84.
Reset:
Read:
0
0
0
PLL VCO Select Range
VRS7
VRS6
VRS5
VRS4
VRS3
0
VRS2
VRS1
VRS0
$003A
$003B
NOTES:
Register (PMRS) Write:
See page 84.
Reset:
Read:
0
0
1
0
0
0
0
0
0
R
0
0
R
0
0
R
1
R
Reserved Register Write:
Reset:
0
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 4-3. CGM I/O Register Summary
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
80
CGM Registers
4.5.1 PLL Control Register
The PLL control register (PCTL) contains the interrupt enable and flag bits, the on/off switch, the base
clock selector bit, and the VCO power-of-two range selector bits.
Address:
$0036
Bit 7
6
5
PLLON
1
4
BCS
0
3
2
1
VPR1
0
Bit 0
VPR0
0
Read:
Write:
Reset:
PLLF
PLLIE
0
R
R
0
0
0
= Unimplemented
R
= Reserved
Figure 4-4. 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 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 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.
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 4.3.8 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 crystal oscillator output, CGMXCLK, or the VCO clock,
CGMVCLK, 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 CGMVCLK cycles to complete the transition from one
source clock to the other. During the transition, CGMOUT is held in stasis. (See 4.3.8 Base Clock
Selector Circuit.) Reset clears the BCS bit.
1 = CGMVCLK 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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
81
Clock Generator Module (CGM)
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 CGMVCLK requires two writes to the PLL control register. (See
4.3.8 Base Clock Selector Circuit.).
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 controls the hardware center-of-range frequency, fVRS. VPR1:VPR0 cannot be written when the
PLLON bit is set. Reset clears these bits. (See 4.3.3 PLL Circuits, 4.3.6 Programming the PLL, and
4.5.5 PLL VCO Range Select Register.)
Table 4-4. VPR1 and VPR0 Programming
VCO Power-of-Two
Range Multiplier
VPR1 and VPR0
E
00
01
10
0
1
1
2
4
2(1)
1. Do not program E to a value of 3.
NOTE
Verify that the value of the VPR1 and VPR0 bits in the PCTL register are
appropriate for the given reference and VCO clock frequencies before
enabling the PLL. See 4.3.6 Programming the PLL for detailed instructions
on selecting the proper value for these control bits.
4.5.2 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
Address:
$0037
Bit 7
6
5
ACQ
0
4
0
3
0
2
0
1
0
Bit 0
R
Read:
Write:
Reset:
LOCK
AUTO
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 4-5. PLL Bandwidth Control Register (PBWC)
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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
82
Freescale Semiconductor
CGM Registers
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 0 and
has no meaning. The write one function of this bit is reserved for test, so this bit must always be written
as 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
4.5.3 PLL Multiplier Select Register High
The PLL multiplier select register high (PMSH) contains the programming information for the high byte of
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 4-6. PLL Multiplier Select Register High (PMSH)
MUL11–MUL8 — Multiplier Select Bits
These read/write bits control the high byte of the modulo feedback divider that selects the VCO
frequency multiplier N. (See 4.3.3 PLL Circuits and 4.3.6 Programming the PLL.) A value of $0000 in
the multiplier select registers configures 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).
PMSH[7:4] — Unimplemented Bits
These bits have no function and always read as 0s.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
83
Clock Generator Module (CGM)
4.5.4 PLL Multiplier Select Register Low
The PLL multiplier select register low (PMSL) contains the programming information for the low byte of
the modulo feedback divider.
Address:
$0038
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:
Write:
Reset:
MUL7
0
Figure 4-7. PLL Multiplier Select Register Low (PMSL)
NOTE
For applications using 1–8 MHz reference frequencies this register must be
reprogrammed before enabling the PLL. The reset value of this register will
cause applications using 1–8 MHz reference frequencies to become
unstable if the PLL is enabled without programming an appropriate value.
The programmed value must not allow the VCO clock to exceed 32 MHz.
See 4.3.6 Programming the PLL for detailed instructions on choosing the
proper value for PMSL.
MUL7–MUL0 — Multiplier Select Bits
These read/write bits control the low byte of the modulo feedback divider that selects the VCO
frequency multiplier, N. (See 4.3.3 PLL Circuits and 4.3.6 Programming the PLL.) MUL7–MUL0 cannot
be written when the PLLON bit in the PCTL is set. A value of $0000 in the multiplier select registers
configures the modulo feedback divider the same as a value of $0001. Reset initializes the register to
$40 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).
4.5.5 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
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:
VRS7
0
Figure 4-8. PLL VCO Range Select Register (PMRS)
NOTE
Verify that the value of the PMRS register is appropriate for the given
reference and VCO clock frequencies before enabling the PLL. See 4.3.6
Programming the PLL for detailed instructions on selecting the proper value
for these control bits.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
84
Freescale Semiconductor
Interrupts
VRS7–VRS0 — VCO Range Select Bits
These read/write bits control the hardware center-of-range linear multiplier L which, in conjunction with
E (See 4.3.3 PLL Circuits, 4.3.6 Programming the PLL, and 4.5.1 PLL Control Register.), controls the
hardware center-of-range frequency, fVRS. VRS7–VRS0 cannot be written when the PLLON bit in the
PCTL is set. (See 4.3.7 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 4.3.8 Base
Clock Selector Circuit and 4.3.7 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.
4.6 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 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 VCO clock, CGMVCLK, 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 CGMVCLK 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.
4.7 Special Modes
The WAIT instruction puts the MCU in low power-consumption standby modes.
4.7.1 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
85
Clock Generator Module (CGM)
4.7.2 Stop Mode
If the OSCENINSTOP bit in the CONFIG2 register is cleared (default), then the STOP instruction disables
the CGM (oscillator and phase locked loop) and holds low all CGM outputs (CGMXCLK, CGMOUT, and
CGMINT).
If the OSCENINSTOP bit in the CONFIG2 register is set, then the phase locked loop is shut off but the
oscillator will continue to operate in stop mode.
4.7.3 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 14.7.3 Break Flag Control Register.)
To allow software to clear status bits during a break interrupt, write a 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 0 to the BCFE bit. With BCFE at 0 (its default state),
software can read and write the PLL control register during the break state without affecting the PLLF bit.
4.8 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.
4.8.1 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
0 Hz to 1 MHz, the acquisition time is the time taken for the frequency to reach 1 MHz ±50 kHz. Fifty kHz
= 5% of the 1-MHz step input. If the system is operating at 1 MHz and suffers a –100-kHz noise hit, the
acquisition time is the time taken to return from 900 kHz to 1 MHz ±5 kHz. Five kHz = 5% of the 100-kHz
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.
4.8.2 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.
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Freescale Semiconductor
Acquisition/Lock Time Specifications
The most critical parameter which affects the reaction times of the PLL is the reference frequency, fRCLK
.
This frequency is the input to the phase 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 fXCLK. (See
4.3.3 PLL Circuits and 4.3.6 Programming the PLL.)
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 4.8.3 Choosing a Filter.)
Also important is the operating voltage potential applied to VDDA. The 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.
4.8.3 Choosing a Filter
As described in 4.8.2 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.
Figure 4-9 shows two types of filter circuits. In low-cost applications, where stability and reaction time of
the PLL are not critical, the three component filter network shown in Figure 4-9 (B) can be replaced by a
single capacitor, CF, as shown in shown in Figure 4-9 (A). Refer to Table 4-5 for recommended filter
components at various reference frequencies. For reference frequencies between the values listed in the
table, extrapolate to the nearest common capacitor value. In general, a slightly larger capacitor provides
more stability at the expense of increased lock time.
CGMXFC
CGMXFC
RF1
CF2
CF
CF1
VSSA
VSSA
(A)
(B)
Figure 4-9. PLL Filter
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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Clock Generator Module (CGM)
Table 4-5. Example Filter Component Values
fRCLK
CF1
CF2
RF1
CF
1 MHz
2 MHz
3 MHz
4 MHz
5 MHz
6 MHz
7 MHz
8 MHz
8.2 nF
4.7 nF
3.3 nF
2.2 nF
1.8 nF
1.5 nF
1.2 nF
1 nF
820 pF
470 pF
330 pF
220 pF
180 pF
150 pF
120 pF
100 pF
2k
2k
2k
2k
2k
2k
2k
2k
18 nF
6.8 nF
5.6 nF
4.7 nF
3.9 nF
3.3 nF
2.7 nF
2.2 nF
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Chapter 5
Configuration Register (CONFIG)
5.1 Introduction
This section describes the configuration registers, CONFIG1 and CONFIG2. The configuration registers
enable or disable these options:
•
•
•
•
•
•
•
•
•
Stop mode recovery time (32 CGMXCLK cycles or 4096 CGMXCLK cycles)
COP timeout period (262,128 or 8176 CGMXCLK cycles)
STOP instruction
Computer operating properly module (COP)
Low-voltage inhibit (LVI) module control and voltage trip point selection
Enable/disable the oscillator (OSC) during stop mode
Enable/disable an extra divide by 128 prescaler in timebase module
Selectable clockout (MCLK) feature with divide by 1, 2, and 4 of the bus or crystal frequency
Timebase clock select
5.2 Functional Description
The configuration registers are used in the initialization of various options. The configuration registers can
be written once after each reset. All of the configuration register bits are cleared during reset. Since the
various options affect the operation of the microcontroller unit (MCU), it is recommended that these
registers be written immediately after reset. The configuration registers are located at $001E and $001F
and may be read at anytime.
NOTE
On a FLASH device, the options except LVI5OR3 are one-time writable by
the user after each reset. This bit is one-time writable by the user only after
each POR (power-on reset). The CONFIG 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 5-1 and Figure 5-2.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
89
Configuration Register (CONFIG)
Address: $001E
Bit 7
6
MCLKSEL
0
5
MCLK1
0
4
3
2
1
Bit 0
Read:
Write:
Reset:
0
MCLK0
R
TMBCLKSEL OSCENINSTOP SCIBDSRC
0
0
0
0
0
1
= Unimplemented
R
= Reserved
Figure 5-1. Configuration Register 2 (CONFIG2)
MCLKSEL — MCLK Source Select Bit
1 = Crystal frequency
0 = Bus frequency
MCLK1 and MCLK0 — MCLK Output Select Bits
Setting the MCLK1 and MCLK0 bits enables the PTD0/SS pin to be used as a MCLK output clock.
Once configured for MCLK, the PTD data direction register for PTD0 is used to enable and disable the
MCLK output. See Table 5-1 for MCLK options.
Table 5-1. MCLK Output Select
MCLK1
MCLK0
MCLK Frequency
MCLK not enabled
Clock
0
0
1
1
0
1
0
1
Clock divided by 2
Clock divided by 4
TMBCLKSEL— Timebase Clock Select Bit
TMBCLKSEL enables an extra divide-by-128 prescaler in the timebase module. Setting this bit enables
the extra prescaler and clearing this bit disables it. See Chapter 16 Timebase Module (TBM) for a more
detailed description of the external clock operation.
1 = Enables extra divide-by-128 prescaler in timebase module
0 = Disables extra divide-by-128 prescaler in timebase module
OSCENINSTOP — Oscillator Enable In Stop Mode Bit
OSCENINSTOP, when set, will enable the oscillator to continue to generate clocks in stop mode. See
Chapter 4 Clock Generator Module (CGM). This function is used to keep the timebase running while
the rest of the MCU stops. See Chapter 16 Timebase Module (TBM). When clear, the oscillator will
cease to generate clocks while in stop mode. The default state for this option is clear, disabling the
oscillator in stop mode.
1 = Oscillator enabled during stop mode
0 = Oscillator disabled during stop mode (default)
SCIBDSRC — SCI Baud Rate Clock Source Bit
SCIBDSRC controls the clock source used for the serial communications interface (SCI). The setting
of this bit affects the frequency at which the SCI operates.See Chapter 13 Enhanced Serial
Communications Interface (ESCI) Module.
1 = Internal data bus clock used as clock source for SCI (default)
0 = External oscillator used as clock source for SCI
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Functional Description
Address: $001F
Bit 7
6
5
4
3
2
SSREC
0
1
STOP
0
Bit 0
COPD
0
Read:
COPRS
Write:
LVISTOP LVIRSTD LVIPWRD LVI5OR3
Reset:
0
0
0
0
See note
Note: LVI5OR3 is only reset via POR (power-on reset).
Figure 5-2. Configuration Register 1 (CONFIG1)
COPRS — COP Rate Select Bit
COPRS selects the COP timeout period. Reset clears COPRS. See Chapter 6 Computer Operating
Properly (COP) Module
1 = COP timeout period = 8176 CGMXCLK cycles
0 = COP timeout period = 262,128 CGMXCLK cycles
LVISTOP — LVI Enable in Stop Mode Bit
When the LVIPWRD bit is clear, setting the LVISTOP bit enables the LVI to operate during stop mode.
Reset clears LVISTOP.
1 = LVI enabled during stop mode
0 = LVI disabled during stop mode
LVIRSTD — LVI Reset Disable Bit
LVIRSTD disables the reset signal from the LVI module. See Chapter 11 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 Chapter 11 Low-Voltage Inhibit (LVI).
1 = LVI module power disabled
0 = LVI module power enabled
LVI5OR3 — LVI 5-V or 3-V Operating Mode Bit
LVI5OR3 selects the voltage operating mode of the LVI module (see Chapter 11 Low-Voltage Inhibit
(LVI)). The voltage mode selected for the LVI should match the operating VDD (see Chapter 20
Electrical Specifications) for the LVI’s voltage trip points for each of the modes.
1 = LVI operates in 5-V mode
0 = LVI operates in 3-V mode
NOTE
The LVI5OR3 bit is cleared by a power-on reset (POR) only. Other resets
will leave this bit unaffected.
SSREC — Short Stop Recovery Bit
SSREC enables the CPU to exit stop mode with a delay of 32 CGMXCLK cycles instead of a
4096-CGMXCLK cycle delay.
1 = Stop mode recovery after 32 CGMXCLK cycles
0 = Stop mode recovery after 4096 CGMXCLK cycles
NOTE
Exiting stop mode by any reset will result in the long stop recovery.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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Configuration Register (CONFIG)
The short stop recovery delay can be enabled when using a crystal or resonator and the
OSCENINSTOP bit is set. The short stop recovery delay can be enabled when an external oscillator
is used, regardless of the OSCENINSTOP setting.
The short stop recovery delay must be disabled when the OSCENINSTOP bit is clear and a crystal or
resonator is used.
STOP — STOP Instruction Enable Bit
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 Chapter 6 Computer Operating Properly (COP) Module.
1 = COP module disabled
0 = COP module enabled
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Chapter 6
Computer Operating Properly (COP) Module
6.1 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
CONFIG register.
6.2 Functional Description
Figure 6-1 shows the structure of the COP module.
CGMXCLK
RESET CIRCUIT
12-BIT SIM COUNTER
RESET STATUS REGISTER
STOP INSTRUCTION
INTERNAL RESET SOURCES
COPCTL WRITE
COP CLOCK
COP MODULE
6-BIT COP COUNTER
COPEN (FROM SIM)
COP DISABLE
(FROM CONFIG)
RESET
CLEAR
COP COUNTER
COPCTL WRITE
COP RATE SEL
(FROM CONFIG)
Figure 6-1. COP Block Diagram
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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Computer Operating Properly (COP) Module
The COP counter is a free-running 6-bit counter preceded by the 12-bit SIM counter. If not cleared by
software, the COP counter overflows and generates an asynchronous reset after 262,128 or 8176
CGMXCLK cycles, depending on the state of the COP rate select bit, COPRS, in the configuration
register. With a 262,128 CGMXCLK cycle overflow option, a 4.9152-MHz crystal gives a COP timeout
period of 53.3 ms. Writing any value to location $FFFF before an overflow occurs prevents a COP reset
by clearing the COP counter and stages 12–5 of the SIM counter.
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.
A COP reset pulls the RST pin low for 32 CGMXCLK cycles and sets the COP bit in the reset status
register (RSR).
In monitor mode, the COP is disabled if the RST pin or the IRQ is held at VTST. During the break state,
VTST on the RST pin disables the COP.
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.
6.3 I/O Signals
The following paragraphs describe the signals shown in Figure 6-1.
6.3.1 CGMXCLK
CGMXCLK is the crystal oscillator output signal. CGMXCLK frequency is equal to the crystal frequency.
6.3.2 STOP Instruction
The STOP instruction clears the SIM counter.
6.3.3 COPCTL Write
Writing any value to the COP control register (COPCTL) clears the COP counter and clears stages 12–5
of the SIM counter. Reading the COP control register returns the low byte of the reset vector. See 6.4
COP Control Register.
6.3.4 Power-On Reset
The power-on reset (POR) circuit clears the SIM counter 4096 CGMXCLK cycles after power-up.
6.3.5 Internal Reset
An internal reset clears the SIM counter and the COP counter.
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COP Control Register
6.3.6 COPD (COP Disable)
The COPD signal reflects the state of the COP disable bit (COPD) in the configuration register. See
Chapter 5 Configuration Register (CONFIG).
6.3.7 COPRS (COP Rate Select)
The COPRS signal reflects the state of the COP rate select bit (COPRS) in the configuration register. See
Chapter 5 Configuration Register (CONFIG).
6.4 COP Control Register
The COP control register (COPCTL) 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 6-2. COP Control Register (COPCTL)
6.5 Interrupts
The COP does not generate central processor unit (CPU) interrupt requests.
6.6 Monitor Mode
When monitor mode is entered with VTST on the IRQ pin, the COP is disabled as long as VTST remains
on the IRQ pin or the RST pin. When monitor mode is entered by having blank reset vectors and not
having VTST on the IRQ pin, the COP is automatically disabled until a POR occurs.
6.7 Low-Power Modes
The WAIT and STOP instructions put the microcontroller unit (MCU) in low power-consumption standby
modes.
6.7.1 Wait Mode
The COP remains active during wait mode. If COP is enabled, a reset will occur at COP timeout.
6.7.2 Stop Mode
Stop mode turns off the CGMXCLK input to the COP and clears the SIM counter. Service the COP
immediately before entering or after exiting stop mode to ensure a full COP timeout period after entering
or exiting stop mode.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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Computer Operating Properly (COP) Module
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 disabled, execution of a STOP instruction results in an illegal opcode reset.
6.8 COP Module During Break Mode
The COP is disabled during a break interrupt when VTST is present on the RST pin.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Chapter 7
Central Processor Unit (CPU)
7.1 Introduction
The M68HC08 CPU (central processor unit) is an enhanced and fully object-code-compatible version of
the M68HC05 CPU. The CPU08 Reference Manual (document order number CPU08RM/AD) contains a
description of the CPU instruction set, addressing modes, and architecture.
7.2 Features
Features 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
7.3 CPU Registers
Figure 7-1 shows the five CPU registers. CPU registers are not part of the memory map.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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Central Processor Unit (CPU)
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 7-1. CPU Registers
7.3.1 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 7-2. Accumulator (A)
7.3.2 Index Register
The 16-bit index register allows indexed addressing of a 64-Kbyte 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
Bit
0
15 14 13 12 11 10
9
0
8
0
7
6
5
4
3
2
1
Read:
Write:
Reset:
0
0
0
0
0
0
X
X
X
X
X
X
X
X
X = Indeterminate
Figure 7-3. Index Register (H:X)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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CPU Registers
7.3.3 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
Bit
0
15 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 7-4. Stack Pointer (SP)
NOTE
The location of the stack is arbitrary and may be relocated anywhere in
random-access memory (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.
7.3.4 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
Bit
0
15 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 7-5. Program Counter (PC)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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Central Processor Unit (CPU)
7.3.5 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 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 7-6. 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
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
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Freescale Semiconductor
Arithmetic/Logic Unit (ALU)
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
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
7.4 Arithmetic/Logic Unit (ALU)
The ALU performs the arithmetic and logic operations defined by the instruction set.
Refer to the CPU08 Reference Manual (document order number CPU08RM/AD) for a description of the
instructions and addressing modes and more detail about the architecture of the CPU.
7.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby modes.
7.5.1 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
•
7.5.2 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.
7.6 CPU During Break Interrupts
If a break module is present on the MCU, the CPU starts a break interrupt by:
•
•
Loading the instruction register with the SWI instruction
Loading the program counter with $FFFC:$FFFD or with $FEFC:$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.
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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Central Processor Unit (CPU)
7.7 Instruction Set Summary
Table 7-1 provides a summary of the M68HC08 instruction set.
Table 7-1. Instruction Set Summary (Sheet 1 of 6)
Effect
on CCR
Source
Form
Operation
Description
V H I N Z C
ADC #opr
IMM
DIR
EXT
IX2
A9 ii
B9 dd
C9 hh ll
D9 ee ff
E9 ff
2
3
4
4
3
2
4
5
ADC opr
ADC opr
ADC opr,X
ADC opr,X
ADC ,X
Add with Carry
A ← (A) + (M) + (C)
ꢀ
ꢀ
ꢀ
ꢀ
–
–
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
IX1
IX
SP1
SP2
F9
ADC opr,SP
ADC opr,SP
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
AB ii
BB dd
CB hh ll
DB ee ff
EB ff
FB
9EEB ff
9EDB ee ff
2
3
4
4
3
2
4
5
Add without Carry
A ← (A) + (M)
IX1
IX
SP1
SP2
AIS #opr
AIX #opr
Add Immediate Value (Signed) to SP
Add Immediate Value (Signed) to H:X
–
–
–
–
–
–
–
–
–
–
– IMM
– IMM
A7 ii
AF ii
2
2
SP ← (SP) + (16 « M)
H:X ← (H:X) + (16 « M)
AND #opr
AND opr
IMM
DIR
EXT
A4 ii
B4 dd
C4 hh ll
D4 ee ff
E4 ff
2
3
4
4
3
2
4
5
AND opr
AND opr,X
AND opr,X
AND ,X
AND opr,SP
AND opr,SP
IX2
Logical AND
A ← (A) & (M)
0
–
–
–
–
ꢀ
ꢀ
ꢀ
ꢀ
–
IX1
IX
F4
SP1
SP2
9EE4 ff
9ED4 ee ff
ASL opr
ASLA
DIR
INH
38 dd
48
4
1
1
4
3
5
ASLX
Arithmetic Shift Left
(Same as LSL)
INH
58
C
0
ꢀ
ꢀ
ASL opr,X
ASL ,X
IX1
68 ff
78
b7
b7
b0
b0
IX
ASL opr,SP
SP1
9E68 ff
ASR opr
ASRA
ASRX
ASR opr,X
ASR opr,X
ASR opr,SP
DIR
INH
37 dd
47
4
1
1
4
3
5
INH
57
C
Arithmetic Shift Right
ꢀ
–
–
–
–
ꢀ
ꢀ
ꢀ
IX1
67 ff
77
IX
SP1
9E67 ff
BCC rel
Branch if Carry Bit Clear
PC ← (PC) + 2 + rel ? (C) = 0
–
–
–
– REL
24 rr
3
DIR (b0) 11 dd
DIR (b1) 13 dd
DIR (b2) 15 dd
DIR (b3) 17 dd
DIR (b4) 19 dd
DIR (b5) 1B dd
DIR (b6) 1D dd
DIR (b7) 1F dd
4
4
4
4
4
4
4
4
BCLR n, opr
Clear Bit n in M
Mn ← 0
–
–
–
–
–
–
BCS rel
BEQ 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 rr
27 rr
3
3
Branch if Greater Than or Equal To
(Signed Operands)
BGE opr
BGT opr
–
–
–
–
–
–
–
–
–
–
– REL
– REL
90 rr
92 rr
3
PC ← (PC) + 2 + rel ? (N ⊕ V) = 0
Branch if Greater Than (Signed
Operands)
3
3
PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 0
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 rr
29 rr
22 rr
3
3
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
102
Instruction Set Summary
Table 7-1. Instruction Set Summary (Sheet 2 of 6)
Effect
on CCR
Source
Form
Operation
Description
V H I N Z C
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 rr
2E rr
3
3
BIT #opr
BIT opr
IMM
DIR
EXT
A5 ii
B5 dd
C5 hh ll
D5 ee ff
E5 ff
2
3
4
4
3
2
4
5
BIT opr
BIT opr,X
BIT opr,X
BIT ,X
BIT opr,SP
BIT opr,SP
IX2
Bit Test
(A) & (M)
0
–
–
ꢀ
ꢀ
–
IX1
IX
F5
SP1
SP2
9EE5 ff
9ED5 ee ff
Branch if Less Than or Equal To
(Signed Operands)
BLE opr
–
–
–
–
–
– REL
93 rr
3
PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 1
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
Branch if Less Than (Signed Operands)
Branch if Interrupt Mask Clear
Branch if Minus
PC ← (PC) + 2 + rel ? (C) = 1
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
– REL
– REL
– REL
– REL
– REL
– REL
– REL
– REL
– REL
25 rr
23 rr
91 rr
2C rr
2B rr
2D rr
26 rr
2A rr
20 rr
3
3
3
3
3
3
3
3
3
PC ← (PC) + 2 + rel ? (C) | (Z) = 1
PC ← (PC) + 2 + rel ? (N ⊕ V) =1
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
DIR (b0) 01 dd rr
DIR (b1) 03 dd rr
DIR (b2) 05 dd rr
DIR (b3) 07 dd rr
DIR (b4) 09 dd rr
DIR (b5) 0B dd rr
DIR (b6) 0D dd rr
DIR (b7) 0F 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
PC ← (PC) + 2
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
ꢀ
BRN rel
Branch Never
– REL
21 rr
3
DIR (b0) 00 dd rr
DIR (b1) 02 dd rr
DIR (b2) 04 dd rr
DIR (b3) 06 dd rr
DIR (b4) 08 dd rr
DIR (b5) 0A dd rr
DIR (b6) 0C dd rr
DIR (b7) 0E dd rr
5
5
5
5
5
5
5
5
BRSET n,opr,rel Branch if Bit n in M Set
PC ← (PC) + 3 + rel ? (Mn) = 1
ꢀ
DIR (b0) 10 dd
DIR (b1) 12 dd
DIR (b2) 14 dd
DIR (b3) 16 dd
DIR (b4) 18 dd
DIR (b5) 1A dd
DIR (b6) 1C dd
DIR (b7) 1E dd
4
4
4
4
4
4
4
4
BSET n,opr
BSR rel
Set Bit n in M
Mn ← 1
–
–
–
–
–
–
PC ← (PC) + 2; push (PCL)
SP ← (SP) – 1; push (PCH)
SP ← (SP) – 1
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
31 dd rr
41 ii rr
51 ii rr
61 ff rr
71 rr
5
4
4
5
4
6
CBEQA #opr,rel
CBEQX #opr,rel
CBEQ opr,X+,rel
CBEQ X+,rel
IMM
IMM
Compare and Branch if Equal
–
IX1+
IX+
CBEQ opr,SP,rel
SP1
9E61 ff rr
CLC
CLI
Clear Carry Bit
C ← 0
I ← 0
–
–
–
–
–
0
–
–
–
–
0 INH
– INH
98
9A
1
2
Clear Interrupt Mask
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
103
Central Processor Unit (CPU)
Table 7-1. Instruction Set Summary (Sheet 3 of 6)
Effect
on CCR
Source
Form
Operation
Description
V H I N Z C
CLR opr
CLRA
M ← $00
A ← $00
X ← $00
H ← $00
M ← $00
M ← $00
M ← $00
DIR
INH
INH
3F dd
4F
3
1
1
1
3
2
4
CLRX
5F
CLRH
Clear
0
–
–
–
–
0
1
– INH
IX1
8C
CLR opr,X
CLR ,X
6F ff
7F
IX
SP1
CLR opr,SP
9E6F ff
CMP #opr
CMP opr
CMP opr
CMP opr,X
CMP opr,X
CMP ,X
CMP opr,SP
CMP opr,SP
IMM
DIR
EXT
A1 ii
B1 dd
C1 hh ll
D1 ee ff
E1 ff
2
3
4
4
3
2
4
5
IX2
Compare A with M
(A) – (M)
ꢀ
ꢀ
ꢀ
ꢀ
IX1
IX
F1
SP1
SP2
9EE1 ff
9ED1 ee ff
COM opr
COMA
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
33 dd
43
4
1
1
4
3
5
COMX
INH
53
Complement (One’s Complement)
Compare H:X with M
0
–
–
–
–
ꢀ
ꢀ
ꢀ
ꢀ
1
COM opr,X
COM ,X
COM opr,SP
IX1
63 ff
73
9E63 ff
IX
SP1
CPHX #opr
CPHX opr
IMM
ꢀ
65 ii ii+1
75 dd
3
4
(H:X) – (M:M + 1)
ꢀ
DIR
CPX #opr
CPX opr
IMM
DIR
EXT
A3 ii
B3 dd
C3 hh ll
D3 ee ff
E3 ff
2
3
4
4
3
2
4
5
CPX opr
CPX ,X
IX2
Compare X with M
(X) – (M)
(A)10
ꢀ
–
–
ꢀ
ꢀ
ꢀ
CPX opr,X
CPX opr,X
CPX opr,SP
CPX opr,SP
IX1
IX
F3
SP1
SP2
9EE3 ff
9ED3 ee ff
DAA
Decimal Adjust A
U
–
–
–
–
–
ꢀ
ꢀ
ꢀ 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
5
3
3
5
4
6
DBNZ opr,rel
DBNZA rel
DIR
INH
3B dd rr
4B rr
DBNZX rel
Decrement and Branch if Not Zero
–
–
– INH
IX1
5B rr
DBNZ opr,X,rel
DBNZ X,rel
6B ff rr
7B rr
IX
SP1
DBNZ opr,SP,rel
9E6B ff rr
DEC opr
DECA
M ← (M) – 1
A ← (A) – 1
X ← (X) – 1
M ← (M) – 1
M ← (M) – 1
M ← (M) – 1
DIR
INH
3A dd
4A
4
1
1
4
3
5
DECX
INH
5A
Decrement
Divide
ꢀ
–
–
–
–
ꢀ
ꢀ
ꢀ
–
DEC opr,X
DEC ,X
DEC opr,SP
IX1
6A ff
7A
9E6A ff
IX
SP1
A ← (H:A)/(X)
H ← Remainder
DIV
–
–
ꢀ INH
52
7
EOR #opr
EOR opr
IMM
DIR
EXT
A8 ii
B8 dd
C8 hh ll
D8 ee ff
E8 ff
2
3
4
4
3
2
4
5
EOR opr
EOR opr,X
EOR opr,X
EOR ,X
EOR opr,SP
EOR opr,SP
IX2
Exclusive OR M with A
0
–
–
–
–
ꢀ
ꢀ
ꢀ
ꢀ
–
A ← (A ⊕ M)
IX1
IX
F8
SP1
SP2
9EE8 ff
9ED8 ee ff
INC opr
INCA
M ← (M) + 1
A ← (A) + 1
X ← (X) + 1
M ← (M) + 1
M ← (M) + 1
M ← (M) + 1
DIR
INH
3C dd
4C
4
1
1
4
3
5
INCX
INH
5C
Increment
ꢀ
–
INC opr,X
INC ,X
IX1
6C ff
7C
IX
INC opr,SP
SP1
9E6C ff
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
104
Instruction Set Summary
Table 7-1. Instruction Set Summary (Sheet 4 of 6)
Effect
on CCR
Source
Form
Operation
Description
V H I N Z C
JMP opr
DIR
BC dd
CC hh ll
DC ee ff
EC ff
2
3
4
3
2
JMP opr
JMP opr,X
JMP opr,X
JMP ,X
EXT
Jump
PC ← Jump Address
–
–
–
–
–
–
–
–
–
–
– IX2
IX1
IX
FC
JSR opr
JSR opr
JSR opr,X
JSR opr,X
JSR ,X
DIR
EXT
– IX2
IX1
BD dd
CD hh ll
DD ee ff
ED ff
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
Jump to Subroutine
IX
FD
LDA #opr
LDA opr
IMM
DIR
EXT
A6 ii
B6 dd
C6 hh ll
D6 ee ff
E6 ff
2
3
4
4
3
2
4
5
LDA opr
LDA opr,X
LDA opr,X
LDA ,X
LDA opr,SP
LDA opr,SP
IX2
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
–
–
–
–
–
–
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
–
IX1
IX
F6
SP1
SP2
9EE6 ff
9ED6 ee ff
LDHX #opr
LDHX opr
IMM
–
45 ii jj
55 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
AE ii
BE dd
CE hh ll
DE ee ff
EE ff
FE
9EEE ff
9EDE ee ff
2
3
4
4
3
2
4
5
IX2
–
IX1
IX
SP1
SP2
LSL opr
LSLA
DIR
INH
38 dd
48
4
1
1
4
3
5
LSLX
Logical Shift Left
(Same as ASL)
INH
58
C
0
ꢀ
ꢀ
–
–
–
–
ꢀ
ꢀ
ꢀ
ꢀ
LSL opr,X
LSL ,X
LSL opr,SP
IX1
68 ff
78
9E68 ff
b7
b7
b0
b0
IX
SP1
LSR opr
LSRA
DIR
INH
34 dd
44
4
1
1
4
3
5
LSRX
INH
54
0
C
Logical Shift Right
0
ꢀ
LSR opr,X
LSR ,X
IX1
64 ff
74
IX
LSR opr,SP
SP1
9E64 ff
MOV opr,opr
MOV opr,X+
MOV #opr,opr
MOV X+,opr
DD
4E dd dd
5E dd
5
4
4
4
(M)Destination ← (M)Source
DIX+
Move
0
–
–
0
–
–
ꢀ
ꢀ
–
IMD
IX+D
6E ii dd
7E dd
H:X ← (H:X) + 1 (IX+D, DIX+)
X:A ← (X) × (A)
MUL
Unsigned multiply
–
–
0 INH
42
5
NEG opr
NEGA
DIR
INH
30 dd
40
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)
NEGX
INH
50
Negate (Two’s Complement)
ꢀ
–
–
ꢀ
ꢀ
ꢀ
NEG opr,X
NEG ,X
NEG opr,SP
IX1
60 ff
70
9E60 ff
IX
SP1
NOP
NSA
No Operation
Nibble Swap A
None
–
–
–
–
–
–
–
–
–
–
– INH
– INH
9D
62
1
3
A ← (A[3:0]:A[7:4])
ORA #opr
ORA opr
IMM
DIR
EXT
AA ii
BA dd
CA hh ll
DA ee ff
EA ff
2
3
4
4
3
2
4
5
ORA opr
ORA opr,X
ORA opr,X
ORA ,X
ORA opr,SP
ORA opr,SP
IX2
Inclusive OR A and M
A ← (A) | (M)
0
–
–
ꢀ
ꢀ
–
IX1
IX
FA
SP1
SP2
9EEA ff
9EDA ee ff
PSHA
PSHH
PSHX
Push A onto Stack
Push H onto Stack
Push X onto Stack
Push (A); SP ← (SP) – 1
Push (H); SP ← (SP) – 1
Push (X); SP ← (SP) – 1
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
– INH
– INH
– INH
87
8B
89
2
2
2
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
105
Central Processor Unit (CPU)
Table 7-1. Instruction Set Summary (Sheet 5 of 6)
Effect
on CCR
Source
Form
Operation
Description
V H I N Z C
PULA
PULH
PULX
Pull A from Stack
Pull H from Stack
Pull X from Stack
SP ← (SP + 1); Pull (A)
SP ← (SP + 1); Pull (H)
SP ← (SP + 1); Pull (X)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
– INH
– INH
– INH
86
8A
88
2
2
2
ROL opr
ROLA
DIR
INH
39 dd
49
4
1
1
4
3
5
ROLX
INH
59
C
Rotate Left through Carry
Rotate Right through Carry
ꢀ
ꢀ
–
–
–
–
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ROL opr,X
ROL ,X
ROL opr,SP
IX1
69 ff
79
9E69 ff
b7
b0
IX
SP1
ROR opr
RORA
DIR
INH
36 dd
46
4
1
1
4
3
5
RORX
INH
56
C
ꢀ
ROR opr,X
ROR ,X
IX1
66 ff
76
b7
b0
IX
ROR opr,SP
SP1
9E66 ff
RSP
Reset Stack Pointer
Return from Interrupt
SP ← $FF
–
–
–
–
–
– INH
9C
1
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
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ INH
80
7
SP ← SP + 1; Pull (PCH)
SP ← SP + 1; Pull (PCL)
RTS
Return from Subroutine
Subtract with Carry
–
–
–
–
–
–
–
– INH
81
4
SBC #opr
SBC opr
SBC opr
SBC opr,X
SBC opr,X
SBC ,X
SBC opr,SP
SBC opr,SP
IMM
DIR
EXT
A2 ii
B2 dd
C2 hh ll
D2 ee ff
E2 ff
2
3
4
4
3
2
4
5
IX2
A ← (A) – (M) – (C)
ꢀ
ꢀ
ꢀ
ꢀ
IX1
IX
SP1
SP2
F2
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
DIR
EXT
IX2
B7 dd
C7 hh ll
D7 ee ff
E7 ff
3
4
4
3
2
4
5
STA opr
STA opr,X
STA opr,X
STA ,X
STA opr,SP
STA opr,SP
Store A in M
M ← (A)
0
–
–
ꢀ
ꢀ
– IX1
IX
F7
SP1
SP2
9EE7 ff
9ED7 ee ff
STHX opr
Store H:X in M
(M:M + 1) ← (H:X)
0
–
–
–
–
0
ꢀ
ꢀ
– DIR
35 dd
4
Enable Interrupts, Stop Processing,
Refer to MCU Documentation
STOP
I ← 0; Stop Processing
–
–
– INH
8E
1
STX opr
DIR
EXT
IX2
BF dd
CF hh ll
DF ee ff
EF ff
3
4
4
3
2
4
5
STX opr
STX opr,X
STX opr,X
STX ,X
STX opr,SP
STX opr,SP
Store X in M
M ← (X)
0
–
–
–
–
ꢀ
ꢀ
ꢀ
ꢀ
– IX1
IX
FF
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
A0 ii
B0 dd
C0 hh ll
D0 ee ff
E0 ff
2
3
4
4
3
2
4
5
IX2
Subtract
A ← (A) – (M)
ꢀ
ꢀ
IX1
IX
F0
SP1
SP2
9EE0 ff
9ED0 ee ff
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
106
Opcode Map
Table 7-1. Instruction Set Summary (Sheet 6 of 6)
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)
SWI
Software Interrupt
–
–
1
–
–
– INH
83
9
SP ← (SP) – 1; Push (CCR)
SP ← (SP) – 1; I ← 1
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)
ꢀ
–
–
ꢀ
–
–
ꢀ
–
–
ꢀ
–
–
ꢀ
–
–
ꢀ INH
– INH
– INH
84
97
85
2
1
1
Transfer CCR to A
A ← (CCR)
TST opr
TSTA
DIR
INH
3D dd
4D
3
1
1
3
2
4
TSTX
INH
5D
Test for Negative or Zero
(A) – $00 or (X) – $00 or (M) – $00
0
–
–
ꢀ
ꢀ
–
TST opr,X
TST ,X
TST opr,SP
IX1
6D ff
7D
9E6D ff
IX
SP1
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
I bit ← 0; Inhibit CPU clocking
WAIT
Enable Interrupts; Wait for Interrupt
–
–
0
–
–
– INH
8F
1
until interrupted
A
Accumulator
n
Any bit
C
Carry/borrow bit
opr Operand (one or two bytes)
PC Program counter
CCR
dd
Condition code register
Direct address of operand
Direct address of operand and relative offset of branch instruction
Direct to direct addressing mode
Direct addressing mode
Direct to indexed with post increment addressing mode
High and low bytes of offset in indexed, 16-bit offset addressing
Extended addressing mode
Offset byte in indexed, 8-bit offset addressing
Half-carry bit
Index register high byte
PCH Program counter high byte
PCL Program counter low byte
REL Relative addressing mode
rel
rr
SP1 Stack pointer, 8-bit offset addressing mode
SP2 Stack pointer 16-bit offset addressing mode
SP Stack pointer
U
V
X
Z
&
|
dd rr
DD
DIR
DIX+
ee ff
EXT
ff
Relative program counter offset byte
Relative program counter offset byte
H
H
Undefined
Overflow bit
Index register low byte
Zero bit
hh ll
I
High and low bytes of operand address in extended addressing
Interrupt mask
Immediate operand byte
Immediate source to direct destination addressing mode
ii
Logical AND
Logical OR
IMD
IMM
INH
IX
Immediate addressing mode
Inherent addressing mode
Indexed, no offset addressing mode
Indexed, no offset, post increment addressing mode
⊕
Logical EXCLUSIVE OR
Contents of
( )
–( ) Negation (two’s complement)
#
IX+
Immediate value
IX+D
IX1
IX1+
IX2
M
Indexed with post increment to direct addressing mode
Indexed, 8-bit offset addressing mode
Indexed, 8-bit offset, post increment addressing mode
Indexed, 16-bit offset addressing mode
Memory location
«
←
?
Sign extend
Loaded with
If
Concatenated with
Set or cleared
Not affected
:
ꢀ
—
N
Negative bit
7.8 Opcode Map
See Table 7-2.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
107
Table 7-2. 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
1
1
2
IX1 3 SP1 1 IX
5
1
1
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
EXT 3 IX2
4
4
4
4
4
4
4
4
4
4
4
4
SP2 2 IX1
3
3
3
3
3
3
3
3
3
3
3
3
SP1 1 IX
3
BRN
REL 3 DIR
5
4
4
6
4
4
3
BLT
2
3
4
4
5
3
4
2
1
2
BRCLR0 BCLR0
CBEQ CBEQA CBEQX CBEQ
CBEQ
CBEQ
RTS
CMP
CMP
CMP
CMP
CMP
CMP
CMP
CMP
3
DIR
5
2
DIR
4
3
IMM 3 IMM 3 IX1+
4
SP1 2 IX+
INH
REL 2 IMM 2 DIR
EXT 3 IX2
SP2 2 IX1
SP1 1 IX
3
5
7
3
2
DAA
3
BGT
2
SBC
3
SBC
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
EXT 3 IX2
4
LDX
EXT 3 IX2
4
STX
EXT 3 IX2
4
SBC
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
3
SBC
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
2
SBC
BRSET1 BSET1
BHI
MUL
INH
DIV
INH
NSA
3
DIR
5
2
DIR
4
REL
1
1
1
2
2
3
2
2
2
2
2
INH
1
INH
3
REL 2 IMM 2 DIR
3
BLS
REL 2 DIR
3
BCC
REL 2 DIR
3
BCS
REL 2 DIR
3
BNE
REL 2 DIR
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
3
BLE
2
CPX
3
CPX
4
CPX
3
CPX
2
CPX
3
BRCLR1 BCLR1
COM
COMA
COMX
COM
COM
SWI
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
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
2
BIT
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
IMM 2 DIR
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
2
LDA
IMM 2 DIR
2
AIS
IMM 2 DIR
2
EOR
IMM 2 DIR
2
ADC
IMM 2 DIR
2
ORA
IMM 2 DIR
2
ADD
IMM 2 DIR
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
ROR
3
DIR
5
2
DIR
4
1
INH
1
INH
3
3
3
3
3
4
3
3
3
BEQ
REL 2 DIR
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
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
INH
4
LSL
3
LSL
1
3
EOR
4
EOR
3
EOR
2
EOR
8
BRSET4 BSET4 BHCC
CLC
3
DIR
5
2
DIR
4
2
REL 2 DIR
3
INH
4
ROL
3
ROL
1
3
ADC
4
ADC
3
ADC
2
ADC
9
BRCLR4 BCLR4 BHCS
SEC
3
DIR
5
2
DIR
4
2
2
2
2
2
2
2
REL 2 DIR
INH
3
BPL
REL 2 DIR
3
BMI
REL 3 DIR
4
DEC
5
DEC
SP1 1 IX
3
DEC
2
3
ORA
4
ORA
5
ORA
SP2 2 IX1
5
ADD
SP2 2 IX1
3
ORA
4
ORA
SP1 1 IX
4
ADD
SP1 1 IX
2
ORA
A
B
C
D
E
F
BRSET5 BSET5
CLI
3
DIR
5
2
DIR
4
INH
5
3
3
5
6
4
2
3
ADD
4
ADD
3
ADD
2
ADD
BRCLR5 BCLR5
DBNZ DBNZA DBNZX DBNZ
DBNZ
DBNZ
SEI
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
SP1 2 IX
INH
3
4
INC
5
INC
SP1 1 IX
4
TST
SP1 1 IX
3
INC
1
2
JMP
4
JMP
3
JMP
2
BRSET6 BSET6
BMC
INCA
INCX
INC
RSP
JMP
3
DIR
5
2
DIR
4
REL 2 DIR
INH
1
INH
1
IX1
3
INH
2
DIR
4
2
2
IX1
5
1
1
IX
3
BMS
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
TSTA
TSTX
TST
NOP
JSR
JSR
3
DIR
5
2
DIR
4
REL 2 DIR
3
INH
5
INH
4
IX1
4
INH
2
2
2
IX1
3
4
1
STOP
INH
1
WAIT
INH
3
LDX
4
LDX
5
LDX
SP2 2 IX1
5
STX
SP2 2 IX1
4
LDX
SP1 1 IX
4
STX
SP1 1 IX
BRSET7 BSET7
BIL
MOV
MOV
MOV
MOV
LDX
*
1
TXA
INH
3
DIR
5
2
DIR
4
REL
3
DD
DIX+
IMD
3
2
IX+D
1
1
4
4
3
3
3
CLR
1
CLRA
INH
1
CLRX
INH
4
CLR
SP1 1 IX
2
CLR
3
STX
4
STX
3
STX
2
STX
BRCLR7 BCLR7
BIH
CLR
IX1
3
DIR
2
DIR
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
Chapter 8
External Interrupt (IRQ)
8.1 Introduction
The IRQ (external interrupt) module provides a maskable interrupt input.
8.2 Features
•
•
•
•
•
•
•
Features of the IRQ module include:
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
8.3 Functional Description
A low applied to the external interrupt pin can latch a central processor unit (CPU) interrupt request.
Figure 8-1 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 latch that caused the vector fetch.
•
Software clear — Software can clear an interrupt latch by writing to the appropriate acknowledge
bit in the interrupt status and control register (INTSCR). Writing a 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 out of reset and is software-configurable to be either
falling-edge or falling-edge and low-level triggered. The MODE bit in the INTSCR controls the triggering
sensitivity of the IRQ pin.
When an interrupt pin is edge-triggered only (MODE = 0), the interrupt remains set until a vector fetch,
software clear, or reset occurs.
When an interrupt pin is both falling-edge and low-level triggered (MODE = 1), the interrupt remains set
until both of these events occur:
•
•
Vector fetch or software clear
Return of the interrupt pin to a high level
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
109
External Interrupt (IRQ)
RESET
ACK
TO CPU FOR
BIL/BIH
INSTRUCTIONS
VECTOR
FETCH
DECODER
VDD
INTERNAL
PULLUP
DEVICE
VDD
IRQF
CLR
D
Q
IRQ
SYNCHRONIZER
INTERRUPT
REQUEST
CK
IRQ
IMASK
MODE
TO MODE
SELECT
LOGIC
HIGH
VOLTAGE
DETECT
Figure 8-1. IRQ Module Block Diagram
The vector fetch or software clear may occur before or after the interrupt pin returns to a high level. 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 masks 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.
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
$001D
Register (INTSCR) Write:
ACK
0
See page 112.
Reset:
0
0
0
0
0
= Unimplemented
Figure 8-2. IRQ I/O Register Summary
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
110
IRQ Pin
8.4 IRQ Pin
A falling edge 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 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 a high level — As long as the IRQ pin is low, IRQ remains active.
The vector fetch or software clear and the return of the IRQ pin to a high level may occur in any order.
The interrupt request remains pending as long as the IRQ pin is low. 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 or 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.
8.5 IRQ Module During Break Interrupts
The BCFE bit in the SIM break flag control register (SBFCR) enables software to clear the latch during
the break state. See Chapter 19 Development Support.
To allow software to clear the IRQ latch during a break interrupt, write a 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 CPU interrupt flags during the break state, write a 0 to the BCFE bit. With BCFE at 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 interrupt flags.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
111
External Interrupt (IRQ)
8.6 IRQ Status and Control Register
The IRQ status and control register (INTSCR) controls and monitors operation of the IRQ module. The
INTSCR:
•
•
•
•
Shows the state of the IRQ flag
Clears the IRQ latch
Masks IRQ interrupt request
Controls triggering sensitivity of the IRQ interrupt pin
Address:
$001D
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 8-3. 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 1 to this write-only bit clears the IRQ latch. ACK always reads as 0. Reset clears ACK.
IMASK — IRQ Interrupt Mask Bit
Writing a 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
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Chapter 9
Keyboard Interrupt Module (KBI)
9.1 Introduction
The keyboard interrupt module (KBI) provides eight independently maskable external interrupts which are
accessible via PTA0–PTA7. When a port pin is enabled for keyboard interrupt function, an internal
pullup/pulldown device is also enabled on the pin.
9.2 Features
Features include:
•
Eight keyboard interrupt pins with separate keyboard interrupt enable bits and one keyboard
interrupt mask
•
•
•
•
•
•
Hysteresis buffers
Programmable edge-only or edge- and level- interrupt sensitivity
Edge detect programmable for rising or falling edges
Level detect programmable for high or low levels
Exit from low-power modes
Pullup/pulldown device automatically configured based on polarity of edge/level selection
9.3 Functional Description
Writing to the KBIE7–KBIE0 bits in the keyboard interrupt enable register independently enables or
disables each port A pin as a keyboard interrupt pin. Enabling a keyboard interrupt pin also enables its
internal pullup/pulldown device. On falling edge or low level selection a pullup device is configured. On
rising edge or high level selection a pulldown device is configured.
•
A falling edge is detected when an enabled keyboard input signal is seen as a 1 (the deasserted
level) during one bus cycle and then a 0 (the asserted level) during the next cycle.
A rising edge is detected when the input signal is seen as a 0 during one bus cycle and then a 1
during the next cycle.
•
A keyboard interrupt is latched when one or more keyboard pins are asserted. The MODEK bit in the
keyboard status and control register controls the triggering mode of the keyboard interrupt.
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Keyboard Interrupt Module (KBI)
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 62,078 BYTES
USER RAM — 2048 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
MONITOR ROM
2-CHANNEL TIMER INTERFACE
MODULE
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure 9-1. Block Diagram Highlighting KBI Block and Pins
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Functional Description
The KBIP7–KBIP0 bits determine the polarity of the keyboard pin detection. These bits along with the
MODEK bit determine whether a logic level (0 or 1) and/or a falling (or rising) edge is being detected.
•
If the keyboard interrupt is edge-sensitive only, a falling (or rising) edge on a keyboard pin does not
latch an interrupt request if another keyboard pin is already asserted. To prevent losing an interrupt
request on one pin because another pin is still asserted, software can disable the latter pin while it
is asserted.
•
If the keyboard interrupt is edge and level sensitive, an interrupt request is present as long as any
keyboard interrupt pin is asserted and the pin is keyboard interrupt enabled.
INTERNAL BUS
VECTOR FETCH
DECODER
ACKK
RESET
1
0
KBD0
VDD
S
KBIE0
KEYF
CLR
TO PULLUP/
PULLDOWN ENABLE
D
Q
SYNCHRONIZER
KBIP0
CK
1
0
IMASKK
KBD7
KEYBOARD
INTERRUPT
REQUEST
S
KBIE7
MODEK
TO PULLUP/
KBIP7
PULLDOWN ENABLE
Figure 9-2. Keyboard Module Block Diagram
Addr.
Register Name
Keyboard Status and Control
Bit 7
6
5
4
3
2
1
Bit 0
MODEK
0
Read:
0
0
0
0
KEYF
0
ACKK
0
IMASKK
$001A
$001B
$0448
Register (INTKBSCR) Write:
See page 118.
Reset:
0
KBIE7
0
0
KBIE6
0
0
KBIE5
0
0
KBIE4
0
0
KBIE3
0
0
KBIE1
0
Read:
Keyboard Interrupt Enable
KBIE2
KBIE0
0
Register (INTKBIER) Write:
See page 119.
Reset:
0
KBIP2
0
Read:
Keyboard Interrupt Polarity
KBIP7
0
KBIP6
0
KBIP5
0
KBIP4
0
KBIP3
0
KBIP1
0
KBIP0
0
Register (INTKBIPR) Write:
See page 119.
Reset:
= Unimplemented
Figure 9-3. I/O Register Summary
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Keyboard Interrupt Module (KBI)
If the MODEK bit is set and depending on the KBIPx bit, the keyboard interrupt pins are both falling (or
rising) edge and low (or high) 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 1 to the
ACKK bit in the keyboard status and control register (INTKBSCR). 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 (or rising) 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 $FFE0 and $FFE1.
Return of all enabled keyboard interrupt pins to 1 (or 0) — As long as any enabled keyboard
interrupt pin is 0 (or 1), the keyboard interrupt remains set.
•
The vector fetch or software clear and the return of all enabled keyboard interrupt pins to 1 (or 0) may
occur in any order.
If the MODEK bit is clear and depending on the KBIPx bit, the keyboard interrupt pin is falling (or rising)
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 0 (or 1).
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.
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 0 for software to read the
pin.
9.4 Keyboard Initialization
When a keyboard interrupt pin is enabled, it takes time for the internal pullup/pulldown device to reach a 1
(or 0). 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 and polarity by setting the appropriate KBIEx bits in the keyboard interrupt
enable register and the KBIPx bits in the keyboard interrupt polarity register.
3. Write to the ACKK bit in the keyboard status and control register to clear any false interrupts.
4. Clear the IMASKK bit.
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Low-Power Modes
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 DDRA bits in data direction
register A.
2. Write 1s (or 0s) to the appropriate port A data register bits.
3. Enable the KBI pins and polarity by setting the appropriate KBIEx bits in the keyboard interrupt
enable register and the KBIPx bits in the keyboard interrupt polarity register.
9.5 Low-Power Modes
The WAIT and STOP instructions put the microcontroller unit (MCU) in low power-consumption standby
modes.
9.5.1 Wait Mode
The keyboard 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.
9.5.2 Stop Mode
The keyboard 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.
9.6 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 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 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 0 to the BCFE bit. With BCFE at 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. See 9.7.1 Keyboard Status and Control Register.
9.7 I/O Registers
These registers control and monitor operation of the keyboard module:
•
•
•
Keyboard status and control register (INTKBSCR)
Keyboard interrupt enable register (INTKBIER)
Keyboard interrupt polarity register (INTKBIPR)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Keyboard Interrupt Module (KBI)
9.7.1 Keyboard Status and Control Register
The keyboard status and control register:
•
•
•
•
Flags keyboard interrupt requests
Acknowledges keyboard interrupt requests
Masks keyboard interrupt requests
Controls keyboard interrupt triggering sensitivity
Address: $001A
Bit 7
0
6
0
5
0
4
0
3
2
1
IMASKK
0
Bit 0
MODEK
0
Read:
Write:
Reset:
KEYF
0
ACKK
0
0
0
0
0
0
= Unimplemented
Figure 9-4. Keyboard Status and Control Register (INTKBSCR)
Bits 7–4 — Not used
These read-only bits always read as 0s.
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 1 to this write-only bit clears the keyboard interrupt request. ACKK always reads as 0. Reset
clears ACKK.
IMASKK — Keyboard Interrupt Mask Bit
Writing a 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 edge and level detect
0 = Keyboard interrupt requests on edges only
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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I/O Registers
9.7.2 Keyboard Interrupt Enable Register
The keyboard interrupt enable register enables or disables each port A pin to operate as a keyboard
interrupt pin.
Address: $001B
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 9-5. Keyboard Interrupt Enable Register (INTKBIER)
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 = PTAx pin enabled as keyboard interrupt pin
0 = PTAx pin not enabled as keyboard interrupt pin
9.7.3 Keyboard Interrupt Polarity Register
The KBIP7–KBIP0 bits determine the polarity of the keyboard pin detection. These bits along with the
MODEK bit determine whether a logic level (0 or 1) and/or a falling (or rising) edge is being detected. The
KBIPx bits also select the pullup resistor (KBIPx = 0) or pulldown resistor (KBIPx = 1) for each enabled
keyboard interrupt pin.
Address: $0448
Bit 7
KBIP7
0
6
KBIP6
0
5
KBIP5
0
4
KBIP4
0
3
KBIP3
0
2
KBIP2
0
1
KBIP1
0
Bit 0
KBIP0
0
Read:
Write:
Reset:
Figure 9-6. Keyboard Interrupt Polarity Register (INTKBIPR)
KBIP7–KBIP0 — Keyboard Interrupt Polarity Bits
Each of these read/write bits enables the polarity of the keyboard interrupt pin. Reset clears the
keyboard interrupt polarity register.
1 = Keyboard polarity is rising edge and/or high level
0 = Keyboard polarity is falling edge and/or low level
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Keyboard Interrupt Module (KBI)
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Chapter 10
Low-Power Modes
10.1 Introduction
The microcontroller (MCU) may enter two low-power modes: wait mode and stop mode. They are
common to all HC08 MCUs and are entered through instruction execution. This section describes how
each module acts in the low-power modes.
10.1.1 Wait Mode
The WAIT instruction puts the MCU in a low-power standby mode in which the central processor unit
(CPU) clock is disabled but the bus clock continues to run. Power consumption can be further reduced by
disabling the low-voltage inhibit (LVI) module through bits in the CONFIG1 register. See Chapter 5
Configuration Register (CONFIG).
10.1.2 Stop Mode
Stop mode is entered when a STOP instruction is executed. The CPU clock is disabled and the bus clock
is disabled if the OSCENINSTOP bit in the CONFIG2 register is a 0. See Chapter 5 Configuration Register
(CONFIG).
10.2 Analog-to-Digital Converter (ADC)
10.2.1 Wait Mode
The analog-to-digital converter (ADC) continues normal operation during 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 ADCH4–ADCH0 bits in the ADC status and
control register before executing the WAIT instruction.
10.2.2 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 after an external interrupt. Allow one
conversion cycle to stabilize the analog circuitry.
10.3 Break Module (BRK)
10.3.1 Wait Mode
The break (BRK) module is active in wait mode. In the break routine, the user can subtract one from the
return address on the stack if the SBSW bit in the break status register is set.
10.3.2 Stop Mode
The break module is inactive in stop mode. The STOP instruction does not affect break module register
states.
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Low-Power Modes
10.4 Central Processor Unit (CPU)
10.4.1 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
•
10.4.2 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.
10.5 Clock Generator Module (CGM)
10.5.1 Wait Mode
The clock generator module (CGM) remains active in wait mode. 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).
Less power-sensitive applications can disengage the PLL without turning it off. Applications that require
the PLL to wake the MCU from wait mode also can deselect the PLL output without turning off the PLL.
10.5.2 Stop Mode
If the OSCENINSTOP bit in the CONFIG2 register is cleared (default), then the STOP instruction disables
the CGM (oscillator and phase-locked loop) and holds low all CGM outputs (CGMXCLK, CGMOUT, and
CGMINT).
If the OSCENINSTOP bit in the CONFIG2 register is set, then the phase locked loop is shut off, but the
oscillator will continue to operate in stop mode.
10.6 Computer Operating Properly Module (COP)
10.6.1 Wait Mode
The COP remains active during wait mode. If COP is enabled, a reset will occur at COP timeout.
10.6.2 Stop Mode
Stop mode turns off the CGMXCLK input to the COP and clears the SIM counter. Service the COP
immediately before entering or after exiting stop mode to ensure a full COP timeout period after entering
or exiting stop mode.
The STOP bit in the CONFIG1 register enables the STOP instruction. To prevent inadvertently turning off
the COP with a STOP instruction, disable the STOP instruction by clearing the STOP bit.
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External Interrupt Module (IRQ)
10.7 External Interrupt Module (IRQ)
10.7.1 Wait Mode
The external interrupt (IRQ) module remains active in wait mode. Clearing the IMASK bit in the IRQ status
and control register enables IRQ CPU interrupt requests to bring the MCU out of wait mode.
10.7.2 Stop Mode
The IRQ module remains active in stop mode. Clearing the IMASK bit in the IRQ status and control
register enables IRQ CPU interrupt requests to bring the MCU out of stop mode.
10.8 Keyboard Interrupt Module (KBI)
10.8.1 Wait Mode
The keyboard interrupt (KBI) 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.
10.8.2 Stop Mode
The keyboard 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.
10.9 Low-Voltage Inhibit Module (LVI)
10.9.1 Wait Mode
If enabled, the low-voltage inhibit (LVI) module remains active in wait mode. If enabled to generate resets,
the LVI module can generate a reset and bring the MCU out of wait mode.
10.9.2 Stop Mode
If enabled, the LVI module remains active in stop mode. If enabled to generate resets, the LVI module
can generate a reset and bring the MCU out of stop mode.
10.10 Enhanced Serial Communications Interface Module (ESCI)
10.10.1 Wait Mode
The enhanced serial communications interface (ESCI), or SCI module for short, module remains active
in wait mode. 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.
10.10.2 Stop Mode
The SCI module is inactive in stop mode. The STOP instruction does not affect SCI register states. SCI
module operation resumes after the MCU exits stop mode.
Because the internal clock is inactive during stop mode, entering stop mode during an SCI transmission
or reception results in invalid data.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Low-Power Modes
10.11 Serial Peripheral Interface Module (SPI)
10.11.1 Wait Mode
The serial peripheral interface (SPI) module remains active in wait mode. 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.
10.11.2 Stop Mode
The SPI module is inactive in stop mode. The STOP instruction does not affect SPI register states. 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.
10.12 Timer Interface Module (TIM1 and TIM2)
10.12.1 Wait Mode
The timer interface modules (TIM) remain active in wait mode. 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.
10.12.2 Stop Mode
The TIM is inactive in stop mode. The STOP instruction does not affect register states or the state of the
TIM counter. TIM operation resumes when the MCU exits stop mode after an external interrupt.
10.13 Timebase Module (TBM)
10.13.1 Wait Mode
The timebase module (TBM) remains active after execution of the WAIT instruction. In wait mode, the
timebase register is not accessible by the CPU.
If the timebase functions are not required during wait mode, reduce the power consumption by stopping
the timebase before enabling the WAIT instruction.
10.13.2 Stop Mode
The timebase module may remain active after execution of the STOP instruction if the oscillator has been
enabled to operate during stop mode through the OSCENINSTOP bit in the CONFIG2 register. The
timebase module can be used in this mode to generate a periodic wakeup from stop mode.
If the oscillator has not been enabled to operate in stop mode, the timebase module will not be active
during stop mode. In stop mode, the timebase register is not accessible by the CPU.
If the timebase functions are not required during stop mode, reduce the power consumption by stopping
the timebase before enabling the STOP instruction.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Exiting Wait Mode
10.14 Exiting Wait Mode
These events restart the CPU clock and load the program counter with the reset vector or with an interrupt
vector:
•
•
•
•
•
•
•
•
External reset — A low on the RST pin resets the MCU and loads the program counter with the
contents of locations $FFFE and $FFFF.
External interrupt — A high-to-low transition on an external interrupt pin (IRQ pin) loads the
program counter with the contents of locations: $FFFA and $FFFB; IRQ pin.
Break interrupt — In emulation mode, a break interrupt loads the program counter with the contents
of $FFFC and $FFFD.
Computer operating properly (COP) module reset — A timeout of the COP counter resets the MCU
and loads the program counter with the contents of $FFFE and $FFFF.
Low-voltage inhibit (LVI) module reset — A power supply voltage below the VTRIPF voltage resets
the MCU and loads the program counter with the contents of locations $FFFE and $FFFF.
Clock generator module (CGM) interrupt — A CPU interrupt request from the CGM loads the
program counter with the contents of $FFF8 and $FFF9.
Keyboard interrupt (KBI) module — A CPU interrupt request from the KBI module loads the
program counter with the contents of $FFE0 and $FFE1.
Timer 1 interface (TIM1) module interrupt — A CPU interrupt request from the TIM1 loads the
program counter with the contents of:
–
–
–
$FFF2 and $FFF3; TIM1 overflow
$FFF4 and $FFF5; TIM1 channel 1
$FFF6 and $FFF7; TIM1 channel 0
•
Timer 2 interface module (TIM2) interrupt — A CPU interrupt request from the TIM2 loads the
program counter with the contents of:
–
–
–
–
–
–
–
$FFEC and $FFED; TIM2 overflow
$FFEE and $FFEF; TIM2 channel 1
$FFF0 and $FFF1; TIM2 channel 0
$FFCC and $FFCD; TIM2 channel 5
$FFCE and $FFCF; TIM2 channel 4
$FFD0 and $FFD1; TIM2 channel 3
$FFD2 and $FFD3; TIM2 channel 2
•
•
Serial peripheral interface (SPI) module interrupt — A CPU interrupt request from the SPI loads
the program counter with the contents of:
–
–
$FFE8 and $FFE9; SPI transmitter
$FFEA and $FFEB; SPI receiver
Serial communications interface (SCI) module interrupt — A CPU interrupt request from the SCI
loads the program counter with the contents of:
–
–
–
$FFE2 and $FFE3; SCI transmitter
$FFE4 and $FFE5; SCI receiver
$FFE6 and $FFE7; SCI receiver error
•
•
Analog-to-digital converter (ADC) module interrupt — A CPU interrupt request from the ADC loads
the program counter with the contents of: $FFDE and $FFDF; ADC conversion complete.
Timebase module (TBM) interrupt — A CPU interrupt request from the TBM loads the program
counter with the contents of: $FFDC and $FFDD; TBM interrupt.
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Low-Power Modes
10.15 Exiting Stop Mode
These events restart the system clocks and load the program counter with the reset vector or with an
interrupt vector:
•
External reset — A low on the RST pin resets the MCU and loads the program counter with the
contents of locations $FFFE and $FFFF.
•
External interrupt — A high-to-low transition on an external interrupt pin loads the program counter
with the contents of locations:
–
–
$FFFA and $FFFB; IRQ pin
$FFE0 and $FFE1; keyboard interrupt pins (low-to-high transition when KBIPx bits are set)
•
•
•
Low-voltage inhibit (LVI) reset — A power supply voltage below the VTRIPF voltage resets the MCU
and loads the program counter with the contents of locations $FFFE and $FFFF.
Break interrupt — In emulation mode, a break interrupt loads the program counter with the contents
of locations $FFFC and $FFFD.
Timebase module (TBM) interrupt — A TBM interrupt loads the program counter with the contents
of locations $FFDC and $FFDD when the timebase counter has rolled over. This allows the TBM
to generate a periodic wakeup from stop mode.
Upon exit from stop mode, the system clocks begin running after an oscillator stabilization delay. A 12-bit
stop recovery counter inhibits the system clocks for 4096 CGMXCLK cycles after the reset or external
interrupt.
The short stop recovery bit, SSREC, in the CONFIG1 register controls the oscillator stabilization delay
during stop recovery. Setting SSREC reduces stop recovery time from 4096 CGMXCLK cycles to 32
CGMXCLK cycles.
NOTE
Use the full stop recovery time (SSREC = 0) in applications that use an
external crystal unless the OSCENINSTOP bit is set.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
126
Freescale Semiconductor
Chapter 11
Low-Voltage Inhibit (LVI)
11.1 Introduction
This section describes the low-voltage inhibit (LVI) module, which monitors the voltage on the VDD pin
and can force a reset when the VDD voltage falls below the LVI trip falling voltage, VTRIPF
.
11.2 Features
Features of the LVI module include:
•
•
•
Programmable LVI reset
Selectable LVI trip voltage
Programmable stop mode operation
11.3 Functional Description
Figure 11-1 shows the structure of the LVI module. 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 VDD voltage. Clearing the LVI reset disable bit, LVIRSTD, enables the LVI
module to generate a reset when VDD falls below a voltage, VTRIPF. Setting the LVI enable in stop mode
bit, LVISTOP, enables the LVI to operate in stop mode. Setting the LVI 5-V or 3-V trip point bit, LVI5OR3,
enables the trip point voltage, VTRIPF, to be configured for 5-V operation. Clearing the LVI5OR3 bit
enables the trip point voltage, VTRIPF, to be configured for 3-V operation. The actual trip points are shown
in Chapter 20 Electrical Specifications.
NOTE
After a power-on reset (POR) the LVI’s default mode of operation is 3 V. If
a 5-V system is used, the user must set the LVI5OR3 bit to raise the trip
point to 5-V operation. Note that this must be done after every power-on
reset since the default will revert back to 3-V mode after each power-on
reset. If the VDD supply is below the 5-V mode trip voltage but above the
3-V mode trip voltage when POR is released, the part will operate because
VTRIPF defaults to 3-V mode after a POR. So, in a 5-V system care must be
taken to ensure that VDD is above the 5-V mode trip voltage after POR is
released.
If the user requires 5-V mode and sets the LVI5OR3 bit after a power-on
reset while the VDD supply is not above the VTRIPR for 5-V mode, the
microcontroller unit (MCU) will immediately go into reset. The LVI in this
case will hold the part in reset until either VDD goes above the rising 5-V trip
point, VTRIPR, which will release reset or VDD decreases to approximately 0
V which will re-trigger the power-on reset and reset the trip point to 3-V
operation.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
127
Low-Voltage Inhibit (LVI)
LVISTOP, LVIPWRD, LVI5OR3, and LVIRSTD are in the configuration register (CONFIG1). See
Figure 5-2. Configuration Register 1 (CONFIG1) for details of the LVI’s configuration bits. Once an LVI
reset occurs, the MCU remains in reset until VDD rises above a voltage, VTRIPR, which causes the MCU
to exit reset. See 14.3.2.5 Low-Voltage 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).
An LVI reset also drives the RST pin low to provide low-voltage protection to external peripheral devices.
VDD
STOP INSTRUCTION
LVISTOP
FROM CONFIG1
FROM CONFIG1
LVIRSTD
LVIPWRD
FROM CONFIG
VDD > LVITrip = 0
LVI RESET
LOW VDD
DETECTOR
VDD ≤ LVITrip = 1
LVIOUT
LVI5OR3
FROM CONFIG1
Figure 11-1. LVI Module Block Diagram
Addr.
Register Name
Bit 7
Read: LVIOUT
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
LVI Status Register
$FE0C
(LVISR) Write:
See page 129.
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 11-2. LVI I/O Register Summary
11.3.1 Polled LVI Operation
In applications that can operate at VDD levels below the VTRIPF level, software can monitor VDD by polling
the LVIOUT bit. In the configuration register, the LVIPWRD bit must be 0 to enable the LVI module, and
the LVIRSTD bit must be 1 to disable LVI resets.
11.3.2 Forced Reset Operation
In applications that require VDD to remain above the VTRIPF level, enabling LVI resets allows the LVI
module to reset the MCU when VDD falls below the VTRIPF level. In the configuration register, the
LVIPWRD and LVIRSTD bits must be cleared to enable the LVI module and to enable LVI resets.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
128
Freescale Semiconductor
LVI Status Register
11.3.3 Voltage Hysteresis Protection
Once the LVI has triggered (by having VDD fall below VTRIPF), the LVI will maintain a reset condition until
VDD rises above the rising trip point voltage, VTRIPR. This prevents a condition in which the MCU is
continually entering and exiting reset if VDD is approximately equal to VTRIPF. VTRIPR is greater than
VTRIPF by the hysteresis voltage, VHYS.
11.3.4 LVI Trip Selection
The LVI5OR3 bit in the configuration register selects whether the LVI is configured for 5-V or 3-V
protection.
NOTE
The microcontroller is guaranteed to operate at a minimum supply voltage.
The trip point (VTRIPF [5 V] or VTRIPF [3 V]) may be lower than this. See
Chapter 20 Electrical Specifications for the actual trip point voltages.
11.4 LVI Status Register
The LVI status register (LVISR) indicates if the VDD voltage was detected below the VTRIPF level.
Address: $FE0C
Bit 7
Read: LVIOUT
Write:
6
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 11-3. LVI Status Register (LVISR)
LVIOUT — LVI Output Bit
This read-only flag becomes set when the VDD voltage falls below the VTRIPF trip voltage (see
Table 11-1). Reset clears the LVIOUT bit.
Table 11-1. LVIOUT Bit Indication
VDD
LVIOUT
VDD > VTRIPR
0
VDD < VTRIPF
1
VTRIPF < VDD < VTRIPR
Previous value
11.5 LVI Interrupts
The LVI module does not generate interrupt requests.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
129
Low-Voltage Inhibit (LVI)
11.6 Low-Power Modes
The STOP and WAIT instructions put the MCU in low power-consumption standby modes.
11.6.1 Wait Mode
If enabled, the LVI module remains active in wait mode. If enabled to generate resets, the LVI module can
generate a reset and bring the MCU out of wait mode.
11.6.2 Stop Mode
If enabled in stop mode (LVISTOP bit in the configuration register is set), the LVI module remains active
in stop mode. If enabled to generate resets, the LVI module can generate a reset and bring the MCU out
of stop mode.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
130
Freescale Semiconductor
Chapter 12
Input/Output (I/O) Ports
12.1 Introduction
Bidirectional input-output (I/O) pins form seven parallel ports. All I/O pins are programmable as inputs or
outputs. All individual bits within port A, port C, port D and port F are software configurable with pullup
devices if configured as input port bits. The pullup devices are automatically and dynamically disabled
when a port bit is switched to output mode.
12.2 Unused Pin Termination
Input pins and I/O port pins that are not used in the application must be terminated. This prevents excess
current caused by floating inputs, and enhances immunity during noise or transient events. Termination
methods include:
1. Configuring unused pins as outputs and driving high or low;
2. Configuring unused pins as inputs and enabling internal pull-ups;
3. Configuring unused pins as inputs and using external pull-up or pull-down resistors.
Never connect unused pins directly to VDD or VSS
.
Since some general-purpose I/O pins are not available on all packages, these pins must be terminated
as well. Either method 1 or 2 above are appropriate.
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Port A Data Register
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
$0000
(PTA) Write:
See page 135.
Reset:
Read:
Unaffected by reset
Port B Data Register
PTB7
1
PTB6
PTC6
PTB5
PTC5
PTB4
PTB3
PTB2
PTC2
PTB1
PTC1
PTB0
PTC0
$0001
$0002
(PTB) Write:
See page 138.
Reset:
Read:
Unaffected by reset
Port C Data Register
PTC4
PTC3
(PTC) Write:
See page 140.
Reset:
Unaffected by reset
= Unimplemented
Figure 12-1. I/O Port Register Summary (Sheet 1 of 3)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
131
Input/Output (I/O) Ports
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Port D Data Register
PTD7
PTD6
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
$0003
(PTD) Write:
See page 142.
Reset:
Read:
Unaffected by reset
Data Direction Register A
DDRA7
0
DDRA6
0
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
$0004
$0005
$0006
$0007
$0008
$000C
$000D
$000E
$000F
(DDRA) Write:
See page 136.
Reset:
Read:
0
DDRB5
0
0
DDRB4
0
0
DDRB3
0
0
DDRB2
0
0
DDRB1
0
0
DDRB0
0
Data Direction Register B
DDRB7
DDRB6
0
(DDRB) Write:
See page 138.
Reset:
Read:
0
0
Data Direction Register C
DDRC6
0
DDRC5
0
DDRC4
0
DDRC3
0
DDRC2
0
DDRC1
0
DDRC0
0
(DDRC) Write:
See page 140.
Reset:
Read:
0
Data Direction Register D
DDRD7
DDRD6
DDRD5
0
DDRD4
0
DDRD3
0
DDRD2
0
DDRD1
0
DDRD0
0
(DDRD) Write:
See page 143.
Reset:
Read:
0
0
0
0
Port E Data Register
PTE5
PTE4
PTE3
PTE2
PTE1
PTE0
(PTE) Write:
See page 145.
Reset:
Read:
Unaffected by reset
0
0
0
0
Data Direction Register E
DDRE5
0
DDRE4
0
DDRE3
0
DDRE2
0
DDRE1
0
DDRE0
0
(DDRE) Write:
See page 146.
Reset:
Read:
Port A Input Pullup Enable
PTAPUE7 PTAPUE6 PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE1 PTAPUE0
Register (PTAPUE) Write:
See page 137.
Reset:
0
0
0
0
0
0
0
0
0
Read:
Port C Input Pullup Enable
PTCPUE6 PTCPUE5 PTCPUE4 PTCPUE3 PTCPUE2 PTCPUE1 PTCPUE0
Register (PTCPUE) Write:
See page 142.
Reset:
0
0
0
0
0
0
0
0
Read:
Port D Input Pullup Enable
PTDPUE7 PTDPUE6 PTDPUE5 PTDPUE4 PTDPUE3 PTDPUE2 PTDPUE1 PTDPUE0
Register (PTDPUE) Write:
See page 145.
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 12-1. I/O Port Register Summary (Sheet 2 of 3)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
132
Unused Pin Termination
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:
Port F Data Register
(PTF)
PTF7
PTF6
PTF5
PTF4
PTAF3
PTF2
PTF1
PTF0
$0440
See page 147.
Unaffected by reset
Port G Data Register
(PTG)
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2
PTG1
PTG0
$0441
$0444
$0445
See page 149.
Unaffected by reset
Data Direction Register F
(DDRF)
DDRF7
DDRF6
DDRF5
DDRF4
DDRF3
DDRF2
DDRF1
DDRF0
See page 148.
0
DDRG7
0
0
DDRG6
0
0
DDRG5
0
0
DDRG4
0
0
DDRG3
0
0
DDRG2
0
0
DDRG1
0
0
DDRG0
0
Data Direction Register G
(DDRG)
See page 150.
= Unimplemented
Figure 12-1. I/O Port Register Summary (Sheet 3 of 3)
Table 12-1. Port Control Register Bits Summary
Port Bit
DDR
Module Control
KBIE0
Module Control
Pin
0
1
2
DDRA0
DDRA1
DDRA2
DDRA3
DDRA4
DDRA5
DDRA6
DDRA7
DDRB0
DDRB1
DDRB2
DDRB3
DDRB4
DDRB5
DDRB6
DDRB7
PTA0/KBD0/AD8
PTA1/KBD1/AD9
PTA2/KBD2/AD10
PTA3/KBD3/AD11
PTA4/KBD4/AD12
PTA5/KBD5/AD13
PTA6/KBD6/AD14
PTA7/KBD7/AD15
PTB0/AD0
KBIE1
KBIE2
3
KBIE3
A
4
KBD
ADC[15:8]
ADCH4–ADCH0
KBIE4
5
6
7
0
1
2
KBIE5
KBIE6
KBIE7
PTB1/AD1
PTB2/AD2
3
PTB3/AD3
B
4
ADC
ADCH4–ADCH0
—
—
PTB4/AD4
5
6
7
PTB5/AD5
PTB6/AD6
PTB7/AD7
Continued on next page
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
133
Input/Output (I/O) Ports
Table 12-1. Port Control Register Bits Summary (Continued)
Port Bit
DDR
Module Control
Module Control
Pin
PTC0
0
1
2
DDRC0
DDRC1
DDRC2
DDRC3
DDRC4
DDRC5
DDRC6
DDRD0
DDRD1
DDRD2
DDRD3
DDRD4
DDRD5
DDRD6
DDRD7
DDRE0
DDRE1
DDRE2
DDRE3
DDRE4
DDRE5
DDRF0
DDRF1
DDRF2
DDRF3
DDRF4
DDRF5
DDRF6
DDRF7
DDRG0
DDRG1
DDRG2
DDRG3
DDRG4
DDRG5
DDRG6
DDRG7
PTC1
PTC2
C
3
4
5
6
0
1
2
3
4
5
6
7
0
1
2
3
4
5
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
—
—
PTC3
PTC4
PTC5
PTC6
PTD0/SS/MCLK
PTD1/MISO
PTD2/MOSI
PTD3/SPSCK
PTD4/T1CH0
PTD5/T1CH1
PTD6/T2CH0
PTD7/T2CH1
PTE0/TxD
PTE1/RxD
PTE2
SPI
SPE
D
E
F
—
—
—
—
—
—
ELS0B:ELS0A
TIM1
TIM2
SCI
ELS1B:ELS1A
ELS0B:ELS0A
ELS1B:ELS1A
ENSCI
PTE3
PTE4
PTE5
PTF0
PTF1
PTF2
PTF3
ELS2B:ELS2A
ELS3B:ELS3A
ELS4B:ELS4A
ELS5B:ELS5A
PTF4/T2CH2
PTF5/T2CH3
PTF6/T2CH4
PTF7/T2CH5
PTG0/AD16
PTG1/AD17
PTG2/AD18
PTG3/AD19
PTG4/AD20
PTG5/AD21
PTG6/AD22
PTG7/AD23
TIM2
G
ADC
ADCH[23:16]
—
—
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
134
Port A
12.3 Port A
Port A is an 8-bit special-function port that shares all eight of its pins with the keyboard interrupt (KBI)
module and the ADC module. Port A also has software configurable pullup devices if configured as an
input port.
12.3.1 Port A Data Register
The port A data register (PTA) 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:
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
Reset:
Unaffected by reset
Alternate Function:
Alternate Function:
KBD7
AD15
KBD6
AD14
KBD5
AD13
KBD4
AD12
KBD3
AD11
KBD2
AD10
KBD1
AD9
KBD0
AD8
Figure 12-2. Port A Data Register (PTA)
PTA7–PTA0 — 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.
KBD7–KBD0 — Keyboard Inputs
The keyboard interrupt enable bits, KBIE7–KBIE0, in the keyboard interrupt control register (KBICR)
enable the port A pins as external interrupt pins. See Chapter 9 Keyboard Interrupt Module (KBI)
AD15–AD8 — Analog-to-Digital Input Bits
AD15–AD8 are pins used for the input channels to the analog-to-digital converter module. The channel
select bits in the ADC status and control register define which port A pin will be used as an ADC input
and overrides any control from the port I/O logic by forcing that pin as the input to the analog circuitry.
NOTE
Care must be taken when reading port A while applying analog voltages to
AD15–AD8 pins. If the appropriate ADC channel is not enabled, excessive
current drain may occur if analog voltages are applied to the
PTAx/KBDx/ADx pin, while PTA is read as a digital input during the CPU
read cycle. Those ports not selected as analog input channels are
considered digital I/O ports.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
135
Input/Output (I/O) Ports
12.3.2 Data Direction Register A
Data direction register A (DDRA) determines whether each port A pin is an input or an output. Writing a 1
to a DDRA bit enables the output buffer for the corresponding port A pin; a 0 disables the output buffer.
Address:
$0004
Bit 7
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:
DDRA7
0
Figure 12-3. Data Direction Register A (DDRA)
DDRA7–DDRA0 — Data Direction Register A Bits
These read/write bits control port A data direction. Reset clears DDRA7–DDRA0, 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 12-4 shows the port A I/O logic.
When bit DDRAx is a 1, reading address $0000 reads the PTAx data latch. When bit DDRAx is a 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 12-2 summarizes the operation of the port A pins.
VDD
PTAPUEx
READ DDRA ($0004)
INTERNAL
WRITE DDRA ($0004)
PULLUP
DEVICE
DDRAx
RESET
WRITE PTA ($0000)
PTAx
PTAx
READ PTA ($0000)
Figure 12-4. Port A I/O Circuit
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
136
Port A
Table 12-2. Port A Pin Functions
Accesses to DDRA
Read/Write
Accesses to PTA
Read Write
PTAPUE
Bit
DDRA
Bit
PTA
Bit
I/O Pin
Mode
(2)
X(1)
X
PTA7–PTA0(3)
1
0
DDRA7–DDRA0
Pin
Input, VDD
Input, Hi-Z(4)
Output
PTA7–PTA0(3)
PTA7–PTA0
0
0
1
DDRA7–DDRA0
DDRA7–DDRA0
Pin
X
X
PTA7–PTA0
1. X = Don’t care
2. I/O pin pulled up to VDD by internal pullup device
3. Writing affects data register, but does not affect input.
4. Hi-Z = High impedance
12.3.3 Port A Input Pullup Enable Register
The port A input pullup enable register (PTAPUE) contains a software configurable pullup device for each
of the eight port A pins. Each bit is individually configurable and requires that the data direction register,
DDRA, bit be configured as an input. Each pullup is automatically and dynamically disabled when a port
bit’s DDRA is configured for output mode.
NOTE
Pullup or pulldown resistors are automatically selected for keyboard
interrupt pins depending on the bit settings in the keyboard interrupt polarity
register (INTKBIPR) see 9.7.3 Keyboard Interrupt Polarity Register.
Address:
$000D
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTAPUE7 PTAPUE6 PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE1 PTAPUE0
0
0
0
0
0
0
0
0
Figure 12-5. Port A Input Pullup Enable Register (PTAPUE)
PTAPUE7–PTAPUE0 — Port A Input Pullup Enable Bits
These writable bits are software programmable to enable pullup devices on an input port bit.
1 = Corresponding port A pin configured to have internal pullup
0 = Corresponding port A pin has internal pullup disconnected
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
137
Input/Output (I/O) Ports
12.4 Port B
Port B is an 8-bit special-function port that shares all eight of its pins with the analog-to-digital converter
(ADC) module.
12.4.1 Port B Data Register
The port B data register (PTB) contains a data latch for each of the eight port pins.
Address:
$0001
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
PTB7
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Reset:
Unaffected by reset
AD4 AD3
Alternate Function:
AD7
AD6
AD5
AD2
AD1
AD0
Figure 12-6. Port B Data Register (PTB)
PTB7–PTB0 — 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.
AD7–AD0 — Analog-to-Digital Input Bits
AD7–AD0 are pins used for the input channels to the analog-to-digital converter module. The channel
select bits in the ADC status and control register define which port B pin will be used as an ADC input
and overrides any control from the port I/O logic by forcing that pin as the input to the analog circuitry.
NOTE
Care must be taken when reading port B while applying analog voltages to
AD7–AD0 pins. If the appropriate ADC channel is not enabled, excessive
current drain may occur if analog voltages are applied to the PTBx/ADx pin,
while PTB is read as a digital input during the CPU read cycle. Those ports
not selected as analog input channels are considered digital I/O ports.
12.4.2 Data Direction Register B
Data direction register B (DDRB) determines whether each port B pin is an input or an output. Writing a 1
to a DDRB bit enables the output buffer for the corresponding port B pin; a 0 disables the output buffer.
Address:
$0005
Bit 7
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:
DDRB7
0
Figure 12-7. Data Direction Register B (DDRB)
DDRB7–DDRB0 — Data Direction Register B Bits
These read/write bits control port B data direction. Reset clears DDRB7–DDRB0, configuring all port
B pins as inputs.
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
138
Freescale Semiconductor
Port B
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 12-8 shows the port B I/O logic.
When bit DDRBx is a 1, reading address $0001 reads the PTBx data latch. When bit DDRBx is a 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. Table 12-3 summarizes the operation of the port B pins.
READ DDRB ($0005)
WRITE DDRB ($0005)
DDRBx
RESET
WRITE PTB ($0001)
PTBx
PTBx
READ PTB ($0001)
Figure 12-8. Port B I/O Circuit
Table 12-3. Port B Pin Functions
Accesses to DDRB
Read/Write
Accesses to PTB
DDRB
Bit
PTB
Bit
I/O Pin
Mode
Read
Write
X(1)
X
Input, Hi-Z(2)
Output
PTB7–PTB0(3)
PTB7–PTB0
0
1
DDRB7–DDRB0
Pin
DDRB7–DDRB0
PTB7–PTB0
1. X = Don’t care
2. Hi-Z = High impedance
3. Writing affects data register, but does not affect input.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
139
Input/Output (I/O) Ports
12.5 Port C
Port C is a 7-bit, general-purpose bidirectional I/O port. Port C also has software configurable pullup
devices if configured as an input port.
12.5.1 Port C Data Register
The port C data register (PTC) contains a data latch for each of the seven port C pins.
NOTE
Bit 6 through bit 2 of PTC are not available in the 32-pin LQFP package.
Address:
$0002
Bit 7
1
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
Unaffected by reset
= Unimplemented
Figure 12-9. Port C Data Register (PTC)
PTC6–PTC0 — 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.
12.5.2 Data Direction Register C
Data direction register C (DDRC) determines whether each port C pin is an input or an output. Writing a
1 to a DDRC bit enables the output buffer for the corresponding port C pin; a 0 disables the output buffer.
Address:
$0006
Bit 7
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:
0
= Unimplemented
Figure 12-10. Data Direction Register C (DDRC)
DDRC6–DDRC0 — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears DDRC6–DDRC0, 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Port C
Figure 12-11 shows the port C I/O logic.
When bit DDRCx is a 1, reading address $0002 reads the PTCx data latch. When bit DDRCx is a 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 12-4 summarizes the operation of the port C pins.
VDD
PTCPUEx
READ DDRC ($0006)
INTERNAL
WRITE DDRC ($0006)
PULLUP
DEVICE
DDRCx
RESET
WRITE PTC ($0002)
PTCx
PTCx
READ PTC ($0002)
Figure 12-11. Port C I/O Circuit
Table 12-4. Port C Pin Functions
Accesses to DDRC
Read/Write
Accesses to PTC
PTCPUE
Bit
DDRC
Bit
PTC
Bit
I/O Pin
Mode
Read
Write
(2)
X(1)
X
PTC6–PTC0(3)
1
0
DDRC6–DDRC0
Pin
Input, VDD
Input, Hi-Z(4)
Output
PTC6–PTC0(3)
PTC6–PTC0
0
0
1
DDRC6–DDRC0
DDRC6–DDRC0
Pin
X
X
PTC6–PTC0
1. X = Don’t care
2. I/O pin pulled up to VDD by internal pullup device.
3. Writing affects data register, but does not affect input.
4. Hi-Z = High impedance
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
141
Input/Output (I/O) Ports
12.5.3 Port C Input Pullup Enable Register
The port C input pullup enable register (PTCPUE) contains a software configurable pullup device for each
of the seven port C pins. Each bit is individually configurable and requires that the data direction register,
DDRC, bit be configured as an input. Each pullup is automatically and dynamically disabled when a port
bit’s DDRC is configured for output mode.
Address:
$000E
Bit 7
0
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTCPUE6 PTCPUE5 PTCPUE4 PTCPUE3 PTCPUE2 PTCPUE1 PTCPUE0
0
0
0
0
0
0
0
0
= Unimplemented
Figure 12-12. Port C Input Pullup Enable Register (PTCPUE)
PTCPUE6–PTCPUE0 — Port C Input Pullup Enable Bits
These writable bits are software programmable to enable pullup devices on an input port bit.
1 = Corresponding port C pin configured to have internal pullup
0 = Corresponding port C pin internal pullup disconnected
12.6 Port D
Port D is an 8-bit special-function port that shares four of its pins with the serial peripheral interface (SPI)
module and four of its pins with two timer interface (TIM1 and TIM2) modules. Port D also has software
configurable pullup devices if configured as an input port. PTD0 is shared with the MCLK output.
12.6.1 Port D Data Register
The port D data register (PTD) 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
T1CH0 SPSCK
Alternate Function: T2CH1
T2CH0
T1CH1
MOSI
MISO
SS
MCLK
Figure 12-13. Port D Data Register (PTD)
PTD7–PTD0 — 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.
T2CH1 and T2CH0 — Timer 2 Channel I/O Bits
The PTD5/T2CH1–PTD4/T2CH0 pins are the TIM2 input capture/output compare pins. The edge/level
select bits, ELSxB:ELSxA, determine whether the PTD7/T2CH1–PTD6/T2CH0 pins are timer channel
I/O pins or general-purpose I/O pins. See Chapter 17 Timer Interface Module (TIM1) and Chapter 18
Timer Interface Module (TIM2).
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Port D
T1CH1 and T1CH0 — Timer 1 Channel I/O Bits
The PTD7/T1CH1–PTD6/T1CH0 pins are the TIM1 input capture/output compare pins. The edge/level
select bits, ELSxB and ELSxA, determine whether the PTD7/T1CH1–PTD6/T1CH0 pins are timer
channel I/O pins or general-purpose I/O pins. See Chapter 17 Timer Interface Module (TIM1) and
Chapter 18 Timer Interface Module (TIM2).
SPSCK — SPI Serial Clock
The PTD3/SPSCK pin is the serial clock input of the SPI module. When the SPE bit is clear, the
PTD3/SPSCK pin is available for general-purpose I/O.
MOSI — Master Out/Slave In
The PTD2/MOSI pin is the master out/slave in terminal of the SPI module. When the SPE bit is clear,
the PTD2/MOSI pin is available for general-purpose I/O.
MISO — Master In/Slave Out
The PTD1/MISO pin is the master in/slave out terminal of the SPI module. When the SPI enable bit,
SPE, is clear, the SPI module is disabled, and the PTD1/MISO pin is available for general-purpose I/O.
SS — Slave Select
The PTD0/SS pin is the slave select input of the SPI module. When the SPE bit is clear, or when the
SPI master bit, SPMSTR, is set, the PTD0/SS pin is available for general-purpose I/O. When the SPI
is enabled, the DDRD0 bit in data direction register D (DDRD) has no effect on the PTD0/SS pin.
Data direction register D (DDRD) does not affect the data direction of port D pins that are being used by
the SPI module. However, the DDRD bits always determine whether reading port D returns the states of
the latches or the states of the pins. See Table 12-5.
12.6.2 Data Direction Register D
Data direction register D (DDRD) determines whether each port D pin is an input or an output. Writing a
1 to a DDRD bit enables the output buffer for the corresponding port D pin; a 0 disables the output buffer.
Address:
$0007
Bit 7
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:
DDRD7
0
Figure 12-14. Data Direction Register D (DDRD)
DDRD7–DDRD0 — Data Direction Register D Bits
These read/write bits control port D data direction. Reset clears DDRD7–DDRD0, 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 12-15 shows the port D I/O logic.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
143
Input/Output (I/O) Ports
When bit DDRDx is a 1, reading address $0003 reads the PTDx data latch. When bit DDRDx is a 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 12-5 summarizes the operation of the port D pins.
VDD
PTDPUEx
READ DDRD ($0007)
INTERNAL
WRITE DDRD ($0007)
PULLUP
DEVICE
DDRDx
RESET
WRITE PTD ($0003)
PTDx
PTDx
READ PTD ($0003)
Figure 12-15. Port D I/O Circuit
Table 12-5. Port D Pin Functions
Accesses to DDRD
Read/Write
Accesses to PTD
PTDPUE
Bit
DDRD
Bit
PTD
Bit
I/O Pin
Mode
Read
Write
(2)
X(1)
X
PTD7–PTD0(3)
1
0
DDRD7–DDRD0
Pin
Input, VDD
Input, Hi-Z(4)
Output
PTD7–PTD0(3)
PTD7–PTD0
0
0
1
DDRD7–DDRD0
DDRD7–DDRD0
Pin
X
X
PTD7–PTD0
1. X = Don’t care
2. I/O pin pulled up to VDD by internal pullup device.
3. Writing affects data register, but does not affect input.
4. Hi-Z = High imp[edance
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
144
Port E
12.6.3 Port D Input Pullup Enable Register
The port D input pullup enable register (PTDPUE) contains a software configurable pullup device for each
of the eight port D pins. Each bit is individually configurable and requires that the data direction register,
DDRD, bit be configured as an input. Each pullup is automatically and dynamically disabled when a port
bit’s DDRD is configured for output mode.
Address:
$000F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTDPUE7 PTDPUE6 PTDPUE5 PTDPUE4 PTDPUE3 PTDPUE2 PTDPUE1 PTDPUE0
0
0
0
0
0
0
0
0
Figure 12-16. Port D Input Pullup Enable Register (PTDPUE)
PTDPUE7–PTDPUE0 — Port D Input Pullup Enable Bits
These writable bits are software programmable to enable pullup devices on an input port bit.
1 = Corresponding port D pin configured to have internal pullup
0 = Corresponding port D pin has internal pullup disconnected
12.7 Port E
Port E is a 6-bit special-function port that shares two of its pins with the enhanced serial communications
interface (ESCI) module.
12.7.1 Port E Data Register
The port E data register contains a data latch for each of the six port E pins.
Address:
$0008
Bit 7
0
6
0
5
4
3
2
1
Bit 0
Read:
Write:
PTE5
PTE4
PTE3
PTE2
PTE1
PTE0
Reset:
Unaffected by reset
Alternate Function:
RxD
TxD
= Unimplemented
Figure 12-17. Port E Data Register (PTE)
PTE5–PTE0 — 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.
NOTE
Data direction register E (DDRE) does not affect the data direction of port
E pins that are being used by the ESCI module. However, the DDRE bits
always determine whether reading port E returns the states of the latches
or the states of the pins. See Table 12-6.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Input/Output (I/O) Ports
RxD — SCI Receive Data Input
The PTE1/RxD pin is the receive data input for the ESCI module.
When the enable SCI bit, ENSCI, is clear, the ESCI module is disabled, and the PTE1/RxD pin is
available for general-purpose I/O. See Chapter 13 Enhanced Serial Communications Interface (ESCI)
Module.
TxD — SCI Transmit Data Output
The PTE0/TxD pin is the transmit data output for the ESCI module. When the enable SCI bit, ENSCI,
is clear, the ESCI module is disabled, and the PTE0/TxD pin is available for general-purpose I/O. See
Chapter 13 Enhanced Serial Communications Interface (ESCI) Module.
12.7.2 Data Direction Register E
Data direction register E (DDRE) determines whether each port E pin is an input or an output. Writing a
1 to a DDRE bit enables the output buffer for the corresponding port E pin; a 0 disables the output buffer.
Address:
$000C
Bit 7
0
6
0
5
DDRE5
0
4
DDRE4
0
3
DDRE3
0
2
DDRE2
0
1
DDRE1
0
Bit 0
DDRE0
0
Read:
Write:
Reset:
0
0
= Unimplemented
Figure 12-18. Data Direction Register E (DDRE)
DDRE5–DDRE0 — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears DDRE5–DDRE0, 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 12-19 shows the port E I/O logic.
When bit DDREx is a 1, reading address $0008 reads the PTEx data latch. When bit DDREx is a 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 12-6 summarizes the operation of the port E pins.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Port F
READ DDRE ($000C)
WRITE DDRE ($000C)
DDREx
PTEx
RESET
WRITE PTE ($0008)
READ PTE ($0008)
PTEx
Figure 12-19. Port E I/O Circuit
Table 12-6. Port E Pin Functions
Accesses to DDRE
Read/Write
Accesses to PTE
DDRE
Bit
PTE
Bit
I/O Pin
Mode
Read
Write
X(1)
X
Input, Hi-Z(2)
Output
PTE5–PTE0(3)
PTE5–PTE0
0
1
DDRE5–DDRE0
Pin
DDRE5–DDRE0
PTE5–PTE0
1. X = Don’t care
2. Hi-Z = High impedance
3. Writing affects data register, but does not affect input.
12.8 Port F
Port F is an 8-bit special-function port that shares four of its pins with the timer interface (TIM2) module.
12.8.1 Port F Data Register
The port F data register (PTF) contains a data latch for each of the eight port F pins.
Address:
$0440
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTF7
PTF6
PTF5
PTF4
PTF3
PTF2
PTF1
PTF0
Unaffected by reset
T2CH2
Alternate Function: T2CH5
T2CH4
T2CH3
= Unimplemented
Figure 12-20. Port F Data Register (PTF)
PTF7–PTF0 — 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
147
Input/Output (I/O) Ports
T2CH5–T2CH2 — Timer 2 Channel I/O Bits
The PTF7/T2CH5–PTF4/T2CH2 pins are the TIM2 input capture/output compare pins. The edge/level
select bits, ELSxB:ELSxA, determine whether the PTF7/T2CH5–PTF4/T2CH2 pins are timer channel
I/O pins or general-purpose I/O pins. See Chapter 17 Timer Interface Module (TIM1) and Chapter 18
Timer Interface Module (TIM2).
12.8.2 Data Direction Register F
Data direction register F (DDRF) determines whether each port F pin is an input or an output. Writing a 1
to a DDRF bit enables the output buffer for the corresponding port F pin; a 0 disables the output buffer.
Address:
$0444
Bit 7
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:
DDRF7
0
Figure 12-21. Data Direction Register F (DDRF)
DDRF7–DDRF0 — Data Direction Register F Bits
These read/write bits control port F data direction. Reset clears DDRF7–DDRF0, 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 12-22 shows the port F I/O logic.
READ DDRF ($0444)
WRITE DDRF ($0444)
DDRFx
RESET
WRITE PTF ($0440)
PTFx
PTFx
READ PTD ($0440)
Figure 12-22. Port F I/O Circuit
When bit DDRFx is a 1, reading address $0440 reads the PTFx data latch. When bit DDRFx is a 0,
reading address $0440 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 12-7 summarizes the operation of the port F pins.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Port G
Table 12-7. Port F Pin Functions
Accesses to DDRF
Read/Write
Accesses to PTF
WritE
DDRF
Bit
PTF
Bit
I/O Pin
Mode
Read
X(1)
X
Input, Hi-Z(2)
Output
PTF7–PTF0(3)
PTF7–PTF0
0
1
DDRF7–DDRF0
Pin
DDRF7–DDRF0
PTF7–PTF0
1. X = Don’t care
2. Hi-Z = High impedance
3. Writing affects data register, but does not affect input.
12.9 Port G
Port G is an 8-bit special-function port that shares all eight of its pins with the analog-to-digital converter
(ADC) module.
12.9.1 Port G Data Register
The port G data register (PTG) contains a data latch for each of the eight port pins.
Address:
$0441
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2
PTG1
PTG0
Reset:
Unaffected by reset
AD20 AD19
Alternate Function:
AD23
AD22
AD21
AD18
AD17
AD16
Figure 12-23. Port G Data Register (PTG)
PTG7–PTG0 — Port G Data Bits
These read/write bits are software-programmable. Data direction of each port G pin is under the control
of the corresponding bit in data direction register G. Reset has no effect on port G data.
AD23–AD16 — Analog-to-Digital Input Bits
AD23–AD16 are pins used for the input channels to the analog-to-digital converter module. The
channel select bits in the ADC status and control register define which port G pin will be used as an
ADC input and overrides any control from the port I/O logic by forcing that pin as the input to the analog
circuitry.
NOTE
Care must be taken when reading port G while applying analog voltages to
AD23–AD16 pins. If the appropriate ADC channel is not enabled, excessive
current drain may occur if analog voltages are applied to the PTGx/ADx pin,
while PTG is read as a digital input during the CPU read cycle. Those ports
not selected as analog input channels are considered digital I/O ports.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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Input/Output (I/O) Ports
12.9.2 Data Direction Register G
Data direction register G (DDRG) determines whether each port G pin is an input or an output. Writing a 1
to a DDRG bit enables the output buffer for the corresponding port G pin; a 0 disables the output buffer.
Address:
$0445
Bit 7
6
DDRG6
0
5
DDRG5
0
4
DDRG4
0
3
DDRG3
0
2
DDRG2
0
1
DDRG1
0
Bit 0
DDRG0
0
Read:
Write:
Reset:
DDRG7
0
Figure 12-24. Data Direction Register G (DDRG)
DDRG7–DDRG0 — Data Direction Register G Bits
These read/write bits control port G data direction. Reset clears DDRG7–DDRG0], configuring all port
G pins as inputs.
1 = Corresponding port G pin configured as output
0 = Corresponding port G pin configured as input
NOTE
Avoid glitches on port G pins by writing to the port G data register before
changing data direction register G bits from 0 to 1.
Figure 12-25 shows the port G I/O logic.
READ DDRG ($0445)
WRITE DDRG ($0445)
DDRGx
RESET
WRITE PTG ($0441)
PTGx
PTGx
READ PTG ($0441)
Figure 12-25. Port G I/O Circuit
When bit DDRGx is a 1, reading address $0441 reads the PTGx data latch. When bit DDRGx is a 0,
reading address $0441 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 12-8 summarizes the operation of the port G pins.
Table 12-8. Port G Pin Functions
Accesses to DDRG
Read/Write
Accesses to PTG
Write
DDRG
Bit
PTG
Bit
I/O Pin
Mode
Read
Pin
X(1)
X
Input, Hi-Z(2)
Output
PTG7–PTG0(3)
PTG7–PTG0
0
1
DDRG7–DDRG0
DDRG7–DDRG0
PTG7–PTG0
1. X = Don’t care
2. Hi-Z = High impedance
3. Writing affects data register, but does not affect input.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Chapter 13
Enhanced Serial Communications Interface (ESCI) Module
13.1 Introduction
The enhanced serial communications interface (ESCI) module allows asynchronous communications
with peripheral devices and other microcontroller units (MCU).
13.2 Features
Features include:
•
•
•
•
•
•
•
•
Full-duplex operation
Standard mark/space non-return-to-zero (NRZ) format
Programmable baud rates
Programmable 8-bit or 9-bit character length
Separately enabled transmitter and receiver
Separate receiver and transmitter central processor unit (CPU) interrupt requests
Programmable transmitter output polarity
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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
151
Enhanced Serial Communications Interface (ESCI) Module
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 62,078 BYTES
USER RAM — 2048 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
MONITOR ROM
2-CHANNEL TIMER INTERFACE
MODULE
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure 13-1. Block Diagram Highlighting ESCI Block and Pins
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
152
Freescale Semiconductor
Pin Name Conventions
13.3 Pin Name Conventions
The generic names of the ESCI input/output (I/O) pins are:
•
•
RxD (receive data)
TxD (transmit data)
ESCI I/O lines are implemented by sharing parallel I/O port pins. The full name of an ESCI input or output
reflects the name of the shared port pin. Table 13-1 shows the full names and the generic names of the
ESCI 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
PTE1/RxD
PTE0/TxD
13.4 Functional Description
Figure 13-3 shows the structure of the ESCI module. The ESCI allows full-duplex, asynchronous, NRZ
serial communication between the MCU and remote devices, including other MCUs. The transmitter and
receiver of the ESCI operate independently, although they use the same baud rate generator. During
normal operation, the CPU monitors the status of the ESCI, writes the data to be transmitted, and
processes received data.
The baud rate clock source for the ESCI can be selected via the configuration bit, SCIBDSRC, of the
CONFIG2 register ($001E)
For reference, a summary of the ESCI module input/output registers is provided in Figure 13-4.
13.4.1 Data Format
The SCI uses the standard non-return-to-zero mark/space data format illustrated in Figure 13-2.
PARITY
8-BIT DATA FORMAT
(BIT M IN SCC1 CLEAR)
OR DATA
BIT
NEXT
START
BIT
START
BIT
BIT 0
BIT 0
BIT 1
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5 BIT 6
BIT 7
STOP
BIT
PARITY
OR DATA
BIT
9-BIT DATA FORMAT
(BIT M IN SCC1 SET)
NEXT
START
BIT
START
BIT
BIT 2
BIT 3
BIT 4
BIT 5 BIT 6
BIT 7
BIT 8
STOP
BIT
Figure 13-2. SCI Data Formats
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
153
Enhanced Serial Communications Interface (ESCI) Module
INTERNAL BUS
ESCI DATA
REGISTER
ESCI DATA
REGISTER
RxD
SCI_TxD
TxD
RECEIVE
SHIFT REGISTER
TRANSMIT
SHIFT REGISTER
RxD
BUS CLOCK
TXINV
LINR
SCTIE
TCIE
SCRIE
ILIE
R8
T8
SL
ACLK BIT
IN SCIACTL
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
BUS
CLOCK
LINT
ENSCI
WAKE
ILTY
PEN
PTY
ENHANCED
PRESCALER
CGMXCLK
PRE-
BAUD RATE
÷ 4
SCALER GENERATOR
SL
DATA SELECTION
CONTROL
÷ 16
SL = 1 -> SCI_CLK = BUSCLK
SL = 0 -> SCI_CLK = CGMXCLK
Figure 13-3. ESCI Module Block Diagram
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
154
Functional Description
Addr.
Register Name
Bit 7
PDS2
0
6
5
PDS0
0
4
PSSB4
0
3
2
1
Bit 0
Read:
ESCI Prescaler Register
PDS1
PSSB3
PSSB2
PSSB1
PSSB0
$0009
(SCPSC) Write:
See page 175.
Reset:
Read:
0
0
0
0
0
ALOST
AFIN
ARUN
AROVFL
ARD8
ESCI Arbiter Control
Register (SCIACTL) Write:
AM1
AM0
ACLK
$000A
$000B
$0013
$0014
$0015
$0016
$0017
$0018
$0019
See page 179.
Reset:
0
0
0
0
0
0
0
0
Read:
ARD7
ARD6
ARD5
ARD4
ARD3
ARD2
ARD1
ARD0
ESCI Arbiter Data
Register (SCIADAT) Write:
See page 180.
Reset:
0
0
ENSCI
0
0
0
M
0
WAKE
0
0
ILTY
0
0
PEN
0
0
PTY
0
Read:
ESCI Control Register 1
LOOPS
0
TXINV
(SCC1) Write:
See page 166.
Reset:
0
0
Read:
ESCI Control Register 2
SCTIE
TCIE
0
SCRIE
ILIE
0
TE
RE
0
RWU
0
SBK
0
(SCC2) Write:
See page 168.
Reset:
0
0
0
Read:
R8
ESCI Control Register 3
T8
R
R
ORIE
NEIE
FEIE
PEIE
(SCC3) Write:
See page 169.
Reset:
U
0
0
0
0
0
0
0
Read:
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
ESCI Status Register 1
(SCS1) Write:
See page 170.
Reset:
1
0
1
0
0
0
0
0
0
0
0
0
0
0
Read:
BKF
RPF
ESCI Status Register 2
(SCS2) Write:
See page 173.
Reset:
0
0
0
0
0
0
0
0
Read:
R7
T7
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
R0
T0
ESCI Data Register
(SCDR) Write:
See page 173.
Reset:
Unaffected by reset
Read:
ESCI Baud Rate Register
LINT
0
LINR
0
SCP1
0
SCP0
R
SCR2
0
SCR1
0
SCR0
0
(SCBR) Write:
See page 174.
Reset:
0
0
= Unimplemented
R
= Reserved
Figure 13-4. ESCI I/O Register Summary
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
155
Enhanced Serial Communications Interface (ESCI) Module
13.4.2 Transmitter
Figure 13-5 shows the structure of the SCI transmitter and the registers are summarized in Figure 13-4.
The baud rate clock source for the ESCI can be selected via the configuration bit, SCIBDSRC.
INTERNAL BUS
PRE-
BAUD
÷ 16
÷ 4
ESCI DATA REGISTER
SCALER DIVIDER
SCP1
SCP0
SCR2
SCR1
SCR0
11-BIT
TRANSMIT
SHIFT REGISTER
H
8
7
6
5
4
3
2
1
0
L
SCI_TxD
TXINV
M
PDS2
PDS1
PEN
PTY
PARITY
CGMXCLK
OR
BUS CLOCK
GENERATION
T8
PDS0
PSSB4
PSSB3
PSSB2
PSSB1
PSSB0
TRANSMITTER
CONTROL LOGIC
TRANSMITTER CPU
INTERRUPT REQUEST
SCTE
SBK
SCTE
SCTIE
LOOPS
ENSCI
TE
SCTIE
TC
TC
TCIE
TCIE
LINT
Figure 13-5. ESCI Transmitter
13.4.2.1 Character Length
The transmitter can accommodate either 8-bit or 9-bit data. The state of the M bit in ESCI control
register 1 (SCC1) determines character length. When transmitting 9-bit data, bit T8 in ESCI control
register 3 (SCC3) is the ninth bit (bit 8).
13.4.2.2 Character Transmission
During an ESCI transmission, the transmit shift register shifts a character out to the TxD pin. The ESCI
data register (SCDR) is the write-only buffer between the internal data bus and the transmit shift register.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
156
Freescale Semiconductor
Functional Description
To initiate an ESCI transmission:
1. Enable the ESCI by writing a 1 to the enable ESCI bit (ENSCI) in ESCI control register 1 (SCC1).
2. Enable the transmitter by writing a 1 to the transmitter enable bit (TE) in ESCI control register 2
(SCC2).
3. Clear the ESCI transmitter empty bit (SCTE) by first reading ESCI status register 1 (SCS1) and
then writing to the SCDR. For 9-bit data, also write the T8 bit in SCC3.
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 1s. After the preamble shifts out, control logic transfers the SCDR data into the transmit
shift register. A 0 start bit automatically goes into the least significant bit (LSB) position of the transmit shift
register. A 1 stop bit goes into the most significant bit (MSB) position.
The ESCI 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 ESCI transmit interrupt enable bit, SCTIE, in SCC2 is also set, the SCTE bit generates a
transmitter CPU interrupt request.
When the transmit shift register is not transmitting a character, the TxD pin goes to the idle condition, high.
If at any time software clears the ENSCI bit in ESCI control register 1 (SCC1), the transmitter and receiver
relinquish control of the port E pins.
13.4.2.3 Break Characters
Writing a 1 to the send break bit, SBK, in SCC2 loads the transmit shift register with a break character.
For TXINV = 0 (output not inverted), a transmitted break character contains all 0s and has no start, stop,
or parity bit. Break character length depends on the M bit in SCC1 and the LINR bits in SCBR. As long as
SBK is at 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 1. The automatic 1 at the end of a break character guarantees the recognition of
the start bit of the next character.
When LINR is cleared in SCBR, the ESCI recognizes a break character when a start bit is followed by
eight or nine 0 data bits and a 0 where the stop bit should be, resulting in a total of 10 or 11 consecutive
0 data bits. When LINR is set in SCBR, the ESCI recognizes a break character when a start bit is followed
by 9 or 10 0 data bits and a 0 where the stop bit should be, resulting in a total of 11 or 12 consecutive 0
data bits.
Receiving a break character has these effects on ESCI registers:
•
•
•
•
•
•
Sets the framing error bit (FE) in SCS1
Sets the ESCI receiver full bit (SCRF) in SCS1
Clears the ESCI 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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
157
Enhanced Serial Communications Interface (ESCI) Module
13.4.2.4 Idle Characters
For TXINV = 0 (output not inverted), a transmitted idle character contains all 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.
NOTE
When a break sequence is followed immediately by an idle character, this
SCI design exhibits a condition in which the break character length is
reduced by one half bit time. In this instance, the break sequence will
consist of a valid start bit, eight or nine data bits (as defined by the M bit in
SCC1) of 0 and one half data bit length of 0 in the stop bit position followed
immediately by the idle character. To ensure a break character of the
proper length is transmitted, always queue up a byte of data to be
transmitted while the final break sequence is in progress.
When queueing an idle character, return the TE bit to 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.
A good time to toggle the TE bit for a queued idle character is when the
SCTE bit becomes set and just before writing the next byte to the SCDR.
13.4.2.5 Inversion of Transmitted Output
The transmit inversion bit (TXINV) in ESCI control register 1 (SCC1) reverses the polarity of transmitted
data. All transmitted values including idle, break, start, and stop bits, are inverted when TXINV is at 1.
See 13.8.1 ESCI Control Register 1.
13.4.2.6 Transmitter Interrupts
These conditions can generate CPU interrupt requests from the ESCI transmitter:
•
ESCI 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 ESCI 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.
13.4.3 Receiver
Figure 13-6 shows the structure of the ESCI receiver. The receiver I/O registers are summarized in
Figure 13-4.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
158
Freescale Semiconductor
Functional Description
INTERNAL BUS
LINR
SCP1
SCP0
SCR2
SCR1
SCR0
ESCI DATA REGISTER
PRE-
BAUD
÷ 4
÷ 16
SCALER DIVIDER
11-BIT
RECEIVE SHIFT REGISTER
DATA
RECOVERY
H
8
7
6
5
4
3
2
1
0
L
RxD
ALL ZEROS
BKF
RPF
PDS2
PDS1
CGMXCLK
OR
BUS CLOCK
PDS0
M
RWU
PSSB4
PSSB3
PSSB2
PSSB1
PSSB0
SCRF
IDLE
WAKE
ILTY
WAKEUP
LOGIC
PEN
PTY
R8
PARITY
CHECKING
IDLE
ILIE
ILIE
CPU INTERRUPT
REQUEST
SCRF
SCRIE
SCRIE
OR
OR
ORIE
ORIE
NF
NF
NEIE
NEIE
ERROR CPU
INTERRUPT REQUEST
FE
FE
FEIE
FEIE
PE
PE
PEIE
PEIE
Figure 13-6. ESCI Receiver Block Diagram
13.4.3.1 Character Length
The receiver can accommodate either 8-bit or 9-bit data. The state of the M bit in ESCI control register 1
(SCC1) determines character length. When receiving 9-bit data, bit R8 in ESCI control register 3 (SCC3)
is the ninth bit (bit 8). When receiving 8-bit data, bit R8 is a copy of the eighth bit (bit 7).
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
159
Enhanced Serial Communications Interface (ESCI) Module
13.4.3.2 Character Reception
During an ESCI reception, the receive shift register shifts characters in from the RxD pin. The ESCI 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 ESCI receiver full bit, SCRF, in ESCI status register 1 (SCS1) becomes set, indicating
that the received byte can be read. If the ESCI receive interrupt enable bit, SCRIE, in SCC2 is also set,
the SCRF bit generates a receiver CPU interrupt request.
13.4.3.3 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 these times
(see Figure 13-7):
•
•
After every start bit
After the receiver detects a data bit change from 1 to 0 (after the majority of data bit samples at
RT8, RT9, and RT10 returns a valid 1 and the majority of the next RT8, RT9, and RT10 samples
returns a valid 0)
To locate the start bit, data recovery logic does an asynchronous search for a 0 preceded by three 1s.
When the falling edge of a possible start bit occurs, the RT clock begins to count to 16.
START BIT
LSB
RxD
START BIT
QUALIFICATION
START BIT
DATA
SAMPLES
VERIFICATION SAMPLING
RT
CLOCK
RT CLOCK
STATE
RT CLOCK
RESET
Figure 13-7. Receiver Data Sampling
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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
160
Functional Description
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
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 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
13.4.3.4 Framing Errors
If the data recovery logic does not detect a 1 where the stop bit should be in an incoming character, it sets
the framing error bit, FE, in SCS1. A break character also sets the FE bit because a break character has
no stop bit. The FE bit is set at the same time that the SCRF bit is set.
13.4.3.5 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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
161
Enhanced Serial Communications Interface (ESCI) Module
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.
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 13-8 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 13-8. 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 13-8, 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 13-8, 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.
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 13-9 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
162
Freescale Semiconductor
Functional Description
STOP
IDLE OR NEXT CHARACTER
RECEIVER
RT CLOCK
DATA
SAMPLES
Figure 13-9. 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 13-9, 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 13-9, 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.
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
13.4.3.6 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:
1. Address mark — An address mark is a 1 in the MSB 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 ESCI 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.
2. 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 ESCI receiver full bit, SCRF. The idle line type bit,
ILTY, determines whether the receiver begins counting 1s as idle character bits after the start bit
or after the stop bit.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
163
Enhanced Serial Communications Interface (ESCI) Module
NOTE
With the WAKE bit clear, setting the RWU bit after the RxD pin has been
idle will cause the receiver to wake up.
13.4.3.7 Receiver Interrupts
These sources can generate CPU interrupt requests from the ESCI receiver:
•
ESCI 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 CPU interrupt request. Setting
the ESCI 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 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.
13.4.3.8 Error Interrupts
These 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 ESCI error CPU interrupt requests.
•
•
•
Noise flag (NF) — The NF bit is set when the ESCI 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 ESCI error CPU interrupt requests.
Framing error (FE) — The FE bit in SCS1 is set when a 0 occurs where the receiver expects a stop
bit. The framing error interrupt enable bit, FEIE, in SCC3 enables FE to generate ESCI error CPU
interrupt requests.
Parity error (PE) — The PE bit in SCS1 is set when the ESCI detects a parity error in incoming
data. The parity error interrupt enable bit, PEIE, in SCC3 enables PE to generate ESCI error CPU
interrupt requests.
13.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby modes.
13.5.1 Wait Mode
The ESCI module remains active in wait mode. Any enabled CPU interrupt request from the ESCI module
can bring the MCU out of wait mode.
If ESCI module functions are not required during wait mode, reduce power consumption by disabling the
module before executing the WAIT instruction.
13.5.2 Stop Mode
The ESCI module is inactive in stop mode. The STOP instruction does not affect ESCI register states.
ESCI module operation resumes after the MCU exits stop mode.
Because the internal clock is inactive during stop mode, entering stop mode during an ESCI transmission
or reception results in invalid data.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
164
Freescale Semiconductor
ESCI During Break Module Interrupts
13.6 ESCI During Break Module Interrupts
The BCFE bit in the break flag control register (SBFCR) enables software to clear status bits during the
break state. See 19.2 Break Module (BRK).
To allow software to clear status bits during a break interrupt, write a 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 0 to the BCFE bit. With BCFE at 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 0. After the break, doing the
second step clears the status bit.
13.7 I/O Signals
Port E shares two of its pins with the ESCI module. The two ESCI I/O pins are:
•
•
PTE0/TxD — transmit data
PTE1/RxD — receive data
13.7.1 PTE0/TxD (Transmit Data)
The PTE0/TxD pin is the serial data output from the ESCI transmitter. The ESCI shares the PTE0/TxD
pin with port E. When the ESCI is enabled, the PTE0/TxD pin is an output regardless of the state of the
DDRE0 bit in data direction register E (DDRE).
13.7.2 PTE1/RxD (Receive Data)
The PTE1/RxD pin is the serial data input to the ESCI receiver. The ESCI shares the PTE1/RxD pin with
port E. When the ESCI is enabled, the PTE1/RxD pin is an input regardless of the state of the DDRE1 bit
in data direction register E (DDRE).
13.8 I/O Registers
These I/O registers control and monitor ESCI operation:
•
•
•
•
•
•
•
•
•
•
ESCI control register 1, SCC1
ESCI control register 2, SCC2
ESCI control register 3, SCC3
ESCI status register 1, SCS1
ESCI status register 2, SCS2
ESCI data register, SCDR
ESCI baud rate register, SCBR
ESCI prescaler register, SCPSC
ESCI arbiter control register, SCIACTL
ESCI arbiter data register, SCIADAT
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
165
Enhanced Serial Communications Interface (ESCI) Module
13.8.1 ESCI Control Register 1
ESCI control register 1 (SCC1):
•
•
•
•
•
•
•
•
Enables loop mode operation
Enables the ESCI
Controls output polarity
Controls character length
Controls ESCI wakeup method
Controls idle character detection
Enables parity function
Controls parity type
Address: $0013
Bit 7
LOOPS
0
6
ENSCI
0
5
TXINV
0
4
M
0
3
WAKE
0
2
ILTY
0
1
PEN
0
Bit 0
PTY
0
Read:
Write:
Reset:
Figure 13-10. ESCI Control Register 1 (SCC1)
LOOPS — Loop Mode Select Bit
This read/write bit enables loop mode operation. In loop mode the RxD pin is disconnected from the
ESCI, and the transmitter output goes into the receiver input. Both the transmitter and the receiver
must be enabled to use loop mode. Reset clears the LOOPS bit.
1 = Loop mode enabled
0 = Normal operation enabled
ENSCI — Enable ESCI Bit
This read/write bit enables the ESCI and the ESCI baud rate generator. Clearing ENSCI sets the SCTE
and TC bits in ESCI status register 1 and disables transmitter interrupts. Reset clears the ENSCI bit.
1 = ESCI enabled
0 = ESCI disabled
TXINV — Transmit Inversion Bit
This read/write bit reverses the polarity of transmitted data. Reset clears the TXINV bit.
1 = Transmitter output inverted
0 = Transmitter output not inverted
NOTE
Setting the TXINV bit inverts all transmitted values including idle, break,
start, and stop bits.
M — Mode (Character Length) Bit
This read/write bit determines whether ESCI characters are eight or nine bits long (See
Table 13-5).The ninth bit can serve as a receiver wakeup signal or as a parity bit. Reset clears the M
bit.
1 = 9-bit ESCI characters
0 = 8-bit ESCI characters
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
166
Freescale Semiconductor
I/O Registers
Table 13-5. Character Format Selection
Control Bits
Character Format
M
0
1
0
0
1
1
PEN:PTY Start Bits Data Bits Parity Stop Bits Character Length
0 X
0 X
1 0
1 1
1 0
1 1
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
WAKE — Wakeup Condition Bit
This read/write bit determines which condition wakes up the ESCI: a 1 (address mark) in the MSB
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 ESCI starts counting 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 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 ESCI parity function (see Table 13-5). When enabled, the parity
function inserts a parity bit in the MSB position (see Table 13-3). Reset clears the PEN bit.
:
1 = Parity function enabled
0 = Parity function disabled
PTY — Parity Bit
This read/write bit determines whether the ESCI generates and checks for odd parity or even parity
(see Table 13-5). 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.
13.8.2 ESCI Control Register 2
ESCI control register 2 (SCC2):
•
Enables these CPU interrupt requests:
–
–
–
–
SCTE bit to generate transmitter CPU interrupt requests
TC bit to generate transmitter CPU interrupt requests
SCRF bit to generate receiver CPU interrupt requests
IDLE bit to generate receiver CPU interrupt requests
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
167
Enhanced Serial Communications Interface (ESCI) Module
•
•
•
•
Enables the transmitter
Enables the receiver
Enables ESCI wakeup
Transmits ESCI break characters
Address: $0014
Bit 7
SCTIE
0
6
TCIE
0
5
SCRIE
0
4
ILIE
0
3
TE
0
2
RE
0
1
RWU
0
Bit 0
SBK
0
Read:
Write:
Reset:
Figure 13-11. ESCI Control Register 2 (SCC2)
SCTIE — ESCI Transmit Interrupt Enable Bit
This read/write bit enables the SCTE bit to generate ESCI transmitter CPU interrupt requests. Setting
the SCTIE bit in SCC2 enables the SCTE bit to generate 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 ESCI 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 — ESCI Receive Interrupt Enable Bit
This read/write bit enables the SCRF bit to generate ESCI receiver CPU interrupt requests. Setting the
SCRIE bit in SCC2 enables the SCRF bit to generate 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 ESCI 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 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 (high). 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 ESCI bit (ENSCI) is
clear. ENSCI is in ESCI control register 1.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
168
Freescale Semiconductor
I/O Registers
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 ESCI bit (ENSCI) is
clear. ENSCI is in ESCI 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 1. The 1 after the
break character guarantees recognition of a valid start bit. If SBK remains set, the transmitter
continuously transmits break characters with no 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 ESCI to send a break
character instead of a preamble.
13.8.3 ESCI Control Register 3
ESCI control register 3 (SCC3):
•
•
Stores the ninth ESCI data bit received and the ninth ESCI data bit to be transmitted.
Enables these interrupts:
–
–
–
–
Receiver overrun
Noise error
Framing error
Parity error
Address:
$0015
Bit 7
R8
6
T8
0
5
R
0
4
3
2
NEIE
0
1
FEIE
0
Bit 0
PEIE
0
Read:
Write:
Reset:
R
ORIE
U
0
0
= Unimplemented
R
= Reserved
U = Unaffected
Figure 13-12. ESCI Control Register 3 (SCC3)
R8 — Received Bit 8
When the ESCI 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
169
Enhanced Serial Communications Interface (ESCI) Module
When the ESCI 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 ESCI 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 clears the T8 bit.
ORIE — Receiver Overrun Interrupt Enable Bit
This read/write bit enables ESCI error CPU interrupt requests generated by the receiver overrun bit,
OR. Reset clears ORIE.
1 = ESCI error CPU interrupt requests from OR bit enabled
0 = ESCI error CPU interrupt requests from OR bit disabled
NEIE — Receiver Noise Error Interrupt Enable Bit
This read/write bit enables ESCI error CPU interrupt requests generated by the noise error bit, NE.
Reset clears NEIE.
1 = ESCI error CPU interrupt requests from NE bit enabled
0 = ESCI error CPU interrupt requests from NE bit disabled
FEIE — Receiver Framing Error Interrupt Enable Bit
This read/write bit enables ESCI error CPU interrupt requests generated by the framing error bit, FE.
Reset clears FEIE.
1 = ESCI error CPU interrupt requests from FE bit enabled
0 = ESCI error CPU interrupt requests from FE bit disabled
PEIE — Receiver Parity Error Interrupt Enable Bit
This read/write bit enables ESCI receiver CPU interrupt requests generated by the parity error bit, PE.
Reset clears PEIE.
1 = ESCI error CPU interrupt requests from PE bit enabled
0 = ESCI error CPU interrupt requests from PE bit disabled
13.8.4 ESCI Status Register 1
ESCI status register 1 (SCS1) 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
6
5
4
3
2
1
Bit 0
PE
Read:
Write:
Reset:
SCTE
TC
SCRF
IDLE
OR
NF
FE
1
1
0
0
0
0
0
0
= Unimplemented
Figure 13-13. ESCI Status Register 1 (SCS1)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
170
I/O Registers
SCTE — ESCI 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 ESCI transmitter CPU interrupt request. When the SCTIE bit in SCC2 is set,
SCTE generates an ESCI transmitter CPU interrupt request. In normal 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 ESCI transmitter CPU interrupt request if the TCIE bit in SCC2 is also
set. TC is cleared automatically 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 — ESCI Receiver Full Bit
This clearable, read-only bit is set when the data in the receive shift register transfers to the ESCI data
register. SCRF can generate an ESCI receiver CPU interrupt request. When the SCRIE bit in SCC2 is
set the 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 1s appear on the receiver input. IDLE
generates an ESCI 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)
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 ESCI 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 13-14 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
171
Enhanced Serial Communications Interface (ESCI) Module
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 3
READ SCDR
BYTE 2
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 13-14. Flag Clearing Sequence
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 ESCI detects noise on the RxD pin. NF generates an NF
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 0 is accepted as the stop bit. FE generates an ESCI 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
PE — Receiver Parity Error Bit
This clearable, read-only bit is set when the ESCI detects a parity error in incoming data. PE generates
a PE 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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
172
Freescale Semiconductor
I/O Registers
13.8.5 ESCI Status Register 2
ESCI status register 2 (SCS2) contains flags to signal these conditions:
•
•
Break character detected
Incoming data
Address:
$0017
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
Bit 0
RPF
Read:
Write:
Reset:
BKF
0
0
0
0
0
0
0
0
= Unimplemented
Figure 13-15. ESCI Status Register 2 (SCS2)
BKF — Break Flag Bit
This clearable, read-only bit is set when the ESCI 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 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 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 ESCI module or entering stop mode can show whether a reception is in
progress.
1 = Reception in progress
0 = No reception in progress
13.8.6 ESCI Data Register
The ESCI data register (SCDR) is the buffer between the internal data bus and the receive and transmit
shift registers. Reset has no effect on data in the ESCI 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 13-16. ESCI Data Register (SCDR)
R7/T7:R0/T0 — Receive/Transmit Data Bits
Reading address $0018 accesses the read-only received data bits, R7:R0. Writing to address $0018
writes the data to be transmitted, T7:T0. Reset has no effect on the ESCI data register.
NOTE
Do not use read-modify-write instructions on the ESCI data register.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
173
Enhanced Serial Communications Interface (ESCI) Module
13.8.7 ESCI Baud Rate Register
The ESCI baud rate register (SCBR) together with the ESCI prescaler register selects the baud rate for
both the receiver and the transmitter.
NOTE
There are two prescalers available to adjust the baud rate. One in the ESCI
baud rate register and one in the ESCI prescaler register.
Address:
$0019
Bit 7
6
5
SCP1
0
4
SCP0
0
3
R
0
2
SCR2
0
1
SCR1
0
Bit 0
SCR0
0
Read:
Write:
Reset:
LINT
LINR
0
0
R
= Reserved
Figure 13-17. ESCI Baud Rate Register (SCBR)
LINT — LIN Transmit Enable
This read/write bit selects the enhanced ESCI features for the local interconnect network (LIN) protocol
as shown in Table 13-6. Reset clears LINT.
LINR — LIN Receiver Bits
This read/write bit selects the enhanced ESCI features for the local interconnect network (LIN) protocol
as shown in Table 13-6. Reset clears LINR.
Table 13-6. ESCI LIN Control Bits
LINT
LINR
M
X
0
1
0
1
0
1
Functionality
Normal ESCI functionality
0
0
0
1
1
1
1
0
1
1
0
0
1
1
11-bit break detect enabled for LIN receiver
12-bit break detect enabled for LIN receiver
13-bit generation enabled for LIN transmitter
14-bit generation enabled for LIN transmitter
11-bit break detect/13-bit generation enabled for LIN
12-bit break detect/14-bit generation enabled for LIN
In LIN (version 1.2) systems, the master node transmits a break character which will appear as
11.05–14.95 dominant bits to the slave node. A data character of 0x00 sent from the master might
appear as 7.65–10.35 dominant bit times. This is due to the oscillator tolerance requirement that the
slave node must be within 15% of the master node's oscillator. Since a slave node cannot know if it
is running faster or slower than the master node (prior to synchronization), the LINR bit allows the slave
node to differentiate between a 0x00 character of 10.35 bits and a break character of 11.05 bits. The
break symbol length must be verified in software in any case, but the LINR bit serves as a filter,
preventing false detections of break characters that are really 0x00 data characters.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
174
Freescale Semiconductor
I/O Registers
SCP1 and SCP0 — ESCI Baud Rate Register Prescaler Bits
These read/write bits select the baud rate register prescaler divisor as shown in Table 13-7. Reset
clears SCP1 and SCP0.
Table 13-7. ESCI Baud Rate Prescaling
Baud Rate Register
SCP[1:0]
Prescaler Divisor (BPD)
0 0
0 1
1 0
1 1
1
3
4
13
SCR2–SCR0 — ESCI Baud Rate Select Bits
These read/write bits select the ESCI baud rate divisor as shown in Table 13-8. Reset clears
SCR2–SCR0.
Table 13-8. ESCI Baud Rate Selection
SCR[2:1:0]
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
Baud Rate Divisor (BD)
1
2
4
8
16
32
64
128
13.8.8 ESCI Prescaler Register
The ESCI prescaler register (SCPSC) together with the ESCI baud rate register selects the baud rate for
both the receiver and the transmitter.
NOTE
There are two prescalers available to adjust the baud rate. One in the ESCI
baud rate register and one in the ESCI prescaler register.
;
Address:
$0009
Bit 7
6
PDS1
0
5
PDS0
0
4
PSSB4
0
3
PSSB3
0
2
PSSB2
0
1
PSSB1
0
Bit 0
PSSB0
0
Read:
Write:
Reset:
PDS2
0
Figure 13-18. ESCI Prescaler Register (SCPSC)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
175
Enhanced Serial Communications Interface (ESCI) Module
PDS2–PDS0 — Prescaler Divisor Select Bits
These read/write bits select the prescaler divisor as shown in Table 13-9. Reset clears PDS2–PDS0.
NOTE
The setting of ‘000’ will bypass this prescaler. It is not recommended to
bypass the prescaler while ENSCI is set, because the switching is not glitch
free.
Table 13-9. ESCI Prescaler Division Ratio
PDS[2:1:0]
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
Prescaler Divisor (PD)
Bypass this prescaler
2
3
4
5
6
7
8
PSSB4–PSSB0 — Clock Insertion Select Bits
These read/write bits select the number of clocks inserted in each 32 output cycle frame to achieve
more timing resolution on the average prescaler frequency as shown in Table 13-10. Reset clears
PSSB4–PSSB0.
Table 13-10. ESCI Prescaler Divisor Fine Adjust
PSSB[4:3:2:1:0]
0 0 0 0 0
0 0 0 0 1
0 0 0 1 0
0 0 0 1 1
0 0 1 0 0
0 0 1 0 1
0 0 1 1 0
0 0 1 1 1
0 1 0 0 0
0 1 0 0 1
0 1 0 1 0
0 1 0 1 1
0 1 1 0 0
0 1 1 0 1
0 1 1 1 0
0 1 1 1 1
Prescaler Divisor Fine Adjust (PDFA)
0/32 = 0
1/32 = 0.03125
2/32 = 0.0625
3/32 = 0.09375
4/32 = 0.125
5/32 = 0.15625
6/32 = 0.1875
7/32 = 0.21875
8/32 = 0.25
9/32 = 0.28125
10/32 = 0.3125
11/32 = 0.34375
12/32 = 0.375
13/32 = 0.40625
14/32 = 0.4375
15/32 = 0.46875
Continued on next page
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
176
ESCI Arbiter
Table 13-10. ESCI Prescaler Divisor Fine Adjust (Continued)
PSSB[4:3:2:1:0]
1 0 0 0 0
1 0 0 0 1
1 0 0 1 0
1 0 0 1 1
1 0 1 0 0
1 0 1 0 1
1 0 1 1 0
1 0 1 1 1
1 1 0 0 0
1 1 0 0 1
1 1 0 1 0
1 1 0 1 1
1 1 1 0 0
1 1 1 0 1
1 1 1 1 0
1 1 1 1 1
Prescaler Divisor Fine Adjust (PDFA)
16/32 = 0.5
17/32 = 0.53125
18/32 = 0.5625
19/32 = 0.59375
20/32 = 0.625
21/32 = 0.65625
22/32 = 0.6875
23/32 = 0.71875
24/32 = 0.75
25/32 = 0.78125
26/32 = 0.8125
27/32 = 0.84375
28/32 = 0.875
29/32 = 0.90625
30/32 = 0.9375
31/32 = 0.96875
Use the following formula to calculate the ESCI baud rate:
Frequency of the SCI clock source
64 x BPD x BD x (PD + PDFA)
Baud rate =
where:
Frequency of the SCI clock source = fBus or CGMXCLK (selected by
SCIBDSRC in the CONFIG2 register)
BPD = Baud rate register prescaler divisor
BD = Baud rate divisor
PD = Prescaler divisor
PDFA = Prescaler divisor fine adjust
Table 13-11 shows the ESCI baud rates that can be generated with a 4.9152-MHz bus frequency.
13.9 ESCI Arbiter
The ESCI module comprises an arbiter module designed to support software for communication tasks as
bus arbitration, baud rate recovery and break time detection. The arbiter module consists of an 9-bit
counter with 1-bit overflow and control logic. The CPU can control operation mode via the ESCI arbiter
control register (SCIACTL).
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
177
Enhanced Serial Communications Interface (ESCI) Module
Table 13-11. ESCI Baud Rate Selection Examples
Prescaler
Divisor
(BPD)
Baud Rate
Divisor
(BD)
Baud Rate
(fBus= 4.9152 MHz)
PDS[2:1:0]
PSSB[4:3:2:1:0]
SCP[1:0]
SCR[2:1:0]
0 0 0
1 1 1
1 1 1
1 1 1
1 1 1
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
X X X X X
0 0 0 0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 1
0 1
0 1
0 1
0 1
0 1
0 1
0 1
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 0
1 1
1 1
1 1
1 1
1 1
1 1
1 1
1 1
1
1
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
1
76,800
1
1
9600
9562.65
9525.58
8563.07
38,400
19,200
9600
4800
2400
1200
600
0 0 0 0 1
1
0 0 0 1 0
1
1
1 1 1 1 1
1
1
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
X X X X X
1
2
1
4
1
8
1
16
32
64
128
1
1
1
1
3
25,600
12,800
6400
3200
1600
800
3
2
3
4
3
8
3
16
32
64
128
1
3
3
400
3
200
4
19,200
9600
4800
2400
1200
600
4
2
4
4
4
8
4
16
32
64
128
1
4
4
300
4
150
13
13
13
13
13
13
13
13
5908
2954
1477
739
2
4
8
16
32
64
128
369
185
92
46
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
178
ESCI Arbiter
13.9.1 ESCI Arbiter Control Register
Address:
$000A
Bit 7
6
5
AM0
0
4
ACLK
0
3
2
1
Bit 0
Read:
Write:
Reset:
ALOST
AFIN
ARUN
AROVFL
ARD8
AM1
0
0
0
0
0
0
= Unimplemented
Figure 13-19. ESCI Arbiter Control Register (SCIACTL)
AM1 and AM0 — Arbiter Mode Select Bits
These read/write bits select the mode of the arbiter module as shown in
Table 13-12. Reset clears AM1 and AM0.
Table 13-12. ESCI Arbiter Selectable Modes
AM[1:0]
0 0
ESCI Arbiter Mode
Idle / counter reset
0 1
Bit time measurement
Bus arbitration
1 0
1 1
Reserved / do not use
ALOST — Arbitration Lost Flag
This read-only bit indicates loss of arbitration. Clear ALOST by writing a 0 to AM1. Reset clears
ALOST.
ACLK — Arbiter Counter Clock Select Bit
This read/write bit selects the arbiter counter clock source. Reset clears ACLK.
1 = Arbiter counter is clocked with one half of the ESCI input clock generated by the ESCI prescaler
0 = Arbiter counter is clocked with the bus clock divided by four
NOTE
For ACLK = 1, the arbiter input clock is driven from the ESCI prescaler. The
prescaler can be clocked by either the bus clock or CGMXCLK depending
on the state of the SCIBDSRC bit in CONFIG2.
AFIN— Arbiter Bit Time Measurement Finish Flag
This read-only bit indicates bit time measurement has finished. Clear AFIN by writing any value to
SCIACTL. Reset clears AFIN.
1 = Bit time measurement has finished
0 = Bit time measurement not yet finished
ARUN— Arbiter Counter Running Flag
This read-only bit indicates the arbiter counter is running. Reset clears ARUN.
1 = Arbiter counter running
0 = Arbiter counter stopped
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
179
Enhanced Serial Communications Interface (ESCI) Module
AROVFL— Arbiter Counter Overflow Bit
This read-only bit indicates an arbiter counter overflow. Clear AROVFL by writing any value to
SCIACTL. Writing 0s to AM1 and AM0 resets the counter keeps it in this idle state. Reset clears
AROVFL.
1 = Arbiter counter overflow has occurred
0 = No arbiter counter overflow has occurred
ARD8— Arbiter Counter MSB
This read-only bit is the MSB of the 9-bit arbiter counter. Clear ARD8 by writing any value to SCIACTL.
Reset clears ARD8.
13.9.2 ESCI Arbiter Data Register
Address: $000B
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
ARD7
ARD6
ARD5
ARD4
ARD3
ARD2
ARD1
ARD0
0
0
0
0
0
0
0
0
= Unimplemented
Figure 13-20. ESCI Arbiter Data Register (SCIADAT)
ARD7–ARD0 — Arbiter Least Significant Counter Bits
These read-only bits are the eight LSBs of the 9-bit arbiter counter. Clear ARD7–ARD0 by writing any
value to SCIACTL. Writing 0s to AM1 and AM0 permanently resets the counter and keeps it in this idle
state. Reset clears ARD7–ARD0.
13.9.3 Bit Time Measurement
Two bit time measurement modes, described here, are available according to the state of ACLK.
1. ACLK = 0 — The counter is clocked with the bus clock divided by four. The counter is started when
a falling edge on the RxD pin is detected. The counter will be stopped on the next falling edge.
ARUN is set while the counter is running, AFIN is set on the second falling edge on RxD (for
instance, the counter is stopped). This mode is used to recover the received baud rate. See
Figure 13-21.
2. ACLK = 1 — The counter is clocked with one half of the ESCI input clock generated by the ESCI
prescaler. The counter is started when a 0 is detected on RxD (see Figure 13-22). A 0 on RxD on
enabling the bit time measurement with ACLK = 1 leads to immediate start of the counter (see
Figure 13-23). The counter will be stopped on the next rising edge of RxD. This mode is used to
measure the length of a received break.
13.9.4 Arbitration Mode
If AM[1:0] is set to 10, the arbiter module operates in arbitration mode. On every rising edge of SCI_TxD
(output of the ESCI module, internal chip signal), the counter is started. When the counter reaches $38
(ACLK = 0) or $08 (ACLK = 1), RxD is statically sensed. If in this case, RxD is sensed low (for example,
another bus is driving the bus dominant) ALOST is set. As long as ALOST is set, the TxD pin is forced
to 1, resulting in a seized transmission.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
180
Freescale Semiconductor
ESCI Arbiter
If SCI_TxD senses 0 without having sensed a 0 before on RxD, the counter will be reset, arbitration
operation will be restarted after the next rising edge of SCI_TxD.
MEASURED TIME
RXD
Figure 13-21. Bit Time Measurement with ACLK = 0
MEASURED TIME
RXD
Figure 13-22. Bit Time Measurement with ACLK = 1, Scenario A
MEASURED TIME
RXD
Figure 13-23. Bit Time Measurement with ACLK = 1, Scenario B
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
181
Enhanced Serial Communications Interface (ESCI) Module
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
182
Chapter 14
System Integration Module (SIM)
14.1 Introduction
This section describes the system integration module (SIM). Together with the central processor unit
(CPU), the SIM controls all microcontroller unit (MCU) activities. A block diagram of the SIM is shown in
Figure 14-1. Table 14-1 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 computer operating properly (COP)
timeout
Interrupt arbitration
Table 14-1 shows the internal signal names used in this section.
Table 14-1. Signal Name Conventions
Signal Name
CGMXCLK
CGMVCLK
Description
Buffered version of OSC1 from clock generator module (CGM)
PLL output
PLL-based or OSC1-based clock output from CGM module
(Bus clock = CGMOUT divided by two)
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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
183
System Integration Module (SIM)
MODULE STOP
MODULE WAIT
CPU STOP (FROM CPU)
CPU WAIT (FROM CPU)
STOP/WAIT
CONTROL
SIMOSCEN (TO CGM)
SIM
COUNTER
CGMXCLK (FROM CGM)
CGMOUT (FROM CGM)
÷ 2
CLOCK
CONTROL
VDD
CLOCK GENERATORS
INTERNAL CLOCKS
INTERNAL
PULLUP
DEVICE
FORCED MONITOR MODE ENTRY
LVI (FROM LVI MODULE)
RESET
PIN LOGIC
POR CONTROL
MASTER
ILLEGAL OPCODE (FROM CPU)
ILLEGAL ADDRESS (FROM ADDRESS
MAP DECODERS)
RESET
RESET PIN CONTROL
CONTROL
SIM RESET STATUS REGISTER
COP (FROM COP MODULE)
RESET
INTERRUPT SOURCES
CPU INTERFACE
INTERRUPT CONTROL
AND PRIORITY DECODE
Figure 14-1. SIM Block Diagram
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
184
Introduction
7
Addr.
Register Name
Bit 7
R
6
R
0
5
R
0
4
R
0
3
R
0
2
R
0
1
Bit 0
R
Read:
SBSW
Note(1)
0
Break Status Register
$FE00
(BSR) Write:
See page 199.
Reset:
0
0
1. Writing a 0 clears SBSW.
Read:
POR
PIN
COP
ILOP
ILAD
MODRST
LVI
0
SIM Reset Status Register
$FE01
$FE03
$FE04
$FE05
$FE06
$FE07
(SRSR) Write:
See page 199.
POR:
Read:
1
0
0
0
0
0
0
0
Break Flag Control Register
BCFE
R
R
R
R
R
R
R
(BFCR) Write:
See page 200.
Reset:
Read:
0
IF6
R
IF5
R
IF4
R
IF3
R
IF2
IF1
R
0
R
0
R
Interrupt Status Register 1
(INT1) Write:
R
See page 195.
Reset:
Read:
0
0
0
0
0
0
0
0
IF14
R
IF13
R
IF12
R
IF11
R
IF10
IF9
R
IF8
R
IF7
R
Interrupt Status Register 2
(INT2) Write:
R
See page 195.
Reset:
Read:
0
0
0
0
0
0
0
0
IF22
R
IF32
R
IF20
R
IF19
R
IF18
IF17
R
IF16
R
IF15
R
Interrupt Status Register 3
(INT3) Write:
R
See page 195.
Reset:
Read:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
IF24
R
IF23
R
Interrupt Status Register 4
(INT4) Write:
See page 196.
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 14-2. SIM I/O Register Summary
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
185
System Integration Module (SIM)
14.2 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 14-3. This clock
originates from either an external oscillator or from the on-chip PLL.
14.2.1 Bus Timing
In user mode, the internal bus frequency is either the crystal oscillator output (CGMXCLK) divided by four
or the PLL output (CGMVCLK) divided by four.
14.2.2 Clock Startup 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 CGMXCLK cycle POR
timeout has completed. The RST pin is driven low by the SIM during this entire period. The bus clocks
start upon completion of the timeout.
14.2.3 Clocks in Stop Mode and Wait Mode
Upon exit from stop mode by an interrupt or reset, the SIM allows CGMXCLK 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 CGMXCLK cycles. See 14.6.2 Stop Mode.
OSC2
OSC1
OSCILLATOR (OSC)
CGMXCLK
TO TBM,TIM1,TIM2, ADC,
SIM
SIMOSCEN
IT12
OSCENINSTOP
FROM
CONFIG
SIM COUNTER
CGMRCLK
TO REST
OF CHIP
BUS CLOCK
÷ 2
IT23
TO REST
OF CHIP
GENERATORS
PHASE-LOCKED LOOP (PLL)
Figure 14-3. System Clock Signals
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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
186
Freescale Semiconductor
Reset and System Initialization
14.3 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
Forced monitor mode entry reset (MODRST)
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 14.4 SIM Counter), but an external reset does not. Each of
the resets sets a corresponding bit in the SIM reset status register (SRSR). See 14.7 SIM Registers.
A reset immediately stops the operation of the instruction being executed. Reset initializes certain control
and status bits. Reset selects CGMXCLK divided by four as the bus clock.
14.3.1 External Pin Reset
The RST pin circuit includes an internal pullup 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 at
least the minimum tRL time and no other reset sources are present. Figure 14-4 shows the relative timing.
CGMOUT
RST
IAB
VECT H VECT L
PC
Figure 14-4. External Reset Timing
14.3.2 Active Resets from Internal Sources
All internal reset sources actively pull the RST pin low for 32 CGMXCLK cycles to allow resetting of
external peripherals. The internal reset continues to be asserted for an additional 32 cycles at which point
the reset vector will be fetched. See Figure 14-5. An internal reset can be caused by an illegal address,
illegal opcode, COP timeout, LVI, or POR. See Figure 14-6.
NOTE
For LVI or POR resets, the SIM cycles through 4096 CGMXCLK 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 14-5.
The COP reset is asynchronous to the bus clock.
The active reset feature allows the part to issue a reset to peripherals and other chips within a system
built around the MCU.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
187
System Integration Module (SIM)
RST PULLED LOW BY MCU
32 CYCLES
RST
32 CYCLES
CGMXCLK
IAB
VECTOR HIGH
Figure 14-5. Internal Reset Timing
ILLEGAL ADDRESS RST
ILLEGAL OPCODE RST
COPRST
INTERNAL RESET
LVI
POR
MODRST
Figure 14-6. Sources of Internal Reset
Table 14-2. Reset Recovery
Reset Recovery Type
Actual Number of Cycles
4163 (4096 + 64 + 3)
67 (64 + 3)
POR/LVI
All others
14.3.2.1 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 CGMXCLK cycles. Thirty-two CGMXCLK 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 CGMXCLK 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.
14.3.2.2 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) if the COPD bit in the CONFIG1
register is cleared. The SIM actively pulls down the RST pin for all internal reset sources.
The COP module is disabled if the RST pin or the IRQ pin is held at VTST while the MCU is in monitor
mode. During a break state, VTST on the RST pin disables the COP module.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
188
Freescale Semiconductor
Reset and System Initialization
OSC1
PORRST
4096
CYCLES
32
CYCLES
32
CYCLES
CGMXCLK
CGMOUT
RST
IAB
$FFFE
$FFFF
Figure 14-7. POR Recovery
14.3.2.3 Illegal Opcode Reset
The SIM decodes signals from the CPU to detect illegal instructions. An illegal instruction sets the ILOP
bit in the SIM reset status register (SRSR) and causes a reset.
If the stop enable bit, STOP, in the CONFIG1 register is 0, the SIM treats the STOP instruction as an
illegal opcode and causes an illegal opcode reset. The SIM actively pulls down the RST pin for all internal
reset sources.
14.3.2.4 Illegal Address Reset
An opcode fetch from an unmapped address generates an illegal address reset. The SIM verifies that the
CPU is fetching an opcode prior to asserting the ILAD bit in the SIM reset status register (SRSR) and
resetting the MCU. A data fetch from an unmapped address does not generate a reset. The SIM actively
pulls down the RST pin for all internal reset sources.
14.3.2.5 Low-Voltage Inhibit (LVI) Reset
The low-voltage inhibit module (LVI) asserts its output to the SIM when the VDD voltage falls to the VTRIPF
voltage. The LVI bit in the SIM reset status register (SRSR) is set, and the external reset pin (RST) is
asserted if the LVIPWRD and LVIRSTD bits in the CONFIG1 register are 0. The RST pin will be held low
while the SIM counter counts out 4096 + 32 CGMXCLK cycles after VDD rises above VTRIPR. Thirty-two
CGMXCLK cycles later, the CPU is released from reset to allow the reset vector sequence to occur. The
SIM actively pulls down the RST pin for all internal reset sources.
14.3.2.6 Monitor Mode Entry Module Reset (MODRST)
The monitor mode entry module reset (MODRST) asserts its output to the SIM when monitor mode is
entered in the condition where the reset vectors are erased ($FF) (see 19.3.1.1 Normal Monitor Mode).
When MODRST gets asserted, an internal reset occurs. The SIM actively pulls down the RST pin for all
internal reset sources.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
189
System Integration Module (SIM)
14.4 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 clocks. The SIM counter also serves as a
prescaler for the computer operating properly (COP) module. The SIM counter overflow supplies the clock
for the COP module. The SIM counter is 12 bits long.
14.4.1 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.
14.4.2 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
CONFIG1 register. If the SSREC bit is a 1, then the stop recovery is reduced from the normal delay of
4096 CGMXCLK cycles down to 32 CGMXCLK cycles. This is ideal for applications using crystals with
the OSCENINSTOP bit set. External crystal applications should use the full stop recovery time, SSREC
cleared, with the OSCENINSTOP bit cleared. See Chapter 5 Configuration Register (CONFIG).
14.4.3 SIM Counter and Reset States
External reset has no effect on the SIM counter. See 14.6.2 Stop Mode for details. The SIM counter is
free-running after all reset states. See 14.3.2 Active Resets from Internal Sources for counter control and
internal reset recovery sequences.
14.5 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
14.5.1 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 14-8 shows
interrupt entry timing. Figure 14-9 shows interrupt recovery timing.
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 14-10.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Exception Control
14.5.1.1 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.
MODULE
INTERRUPT
I BIT
IAB
IDB
DUMMY
SP
SP – 1
SP – 2
SP – 3
SP – 4
VECT H
VECT L START ADDR
DUMMY PC – 1[7:0] PC – 1[15:8]
X
A
CCR
V DATA H V DATA L OPCODE
R/W
Figure 14-8. Interrupt Entry Timing
MODULE
INTERRUPT
I BIT
IAB
SP – 4
SP – 3
SP – 2
SP – 1
SP
PC
PC + 1
IDB
R/W
CCR
A
X
PC – 1 [7:0] PC – 1 [15:8] OPCODE OPERAND
Figure 14-9. Interrupt Recovery Timing
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
191
System Integration Module (SIM)
FROM RESET
BREAK
YES
INTERRUPT
?
NO
YES
I BIT SET?
NO
YES
YES
IRQ
INTERRUPT
?
NO
CGM
INTERRUPT
?
NO
OTHER
INTERRUPTS
?
YES
NO
STACK CPU REGISTERS
SET I BIT
LOAD PC WITH INTERRUPT VECTOR
FETCH NEXT
INSTRUCTION
SWI
YES
YES
INSTRUCTION
?
NO
RTI
UNSTACK CPU REGISTERS
EXECUTE INSTRUCTION
INSTRUCTION
?
NO
Figure 14-10. Interrupt Processing
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
192
Exception Control
If more than one interrupt is pending at the end of an instruction execution, the highest priority interrupt is
serviced first. Figure 14-11 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
ROUTINE
LDA #$FF
INT1
PSHH
INT1 INTERRUPT SERVICE ROUTINE
PULH
RTI
INT2
PSHH
INT2 INTERRUPT SERVICE ROUTINE
PULH
RTI
Figure 14-11. 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.
14.5.1.2 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.
14.5.1.3 Interrupt Status Registers
The flags in the interrupt status registers identify maskable interrupt sources. Table 14-3 summarizes the
interrupt sources, hardware flag bits, hardware interrupt mask bits, interrupt status register flags, interrupt
priority, and exception vectors. The interrupt status registers can be useful for debugging.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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System Integration Module (SIM)
Table 14-3. Interrupt Sources
INT Register
Vector
Address
Mask(1)
Priority(2)
Source
Flag
Flag
Reset
None
None
IRQF
None
None
None
0
0
1
$FFFE–$FFFF
$FFFC–$FFFD
SWI instruction
IRQ pin
None
IF1
IMASK1
$FFFA–$FFFB
$FFF8–$FFF9
$FFF6–$FFF7
$FFF4–$FFF5
$FFF2–$FFF3
$FFF0–$FFF1
$FFEE–$FFEF
$FFEC–$FFED
CGM change in lock
TIM1 channel 0
TIM1 channel 1
TIM1 overflow
PLLF
CH0F
CH1F
TOF
PLLIE
CH0IE
CH1IE
TOIE
IF2
IF3
IF4
IF5
IF6
IF7
IF8
2
3
4
5
6
7
8
TIM2 channel 0
TIM2 channel 1
TIM2 overflow
CH0F
CH1F
TOF
CH0IE
CH1IE
TOIE
SPI receiver full
SPI overflow
SPRF
OVRF
MODF
SPTE
OR
SPRIE
ERRIE
ERRIE
SPTIE
ORIE
IF9
9
$FFEA–$FFEB
$FFE8–$FFE9
SPI mode fault
SPI transmitter empty
SCI receiver overrun
SCI noise flag
IF10
10
NF
NEIE
IF11
11
$FFE6–$FFE7
SCI framing error
SCI parity error
SCI receiver full
SCI input idle
FE
FEIE
PE
PEIE
SCRF
IDLE
SCTE
TC
SCRIE
ILIE
IF12
IF13
12
13
$FFE4–$FFE5
$FFE2–$FFE3
SCI transmitter empty
SCI transmission complete
Keyboard pin
SCTIE
TCIE
KEYF
COCO
TBIF
CH2F
CH3F
CH4F
CH5F
IMASKK
AIEN
IF14
IF15
IF16
IF21
IF22
IF23
IF24
14
15
16
21
22
23
24
$FFE0–$FFE1
$FFDE–$FFDF
$FFDC–$FFDD
$FFD2–FFD3
$FFD0–FFD1
$FFCE–FFCF
$FFCC–FFCD
ADC conversion complete
Timebase
TBIE
TIM2 channel 2
TIM2 channel 3
TIM2 channel 4
TIM2 channel 5
CH2IE
CH3IE
CH4IE
CH5IE
1. The I bit in the condition code register is a global mask for all interrupt sources except the SWI instruction.
2. 0 = highest priority
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Exception Control
Interrupt Status Register 1
Address:
$FE04
Bit 7
IF6
R
6
5
IF4
R
4
IF3
R
3
IF2
R
2
IF1
R
1
0
Bit 0
Read:
Write:
Reset:
IF5
0
R
0
R
R
0
0
0
0
0
0
0
R
= Reserved
Figure 14-12. Interrupt Status Register 1 (INT1)
IF6–IF1 — Interrupt Flags 1–6
These flags indicate the presence of interrupt requests from the sources shown in Table 14-3.
1 = Interrupt request present
0 = No interrupt request present
Bit 0 and Bit 1 — Always read 0
Interrupt Status Register 2
Address:
$FE05
Bit 7
IF14
R
6
5
IF12
R
4
IF11
R
3
IF10
R
2
IF9
R
1
IF8
R
Bit 0
IF7
R
Read:
Write:
Reset:
IF13
R
0
0
0
0
0
0
0
0
R
= Reserved
Figure 14-13. 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 14-3.
1 = Interrupt request present
0 = No interrupt request present
Interrupt Status Register 3
Address:
$FE06
Bit 7
IF22
R
6
5
IF20
R
4
IF19
R
3
IF18
R
2
IF17
R
1
IF16
R
Bit 0
IF15
R
Read:
Write:
Reset:
IF21
R
0
0
0
0
0
0
0
0
R
= Reserved
Figure 14-14. Interrupt Status Register 3 (INT3)
IF22–IF15 — Interrupt Flags 22–15
These flags indicate the presence of an interrupt request from the source shown in Table 14-3.
1 = Interrupt request present
0 = No interrupt request present
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
195
System Integration Module (SIM)
Interrupt Status Register 4
Address:
$FE07
Bit 7
0
6
5
0
4
0
3
0
2
0
1
IF24
R
Bit 0
IF23
R
Read:
Write:
Reset:
0
R
R
R
0
R
0
R
0
R
0
0
0
0
0
R
= Reserved
Figure 14-15. Interrupt Status Register 4 (INT4)
Bits 7–2 — Always read 0
IF24–IF23 — Interrupt Flags 24–23
These flags indicate the presence of an interrupt request from the source shown in Table 14-3.
1 = Interrupt request present
0 = No interrupt request present
14.5.2 Reset
All reset sources always have equal and highest priority and cannot be arbitrated.
14.5.3 Break Interrupts
The break module can stop normal program flow at a software-programmable break point by asserting its
break interrupt output (see Chapter 17 Timer Interface Module (TIM1) and Chapter 18 Timer Interface
Module (TIM2)). 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.
14.5.4 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 (BFCR).
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.
14.6 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Low-Power Modes
14.6.1 Wait Mode
In wait mode, the CPU clocks are inactive while the peripheral clocks continue to run. Figure 14-16 shows
the timing for wait mode entry.
A module that is active during wait mode can wakeup 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 (BSR). If the COP disable bit, COPD, in the
CONFIG1 register is 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 14-16. Wait Mode Entry Timing
Figure 14-17 and Figure 14-18 show the timing for WAIT recovery.
IAB
$6E0B
$6E0C
$00FF
$00FE
$00FD
$00FC
IDB
$A6
$A6
$A6
$01
$0B
$6E
EXITSTOPWAIT
Note: EXITSTOPWAIT = RST pin, CPU interrupt, or break interrupt
Figure 14-17. Wait Recovery from Interrupt or Break
32
CYCLES
32
CYCLES
IAB
$6E0B
$A6
RSTVCTH RSTVCTL
IDB $A6
RST
$A6
CGMXCLK
Figure 14-18. Wait Recovery from Internal Reset
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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System Integration Module (SIM)
14.6.2 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 also causes an exit from stop mode.
The SIM disables the clock generator module outputs (CGMOUT and CGMXCLK) in stop mode, stopping
the CPU and peripherals. Stop recovery time is selectable using the SSREC bit in CONFIG1. If SSREC
is set, stop recovery is reduced from the normal delay of 4096 CGMXCLK cycles down to 32. This is ideal
for applications using canned oscillators that do not require long startup times from stop mode.
NOTE
External crystal applications should use the full stop recovery time by
clearing the SSREC bit unless OSCENINSTOP bit is set in CONFIG2.
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 14-19 shows stop mode entry timing. Figure
14-20 shows stop mode recovery time from interrupt.
NOTE
To minimize stop current, all pins configured as inputs should be driven to
a 1 or 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 14-19. Stop Mode Entry Timing
STOP RECOVERY PERIOD
CGMXCLK
INT/BREAK
IAB
STOP + 2
STOP + 2
SP
SP – 1
SP – 2
SP – 3
STOP +1
Figure 14-20. Stop Mode Recovery from Interrupt
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
198
SIM Registers
14.7 SIM Registers
The SIM has three memory-mapped registers. Table 14-4 shows the mapping of these registers.
Table 14-4. SIM Registers
Address
$FE00
$FE01
$FE03
Register
BSR
Access Mode
User
SRSR
BFCR
User
User
14.7.1 Break Status Register
The break status register (BSR) contains a flag to indicate that a break caused an exit from wait mode.
This register is only used in emulation mode.
Address:
$FE00
Bit 7
6
5
R
0
4
R
0
3
R
0
2
R
0
1
Bit 0
R
Read:
Write:
Reset:
SBSW
Note(1)
0
R
R
0
0
0
R
= Reserved
1. Writing a 0 clears SBSW.
Figure 14-21. Break Status Register (BSR)
SBSW — SIM Break Stop/Wait
SBSW can be read within the break state SWI routine. The user can modify the return address on the
stack by subtracting one from it.
1 = Wait mode was exited by break interrupt.
0 = Wait mode was not exited by break interrupt.
14.7.2 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.
The register is initialized on power up with the POR bit set and all other bits cleared. During a POR or any
other internal reset, the RST pin is pulled low. After the pin is released, it will be sampled 32 CGMXCLK
cycles later. If the pin is not above VIH at this time, then the PIN bit may be set, in addition to whatever
other bits are set.
Address:
$FE01
Bit 7
6
5
4
3
2
1
Bit 0
0
Read:
Write:
Reset:
POR
PIN
COP
ILOP
ILAD
MODRST
LVI
1
0
0
0
0
0
0
0
= Unimplemented
Figure 14-22. SIM Reset Status Register (SRSR)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
199
System Integration Module (SIM)
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
MODRST — Monitor Mode Entry Module Reset Bit
1 = Last reset caused by monitor mode entry when vector locations $FFFE and $FFFF are $FF after
POR while IRQ = VDD
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
14.7.3 Break Flag Control Register
The break flag 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 14-23. Break Flag Control Register (BFCR)
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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Chapter 15
Serial Peripheral Interface (SPI) Module
15.1 Introduction
This section describes the serial peripheral interface (SPI) module, which allows full-duplex, synchronous,
serial communications with peripheral devices.
The text that follows describes the SPI. The SPI I/O pin names are SS (slave select), SPSCK (SPI serial
clock), MOSI (master out slave in), and MISO (master in/slave out). The SPI shares four I/O pins with four
parallel I/O ports.
15.2 Features
Features of the SPI module include:
•
•
•
•
•
•
•
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
I/O (input/output) port bit(s) software configurable with pullup device(s) if configured as input port
bit(s)
15.3 Functional Description
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.
If a port bit is configured for input, then an internal pullup device may be enabled for that port bit.
The following paragraphs describe the operation of the SPI module. Refer to Figure 15-3 for a summary
of the SPI I/O registers.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
201
Serial Peripheral Interface (SPI) Module
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 62,078 BYTES
USER RAM — 2048 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
2-CHANNEL TIMER INTERFACE
MODULE
MONITOR ROM
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure 15-1. Block Diagram Highlighting SPI Block and Pins
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Functional Description
INTERNAL BUS
TRANSMIT DATA REGISTER
SHIFT REGISTER
BUSCLK
MISO
MOSI
7
6
5
4
3
2
1
0
÷ 2
÷ 8
CLOCK
DIVIDER
RECEIVE DATA REGISTER
÷ 32
÷ 128
PIN
CONTROL
LOGIC
CLOCK
SPSCK
SS
SPMSTR
SPE
SELECT
M
S
CLOCK
LOGIC
SPR1
SPR0
SPMSTR
CPHA
CPOL
MODFEN
ERRIE
SPTIE
SPRIE
SPE
SPWOM
TRANSMITTER CPU INTERRUPT REQUEST
RECEIVER/ERROR CPU INTERRUPT REQUEST
SPI
CONTROL
SPRF
SPTE
OVRF
MODF
Figure 15-2. SPI Module Block Diagram
Addr.
Register Name
Bit 7
6
5
4
3
2
1
SPE
0
Bit 0
SPTIE
0
Read:
SPI Control Register
SPRIE
R
0
SPMSTR
CPOL
CPHA
SPWOM
0
$0010
(SPCR) Write:
See page 217.
Reset:
Read:
0
1
0
1
SPRF
OVRF
MODF
SPTE
SPI Status and Control
ERRIE
MODFEN
SPR1
SPR0
$0011
$0012
Register (SPSCR) Write:
See page 218.
Reset:
0
0
0
0
1
0
0
0
Read:
R7
T7
R6
T6
R5
T5
R4
T4
R3
T3
R2
T2
R1
T1
R0
T0
SPI Data Register
(SPDR) Write:
See page 220.
Reset:
Unaffected by reset
= Unimplemented
= Reserved
R
Figure 15-3. SPI I/O Register Summary
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Serial Peripheral Interface (SPI) Module
15.3.1 Master Mode
The SPI operates in master mode when the SPI master bit, SPMSTR, is set.
NOTE
In a multi-SPI system, 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 15.12.1 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 15-4.
MASTER MCU
SLAVE MCU
MISO
MOSI
MISO
MOSI
SHIFT REGISTER
SHIFT REGISTER
SPSCK
SS
SPSCK
SS
BAUD RATE
GENERATOR
VDD
Figure 15-4. Full-Duplex Master-Slave Connections
The SPR1 and SPR0 bits control the baud rate generator and determine the speed of the shift register.
(See 15.12.2 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 (SPDR)
clears SPTE.
15.3.2 Slave Mode
The SPI operates in slave mode when SPMSTR 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 low. SS must remain low until the transmission is complete. See 15.6.2 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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Transmission Formats
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.
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 15.4 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.
15.4 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.
15.4.1 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.
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).
15.4.2 Transmission Format When CPHA = 0
Figure 15-5 shows an SPI transmission in which CPHA = 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 low, 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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
205
Serial Peripheral Interface (SPI) Module
general-purpose I/O not affecting the SPI. (See 15.6.2 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 15-6.
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.
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 15-5. Transmission Format (CPHA = 0)
MISO/MOSI
MASTER SS
BYTE 1
BYTE 2
BYTE 3
SLAVE SS
CPHA = 0
SLAVE SS
CPHA = 1
Figure 15-6. CPHA/SS Timing
15.4.3 Transmission Format When CPHA = 1
Figure 15-7 shows an SPI transmission in which CPHA = 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 low, 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
15.6.2 Mode Fault Error.) When CPHA = 1, the master begins driving its MOSI pin on the first SPSCK
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Transmission Formats
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 15-7. Transmission Format (CPHA = 1)
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.
15.4.4 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 15-8.) 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. 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 15-8. 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
207
Serial Peripheral Interface (SPI) Module
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 = BUS CLOCK ÷ 2;
2 POSSIBLE START POINTS
EARLIEST
LATEST
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
SPSCK = BUS CLOCK ÷ 8;
LATEST
LATEST
LATEST
8 POSSIBLE START POINTS
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
SPSCK = BUS CLOCK ÷ 32;
32 POSSIBLE START POINTS
WRITE
TO SPDR
BUS
CLOCK
EARLIEST
SPSCK = BUS CLOCK ÷ 128;
128 POSSIBLE START POINTS
Figure 15-8. Transmission Start Delay (Master)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
208
Queuing Transmission Data
15.5 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 SPTE is high. Figure 15-9 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.
BYTE 3 TRANSFERS FROM TRANSMIT DATA
REGISTER TO SHIFT REGISTER, SETTING SPTE 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.
11
12
CPU READS SPSCR WITH SPRF BIT SET.
CPU READS SPDR, CLEARING SPRF BIT.
5
6
BYTE 2 TRANSFERS FROM TRANSMIT DATA
REGISTER TO SHIFT REGISTER, SETTING SPTE BIT.
CPU READS SPSCR WITH SPRF BIT SET.
Figure 15-9. 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.
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. SPTE indicates when the next write can occur.
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Serial Peripheral Interface (SPI) Module
15.6 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.
15.6.1 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 15-5 and Figure 15-7.) 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 interrupts share the same CPU interrupt vector (see Figure 15-12.) 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 15-10 shows how it is possible to miss an overflow. The first part of Figure 15-10 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.
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 15-11 illustrates this process. Generally, to avoid this second
SPSCR read, enable the OVRF to the CPU by setting the ERRIE bit.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Error Conditions
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.
CPU READS SPSCR WITH SPRF BIT SET
AND OVRF BIT CLEAR.
CPU READS BYTE 1 IN SPDR,
CLEARING SPRF BIT.
6
7
BYTE 3 SETS OVRF BIT. BYTE 3 IS LOST.
3
4
CPU READS BYTE 2 IN SPDR, CLEARING SPRF BIT,
BUT NOT OVRF BIT.
BYTE 2 SETS SPRF BIT.
8
BYTE 4 FAILS TO SET SPRF BIT BECAUSE
OVRF BIT IS NOT CLEARED. BYTE 4 IS LOST.
Figure 15-10. Missed Read of Overflow Condition
BYTE 1
1
BYTE 2
5
BYTE 3
7
BYTE 4
11
SPI RECEIVE
COMPLETE
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 15-11. Clearing SPRF When OVRF Interrupt Is Not Enabled
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
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Serial Peripheral Interface (SPI) Module
15.6.2 Mode Fault Error
Setting SPMSTR 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.
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 15-12.)
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 low. 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
15.4 Transmission Formats.
NOTE
Setting the MODF flag does not clear the SPMSTR bit. SPMSTR 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.
NOTE
When CPHA = 0, a MODF occurs if a slave is selected (SS is low) and later
unselected (SS is high) even if no SPSCK is sent to that slave. This
happens because SS low 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Interrupts
In a slave SPI (MSTR = 0), MODF 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 high 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.
15.7 Interrupts
Four SPI status flags can be enabled to generate CPU interrupt requests. See Table 15-1.
Table 15-1. SPI Interrupts
Flag
Request
SPTE
Transmitter empty
SPI transmitter CPU interrupt request
(SPTIE = 1, SPE = 1)
SPRF
Receiver full
SPI receiver CPU interrupt request
(SPRIE = 1)
OVRF
Overflow
SPI receiver/error interrupt request
(ERRIE = 1)
MODF
Mode fault
SPI receiver/error interrupt request
(ERRIE = 1)
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 SPRF to generate receiver CPU interrupt requests,
regardless of the state of SPE. See Figure 15-12.
SPTE
SPTIE
SPRF
SPE
SPI TRANSMITTER
CPU INTERRUPT REQUEST
SPRIE
SPI RECEIVER/ERROR
CPU INTERRUPT REQUEST
ERRIE
MODF
OVRF
Figure 15-12. SPI Interrupt Request Generation
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
213
Serial Peripheral Interface (SPI) Module
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.
The following sources in the SPI status and control register can generate CPU interrupt requests:
•
SPI receiver full bit (SPRF) — SPRF 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) — SPTE 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.
15.8 Resetting the SPI
Any system reset completely resets the SPI. Partial resets occur whenever the SPI enable bit (SPE) is 0.
Whenever SPE is 0, 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.
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.
15.9 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby modes.
15.9.1 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 15.7 Interrupts.
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SPI During Break Interrupts
15.9.2 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.
15.10 SPI During Break Interrupts
The system integration module (SIM) controls whether status bits in other modules can be cleared during
the break state. BCFE in the SIM break flag control register (SBFCR) enables software to clear status bits
during the break state. See Chapter 14 System Integration Module (SIM).
To allow software to clear status bits during a break interrupt, write a 1 to BCFE. 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 0 to BCFE. With BCFE at 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 0. After the break, doing the second step
clears the status bit.
Since the SPTE bit cannot be cleared during a break with BCFE 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 BCFE cleared has no effect.
15.11 I/O Signals
The SPI module has four I/O pins:
•
•
•
•
MISO — Master input/slave output
MOSI — Master output/slave input
SPSCK — Serial clock
SS — Slave select
15.11.1 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 0 and its SS pin is low. To support a multiple-slave system,
a high 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.
15.11.2 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.
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Serial Peripheral Interface (SPI) Module
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.
15.11.3 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.
15.11.4 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 15.4 Transmission Formats.) Since it is used to indicate the start of a transmission, 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 15-13.
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 SS from creating a MODF error. See 15.12.2 SPI Status and Control Register.
MISO/MOSI
MASTER SS
BYTE 1
BYTE 2
BYTE 3
SLAVE SS
CPHA = 0
SLAVE SS
CPHA = 1
Figure 15-13. CPHA/SS Timing
NOTE
A high 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.
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 15.6.2 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 MODFEN is 0 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. When MODFEN is 1, SS 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 15-2.
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I/O Registers
Table 15-2. SPI Configuration
SPE
SPMSTR
MODFEN
SPI Configuration
Not enabled
Function of SS Pin
General-purpose I/O;
SS ignored by SPI
X(1))
0
1
1
1
X
X
0
0
1
1
Slave
Input-only to SPI
General-purpose I/O;
SS ignored by SPI
Master without MODF
Master with MODF
1
Input-only to SPI
1. X = Don’t care
15.12 I/O Registers
Three registers control and monitor SPI operation:
•
•
•
SPI control register (SPCR)
SPI status and control register (SPSCR)
SPI data register (SPDR)
15.12.1 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
6
5
SPMSTR
1
4
CPOL
0
3
CPHA
1
2
SPWOM
0
1
SPE
0
Bit 0
SPTIE
0
Read:
Write:
Reset:
SPRIE
R
0
0
= Reserved
R
Figure 15-14. 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
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
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Serial Peripheral Interface (SPI) Module
CPOL — Clock Polarity Bit
This read/write bit determines the logic state of the SPSCK pin between transmissions. (See
Figure 15-5 and Figure 15-7.) 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 15-5 and Figure 15-7.) 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 high between
bytes. (See Figure 15-13.) 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 15.8
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
15.12.2 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
6
ERRIE
0
5
4
3
2
MODFEN
0
1
SPR1
0
Bit 0
SPR0
0
Read:
Write:
Reset:
SPRF
OVRF
MODF
SPTE
0
0
0
1
= Unimplemented
Figure 15-15. SPI Status and Control Register (SPSCR)
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I/O Registers
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
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
MODFEN 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 MODF 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 SPTIE in the SPI control register is set
also.
NOTE
Do not write to the SPI data register unless SPTE is high.
During an SPTE CPU interrupt, the CPU clears SPTE by writing to the transmit data register.
Reset sets the SPTE bit.
1 = Transmit data register empty
0 = Transmit data register not empty
MODFEN — Mode Fault Enable Bit
This read/write bit, when set, allows the MODF flag to be set. If the MODF flag is set, clearing MODFEN
does not clear the MODF flag. If the SPI is enabled as a master and the MODFEN bit is 0, then the SS
pin is available as a general-purpose I/O.
If the MODFEN bit is 1, then the SS 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 15.11.4 SS (Slave Select).
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Serial Peripheral Interface (SPI) Module
If the MODFEN bit is 0, 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 15.6.2 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 15-3. SPR1 and
SPR0 have no effect in slave mode. Reset clears SPR1 and SPR0.
Table 15-3. 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:
Baud rate =
BUSCLK
BD
15.12.3 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 15-2.
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 15-16. 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.
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Chapter 16
Timebase Module (TBM)
16.1 Introduction
This section describes the timebase module (TBM). The TBM will generate periodic interrupts at user
selectable rates using a counter clocked by the external clock source. This TBM version uses 15 divider
stages, eight of which are user selectable. A configuration option bit to select an additional 128 divide of
the external clock source can be selected. See Chapter 5 Configuration Register (CONFIG)
16.2 Features
Features of the TBM module include:
•
•
External clock or an additional divide-by-128 selected by configuration option bit as clock source
Software configurable periodic interrupts with divide-by: 8, 16, 32, 64, 128, 2048, 8192, and 32768
taps of the selected clock source
•
Configurable for operation during stop mode to allow periodic wakeup from stop
16.3 Functional Description
This module can generate a periodic interrupt by dividing the clock source supplied from the clock
generator module, CGMXCLK.
The counter is initialized to all 0s when TBON bit is cleared. The counter, shown in Figure 16-1, starts
counting when the TBON bit is set. When the counter overflows at the tap selected by TBR2–TBR0, the
TBIF bit gets set. If the TBIE bit is set, an interrupt request is sent to the CPU. The TBIF flag is cleared
by writing a 1 to the TACK bit. The first time the TBIF flag is set after enabling the timebase module, the
interrupt is generated at approximately half of the overflow period. Subsequent events occur at the exact
period.
The timebase module may remain active after execution of the STOP instruction if the crystal oscillator
has been enabled to operate during stop mode through the OSCENINSTOP bit in the configuration
register. The timebase module can be used in this mode to generate a periodic wakeup from stop mode.
16.4 Interrupts
The timebase module can periodically interrupt the CPU with a rate defined by the selected TBMCLK and
the select bits TBR2–TBR0. When the timebase counter chain rolls over, the TBIF flag is set. If the TBIE
bit is set, enabling the timebase interrupt, the counter chain overflow will generate a CPU interrupt
request.
NOTE
Interrupts must be acknowledged by writing a 1 to the TACK bit.
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Timebase Module (TBM)
TMBCLKSEL
FROM CONFIG2
TBMCLK
0
1
CGMXCLK
FROM CGM MODULE
DIVIDE BY 128
PRESCALER
TBON
÷ 2
÷ 2
÷ 2 ÷ 2 ÷ 2
÷ 2
÷ 2
TBMINT
÷ 2 ÷ 2 ÷ 2 ÷ 2
÷ 2 ÷ 2
÷ 2 ÷ 2
TBIF
TBIE
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
R
Figure 16-1. Timebase Block Diagram
16.5 TBM Interrupt Rate
The interrupt rate is determined by the equation:
Divider
t
=
TBMRATE
f
CGMXCLK
where:
CGMXCLK = Frequency supplied from the clock generator (CGM) module
f
Divider = Divider value as determined by TBR2–TBR0 settings and TMBCLKSEL, see Table 16-1
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Low-Power Modes
Table 16-1. Timebase Divider Selection
Divider
TMBCLKSEL
TBR2
TBR1
TBR0
0
32,768
8192
2048
128
64
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
4,194,304
1,048,576
262144
16,384
8192
32
4096
16
2048
8
1024
As an example, a 4.9152 MHz crystal, with the TMBCLKSEL set for divide-by-128 and the TBR2–TBR0
set to {011}, the divider is 16,384 and the interrupt rate calculates to:
16,384
4.9152 x 106
= 3.33 ms
NOTE
Do not change TBR2–TBR0 bits while the timebase is enabled (TBON = 1).
16.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power- consumption standby modes.
16.6.1 Wait Mode
The timebase module remains active after execution of the WAIT instruction. In wait mode the timebase
register is not accessible by the CPU.
If the timebase functions are not required during wait mode, reduce the power consumption by stopping
the timebase before executing the WAIT instruction.
16.6.2 Stop Mode
The timebase module may remain active after execution of the STOP instruction if the oscillator has been
enabled to operate during stop mode through the OSCENINSTOP bit in the configuration register. The
timebase module can be used in this mode to generate a periodic wakeup from stop mode.
If the oscillator has not been enabled to operate in stop mode, the timebase module will not be active
during stop mode. In stop mode, the timebase register is not accessible by the CPU.
If the timebase functions are not required during stop mode, reduce power consumption by disabling the
timebase module before executing the STOP instruction.
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Timebase Module (TBM)
16.7 Timebase Control Register
The timebase has one register, the timebase control register (TBCR), which is used to enable the
timebase interrupts and set the rate.
Address: $001C
Bit 7
6
TBR2
0
5
TBR1
0
4
TBR0
0
3
2
1
TBON
0
Bit 0
Read:
Write:
Reset:
TBIF
0
TACK
0
TBIE
R
0
0
0
= Unimplemented
R
= Reserved
Figure 16-2. Timebase Control Register (TBCR)
TBIF — Timebase Interrupt Flag
This read-only flag bit is set when the timebase counter has rolled over.
1 = Timebase interrupt pending
0 = Timebase interrupt not pending
TBR2–TBR0 — Timebase Divider Selection Bits
These read/write bits select the tap in the counter to be used for timebase interrupts as shown in
Table 16-1.
NOTE
Do not change TBR2–TBR0 bits while the timebase is enabled (TBON = 1).
TACK— Timebase Acknowledge Bit
The TACK bit is a write-only bit and always reads as 0. Writing a 1 to this bit clears TBIF, the timebase
interrupt flag bit. Writing a 0 to this bit has no effect.
1 = Clear timebase interrupt flag
0 = No effect
TBIE — Timebase Interrupt Enabled Bit
This read/write bit enables the timebase interrupt when the TBIF bit becomes set. Reset clears the
TBIE bit.
1 = Timebase interrupt is enabled.
0 = Timebase interrupt is disabled.
TBON — Timebase Enabled Bit
This read/write bit enables the timebase. Timebase may be turned off to reduce power consumption
when its function is not necessary. The counter can be initialized by clearing and then setting this bit.
Reset clears the TBON bit.
1 = Timebase is enabled.
0 = Timebase is disabled and the counter initialized to 0s.
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Chapter 17
Timer Interface Module (TIM1)
17.1 Introduction
This section describes the timer interface module (TIM1). TIM1 is a two-channel timer that provides a
timing reference with input capture, output compare, and pulse-width-modulation functions. Figure 17-2
is a block diagram of the TIM1.
17.2 Features
Features of the TIM1 include the following:
•
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 TIM1 clock input with 7-frequency internal bus clock prescaler selection
Free-running or modulo up-count operation
Toggle any channel pin on overflow
TIM1 counter stop and reset bits
17.3 Functional Description
Figure 17-2 shows the structure of the TIM1. The central component of the TIM1 is the 16-bit TIM1
counter that can operate as a free-running counter or a modulo up-counter. The TIM1 counter provides
the timing reference for the input capture and output compare functions. The TIM1 counter modulo
registers, T1MODH:T1MODL, control the modulo value of the TIM1 counter. Software can read the TIM1
counter value at any time without affecting the counting sequence.
The two TIM1 channels are programmable independently as input capture or output compare channels.
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Timer Interface Module (TIM1)
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 62,078 BYTES
USER RAM — 2048 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
MONITOR ROM
2-CHANNEL TIMER INTERFACE
MODULE
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
PTD1/MISO(2)
PTD0/SS/MCLK(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure 17-1. Block Diagram Highlighting TIM1 Block and Pins
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Freescale Semiconductor
Functional Description
PRESCALER SELECT
INTERNAL
BUS CLOCK
PRESCALER
TSTOP
TRST
PS2
PS1
PS0
16-BIT COUNTER
TOF
INTERRUPT
LOGIC
TOIE
16-BIT COMPARATOR
T1MODH:T1MODL
TOV0
ELS0B
ELS0A
PORT
LOGIC
CHANNEL 0
16-BIT COMPARATOR
T1CH0H:T1CH0L
16-BIT LATCH
CH0MAX
PTD4/T1CH0
CH0F
INTERRUPT
LOGIC
CH0IE
MS0A
MS0B
CH1F
TOV1
ELS1B
ELS1A
PORT
LOGIC
CHANNEL 1
16-BIT COMPARATOR
T1CH1H:T1CH1L
16-BIT LATCH
CH1MAX
PTD5/T1CH1
INTERRUPT
LOGIC
CH1IE
MS1A
Figure 17-2. TIM1 Block Diagram
Addr.
Register Name
Bit 7
TOF
0
6
5
4
0
3
2
1
Bit 0
Read:
0
TIM1 Status and Control
TOIE
TSTOP
PS2
PS1
PS0
$0020
Register (T1SC) Write:
See page 234.
TRST
0
Reset:
0
0
1
0
0
0
0
Read:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
TIM1 Counter Register High
$0021
$0022
(T1CNTH) Write:
See page 235.
Reset:
Read:
0
0
0
0
0
0
0
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TIM1 Counter Register Low
(T1CNTL) Write:
See page 235.
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 17-3. TIM1 I/O Register Summary
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
227
Timer Interface Module (TIM1)
Addr.
Register Name
Bit 7
Bit 15
1
6
Bit 14
1
5
Bit 13
1
4
Bit 12
1
3
Bit 11
1
2
Bit 10
1
1
Bit 9
1
Bit 0
Read:
TIM1 Counter Modulo Register
Bit 8
$0023
High (T1MODH) Write:
See page 236.
Reset:
1
Bit 0
1
Read:
TIM1 Counter Modulo Register
Bit 7
Bit 6
1
Bit 5
1
Bit 4
1
Bit 3
1
Bit 2
1
Bit 1
1
$0024
$0025
$0026
$0027
$0028
$0029
$002A
Low (T1MODL) Write:
See page 236.
Reset:
1
CH0F
0
Read:
TIM1 Channel 0 Status and
Control Register (T1SC0) Write:
CH0IE
0
MS0B
0
MS0A
0
ELS0B
0
ELS0A
0
TOV0
0
CH0MAX
0
See page 237.
Reset:
0
Read:
TIM1 Channel 0 Register High
Bit 15
Bit 7
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
(T1CH0H) Write:
See page 240.
Reset:
Indeterminate after reset
Bit 4 Bit 3
Indeterminate after reset
Read:
TIM1 Channel 0 Register Low
Bit 6
Bit 5
0
Bit 2
Bit 1
Bit 0
(T1CH0L) Write:
See page 240.
Reset:
Read:
CH1F
TIM1 Channel 1 Status and
Control Register (T1SC1) Write:
CH1IE
0
MS1A
0
ELS1B
0
ELS1A
0
TOV1
0
CH1MAX
0
0
See page 237.
Reset:
0
0
Read:
TIM1 Channel 1 Register High
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
(T1CH1H) Write:
See page 240.
Reset:
Indeterminate after reset
Bit 4 Bit 3
Indeterminate after reset
Read:
TIM1 Channel 1 Register Low
Bit 7
Bit 6
Bit 5
Bit 2
Bit 1
Bit 0
(T1CH1L) Write:
See page 240.
Reset:
= Unimplemented
Figure 17-3. TIM1 I/O Register Summary (Continued)
17.3.1 TIM1 Counter Prescaler
The TIM1 clock source is one of the seven prescaler outputs. The prescaler generates seven clock rates
from the internal bus clock. The prescaler select bits, PS[2:0], in the TIM1 status and control register
(T1SC) select the TIM1 clock source.
17.3.2 Input Capture
With the input capture function, the TIM1 can capture the time at which an external event occurs. When
an active edge occurs on the pin of an input capture channel, the TIM1 latches the contents of the TIM1
counter into the TIM1 channel registers, T1CHxH:T1CHxL. The polarity of the active edge is
programmable. Input captures can generate TIM1 central processor unit (CPU) interrupt requests.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
228
Freescale Semiconductor
Functional Description
17.3.3 Output Compare
With the output compare function, the TIM1 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 TIM1 can set, clear, or toggle the channel pin. Output compares can generate TIM1 CPU
interrupt requests.
17.3.3.1 Unbuffered Output Compare
Any output compare channel can generate unbuffered output compare pulses as described in 17.3.3
Output Compare. The pulses are unbuffered because changing the output compare value requires writing
the new value over the old value currently in the TIM1 channel registers.
An unsynchronized write to the TIM1 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 TIM1 overflow interrupt routine to write a new, smaller output
compare value may cause the compare to be missed. The TIM1 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 TIM1 overflow interrupts and write the
new value in the TIM1 overflow interrupt routine. The TIM1 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.
17.3.3.2 Buffered Output Compare
Channels 0 and 1 can be linked to form a buffered output compare channel whose output appears on the
T1CH0 pin. The TIM1 channel registers of the linked pair alternately control the output.
Setting the MS0B bit in TIM1 channel 0 status and control register (TSC0) links channel 0 and channel 1.
The output compare value in the TIM1 channel 0 registers initially controls the output on the T1CH0 pin.
Writing to the TIM1 channel 1 registers enables the TIM1 channel 1 registers to synchronously control the
output after the TIM1 overflows. At each subsequent overflow, the TIM1 channel registers (0 or 1) that
control the output are the ones written to last. T1SC0 controls and monitors the buffered output compare
function, and TIM1 channel 1 status and control register (T1SC1) is unused. While the MS0B bit is set,
the channel 1 pin, T1CH1, 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
229
Timer Interface Module (TIM1)
17.3.4 Pulse Width Modulation (PWM)
By using the toggle-on-overflow feature with an output compare channel, the TIM1 can generate a PWM
signal. The value in the TIM1 counter modulo registers determines the period of the PWM signal. The
channel pin toggles when the counter reaches the value in the TIM1 counter modulo registers. The time
between overflows is the period of the PWM signal.
As Figure 17-4 shows, the output compare value in the TIM1 channel registers determines the pulse width
of the PWM signal. The time between overflow and output compare is the pulse width. Program the TIM1
to clear the channel pin on output compare if the polarity of the PWM pulse is 1 (ELSxA = 0). Program the
TIM1 to set the pin if the polarity of the PWM pulse is 0 (ELSxA = 1).
The value in the TIM1 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 TIM1 counter modulo registers produces a PWM period of 256 times the internal bus
clock period if the prescaler select value is 000. See 17.8.1 TIM1 Status and Control Register.
The value in the TIM1 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 TIM1 channel registers
produces a duty cycle of 128/256 or 50%.
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
POLARITY = 1
(ELSxA = 0)
TCHx
TCHx
PULSE
WIDTH
POLARITY = 0
(ELSxA = 1)
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 17-4. PWM Period and Pulse Width
17.3.4.1 Unbuffered PWM Signal Generation
Any output compare channel can generate unbuffered PWM pulses as described in 17.3.4 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 TIM1 channel registers.
An unsynchronized write to the TIM1 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 TIM1 overflow interrupt routine to write a new, smaller pulse width value may cause
the compare to be missed. The TIM1 may pass the new value before it is written to the timer channel
(T1CHxH:T1CHxL) registers.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
230
Freescale Semiconductor
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 TIM1 overflow interrupts and write the new value
in the TIM1 overflow interrupt routine. The TIM1 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.
17.3.4.2 Buffered PWM Signal Generation
Channels 0 and 1 can be linked to form a buffered PWM channel whose output appears on the T1CH0
pin. The TIM1 channel registers of the linked pair alternately control the pulse width of the output.
Setting the MS0B bit in TIM1 channel 0 status and control register (T1SC0) links channel 0 and channel 1.
The TIM1 channel 0 registers initially control the pulse width on the T1CH0 pin. Writing to the TIM1
channel 1 registers enables the TIM1 channel 1 registers to synchronously control the pulse width at the
beginning of the next PWM period. At each subsequent overflow, the TIM1 channel registers (0 or 1) that
control the pulse width are the ones written to last. T1SC0 controls and monitors the buffered PWM
function, and TIM1 channel 1 status and control register (T1SC1) is unused. While the MS0B bit is set,
the channel 1 pin, T1CH1, is available as a general-purpose I/O pin.
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.
17.3.4.3 PWM Initialization
To ensure correct operation when generating unbuffered or buffered PWM signals, use the following
initialization procedure:
1. In the TIM1 status and control register (T1SC):
a. Stop the TIM1 counter by setting the TIM1 stop bit, TSTOP.
b. Reset the TIM1 counter and prescaler by setting the TIM1 reset bit, TRST.
2. In the TIM1 counter modulo registers (T1MODH:T1MODL), write the value for the required PWM
period.
3. In the TIM1 channel x registers (T1CHxH:T1CHxL), write the value for the required pulse width.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
231
Timer Interface Module (TIM1)
4. In TIM1 channel x status and control register (T1SCx):
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 17-2.
b. Write 1 to the toggle-on-overflow bit, TOVx.
c. Write 1:0 (polarity 1 — to clear output on compare) or 1:1 (polarity 0 — 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 17-2.
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 TIM1 status control register (T1SC), clear the TIM1 stop bit, TSTOP.
Setting MS0B links channels 0 and 1 and configures them for buffered PWM operation. The TIM1
channel 0 registers (TCH0H:TCH0L) initially control the buffered PWM output. TIM1 status control
register 0 (TSCR0) controls and monitors the PWM signal from the linked channels. MS0B takes priority
over MS0A.
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIM1 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 17.8.4 TIM1 Channel Status and Control Registers.
17.4 Interrupts
The following TIM1 sources can generate interrupt requests:
•
TIM1 overflow flag (TOF) — The TOF bit is set when the TIM1 counter reaches the modulo value
programmed in the TIM1 counter modulo registers. The TIM1 overflow interrupt enable bit, TOIE,
enables TIM1 overflow CPU interrupt requests. TOF and TOIE are in the TIM1 status and control
register.
•
TIM1 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 TIM1 channel x status and control register.
17.5 Wait Mode
The WAIT instruction puts the MCU in low power-consumption standby mode.
The TIM1 remains active after the execution of a WAIT instruction. In wait mode the TIM1 registers are
not accessible by the CPU. Any enabled CPU interrupt request from the TIM1 can bring the MCU out of
wait mode.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
232
Freescale Semiconductor
TIM1 During Break Interrupts
If TIM1 functions are not required during wait mode, reduce power consumption by stopping the TIM1
before executing the WAIT instruction.
17.6 TIM1 During Break Interrupts
A break interrupt stops the TIM1 counter and inhibits input captures.
The system integration module (SIM) controls whether status bits in other modules can be cleared during
the break state. The BCFE bit in the break flag control register (BFCR) enables software to clear status
bits during the break state. See Figure 14-21. Break Status Register (BSR).
To allow software to clear status bits during a break interrupt, write a 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 0 to the BCFE bit. With BCFE at 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 0. After the break, doing the
second step clears the status bit.
17.7 Input/Output Signals
Port D shares two of its pins with the TIM1. The two TIM1 channel I/O pins are PTD4/T1CH0 and
PTD5/T1CH1.
Each channel I/O pin is programmable independently as an input capture pin or an output compare pin.
PTD4/T1CH0 can be configured as a buffered output compare or buffered PWM pin.
17.8 Input/Output Registers
The following I/O registers control and monitor operation of the TIM:
•
•
•
•
•
TIM1 status and control register (T1SC)
TIM1 counter registers (T1CNTH:T1CNTL)
TIM1 counter modulo registers (T1MODH:T1MODL)
TIM1 channel status and control registers (T1SC0 and T1SC1)
TIM1 channel registers (T1CH0H:T1CH0L and T1CH1H:T1CH1L)
17.8.1 TIM1 Status and Control Register
The TIM1 status and control register (T1SC) does the following:
•
•
•
•
•
Enables TIM1 overflow interrupts
Flags TIM1 overflows
Stops the TIM1 counter
Resets the TIM1 counter
Prescales the TIM1 counter clock
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
233
Timer Interface Module (TIM1)
Address: $0020
Bit 7
6
TOIE
0
5
TSTOP
1
4
0
3
0
2
PS2
0
1
PS1
0
Bit 0
PS0
0
Read:
Write:
Reset:
TOF
0
0
TRST
0
0
= Unimplemented
Figure 17-5. TIM1 Status and Control Register (T1SC)
TOF — TIM1 Overflow Flag Bit
This read/write flag is set when the TIM1 counter reaches the modulo value programmed in the TIM1
counter modulo registers. Clear TOF by reading the TIM1 status and control register when TOF is set
and then writing a 0 to TOF. If another TIM1 overflow occurs before the clearing sequence is complete,
then writing 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 1 to TOF has no effect.
1 = TIM1 counter has reached modulo value
0 = TIM1 counter has not reached modulo value
TOIE — TIM1 Overflow Interrupt Enable Bit
This read/write bit enables TIM1 overflow interrupts when the TOF bit becomes set. Reset clears the
TOIE bit.
1 = TIM1 overflow interrupts enabled
0 = TIM1 overflow interrupts disabled
TSTOP — TIM1 Stop Bit
This read/write bit stops the TIM1 counter. Counting resumes when TSTOP is cleared. Reset sets the
TSTOP bit, stopping the TIM1 counter until software clears the TSTOP bit.
1 = TIM1 counter stopped
0 = TIM1 counter active
NOTE
Do not set the TSTOP bit before entering wait mode if the TIM1 is required
to exit wait mode. Also, when the TSTOP bit is set and the timer is
configured for input capture operation, input captures are inhibited until the
TSTOP bit is cleared.
TRST — TIM1 Reset Bit
Setting this write-only bit resets the TIM1 counter and the TIM1 prescaler. Setting TRST has no effect
on any other registers. Counting resumes from $0000. TRST is cleared automatically after the TIM1
counter is reset and always reads as 0. Reset clears the TRST bit.
1 = Prescaler and TIM1 counter cleared
0 = No effect
NOTE
Setting the TSTOP and TRST bits simultaneously stops the TIM1 counter
at a value of $0000.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
234
Freescale Semiconductor
Input/Output Registers
PS[2:0] — Prescaler Select Bits
These read/write bits select one of the seven prescaler outputs as the input to the TIM1 counter as
Table 17-1 shows. Reset clears the PS[2:0] bits.
Table 17-1. Prescaler Selection
PS2
0
PS1
0
PS0
0
TIM1 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
Not available
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
17.8.2 TIM1 Counter Registers
The two read-only TIM1 counter registers contain the high and low bytes of the value in the TIM1 counter.
Reading the high byte (T1CNTH) latches the contents of the low byte (T1CNTL) into a buffer. Subsequent
reads of T1CNTH do not affect the latched T1CNTL value until T1CNTL is read. Reset clears the TIM1
counter registers. Setting the TIM1 reset bit (TRST) also clears the TIM1 counter registers.
NOTE
If you read T1CNTH during a break interrupt, be sure to unlatch T1CNTL
by reading T1CNTL before exiting the break interrupt. Otherwise, T1CNTL
retains the value latched during the break.
$0021
T1CNTH
6
Address:
Bit 7
5
4
3
2
1
Bit 0
Bit 8
Read:
Write:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Reset:
0
0
T1CNTL
6
0
0
0
0
0
0
$0022
Address:
Bit 7
Bit 7
5
4
3
2
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
0
0
0
0
0
0
0
0
= Unimplemented
Figure 17-6. TIM1 Counter Registers (T1CNTH:T1CNTL)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
235
Timer Interface Module (TIM1)
17.8.3 TIM1 Counter Modulo Registers
The read/write TIM1 modulo registers contain the modulo value for the TIM1 counter. When the TIM1
counter reaches the modulo value, the overflow flag (TOF) becomes set, and the TIM1 counter resumes
counting from $0000 at the next timer clock. Writing to the high byte (T1MODH) inhibits the TOF bit and
overflow interrupts until the low byte (T1MODL) is written. Reset sets the TIM1 counter modulo registers.
Address: $0023
Bit 7
T1MODH
6
5
Bit13
1
4
Bit12
1
3
Bit11
1
2
Bit10
1
1
Bit9
1
Bit 0
Bit8
1
Read:
Write:
Reset:
Bit15
1
Bit14
1
T1MODL
6
Address: $0024
Bit 7
5
Bit5
1
4
Bit4
1
3
Bit3
1
2
Bit2
1
1
Bit1
1
Bit 0
Bit0
1
Read:
Write:
Reset:
Bit7
1
Bit6
1
Figure 17-7. TIM1 Counter Modulo Registers (T1MODH:T1MODL)
NOTE
Reset the TIM1 counter before writing to the TIM1 counter modulo registers.
17.8.4 TIM1 Channel Status and Control Registers
Each of the TIM1 channel status and control registers does the following:
•
•
•
•
•
•
•
•
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 TIM1 overflow
Selects 0% and 100% PWM duty cycle
Selects buffered or unbuffered output compare/PWM operation
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
236
Freescale Semiconductor
Input/Output Registers
Address: $0025
Bit 7
T1SC0
6
5
MS0B
0
4
MS0A
0
3
ELS0B
0
2
ELS0A
0
1
TOV0
0
Bit 0
CH0MAX
0
Read:
Write:
Reset:
CH0F
CH0IE
0
0
0
$0028
T1SC1
6
Address:
Bit 7
CH1F
0
5
0
4
MS1A
0
3
ELS1B
0
2
ELS1A
0
1
TOV1
0
Bit 0
CH1MAX
0
Read:
Write:
Reset:
CH1IE
0
0
0
= Unimplemented
Figure 17-8. TIM1 Channel Status and Control Registers (T1SC0:T1SC1)
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
TIM1 counter registers matches the value in the TIM1 channel x registers.
Clear CHxF by reading the TIM1 channel x status and control register with CHxF set and then writing
a 0 to CHxF. If another interrupt request occurs before the clearing sequence is complete, then writing
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 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 TIM1 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 status and control register.
Setting MS0B disables the channel 1 status and control register and reverts T1CH1 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:A ≠ 00, this read/write bit selects either input capture operation or unbuffered output
compare/PWM operation. See Table 17-2.
1 = Unbuffered output compare/PWM operation
0 = Input capture operation
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
237
Timer Interface Module (TIM1)
When ELSxB:A = 00, this read/write bit selects the initial output level of the TCHx pin (see Table 17-2).
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 TIM1 status and control register (T1SC).
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 17-2 shows how ELSxB and ELSxA work. Reset clears
the ELSxB and ELSxA bits.
Table 17-2. Mode, Edge, and Level Selection
MSxB MSxA
ELSxB
ELSxA
Mode
Configuration
Pin under port control;
initial output level high
X
X
0
1
0
0
Output preset
Pin under port control;
initial output level low
0
0
0
0
0
0
0
1
1
0
Capture on rising edge only
Capture on falling edge only
Input capture
Capture on rising
or falling edge
0
0
1
1
0
0
0
0
1
1
1
1
1
1
X
X
0
0
1
1
0
1
0
1
0
1
1
0
Software compare only
Toggle output on compare
Clear output on compare
Set output on compare
Toggle output on compare
Clear output on compare
Output compare
or PWM
Buffered
output
compare or
buffered PWM
1
X
1
1
Set output on compare
NOTE
After initially enabling a TIM1 channel register for input capture operation
and selecting the edge sensitivity, clear CHxF to ignore any erroneous
edge detection flags.
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 TIM1 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 TIM1 counter overflow.
0 = Channel x pin does not toggle on TIM1 counter overflow.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Input/Output Registers
NOTE
When TOVx is set, a TIM1 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 1, setting the CHxMAX bit forces the duty cycle of buffered and unbuffered
PWM signals to 100%. As Figure 17-9 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.
NOTE
The 100% PWM duty cycle is defined as a continuous high level if the PWM
polarity is 1 and a continuous low level if the PWM polarity is 0. Conversely,
a 0% PWM duty cycle is defined as a continuous low level if the PWM
polarity is 1 and a continuous high level if the PWM polarity is 0.
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
TCHx
OUTPUT
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
COMPARE
CHxMAX
Figure 17-9. CHxMAX Latency
17.8.5 TIM1 Channel Registers
These read/write registers contain the captured TIM1 counter value of the input capture function or the
output compare value of the output compare function. The state of the TIM1 channel registers after reset
is unknown.
In input capture mode (MSxB:MSxA = 0:0), reading the high byte of the TIM1 channel x registers
(T1CHxH) inhibits input captures until the low byte (T1CHxL) is read.
In output compare mode (MSxB:MSxA ≠ 0:0), writing to the high byte of the TIM1 channel x registers
(T1CHxH) inhibits output compares until the low byte (T1CHxL) is written.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
239
Timer Interface Module (TIM1)
Address: $0026
Bit 7
T1CH0H
6
5
4
3
2
1
Bit 0
Bit 8
Read:
Bit 15
Write:
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Reset:
Indeterminate after reset
$0027
T1CH0L
6
Address:
Bit 7
5
4
3
2
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Indeterminate after reset
$0029
T1CH1H
6
Address:
Bit 7
5
4
3
2
1
Bit 0
Bit 8
Read:
Write:
Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Indeterminate after reset
$02A
T1CH1L
6
Address:
Bit 7
5
4
3
2
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Indeterminate after reset
Figure 17-10. TIM1 Channel Registers (T1CH0H/L:T1CH1H/L)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Chapter 18
Timer Interface Module (TIM2)
18.1 Introduction
This section describes the timer interface module (TIM2). The TIM2 is a 6-channel timer that provides a
timing reference with input capture, output compare, and pulse-width-modulation functions. Figure 18-2
is a block diagram of the TIM2.
18.2 Features
Features of the TIM2 include:
•
Six 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 TIM2 clock input
–
–
7-frequency internal bus clock prescaler selection
External TIM2 clock input (4-MHz maximum frequency)
•
•
•
Free-running or modulo up-count operation
Toggle any channel pin on overflow
TIM2 counter stop and reset bits
18.3 Functional Description
Figure 18-2 shows the TIM2 structure. The central component of the TIM2 is the 16-bit TIM2 counter that
can operate as a free-running counter or a modulo up-counter. The TIM2 counter provides the timing
reference for the input capture and output compare functions. The TIM2 counter modulo registers,
T2MODH:T2MODL, control the modulo value of the TIM2 counter. Software can read the TIM2 counter
value at any time without affecting the counting sequence.
The six TIM2 channels are programmable independently as input capture or output compare channels.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
241
Timer Interface Module (TIM2)
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 62,078 BYTES
USER RAM — 2048 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
2-CHANNEL TIMER INTERFACE
MODULE
MONITOR ROM
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure 18-1. Block Diagram Highlighting TIM2 Block and Pins
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Freescale Semiconductor
Functional Description
TCLK
PTD6/T2CH0
PRESCALER SELECT
INTERNAL
BUS CLOCK
PRESCALER
TSTOP
TRST
PS2
PS1
PS0
16-BIT COUNTER
INTER-
TOF
RUPT
LOGIC
TOIE
16-BIT COMPARATOR
T2MODH:T2MODL
ELS0B
ELS0A
ELS1A
CHANNEL 0
16-BIT COMPARATOR
T2CH0H:T2CH0L
16-BIT LATCH
TOV0
CH0MAX
PTD6
T2CH0
T2CH1
LOGIC
CH0F
MS0B
INTER-
RUPT
LOGIC
CH0IE
MS0A
ELS1B
ELS2B
CHANNEL 1
16-BIT COMPARATOR
T2CH1H:T2CH1L
16-BIT LATCH
TOV1
CH1MAX
PTD7
LOGIC
CH1F
INTER-
RUPT
LOGIC
CH1IE
MS1A
ELS2A
CHANNEL 2
16-BIT COMPARATOR
T2CH2H:T2CH2L
16-BIT LATCH
TOV2
CH2MAX
PTF4
T2CH2
T2CH3
LOGIC
CH2F
MS2B
INTER-
RUPT
LOGIC
CH2IE
MS2A
ELS3B
ELS4B
ELS3A
CHANNEL 3
16-BIT COMPARATOR
T2CH3H:T2CH3L
16-BIT LATCH
TOV3
CH3MAX
PTF5
LOGIG
CH3F
INTER-
RUPT
LOGIC
CH3IE
MS3A
ELS4A
CHANNEL 4
16-BIT COMPARATOR
T2CH4H:T2CH4L
16-BIT LATCH
TOV4
CH4MAX
PTF6
T2CH4
T2CH5
LOGIC
CH4F
MS4B
INTER-
RUPT
LOGIC
CH4IE
MS4A
ELS5B
ELS5A
CHANNEL 5
16-BIT COMPARATOR
T2CH5H:T2CH5L
16-BIT LATCH
TOV5
CH5MAX
PTF7
LOGIC
CH5F
INTER-
RUPT
LOGIC
CH5IE
MS5A
Figure 18-2. TIM2 Block Diagram
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
243
Timer Interface Module (TIM2)
Addr.
Register Name
Bit 7
TOF
0
6
5
4
0
3
2
1
Bit 0
Read:
0
TIM2 Status and Control
TOIE
TSTOP
PS2
PS1
PS0
$002B
Register (T2SC) Write:
See page 252.
TRST
0
Reset:
0
0
1
0
0
0
9
0
Read:
Bit 15
14
13
12
11
10
Bit 8
TIM2 Counter Register High
$002C
$002D
$002E
$002F
$0030
$0031
$0032
$0033
$0034
$0035
$0456
(T2CNTH) Write:
See page 254.
Reset:
Read:
0
0
6
0
5
0
4
0
3
0
2
0
1
0
Bit 7
Bit 0
TIM2 Counter Register Low
(T2CNTL) Write:
See page 254.
Reset:
Read:
0
Bit 15
1
0
0
13
1
0
12
1
0
0
0
0
TIM2 Modulo Register High
14
11
10
9
Bit 8
(T2MODH) Write:
See page 254.
Reset:
1
1
1
1
1
Bit 0
1
Read:
TIM2 Modulo Register Low
Bit 7
6
1
5
4
3
2
1
(T2MODL) Write:
See page 254.
Reset:
1
1
1
1
ELS0B
0
1
ELS0A
0
1
TOV0
0
Read: CH0F
TIM2 Channel 0 Status and
CH0IE
0
MS0B
0
MS0A
0
CH0MAX
0
Control Register (T2SC0) Write:
0
0
See page 255.
Reset:
Read:
TIM2 Channel 0 Register High
Bit 15
14
13
12
11
10
9
Bit 8
(T2CH0H) Write:
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 0 Register Low
Bit 7
6
5
0
4
3
2
1
Bit 0
(T2CH0L) Write:
See page 258.
Reset:
Indeterminate after reset
Read: CH1F
TIM2 Channel 1 Status and
CH1IE
MS1A
0
ELS1B
ELS1A
TOV1
CH1MAX
Control Register (T2SC1) Write:
0
0
See page 255.
Reset:
0
0
0
0
0
9
0
Read:
TIM2 Channel 1 Register High
Bit 15
14
13
12
11
10
Bit 8
(T2CH1H) Write:
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 1 Register Low
Bit 7
6
5
4
3
2
1
Bit 0
(T2CH1L) Write:
See page 258.
Reset:
Indeterminate after reset
Read: CH2F
TIM2 Channel 2 Status and
CH2IE
0
MS2B
0
MS2A
0
ELS2B
0
ELS2A
0
TOV2
0
CH2MAX
0
Control Register (T2SC2) Write:
0
0
See page 255.
Reset:
= Unimplemented
Figure 18-3. TIM2 I/O Register Summary (Sheet 1 of 2)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
244
Freescale Semiconductor
Functional Description
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
TIM2 Channel 2 Register High
Bit 15
14
13
12
11
10
9
Bit 8
$0457
(T2CH2H) Write:
See page 258.
Reset:
Read:
Indeterminate after reset
TIM2 Channel 2 Register Low
Bit 7
6
5
0
4
3
2
1
Bit 0
$0458
$0459
$045A
$045B
$045C
$045D
$045E
$045F
$0460
$0461
(T2CH2L) Write:
See page 258.
Reset:
Read: CH3F
Indeterminate after reset
TIM2 Channel 3 Status and
Control Register (T2SC3) Write:
CH3IE
MS3A
0
ELS3B
ELS3A
TOV3
CH3MAX
0
0
See page 255.
Reset:
0
0
0
0
0
9
0
Read:
TIM2 Channel 3 Register High
Bit 15
14
13
12
11
10
Bit 8
(T2CH3H) Write:
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 3 Register Low
Bit 7
6
5
4
3
2
1
Bit 0
(T2CH3L) Write:
See page 258.
Reset:
Indeterminate after reset
Read: CH4F
TIM2 Channel 4 Status and
CH4IE
MS4B
0
MS4A
0
ELS4B
ELS4A
TOV4
CH4MAX
Control Register (T2SC4) Write:
0
0
See page 255.
Reset:
0
0
0
0
9
0
Read:
TIM2 Channel 4 Register High
Bit 15
14
13
12
11
10
Bit 8
(T2CH4H) Write:
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 4 Register Low
Bit 7
6
5
0
4
3
2
1
Bit 0
(T2CH4L) Write:
See page 258.
Reset:
Indeterminate after reset
Read: CH5F
TIM2 Channel 5 Status and
CH5IE
MS5A
0
ELS5B
ELS5A
TOV5
CH5MAX
Control Register (T2SC5) Write:
0
0
See page 255.
Reset:
0
0
0
0
0
9
0
Read:
TIM2 Channel 5 Register High
Bit 15
14
13
12
11
10
Bit 8
(T2CH5H) Write:
See page 258.
Reset:
Indeterminate after reset
Read:
TIM2 Channel 5 Register Low
Bit 7
6
5
4
3
2
1
Bit 0
(T2CH5L) Write:
See page 258.
Reset:
Indeterminate after reset
= Unimplemented
Figure 18-3. TIM2 I/O Register Summary (Sheet 2 of 2)
18.3.1 TIM2 Counter Prescaler
The TIM2 clock source can be one of the seven prescaler outputs or the TIM2 clock pin, T2CH0. The
prescaler generates seven clock rates from the internal bus clock. The prescaler select bits, PS[2:0], in
the TIM2 status and control register select the TIM2 clock source.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Timer Interface Module (TIM2)
18.3.2 Input Capture
An input capture function has three basic parts: edge select logic, an input capture latch, and a 16-bit
counter. Two 8-bit registers, which make up the 16-bit input capture register, are used to latch the value
of the free-running counter after the corresponding input capture edge detector senses a defined
transition. The polarity of the active edge is programmable. The level transition which triggers the counter
transfer is defined by the corresponding input edge bits (ELSxB and ELSxA in T2SC0 through T2SC5
control registers with x referring to the active channel number). When an active edge occurs on the pin of
an input capture channel, the TIM2 latches the contents of the TIM2 counter into the TIM2 channel
registers, T2CHxH:T2CHxL. Input captures can generate TIM2 CPU interrupt requests. Software can
determine that an input capture event has occurred by enabling input capture interrupts or by polling the
status flag bit.
The free-running counter contents are transferred to the TIM2 channel registers (T2CHxH:T2CHxL) (see
18.8.5 TIM2 Channel Registers) on each proper signal transition regardless of whether the TIM2 channel
flag (CH0F–CH5F in T2SC0–T2SC5 registers) is set or clear. When the status flag is set, a CPU interrupt
is generated if enabled. The value of the count latched or “captured” is the time of the event. Because this
value is stored in the input capture register when the actual event occurs, user software can respond to
this event at a later time and determine the actual time of the event. However, this must be done prior to
another input capture on the same pin; otherwise, the previous time value will be lost.
By recording the times for successive edges on an incoming signal, software can determine the period
and/or pulse width of the signal. To measure a period, two successive edges of the same polarity are
captured. To measure a pulse width, two alternate polarity edges are captured. Software should track the
overflows at the 16-bit module counter to extend its range.
Another use for the input capture function is to establish a time reference. In this case, an input capture
function is used in conjunction with an output compare function. For example, to activate an output signal
a specified number of clock cycles after detecting an input event (edge), use the input capture function to
record the time at which the edge occurred. A number corresponding to the desired delay is added to this
captured value and stored to an output compare register (see 18.8.5 TIM2 Channel Registers). Because
both input captures and output compares are referenced to the same 16-bit modulo counter, the delay
can be controlled to the resolution of the counter independent of software latencies.
Reset does not affect the contents of the input capture channel (T2CHxH:T2CHxL) registers.
18.3.3 Output Compare
With the output compare function, the TIM2 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 TIM2 can set, clear, or toggle the channel pin. Output compares can generate TIM2 CPU
interrupt requests.
18.3.3.1 Unbuffered Output Compare
Any output compare channel can generate unbuffered output compare pulses as described in 18.3.3
Output Compare. The pulses are unbuffered because changing the output compare value requires writing
the new value over the old value currently in the TIM2 channel registers.
An unsynchronized write to the TIM2 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 TIM2 overflow interrupt routine to write a new, smaller output
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Functional Description
compare value may cause the compare to be missed. The TIM2 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 TIM2 overflow interrupts and write the
new value in the TIM2 overflow interrupt routine. The TIM2 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.
18.3.3.2 Buffered Output Compare
Channels 0 and 1 can be linked to form a buffered output compare channel whose output appears on the
T2CH0 pin. The TIM2 channel registers of the linked pair alternately control the output.
Setting the MS0B bit in TIM2 channel 0 status and control register (T2SC0) links channel 0 and channel 1.
The output compare value in the TIM2 channel 0 registers initially controls the output on the T2CH0 pin.
Writing to the TIM2 channel 1 registers enables the TIM2 channel 1 registers to synchronously control the
output after the TIM2 overflows. At each subsequent overflow, the TIM2 channel registers (0 or 1) that
control the output are the ones written to last. T2SC0 controls and monitors the buffered output compare
function, and TIM2 channel 1 status and control register (T2SC1) is unused. While the MS0B bit is set,
the channel 1 pin, T2CH1, is available as a general-purpose I/O pin.
Channels 2 and 3 can be linked to form a buffered output compare channel whose output appears on the
T2CH2 pin. The TIM2 channel registers of the linked pair alternately control the output.
Setting the MS2B bit in TIM2 channel 2 status and control register (T2SC2) links channel 2 and channel 3.
The output compare value in the TIM2 channel 2 registers initially controls the output on the T2CH2 pin.
Writing to the TIM2 channel 3 registers enables the TIM2 channel 3 registers to synchronously control the
output after the TIM2 overflows. At each subsequent overflow, the TIM2 channel registers (2 or 3) that
control the output are the ones written to last. T2SC2 controls and monitors the buffered output compare
function, and TIM2 channel 3 status and control register (T2SC3) is unused. While the MS2B bit is set,
the channel 3 pin, T2CH3, is available as a general-purpose I/O pin.
Channels 4 and 5 can be linked to form a buffered output compare channel whose output appears on the
T2CH4 pin. The TIM2 channel registers of the linked pair alternately control the output.
Setting the MS4B bit in TIM2 channel 4 status and control register (T2SC4) links channel 4 and channel 5.
The output compare value in the TIM2 channel 4 registers initially controls the output on the T2CH4 pin.
Writing to the TIM2 channel 5 registers enables the TIM2 channel 5 registers to synchronously control the
output after the TIM2 overflows. At each subsequent overflow, the TIM2 channel registers (4 or 5) that
control the output are the ones written to last. T2SC4 controls and monitors the buffered output compare
function, and TIM2 channel 5 status and control register (T2SC5) is unused. While the MS4B bit is set,
the channel 5 pin, T2CH5, 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
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
247
Timer Interface Module (TIM2)
channel. Writing to the active channel registers is the same as generating
unbuffered output compares.
18.3.4 Pulse Width Modulation (PWM)
By using the toggle-on-overflow feature with an output compare channel, the TIM2 can generate a PWM
signal. The value in the TIM2 counter modulo registers determines the period of the PWM signal. The
channel pin toggles when the counter reaches the value in the TIM2 counter modulo registers. The time
between overflows is the period of the PWM signal.
As Figure 18-4 shows, the output compare value in the TIM2 channel registers determines the pulse width
of the PWM signal. The time between overflow and output compare is the pulse width. Program the TIM2
to clear the channel pin on output compare if the polarity of the PWM pulse is 1 (ELSxA = 0). Program the
TIM2 to set the pin if the polarity of the PWM pulse is 0 (ELSxA = 1).
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
POLARITY = 1
(ELSxA = 0)
TCHx
TCHx
PULSE
WIDTH
POLARITY = 0
(ELSxA = 1)
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 18-4. PWM Period and Pulse Width
The value in the TIM2 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 TIM2 counter modulo registers produces a PWM period of 256 times the internal bus
clock period if the prescaler select value is 000 (see 18.8.1 TIM2 Status and Control Register).
The value in the TIM2 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 TIM2 channel registers
produces a duty cycle of 128/256 or 50%.
18.3.4.1 Unbuffered PWM Signal Generation
Any output compare channel can generate unbuffered PWM pulses as described in 18.3.4 Pulse Width
Modulation (PWM). The pulses are unbuffered because changing the pulse width requires writing the new
pulse width value over the value currently in the TIM2 channel registers.
An unsynchronized write to the TIM2 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 TIM2 overflow interrupt routine to write a new, smaller pulse width value may cause
the compare to be missed. The TIM2 may pass the new value before it is written to the timer channel
(T2CHxH:T2CHxL) registers.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
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 TIM2 overflow interrupts and write the new value
in the TIM2 overflow interrupt routine. The TIM2 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.
18.3.4.2 Buffered PWM Signal Generation
Channels 0 and 1 can be linked to form a buffered PWM channel whose output appears on the T2CH0
pin. The TIM2 channel registers of the linked pair alternately control the pulse width of the output.
Setting the MS0B bit in TIM2 channel 0 status and control register (T2SC0) links channel 0 and channel 1.
The TIM2 channel 0 registers initially control the pulse width on the T2CH0 pin. Writing to the TIM2
channel 1 registers enables the TIM2 channel 1 registers to synchronously control the pulse width at the
beginning of the next PWM period. At each subsequent overflow, the TIM2 channel registers (0 or 1) that
control the pulse width are the ones written to last. T2SC0 controls and monitors the buffered PWM
function, and TIM2 channel 1 status and control register (T2SC1) is unused. While the MS0B bit is set,
the channel 1 pin, T2CH1, is available as a general-purpose I/O pin.
Channels 2 and 3 can be linked to form a buffered PWM channel whose output appears on the T2CH2
pin. The TIM2 channel registers of the linked pair alternately control the pulse width of the output.
Setting the MS2B bit in TIM2 channel 2 status and control register (T2SC2) links channel 2 and channel 3.
The TIM2 channel 2 registers initially control the pulse width on the T2CH2 pin. Writing to the TIM2
channel 3 registers enables the TIM2 channel 3 registers to synchronously control the pulse width at the
beginning of the next PWM period. At each subsequent overflow, the TIM2 channel registers (2 or 3) that
control the pulse width are the ones written to last. T2SC2 controls and monitors the buffered PWM
function, and TIM2 channel 3 status and control register (T2SC3) is unused. While the MS2B bit is set,
the channel 3 pin, T2CH3, is available as a general-purpose I/O pin.
Channels 4 and 5 can be linked to form a buffered PWM channel whose output appears on the T2CH4
pin. The TIM2 channel registers of the linked pair alternately control the pulse width of the output.
Setting the MS4B bit in TIM2 channel 4 status and control register (T2SC4) links channel 4 and channel 5.
The TIM2 channel 4 registers initially control the pulse width on the T2CH4 pin. Writing to the TIM2
channel 5 registers enables the TIM2 channel 5 registers to synchronously control the pulse width at the
beginning of the next PWM period. At each subsequent overflow, the TIM2 channel registers (4 or 5) that
control the pulse width are the ones written to last. T2SC4 controls and monitors the buffered PWM
function, and TIM2 channel 5 status and control register (T2SC5) is unused. While the MS4B bit is set,
the channel 5 pin, T2CH5, is available as a general-purpose I/O pin.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
249
Timer Interface Module (TIM2)
NOTE
In buffered PWM signal generation, do not write 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.
18.3.4.3 PWM Initialization
To ensure correct operation when generating unbuffered or buffered PWM signals, use the following
initialization procedure:
1. In the TIM2 status and control register (T2SC):
a. Stop the TIM2 counter by setting the TIM2 stop bit, TSTOP.
b. Reset the TIM2 counter and prescaler by setting the TIM2 reset bit, TRST.
2. In the TIM2 counter modulo registers (T2MODH:T2MODL), write the value for the required PWM
period.
3. In the TIM2 channel x registers (T2CHxH:T2CHxL), write the value for the required pulse width.
4. In TIM2 channel x status and control register (T2SCx):
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 18-2.)
b. Write 1 to the toggle-on-overflow bit, TOVx.
c. Write 1:0 (polarity 1 — to clear output on compare) or 1:1 (polarity 0 — 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 18-2.)
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 TIM2 status control register (T2SC), clear the TIM2 stop bit, TSTOP.
Setting MS0B links channels 0 and 1 and configures them for buffered PWM operation. The TIM2
channel 0 registers (T2CH0H:T2CH0L) initially control the buffered PWM output. TIM2 status control
register 0 (T2SC0) controls and monitors the PWM signal from the linked channels. MS0B takes priority
over MS0A.
Setting MS2B links channels 2 and 3 and configures them for buffered PWM operation. The TIM2
channel 2 registers (T2CH2H:T2CH2L) initially control the buffered PWM output. TIM2 status control
register 2 (T2SC2) controls and monitors the PWM signal from the linked channels. MS2B takes priority
over MS2A.
Setting MS4B links channels 4 and 5 and configures them for buffered PWM operation. The TIM2
channel 4 registers (T2CH4H:T2CH4L) initially control the buffered PWM output. TIM2 status control
register 4 (T2SC4) controls and monitors the PWM signal from the linked channels. MS4B takes priority
over MS4A.
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIM2 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
250
Freescale Semiconductor
Interrupts
Setting the channel x maximum duty cycle bit (CHxMAX) and setting the TOVx bit generates a 100% duty
cycle output. (See 18.8.4 TIM2 Channel Status and Control Registers.)
18.4 Interrupts
The following TIM2 sources can generate interrupt requests:
•
TIM2 overflow flag (TOF) — The TOF bit is set when the TIM2 counter reaches the modulo value
programmed in the TIM2 counter modulo registers. The TIM2 overflow interrupt enable bit, TOIE,
enables TIM2 overflow interrupt requests. TOF and TOIE are in the TIM2 status and control
register.
•
TIM2 channel flags (CH5F:CH0F) — The CHxF bit is set when an input capture or output compare
occurs on channel x. Channel x TIM2 CPU interrupt requests are controlled by the channel x
interrupt enable bit, CHxIE.
18.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low-power standby modes.
18.5.1 Wait Mode
The TIM2 remains active after the execution of a WAIT instruction. In wait mode, the TIM2 registers are
not accessible by the CPU. Any enabled CPU interrupt request from the TIM2 can bring the MCU out of
wait mode.
If TIM2 functions are not required during wait mode, reduce power consumption by stopping the TIM2
before executing the WAIT instruction.
18.5.2 Stop Mode
The TIM2 is inactive after the execution of a STOP instruction. The STOP instruction does not affect
register conditions or the state of the TIM2 counter. TIM2 operation resumes when the MCU exits stop
mode.
18.6 TIM2 During Break Interrupts
A break interrupt stops the TIM2 counter and inhibits input captures.
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 14.7.3 Break Flag Control Register.)
To allow software to clear status bits during a break interrupt, write a 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 0 to the BCFE bit. With BCFE at 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 0. After the break, doing the
second step clears the status bit.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
251
Timer Interface Module (TIM2)
18.7 I/O Signals
Port D shares two of its pins with the TIM2. Port F shares four of its pins with the TIM2. PTD6/T2CH0 is
an external clock input to the TIM2 prescaler. The six TIM2 channel I/O pins are PTD6/T2CH0,
PTD7/T2CH1, PTF4/T2CH2, PTF5/T2CH3, PTF6/T2CH4, and PTF7/T2CH5.
18.7.1 TIM2 Clock Pin (T2CH0)
T2CH0 is an external clock input that can be the clock source for the TIM2 counter instead of the
prescaled internal bus clock. Select the T2CH0 input by writing 1s to the three prescaler select bits,
PS[2:0]. (See 18.8.1 TIM2 Status and Control Register.) The minimum TCLK pulse width is specified in
20.14 Timer Interface Module Characteristics. The maximum TCLK frequency is the least: 4 MHz or bus
frequency ÷ 2.
When the PTD6/T2CH0 pin is the TIM2 clock input, it is an input regardless of the state of the DDRD6 bit
in data direction register D.
18.7.2 TIM2 Channel I/O Pins (T2CH5:T2CH2 and T2CH1:T2CH0)
Each channel I/O pin is programmable independently as an input capture pin or an output compare pin.
T2CH0, T2CH2, and T2CH4 can be configured as buffered output compare or buffered PWM pins.
18.8 I/O Registers
These I/O registers control and monitor TIM2 operation:
•
•
•
•
•
TIM2 status and control register (T2SC)
TIM2 counter registers (T2CNTH:T2CNTL)
TIM2 counter modulo registers (T2MODH:T2MODL)
TIM2 channel status and control registers (T2SC0, T2SC1, T2SC2, T2SC3, T2SC4, and T2SC5)
TIM2 channel registers (T2CH0H:T2CH0L, T2CH1H:T2CH1L, T2CH2H:T2CH2L,
T2CH3H:T2CH3L, T2CH4H:T2CH4L, and T2CH5H:T2CH5L)
18.8.1 TIM2 Status and Control Register
The TIM2 status and control register:
•
•
•
•
•
Enables TIM2 overflow interrupts
Flags TIM2 overflows
Stops the TIM2 counter
Resets the TIM2 counter
Prescales the TIM2 counter clock
Address:
$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 18-5. TIM2 Status and Control Register (T2SC)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
252
I/O Registers
TOF — TIM2 Overflow Flag Bit
This read/write flag is set when the TIM2 counter resets reaches the modulo value programmed in the
TIM2 counter modulo registers. Clear TOF by reading the TIM2 status and control register when TOF
is set and then writing a 0 to TOF. If another TIM2 overflow occurs before the clearing sequence is
complete, then writing 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 1 to TOF has no effect.
1 = TIM2 counter has reached modulo value
0 = TIM2 counter has not reached modulo value
TOIE — TIM2 Overflow Interrupt Enable Bit
This read/write bit enables TIM2 overflow interrupts when the TOF bit becomes set. Reset clears the
TOIE bit.
1 = TIM2 overflow interrupts enabled
0 = TIM2 overflow interrupts disabled
TSTOP — TIM2 Stop Bit
This read/write bit stops the TIM2 counter. Counting resumes when TSTOP is cleared. Reset sets the
TSTOP bit, stopping the TIM2 counter until software clears the TSTOP bit.
1 = TIM2 counter stopped
0 = TIM2 counter active
NOTE
Do not set the TSTOP bit before entering wait mode if the TIM2 is required
to exit wait mode. Also when the TSTOP bit is set and the timer is
configured for input capture operation, input captures are inhibited until the
TSTOP bit is cleared.
TRST — TIM2 Reset Bit
Setting this write-only bit resets the TIM2 counter and the TIM2 prescaler. Setting TRST has no effect
on any other registers. Counting resumes from $0000. TRST is cleared automatically after the TIM2
counter is reset and always reads as 0. Reset clears the TRST bit.
1 = Prescaler and TIM2 counter cleared
0 = No effect
NOTE
Setting the TSTOP and TRST bits simultaneously stops the TIM2 counter
at a value of $0000.
PS[2:0] — Prescaler Select Bits
These read/write bits select either the T2CH0 pin or one of the seven prescaler outputs as the input to
the TIM2 counter as Table 18-1 shows. Reset clears the PS[2:0] bits.
Table 18-1. Prescaler Selection
PS[2:0]
000
TIM2 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
T2CH0
001
010
011
100
101
110
111
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
253
Timer Interface Module (TIM2)
18.8.2 TIM2 Counter Registers
The two read-only TIM2 counter registers contain the high and low bytes of the value in the TIM2 counter.
Reading the high byte (T2CNTH) latches the contents of the low byte (T2CNTL) into a buffer. Subsequent
reads of T2CNTH do not affect the latched T2CNTL value until T2CNTL is read. Reset clears the TIM2
counter registers. Setting the TIM2 reset bit (TRST) also clears the TIM2 counter registers.
NOTE
If T2CNTH is read during a break interrupt, be sure to unlatch T2CNTL by
reading T2CNTL before exiting the break interrupt. Otherwise, T2CNTL
retains the value latched during the break.
Address: $002C
Bit 7
T2CNTH
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
BIT 15
BIT 14
BIT 13
BIT 12
BIT 11
BIT 10
BIT 9
BIT 8
0
0
0
0
0
0
0
0
Address: $002D
Bit 7
T2CNTL
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
0
0
0
0
0
0
0
0
= Unimplemented
Figure 18-6. TIM2 Counter Registers (T2CNTH and T2CNTL)
18.8.3 TIM2 Counter Modulo Registers
The read/write TIM2 modulo registers contain the modulo value for the TIM2 counter. When the TIM2
counter reaches the modulo value, the overflow flag (TOF) becomes set, and the TIM2 counter resumes
counting from $0000 at the next timer clock. Writing to the high byte (T2MODH) inhibits the TOF bit and
overflow interrupts until the low byte (T2MODL) is written. Reset sets the TIM2 counter modulo registers.
Address: $002E
Bit 7
T2MODH
6
5
BIT 13
1
4
BIT 12
1
3
BIT 11
1
2
BIT 10
1
1
BIT 9
1
Bit 0
BIT 8
1
Read:
Write:
Reset:
BIT 15
1
BIT 14
1
Address: $002F
Bit 7
T2MODL
6
5
BIT 5
1
4
BIT 4
1
3
BIT 3
1
2
BIT 2
1
1
BIT 1
1
Bit 0
BIT 0
1
Read:
Write:
Reset:
BIT 7
1
BIT 6
1
Figure 18-7. TIM2 Counter Modulo Registers (T2MODH and T2MODL)
NOTE
Reset the TIM2 counter before writing to the TIM2 counter modulo registers.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
254
Freescale Semiconductor
I/O Registers
18.8.4 TIM2 Channel Status and Control Registers
Each of the TIM2 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 TIM2 overflow
Selects 0% and 100% PWM duty cycle
Selects buffered or unbuffered output compare/PWM operation
Address: $0030
Bit 7
T2SC0
6
5
4
3
2
1
TOV0
0
Bit 0
CH0MAX
0
Read:
Write:
Reset:
CH0F
CH0IE
MS0B
0
MS0A
0
ELS0B
0
ELS0A
0
0
0
0
T2SC1
6
Address: $0033
Bit 7
5
0
4
MS1A
0
3
ELS1B
0
2
ELS1A
0
1
TOV1
0
Bit 0
CH1MAX
0
Read:
Write:
Reset:
CH1F
CH1IE
0
0
0
T2SC2
6
0
Address: $0456
Bit 7
5
MS2B
0
4
MS2A
0
3
ELS2B
0
2
ELS2A
0
1
TOV2
0
Bit 0
CH2MAX
0
Read:
Write:
Reset:
CH2F
CH2IE
0
0
0
T2SC3
6
Address: $0459
Bit 7
5
0
4
MS3A
0
3
ELS3B
0
2
ELS3A
0
1
TOV3
0
Bit 0
CH3MAX
0
Read:
Write:
Reset:
CH3F
CH3IE
0
0
0
T2SC4
6
0
Address: $045C
Bit 7
5
MS4B
0
4
MS4A
0
3
ELS4B
0
2
ELS4A
0
1
TOV4
0
Bit 0
CH4MAX
0
Read:
Write:
Reset:
CH4F
CH4IE
0
0
0
T2SC5
6
Address: $045F
Bit 7
5
0
4
MS5A
0
3
ELS5B
0
2
ELS5A
0
1
TOV5
0
Bit 0
CH5MAX
0
Read:
Write:
Reset:
CH5F
CH5IE
0
0
0
0
= Unimplemented
Figure 18-8. TIM2 Channel Status and Control Registers (T2SC0:T2SC5)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
255
Timer Interface Module (TIM2)
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
TIM2 counter registers matches the value in the TIM2 channel x registers.
When CHxIE = 1, clear CHxF by reading TIM2 channel x status and control register with CHxF set,
and then writing a 0 to CHxF. If another interrupt request occurs before the clearing sequence is
complete, then writing 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 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 TIM2 CPU interrupts 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 TIM2
channel 0, TIM2 channel 2, and TIM2 channel 4 status and control registers.
Setting MS0B disables the channel 1 status and control register and reverts T2CH1 pin to
general-purpose I/O.
Setting MS2B disables the channel 3 status and control register and reverts T2CH3 pin to
general-purpose I/O.
Setting MS4B disables the channel 5 status and control register and reverts T2CH5 pin 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 ≠ 00, this read/write bit selects either input capture operation or unbuffered
output compare/PWM operation. (See Table 18-2.)
1 = Unbuffered output compare/PWM operation
0 = Input capture operation
When ELSxB:ELSxA = 00, this read/write bit selects the initial output level of the T2CHx pin once
PWM, input capture, or output compare operation is enabled. (See Table 18-2.) 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 TIM2 status and control register (T2SC).
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
256
Freescale Semiconductor
I/O Registers
Table 18-2. Mode, Edge, and Level Selection
MSxB MSxA
ELSxB
ELSxA
Mode
Configuration
Pin under port control;
initial output level high
X
X
0
1
0
0
Output preset
Pin under port control;
initial output level low
0
0
0
0
0
0
0
1
1
0
Capture on rising edge only
Capture on falling edge only
Input capture
Capture on rising
or falling edge
0
0
1
1
0
0
0
0
1
1
1
1
1
1
X
X
0
0
1
1
0
1
0
1
0
1
1
0
Software compare only
Toggle output on compare
Clear output on compare
Set output on compare
Toggle output on compare
Clear output on compare
Output compare
or PWM
Buffered
output
compare or
buffered PWM
1
X
1
1
Set output on compare
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 port D or port F, and pin
PTDx/T2CHx or pin PTFx/T2CHx is available as a general- purpose I/O pin. Table 18-2 shows how
ELSxB and ELSxA work. Reset clears the ELSxB and ELSxA bits.
NOTE
After initially enabling a TIM2 channel register for input capture operation
and selecting the edge sensitivity, clear CHxF to ignore any erroneous
edge detection flags.
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 TIM2 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 TIM2 counter overflow.
0 = Channel x pin does not toggle on TIM2 counter overflow.
NOTE
When TOVx is set, a TIM2 counter overflow takes precedence over a
channel x output compare if both occur at the same time.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
257
Timer Interface Module (TIM2)
CHxMAX — Channel x Maximum Duty Cycle Bit
When the TOVx bit is at a 1 and clear output on compare is selected, setting the CHxMAX bit forces
the duty cycle of buffered and unbuffered PWM signals to 100%. As Figure 18-9 shows, the CHxMAX
bit takes effect in the cycle after it is set or cleared. The output stays at 100% duty cycle level until the
cycle after CHxMAX is cleared.
NOTE
The 100% PWM duty cycle is defined as a continuous high level if the PWM
polarity is 1 and a continuous low level if the PWM polarity is 0. Conversely,
a 0% PWM duty cycle is defined as a continuous low level if the PWM
polarity is 1 and a continuous high level if the PWM polarity is 0.
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
PTDx/T2CHx
CHxMAX
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 18-9. CHxMAX Latency
18.8.5 TIM2 Channel Registers
These read/write registers contain the captured TIM2 counter value of the input capture function or the
output compare value of the output compare function. The state of the TIM2 channel registers after reset
is unknown.
In input capture mode (MSxB:MSxA = 0:0), reading the high byte of the TIM2 channel x registers
(T2CHxH) inhibits input captures until the low byte (T2CHxL) is read.
In output compare mode (MSxB:MSxA ≠ 0:0), writing to the high byte of the TIM2 channel x registers
(T2CHxH) inhibits output compares until the low byte (T2CHxL) is written.
Address: $0031
Bit 7
T2CH0H
6
5
4
3
2
1
Bit 0
Bit 8
Read:
Write:
Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Indeterminate after reset
Address: $0032
Bit 7
T2CH0L
6
5
4
3
2
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Indeterminate after reset
Figure 18-10. TIM2 Channel Registers (T2CH0H/L:T2CH5H/L) (Sheet 1 of 3)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
258
Freescale Semiconductor
I/O Registers
Address: $0034
Bit 7
T2CH1H
6
5
4
3
2
1
Bit 0
Bit 8
Read:
Write:
Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Indeterminate after reset
Address: $0035
Bit 7
T2CH1L
6
5
4
3
2
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Indeterminate after reset
Address: $0457
Bit 7
T2CH2H
6
5
4
3
2
1
Bit 0
Bit 8
Read:
Write:
Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Indeterminate after reset
Address: $0458
Bit 7
T2CH2L
6
5
4
3
2
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Indeterminate after reset
Address: $045A
Bit 7
T2CH3H
6
5
4
3
2
1
Bit 0
Bit 8
Read:
Write:
Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Indeterminate after reset
Address: $045B
Bit 7
T2CH3L
6
5
4
3
2
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Indeterminate after reset
Address: $045D
Bit 7
T2CH4H
6
5
4
3
2
1
Bit 0
Bit 8
Read:
Write:
Reset:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Indeterminate after reset
Address: $045E
Bit 7
T2CH4L
6
5
4
3
2
1
Bit 0
Bit 0
Read:
Write:
Reset:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Indeterminate after reset
Figure 18-10. TIM2 Channel Registers (T2CH0H/L:T2CH5H/L) (Sheet 2 of 3)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
259
Timer Interface Module (TIM2)
Address: $0460
Bit 7
T2CH5H
6
5
4
3
2
1
Bit 0
Bit 8
Read:
Bit 15
Write:
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Reset:
Indeterminate after reset
Address: $0461
Bit 7
T2CH5L
6
5
4
3
2
1
Bit 0
Bit 0
Read:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Write:
Reset:
Indeterminate after reset
Figure 18-10. TIM2 Channel Registers (T2CH0H/L:T2CH5H/L) (Sheet 3 of 3)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
260
Freescale Semiconductor
Chapter 19
Development Support
19.1 Introduction
This section describes the break module, the monitor module (MON), and the monitor mode entry
methods.
19.2 Break Module (BRK)
The break module can generate a break interrupt that stops normal program flow at a defined address to
enter a background program.
Features of the break module include:
•
•
•
•
Accessible input/output (I/O) registers during the break Interrupt
Central processor unit (CPU) generated break interrupts
Software-generated break interrupts
Computer operating properly (COP) disabling during break interrupts
19.2.1 Functional Description
When the internal address bus matches the value written in the break address registers, the break module
issues a breakpoint signal (BKPT) to the system integration module (SIM). The SIM then causes the CPU
to load the instruction register with a software interrupt instruction (SWI). 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 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
is generated. A return-from-interrupt instruction (RTI) in the break routine ends the break interrupt and
returns the microcontroller unit (MCU) to normal operation.
Figure 19-2 shows the structure of the break module.
Figure 19-3 provides a summary of the I/O registers.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
261
Development Support
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 62,078 BYTES
USER RAM — 2048 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
MONITOR ROM
2-CHANNEL TIMER INTERFACE
MODULE
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure 19-1. Block Diagram Highlighting BRK and MON Blocks
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Break Module (BRK)
ADDRESS BUS[15:8]
BREAK ADDRESS REGISTER HIGH
8-BIT COMPARATOR
ADDRESS BUS[15:0]
CONTROL
BKPT
(TO SIM)
8-BIT COMPARATOR
BREAK ADDRESS REGISTER LOW
ADDRESS BUS[7:0]
Figure 19-2. Break Module Block Diagram
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
Read:
SBSW
Note(1)
0
Break Status Register
(BSR) Write:
R
R
R
R
R
R
R
$FE00
See page 266.
Reset:
Read:
Break Flag Control
BCFE
0
R
R
R
R
R
R
R
$FE03
$FE09
$FE0A
$FE0B
Register (BFCR) Write:
See page 266.
Reset:
Read:
Break Address High
Bit 15
0
Bit 14
0
Bit 13
0
Bit 12
0
Bit 11
0
Bit 10
0
Bit 9
0
Bit 8
0
Register (BRKH) Write:
See page 265.
Reset:
Read:
Break Address Low
Bit 7
0
Bit 6
0
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Register (BRKL) Write:
See page 265.
Reset:
0
0
0
0
0
0
0
0
0
0
0
0
Read:
Break Status and Control
BRKE
0
BRKA
0
Register (BRKSCR) Write:
See page 265.
Reset:
0
0
0
0
0
0
1. Writing a 0 clears SBSW.
= Unimplemented
R
= Reserved
Figure 19-3. Break I/O Register Summary
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
263
Development Support
When the internal address bus matches the value written in the break address registers or when software
writes a 1 to the BRKA bit in the break status and control register, 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 timing is:
•
•
•
When a break address is placed at the address of the instruction opcode, the instruction is not
executed until after completion of the break interrupt routine.
When a break address is placed at an address of an instruction operand, the instruction is executed
before the break interrupt.
When software writes a 1 to the BRKA bit, the break interrupt occurs just before the next instruction
is executed.
By updating a break address and clearing the BRKA bit in a break interrupt routine, a break interrupt can
be generated continuously.
CAUTION
A break address should be placed at the address of the instruction opcode.
When software does not change the break address and clears the BRKA
bit in the first break interrupt routine, the next break interrupt will not be
generated after exiting the interrupt routine even when the internal address
bus matches the value written in the break address registers.
19.2.1.1 Flag Protection During Break Interrupts
The system integration module (SIM) controls whether or not module status bits can be cleared during
the break state. The BCFE bit in the break flag control register (BFCR) enables software to clear status
bits during the break state. See 14.7.3 Break Flag Control Register and the Break Interrupts subsection
for each module.
19.2.1.2 TIM During Break Interrupts
A break interrupt stops the timer counter and inhibits input captures.
19.2.1.3 COP During Break Interrupts
The COP is disabled during a break interrupt when VTST is present on the RST pin.
19.2.2 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)
Break status register (BSR)
Break flag control register (BFCR)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Break Module (BRK)
19.2.2.1 Break Status and Control Register
The break status and control register (BRKSCR) contains break module enable and status bits.
$FE0B
Bit 7
Address:
6
BRKA
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
Read:
Write:
Reset:
BRKE
0
0
0
0
0
0
0
= Unimplemented
Figure 19-4. 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 0 to
bit 7. Reset clears the BRKE bit.
1 = Breaks enabled on 16-bit address match
0 = Breaks disabled
BRKA — Break Active Bit
This read/write status and control bit is set when a break address match occurs. Writing a 1 to BRKA
generates a break interrupt. Clear BRKA by writing a 0 to it before exiting the break routine. Reset
clears the BRKA bit.
1 = Break address match
0 = No break address match
19.2.2.2 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.
$FE09
Address:
Bit 7
6
Bit 14
0
5
Bit 13
0
4
Bit 12
0
3
Bit 11
0
2
Bit 10
0
1
Bit 9
0
Bit 0
Bit 8
0
Read:
Write:
Reset:
Bit 15
0
Figure 19-5. Break Address Register High (BRKH)
$FE0A
Address:
Bit 7
Bit 7
0
6
Bit 6
0
5
Bit 5
0
4
Bit 4
0
3
Bit 3
0
2
Bit 2
0
1
Bit 1
0
Bit 0
Bit 0
0
Read:
Write:
Reset:
Figure 19-6. Break Address Register Low (BRKL)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
265
Development Support
19.2.2.3 Break Status Register
The break status register (BSR) contains a flag to indicate that a break caused an exit from wait mode.
This register is only used in emulation mode.
Address: $FE00
Bit 7
6
5
4
3
2
1
Bit 0
R
Read:
Write:
Reset:
SBSW
Note(1)
0
R
R
R
R
R
R
R
= Reserved
1. Writing a 0 clears SBSW.
Figure 19-7. Break Status Register (BSR)
SBSW — SIM Break Stop/Wait
SBSW can be read within the break state SWI routine. The user can modify the return address on the
stack by subtracting one from it.
1 = Wait mode was exited by break interrupt
0 = Wait mode was not exited by break interrupt
19.2.2.4 Break Flag Control Register
The break control register (BFCR) contains a bit that enables software to clear status bits while the MCU
is in a break state.
$FE03
Address:
Bit 7
6
5
4
3
2
1
Bit 0
R
Read:
Write:
Reset:
BCFE
R
R
R
R
R
R
0
= Reserved
R
Figure 19-8. Break Flag Control Register (BFCR)
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
19.2.3 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power- consumption standby modes. If enabled,
the break module will remain enabled in wait and stop modes. However, since the internal address bus
does not increment in these modes, a break interrupt will never be triggered.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Monitor Module (MON)
19.3 Monitor Module (MON)
The monitor module allows debugging and programming of the microcontroller unit (MCU) through a
single-wire interface with a host computer. Monitor mode entry can be achieved without use of the higher
test voltage, VTST, as long as vector addresses $FFFE and $FFFF are blank, thus reducing the hardware
requirements for in-circuit programming.
Features of the monitor module include:
•
•
•
•
•
•
•
•
Normal user-mode pin functionality
One pin dedicated to serial communication between MCU and host computer
Standard non-return-to-zero (NRZ) communication with host computer
Standard communication baud rate (7200 @ 2-MHz bus frequency)
Execution of code in random-access memory (RAM) or FLASH
FLASH memory security feature(1)
FLASH memory programming interface
Monitor mode entry without high voltage, VTST, if reset vector is blank ($FFFE and $FFFF contain
$FF)
•
Normal monitor mode entry if VTST is applied to IRQ
19.3.1 Functional Description
Figure 19-9 shows a simplified diagram of the monitor mode.
The monitor module receives and executes commands from a host computer.
Figure 19-10 and Figure 19-11 show example circuits 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.
Table 19-1 shows the pin conditions for entering monitor mode. As specified in the table, monitor mode
may be entered after a power-on reset (POR) and will allow communication at 7200 baud provided one
of the following sets of conditions is met:
•
•
•
If $FFFE and $FFFF does not contain $FF (programmed state):
–
–
–
The external clock is 4.0 MHz (7200 baud)
PTB4 = low
IRQ = VTST
If $FFFE and $FFFF do not contain $FF (programmed state):
–
–
–
The external clock is 8.0 MHz (7200 baud)
PTB4 = high
IRQ = VTST
If $FFFE and $FFFF contain $FF (erased state):
–
–
The external clock is 8.0 MHz (7200 baud)
IRQ = VDD (this can be implemented through the internal IRQ pullup) or VSS
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for
unauthorized users.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
267
Development Support
POR RESET
YES
NO
IRQ = VTST
?
CONDITIONS
FROM Table 19-1
PTA0 = 1,
PTA1 = 0, RESET
VECTOR BLANK?
PTA0 = 1, PTA1 = 0,
PTB0 = 1, AND
PTB1 = 0?
NO
NO
YES
YES
FORCED
NORMAL
NORMAL
INVALID
MONITOR MODE
USER MODE
MONITOR MODE
USER MODE
HOST SENDS
8 SECURITY BYTES
YES
IS RESET
POR?
NO
ARE ALL
SECURITY BYTES
CORRECT?
YES
NO
ENABLE FLASH
DISABLE FLASH
MONITOR MODE ENTRY
DEBUGGING
AND FLASH
EXECUTE
PROGRAMMING
(IF FLASH
MONITOR CODE
IS ENABLED)
NO
YES
DOES RESET
OCCUR?
Figure 19-9. Simplified Monitor Mode Entry Flowchart
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
268
Monitor Module (MON)
MC68HC908GR60A
VDD
N.C.
VDD
VDDA
RST
27 pF
27 pF
OSC2
VDDAD
MAX232
VDD
0.1 μF
10 MΩ
1
16
15
VCC
C1+
VDD
+
+
+
OSC1
IRQ
1 μF
1 μF
8 MHz
10 k
3
4
1 μF
GND
C1–
C2+
PTB4
PTB0
+
10 k
1 kΩ
2
6
V+
V–
10 k
10 k
VDD
1 μF
9.1 V
PTB1
PTA1
VSSAD
5
C2–
1 μF
+
10 kΩ
74HC125
DB9
5
10
9
2
7
8
6
PTA0
74HC125
3
2
VSSA
VSS
4
3
5
1
Figure 19-10. Normal Monitor Mode Circuit
MC68HC908GR60A
VDD
N.C.
RST
VDD
VDDA
27 pF
27 pF
OSC2
VDDAD
MAX232
VDD
0.1 μF
10 MΩ
1
16
15
VCC
C1+
+
+
+
OSC1
IRQ
1 μF
1 μF
8 MHz
3
4
1 μF
GND
C1–
C2+
+
PTB4
PTB0
PTB1
N.C.
2
6
N.C.
N.C.
V+
V–
N.C.
VDD
1 μF
5
C2–
10 k
1 μF
+
PTA1
10 kΩ
74HC125
DB9
5
10
9
6
2
7
8
PTA0
VSSAD
VSSA
VSS
74HC125
3
2
4
3
5
1
Figure 19-11. Forced Monitor Mode
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
269
Development Support
Table 19-1. Monitor Mode Signal Requirements and Options
Serial
Communication
Mode
Selection
Communication
Speed
Divider
Reset
Vector
Mode
IRQ RST
PLL
COP
External
Bus
Baud
PTA0
PTA1 PTB0 PTB1 PTB4
Clock Frequency Rate
VDD
VTST
or
VTST
X
X
1
0
0
0
X
1
1
0
0
0
1
OFF Disabled 4.0 MHz
OFF Disabled 8.0 MHz
OFF Disabled 8.0 MHz
2.0 MHz
2.0 MHz
2.0 MHz
7200
7200
7200
Normal
Monitor
VDD
or
VTST
VTST
1
1
VDD
or
VSS
Forced
Monitor
$FF
(blank)
VDD
X
X
X
X
X
X
VDD VDD
or or
VSS VTST
Not
$FF
User
X
X
Enabled
—
X
X
X
MON08
Function
[Pin No.]
VTST
[6]
RST
[4]
COM
[8]
SSEL MOD0 MOD1 DIV4
[10] [12] [14] [16]
OSC1
[13]
—
—
—
—
1. PTA0 must have a pullup resistor to VDD in monitor mode.
2. Communication speed in the table is an example to obtain a baud rate of 7200. Baud rate using external oscillator is bus
frequency / 278.
3. External clock is a 4.0 MHz or 8.0 MHz crystal on OSC1 and OSC2 or a canned oscillator on OSC1.
4. X = don’t care
5. MON08 pin refers to P&E Microcomputer Systems’ MON08-Cyclone 2 by 8-pin connector.
NC
NC
1
3
2
4
GND
RST
NC
5
6
IRQ
NC
7
8
PTA0
PTA1
PTB0
PTB1
PTB4
NC
9
10
12
14
16
NC
11
13
15
OSC1
VDD
Enter monitor mode with pin configuration shown in Table 19-1 by pulling RST low and then high. The
rising edge of RST latches monitor mode. Once monitor mode is latched, the levels on the port pins
except PTA0 can change.
Once out of reset, the MCU waits for the host to send eight security bytes (see 19.3.2 Security). After the
security bytes, the MCU sends a break signal (10 consecutive 0s) to the host, indicating that it is ready to
receive a command.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
270
Freescale Semiconductor
Monitor Module (MON)
19.3.1.1 Normal Monitor Mode
If VTST is applied to IRQ and PTB4 is low upon monitor mode entry, the bus frequency is a divide-by-two
of the input clock. If PTB4 is high with VTST applied to IRQ upon monitor mode entry, the bus frequency
will be a divide-by-four of the input clock. Holding the PTB4 pin low when entering monitor mode causes
a bypass of a divide-by-two stage at the oscillator only if VTST is applied to IRQ. In this event, 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.
When monitor mode was entered with VTST on IRQ, the computer operating properly (COP) is disabled
as long as VTST is applied to either IRQ or RST.
This condition states that as long as VTST is maintained on the IRQ pin after entering monitor mode, or if
VTST is applied to RST after the initial reset to get into monitor mode (when VTST was applied to IRQ),
then the COP will be disabled. In the latter situation, after VTST is applied to the RST pin, VTST can be
removed from the IRQ pin in the interest of freeing the IRQ for normal functionality in monitor mode.
19.3.1.2 Forced Monitor Mode
If entering monitor mode without high voltage on IRQ, then all port B pin requirements and conditions,
including the PTB4 frequency divisor selection, are not in effect. This is to reduce circuit requirements
when performing in-circuit programming.
NOTE
If the reset vector is blank and monitor mode is entered, the chip will see an
additional reset cycle after the initial power-on reset (POR). Once the reset
vector has been programmed, the traditional method of applying a voltage,
VTST, to IRQ must be used to enter monitor mode.
An external oscillator of 8 MHz is required for a baud rate of 7200, as the internal bus frequency is
automatically set to the external frequency divided by four.
When the forced monitor mode is entered the COP is always disabled regardless of the state of IRQ or
RST.
19.3.1.3 Monitor Vectors
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.
Table 19-2 summarizes the differences between user mode and monitor mode.
Table 19-2. Mode Differences
Functions
Break Break
Modes
Reset
Reset
SWI
SWI
Vector High Vector Low Vector High Vector Low Vector High Vector Low
User
$FFFE
$FEFE
$FFFF
$FEFF
$FFFC
$FEFC
$FFFD
$FEFD
$FFFC
$FEFC
$FFFD
$FEFD
Monitor
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
271
Development Support
19.3.1.4 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
BIT 6
STOP
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 7
Figure 19-12. Monitor Data Format
19.3.1.5 Break Signal
A start bit (0) followed by nine 0 bits is a break signal. When the monitor receives a break signal, it drives
the PTA0 pin high for the duration of approximately two bits and then echoes back the break signal.
MISSING STOP BIT
APPROXIMATELY 2 BITS DELAY
BEFORE ZERO ECHO
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
Figure 19-13. Break Transaction
19.3.1.6 Baud Rate
The communication baud rate is controlled by the crystal frequency or external clock and the state of the
PTB4 pin (when IRQ is set to VTST) upon entry into monitor mode. If monitor mode was entered with VDD
on IRQ and the reset vector blank, then the baud rate is independent of PTB4.
Table 19-1 also lists external frequencies required to achieve a standard baud rate of 7200 bps. The
effective baud rate is the bus frequency divided by 278. If using a crystal as the clock source, be aware
of the upper frequency limit that the internal clock module can handle. See 20.7 5.0-Volt Control Timing
or 20.8 3.3-Volt Control Timing for this limit.
19.3.1.7 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Monitor Module (MON)
FROM
HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
READ
READ
DATA
4
4
1
1
4
1
3, 2
4
ECHO
RETURN
Notes:
1 = Echo delay, approximately 2 bit times
2 = Data return delay, approximately 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
Figure 19-14. Read Transaction
FROM
HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
DATA
WRITE
WRITE
3
3
1
1
3
1
3
1
2, 3
ECHO
Notes:
1 = Echo delay, approximately 2 bit times
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
Figure 19-15. Write Transaction
A brief description of each monitor mode command is given in Table 19-3 through Table 19-8.
Table 19-3. READ (Read Memory) Command
Description Read byte from memory
Operand 2-byte address in high-byte:low-byte order
Data Returned Returns contents of specified address
Opcode $4A
Command Sequence
SENT TO MONITOR
ADDRESS ADDRESS ADDRESS
HIGH HIGH LOW
ADDRESS
LOW
READ
READ
DATA
ECHO
RETURN
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
273
Development Support
Table 19-4. WRITE (Write Memory) Command
Description Write byte to memory
Operand 2-byte address in high-byte:low-byte order; low byte followed by data byte
Data Returned None
Opcode $49
Command Sequence
FROM HOST
ADDRESS ADDRESS ADDRESS ADDRESS
DATA
DATA
WRITE
ECHO
WRITE
HIGH
HIGH
LOW
LOW
Table 19-5. IREAD (Indexed Read) Command
Description Read next 2 bytes in memory from last address accessed
Operand None
Data Returned Returns contents of next two addresses
Opcode $1A
Command Sequence
FROM HOST
IREAD
IREAD
DATA
DATA
ECHO
RETURN
Table 19-6. IWRITE (Indexed Write) Command
Description Write to last address accessed + 1
Operand Single data byte
Data Returned None
Opcode $19
Command Sequence
FROM HOST
DATA
DATA
IWRITE
ECHO
IWRITE
A sequence of IREAD or IWRITE commands can access a block of memory sequentially over the full
64-Kbyte memory map.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
274
Freescale Semiconductor
Monitor Module (MON)
Table 19-7. READSP (Read Stack Pointer) Command
Description Reads stack pointer
Operand None
Data Returned Returns incremented stack pointer value (SP + 1) in high-byte:low-byte order
Opcode $0C
Command Sequence
FROM HOST
SP
HIGH
SP
LOW
READSP
READSP
ECHO
RETURN
Table 19-8. RUN (Run User Program) Command
Description Executes PULH and RTI instructions
Operand None
Data Returned None
Opcode $28
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
SP + 5
SP + 6
SP + 7
LOW BYTE OF INDEX REGISTER
HIGH BYTE OF PROGRAM COUNTER
LOW BYTE OF PROGRAM COUNTER
Figure 19-16. Stack Pointer at Monitor Mode Entry
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
275
Development Support
19.3.2 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 19-17.
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 bytes.
VDD
4096 + 32 CGMXCLK CYCLES
RST
FROM HOST
PA0
5
1
1
4
1
4
2
1
FROM MCU
Notes:
1 = Echo delay, approximately 2 bit times
2 = Data return delay, approximately 2 bit times
4 = Wait 1 bit time before sending next byte
5 = Wait until the monitor ROM runs
Figure 19-17. Monitor Mode Entry Timing
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).
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
276
Freescale Semiconductor
Chapter 20
Electrical Specifications
20.1 Introduction
This section contains electrical and timing specifications.
20.2 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 20.5 5.0-Vdc Electrical
Characteristics for guaranteed operating conditions.
Characteristic(1)
Symbol
VDD
Value
Unit
V
Supply voltage
Input voltage
–0.3 to + 6.0
VIn
VSS – 0.3 to VDD + 0.3
V
Maximum current per pin excluding those specified below
Maximum current for pins PTC0–PTC4
Maximum current into VDD
I
± 15
± 25
mA
mA
mA
mA
°C
IPTC0–PTC4
Imvdd
Imvss
Tstg
150
Maximum current out of VSS
150
Storage temperature
–55 to +150
1. Voltages referenced to VSS
NOTE
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 VIn and VOut be constrained to the range
VSS ≤ (VIn or VOut) ≤ VDD. Reliability of operation is enhanced if unused
inputs are connected to an appropriate logic voltage level (for example,
either VSS or VDD).
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
277
Electrical Specifications
20.3 Functional Operating Range
Characteristic
Symbol
Value
Unit
TA
Operating temperature range
–40 to +125
°C
5.0 ±10%
3.3 ±10%
VDD
Operating voltage range
V
20.4 Thermal Characteristics
Characteristic
Symbol
Value
Unit
Thermal resistance
32-pin LQFP
48-pin LQFP
95
95
54
θJA
°C/W
64-pin QFP
PI/O
PD
I/O pin power dissipation
Power dissipation(1)
User determined
W
W
PD = (IDD × VDD) + PI/O
K/(TJ + 273 °C)
=
PD × (TA + 273 °C)
+ PD2 × θJA
Constant(2)
K
W/°C
°C
TJ
TA + (PD × θJA)
Average junction temperature
1. Power dissipation is a function of temperature.
2. K is a 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.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
5.0-Vdc Electrical Characteristics
20.5 5.0-Vdc Electrical Characteristics
Characteristic(1)
Typ(2)
Symbol
Min
Max
Unit
Output high voltage
(ILoad = –2.0 mA) all I/O pins
(ILoad = –10.0 mA) all I/O pins
(ILoad = –20.0 mA) pins PTC0–PTC4, PTF0–PTF3 only
Maximum combined IOH for port PTA7–PTA3,
VOH
VOH
VOH
IOH1
VDD – 0.8
VDD – 1.5
VDD – 1.5
—
—
—
—
—
—
—
—
50
V
V
V
mA
port PTC0–PTC1, port E, port PTD0–PTD3,
port PTF0–PTF3, port PTG4–PTG7
Maximum combined IOH for port PTA2–PTA0,
port B, port PTC2–PTC6, port PTD4–PTD7,
port PTF4–PTF7, port PTG0–PTG3
Maximum total IOH for all port pins
—
—
50
mA
mA
IOH2
—
—
100
IOHT
Output low voltage
(ILoad = 1.6 mA) all I/O pins
(ILoad = 10 mA) all I/O pins
(ILoad = 20 mA) pins PTC0–PTC4, PTF0–PTF3 only
Maximum combined IOH for port PTA7–PTA3,
VOL
VOL
VOL
IOL1
—
—
—
—
—
—
—
—
0.4
1.5
1.5
50
V
V
V
mA
port PTC0–PTC1, port E, port PTD0–PTD3,
port PTF0–PTF3, port PTG4–PTG7
Maximum combined IOH for port PTA2–PTA0,
—
—
50
mA
IOL2
port B, port PTC2–PTC6, port PTD4–PTD7,
port PTF4–PTF7, port PTG0–PTG3
Maximum total IOL for all port pins
—
—
—
—
100
VDD
mA
V
IOLT
VIH
VIL
Input high voltage
All ports, IRQ, RST, OSC1
0.7 × VDD
Input low voltage
All ports, IRQ, RST, OSC1
VSS
0.2 × VDD
V
VDD supply current
Run(3)
Wait(4)
Stop(5)
Stop with TBM enabled(6)
Stop with LVI and TBM enabled(6)
Stop with LVI
—
—
—
—
—
—
20
6
0.6
1
1.25
250
30
12
10
1.25
1.6
350
mA
mA
μA
mA
mA
μA
IDD
DC injection current(7) (8) (9) (10)
Single pin limit
V
in > VDD
0
0
—
—
2
–0.2
Vin < VSS
IIC
mA
Total MCU limit, includes sum of all stressed pins
Vin > VDD
Vin < VSS
0
0
—
—
25
–5
I/O ports Hi-Z leakage current(11)
IIL
0
—
±1
μA
Continued on next page
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
279
Electrical Specifications
Characteristic(1)
Typ(2)
Symbol
Min
Max
Unit
Pullup/pulldown resistors (as input only)
Ports PTA7/KBD7–PTA0/KBD0, PTC6–PTC0/CANTX
,
RPU
20
45
65
kΩ
PTD7/T2CH1–PTD0/SS
COut
CIn
Capacitance
Ports (as input or output)
—
—
—
—
12
8
pF
VTST
VDD + 2.5
3.90
VDD + 4.0
4.50
Monitor mode entry voltage
—
V
V
V
VTRIPF
VTRIPR
Low-voltage inhibit, trip falling voltage
Low-voltage inhibit, trip rising voltage
Low-voltage inhibit reset/recover hysteresis
4.25
4.35
4.0
4.60
VHYS
—
100
—
mV
(VTRIPF + VHYS = VTRIPR
)
POR rearm voltage(12)
POR reset voltage(13)
VPOR
VPORRST
RPOR
0
0
—
700
—
100
800
—
mV
mV
POR rise time ramp rate(14)
0.035
V/ms
1. VDD = 5.0 Vdc ± 10%, VSS = 0 Vdc, TA = TA (min) to TA (max), 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 (fOSC = 32 MHz). 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. Measured with all modules enabled.
4. Wait IDD measured using external square wave clock source (fOSC = 32 MHz). 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. Measured with CGM and LVI enabled.
5. Stop IDD is measured with OSC1 = VSS. All inputs 0.2 V from rail. No dc loads. Less than 100 pF on all outputs. All ports
configured as inputs. Typical values at midpoint of voltage range, 25°C only.
6. Stop IDD with TBM enabled is measured using an external square wave clock source (fOSC = 8 MHz). All inputs 0.2 V from
rail. No dc loads. Less than 100 pF on all outputs. All inputs configured as inputs.
7. This parameter is characterized and not tested on each device.
8. All functional non-supply pins are internally clamped to VSS and VDD
.
9. Input must be current limited to the value specified. To determine the value of the required current-limiting resistor,
calculate resistance values for positive and negative clamp voltages, then use the larger of the two values.
10. Power supply must maintain regulation within operating VDD range during instantaneous and operating maximum current
conditions. If positive injection current (Vin > VDD) is greater than IDD, the injection current may flow out of VDD and could
result in external power supply going out of regulation. Ensure external VDD load will shunt current greater than maximum
injection current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock is
present, or if clock rate is very low (which would reduce overall power consumption).
11. Pullups and pulldowns are disabled. Port B leakage is specified in 20.10 5.0-Volt ADC Characteristics.
12. Maximum is highest voltage that POR is guaranteed.
13. Maximum is highest voltage that POR is possible.
14. If minimum VDD is not reached before the internal POR reset is released, RST must be driven low externally until minimum
VDD is reached.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
280
Freescale Semiconductor
3.3-Vdc Electrical Characteristics
20.6 3.3-Vdc Electrical Characteristics
Characteristic(1)
Typ(2)
Symbol
Min
Max
Unit
Output high voltage
(ILoad = –0.6 mA) all I/O pins
(ILoad = –4.0 mA) all I/O pins
(ILoad = –10.0 mA) pins PTC0–PTC4, PTF0–PTF3 only
Maximum combined IOH for port PTA7–PTA3,
VOH
VOH
VOH
IOH1
VDD – 0.3
VDD – 1.0
VDD – 1.0
—
—
—
—
—
—
—
—
30
V
V
V
mA
port PTC0–PTC1, port E, port PTD0–PTD3,
port PTF0–PTF3, port PTG4–PTG7
Maximum combined IOH for port PTA2–PTA0,
port B, port PTC2–PTC6, port PTD4–PTD7
port PTF4–PTF7, port PTG0–PTG3
Maximum total IOH for all port pins
—
—
30
60
mA
mA
IOH2
—
—
IOHT
Output low voltage
(ILoad = 0.5 mA) all I/O pins
(ILoad = 5 mA) all I/O pins
(ILoad = 10 mA) pins PTC0–PTC4, PTF0–PTF3 only
Maximum combined IOH for port PTA7–PTA3,
VOL
VOL
VOL
IOL1
—
—
—
—
—
—
—
—
0.3
1.0
0.8
30
V
V
V
mA
port PTC0–PTC1, port E, port PTD0–PTD3
port PTF0–PTF3, port PTG4–PTG7
Maximum combined IOH for port PTA2–PTA0,
—
—
30
mA
IOL2
port B, port PTC2–PTC6, port PTD4–PTD7
port PTF4–PTF7, port PTG0–PTG3
Maximum total IOL for all port pins
—
—
—
—
60
mA
V
IOLT
VIH
VIL
Input high voltage
All ports, IRQ, RST, OSC1
0.7 × VDD
VDD
Input low voltage
All ports, IRQ, RST, OSC1
VSS
0.3 × VDD
V
VDD supply current
Run(3)
Wait(4)
Stop(5)
Stop with TBM enabled(6)
Stop with LVI and TBM enabled(6)
Stop with LVI
—
—
—
—
—
—
8
12
6
mA
mA
μA
μA
μA
μA
3
IDD
0.5
500
700
200
6
700
900
300
DC injection current(7) (8) (9) (10)
Single pin limit
V
in > VDD
0
0
—
—
2
–0.2
Vin < VSS
IIC
mA
Total MCU limit, includes sum of all stressed pins
Vin > VDD
Vin < VSS
0
0
—
—
25
–5
I/O ports Hi-Z leakage current(11)
IIL
0
—
±1
μA
Continued on next page
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
281
Electrical Specifications
Characteristic(1)
Typ(2)
Symbol
Min
Max
Unit
Pullup/pulldown resistors (as input only)
Ports PTA7/KBD7–PTA0/KBD0, PTC6–PTC0,
PTD7/T2CH1–PTD0/SS
RPU
20
45
65
kΩ
COut
CIn
Capacitance
Ports (as input or output)
—
—
—
—
12
8
pF
VTST
VDD + 2.5
2.35
VDD + 4.0
2.8
Monitor mode entry voltage
—
2.6
V
V
V
VTRIPF
VTRIPR
Low-voltage inhibit, trip falling voltage
Low-voltage inhibit, trip rising voltage
Low-voltage inhibit reset/recover hysteresis
2.4
2.66
2.9
VHYS
—
100
—
mV
(VTRIPF + VHYS = VTRIPR
)
POR rearm voltage(12)
POR reset voltage(13)
VPOR
VPORRST
RPOR
0
0
—
700
—
100
800
—
mV
mV
POR rise time ramp rate(14)
0.02
V/ms
1. VDD = 3.3 Vdc ± 10%, VSS = 0 Vdc, TA = TA (min) to TA (max), 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 (fOSC = 16 MHz). 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. Measured with all modules enabled.
4. Wait IDD measured using external square wave clock source (fOSC = 16 MHz). 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
I
DD. Measured with CGM and LVI enabled.
5. Stop IDD is measured with OSC1 = VSS. All inputs 0.2 V from rail. No dc loads. Less than 100 pF on all outputs. All ports
configured as inputs. Typical values at midpoint of voltage range, 25°C only.
6. Stop IDD with TBM enabled is measured using an external square wave clock source (fOSC = 4 MHz). All inputs 0.2 V from
rail. No dc loads. Less than 100 pF on all outputs. All inputs configured as inputs.
7. This parameter is characterized and not tested on each device.
8. All functional non-supply pins are internally clamped to VSS and VDD
.
9. Input must be current limited to the value specified. To determine the value of the required current-limiting resistor,
calculate resistance values for positive and negative clamp voltages, then use the larger of the two values.
10. Power supply must maintain regulation within operating VDD range during instantaneous and operating maximum current
conditions. If positive injection current (Vin > VDD) is greater than IDD, the injection current may flow out of VDD and could
result in external power supply going out of regulation. Ensure external VDD load will shunt current greater than maximum
injection current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock
is present, or if clock rate is very low (which would reduce overall power consumption).
11. Pullups and pulldowns are disabled.
12. Maximum is highest voltage that POR is guaranteed.
13. Maximum is highest voltage that POR is possible.
14. If minimum VDD is not reached before the internal POR reset is released, RST must be driven low externally until minimum
VDD is reached.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
282
Freescale Semiconductor
5.0-Volt Control Timing
20.7 5.0-Volt Control Timing
Characteristic(1)
Symbol
Min
Max
Unit
Frequency of operation
Crystal option
External clock option(2)
fOSC
1
dc
8
32
MHz
fOP (fBus
tCYC
tRL
)
Internal operating frequency
—
125
8
MHz
ns
Internal clock period (1/fOP
)
—
—
—
—
RESET input pulse width low
100
ns
tILIH
IRQ interrupt pulse width low (edge-triggered)
100
ns
IRQ interrupt pulse period(3)
tILIL
tCYC
Note 3
1. VSS = 0 Vdc; timing shown with respect to 20% VDD and 70% VDD unless otherwise noted.
2. No more than 10% duty cycle deviation from 50%.
3. The minimum period is the number of cycles it takes to execute the interrupt service routine plus 1 tCYC
.
20.8 3.3-Volt Control Timing
Characteristic(1)
Symbol
Min
Max
Unit
Frequency of operation
Crystal option
External clock option(2)
fOSC
1
dc
8
16
MHz
f
OP (fBus
tCYC
tRL
)
Internal operating frequency
Internal clock period (1/fOP
—
250
4
MHz
ns
)
—
—
—
—
RESET input pulse width low
200
ns
tILIH
IRQ interrupt pulse width low (edge-triggered)
200
ns
IRQ interrupt pulse period(3)
tILIL
tCYC
Note 3
1. VSS = 0 Vdc; timing shown with respect to 20% VDD and 70% VDD unless otherwise noted.
2. No more than 10% duty cycle deviation from 50%.
3. The minimum period is the number of cycles it takes to execute the interrupt service routine plus 1 tCYC
.
tRL
RST
tILIL
tILIH
IRQ
Figure 20-1. RST and IRQ Timing
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
283
Electrical Specifications
20.9 Clock Generation Module (CGM) Characteristics
20.9.1 CGM Operating Conditions
Characteristic
Symbol
Min
Typ
Max
Unit
VDDA
VSSA
VDD – 0.3
VSS – 0.3
V
DD + 0.3
—
—
Operating voltage
V
VSS + 0.3
fRCLK
fXCLK
fNOM
fVRS
Crystal reference frequency
1
—
—
—
8
MHz
MHz
kHz
Hz
Input clock frequency (PLL off)(1)
Range nominal multiplier
32
—
71.42
—
—
VCO center-of-range frequency(2)
VCO operating frequency(3)
71.42k
71.42k
40M
32M
fVCLK
—
Hz
1. External square wave applied to OSC1. Voltage levels must be rail-to-rail and duty cycle must be 50%.
2. Range of frequencies that VCO can produce to generate input clock to frequency divider during acquisition and tracking
modes.
3. Allowed VCO operating range.
20.9.2 CGM Component Information
Characteristic
Symbol
Min
1
Typ
—
Max
8
Unit
MHz
pF
fXCLK
Crystal frequency
Crystal load capacitance(1)
Crystal fixed capacitance(2)
CL
C1
—
20
—
(2 x CL) – 5
—
—
—
0
47
47
10
—
—
pF
pF
Crystal tuning capacitance(3)
Feedback bias resistor
C2
(2 x CL) – 5
RB
1
0
MΩ
kΩ
μF
RS
Series damping resistor
VDDA/VSSA bypass capacitor
CGMXFC filter values
Cbyp
—
0.1
See Table 4-5. Example Filter Component Values
1. Consult crystal manufacturer’s specification.
2. Capacitor on OSC1 pin. Does not include parasitic capacitance due to package, pin, and board.
3. Capacitor on OSC2 pin. Does not include parasitic capacitance due to package, pin, and board.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
Clock Generation Module (CGM) Characteristics
20.9.3 CGM Acquisition/Lock Time Information
Characteristic
Symbol
Min
± 3.6
0
Typ
—
Max
± 7.2
± 3.6
± 0.9
± 1.8
—
Unit
%
Acquisition mode entry frequency tolerance(1)
Tracking mode entry frequency tolerance(2)
LOCK entry frequency tolerance(3)
ΔACQ
ΔTRK
ΔLOCK
ΔUNL
nACQ
nTRK
tACQ
tAL
—
%
0
—
%
LOCK exit frequency tolerance(4)
± 0.9
—
—
%
Reference cycles per acquisition mode period
Reference cycles per tracking mode period
Automatic mode time to stable
32
128
—
—
See note(5)
See note(6)
5
nACQ RCLK
/f
—
s
s
nTRK/fRCLK
Automatic stable to lock time
—
(7)
tLOCK
—
0
25
ms
Automatic lock time (tACQ + tAL
)
fRCLK
x
PLL jitter, deviation of average bus frequency
over 2 ms period
fJ
—
Hz
0.025% x
N/4
1. Deviation between VCO frequency and desired frequency to enter PLL acquisition mode.
2. Deviation between VCO frequency and desired frequency to enter PLL tracking mode (stable).
3. Deviation between VCO frequency and desired frequency to enter locked mode.
4. Deviation between VCO frequency and desired frequency to exit locked mode.
5. Acquisition time is an integer multiple of reference cycles divided by reference clock.
6. Stable to lock time is an integer multiple of reference cycles divided by reference clock.
7. Maximum lock time depends on CGMXFC filter components, power supply filtering, and reference clock stability. PLL may
not lock if improper components or poor filtering and layout are used.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
285
Electrical Specifications
20.10 5.0-Volt ADC Characteristics
Characteristic(1)
Symbol
Min
Max
5.5
Unit
Comments
V
DDAD should be tied to
the same potential as VDD
via separate traces.
VDDAD
Supply voltage
4.5
V
VADIN
BAD
VDDAD
VADIN <= VDDAD
Input voltages
0
10
V
Bits
Resolution
10
+4
AAD
Absolute accuracy
ADC internal clock
Conversion range
Power-up time
–4
LSB
Includes quantization
fADIC
RAD
tAIC = 1/fADIC
500 k
VSSAD
1.048 M
VDDAD
Hz
V
tADPU
tADC
tADS
MAD
ZADI
FADI
CADI
IVREF
tAIC cycles
tAIC cycles
tAIC cycles
16
16
5
—
17
—
Conversion time
Sample time
Monotonicity
Guaranteed
VADIN = VSSA
ADIN = VDDA
Zero input reading
Full-scale reading
Input capacitance
VDDAD/VREFH current
000
3FC
—
003
3FF
30
Hex
Hex
pF
V
Not tested
—
1.6
mA
Absolute accuracy
(8-bit truncation mode)
AAD
—
–1
+1
LSB
LSB
Includes quantization
Quantization error
(8-bit truncation mode)
–1/8
+7/8
1. VDD = 5.0 Vdc ± 10%, VSS = 0 Vdc, VDDAD/VREFH = 5.0 Vdc ± 10%, VSSAD/VREFL = 0 Vdc
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
286
3.3-Volt ADC Characteristics
Comments
20.11 3.3-Volt ADC Characteristics
Characteristic(1)
Symbol
Min
Max
3.6
Unit
VDDAD should be tied to
VDDAD
Supply voltage
3.0
V
the same potential as VDD
via separate traces.
VADIN
BAD
VDDAD
VADIN <= VDDAD
Input voltages
0
10
V
Bits
Resolution
10
+6
AAD
Absolute accuracy
ADC internal clock
Conversion range
Power-up time
–6
LSB
Includes quantization
fADIC
RAD
tAIC = 1/fADIC
500 k
VSSAD
1.048 M
VDDAD
Hz
V
tADPU
tADC
tADS
MAD
ZADI
FADI
CADI
IVREF
tAIC cycles
tAIC cycles
tAIC cycles
16
16
5
—
17
—
Conversion time
Sample time
Monotonicity
Guaranteed
VADIN = VSSA
ADIN = VDDA
Zero input reading
Full-scale reading
Input capacitance
VDDAD/VREFH current
000
3FA
—
005
3FF
30
Hex
Hex
pF
V
Not tested
—
1.2
mA
Absolute accuracy
(8-bit truncation mode)
AAD
—
–1
+1
LSB
LSB
Includes quantization
Quantization error
(8-bit truncation mode)
–1/8
+7/8
1. VDD = 3.3 Vdc ± 10%, VSS = 0 Vdc, VDDAD/VREFH = 3.3 Vdc ± 10%, VSSAD/VREFL = 0 Vdc
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
287
Electrical Specifications
20.12 5.0-Volt SPI Characteristics
Diagram
Characteristic(2)
Number(1)
Symbol
Min
Max
Unit
Operating frequency
Master
Slave
fOP(M)
fOP(S)
fOP/2
fOP
fOP/128
dc
MHz
MHz
Cycle time
Master
Slave
tCYC(M)
tCYC(S)
tCYC
tCYC
1
2
1
128
—
tLead(S)
tLag(S)
tCYC
tCYC
2
3
Enable lead time
Enable lag time
1
1
—
—
Clock (SPSCK) high time
Master
Slave
tSCKH(M)
tSCKH(S)
tCYC –25
1/2 tCYC –25
64 tCYC
—
4
5
6
7
ns
ns
Clock (SPSCK) low time
Master
Slave
tSCKL(M)
tSCKL(S)
tCYC –25
1/2 tCYC –25
64 tCYC
—
ns
ns
Data setup time (inputs)
Master
Slave
tSU(M)
tSU(S)
30
30
—
—
ns
ns
Data hold time (inputs)
Master
Slave
tH(M)
tH(S)
30
30
—
—
ns
ns
Access time, slave(3)
CPHA = 0
CPHA = 1
tA(CP0)
tA(CP1)
8
9
0
0
40
40
ns
ns
Disable time, slave(4)
tDIS(S)
—
40
ns
Data valid time, after enable edge
Master
Slave(5)
tV(M)
tV(S)
10
—
—
50
50
ns
ns
Data hold time, outputs, after enable edge
Master
Slave
tHO(M)
tHO(S)
11
0
0
—
—
ns
ns
1. Numbers refer to dimensions in Figure 20-2 and Figure 20-3.
2. All timing is shown with respect to 20% VDD and 70% VDD, unless noted; 100 pF load on all SPI pins.
3. Time to data active from high-impedance state
4. Hold time to high-impedance state
5. With 100 pF on all SPI pins
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor
3.3-Volt SPI Characteristics
20.13 3.3-Volt SPI Characteristics
Diagram
Characteristic(2)
Number(1)
Symbol
Min
Max
Unit
Operating frequency
Master
Slave
fOP(M)
fOP(S)
fOP/2
fOP
fOP/128
DC
MHz
MHz
Cycle time
Master
Slave
tCYC(M)
tCYC(S)
tcyc
tcyc
1
2
1
128
—
tLead(S)
tLag(S)
tcyc
tcyc
2
3
Enable lead time
Enable lag time
1
1
—
—
Clock (SPSCK) high time
Master
Slave
tSCKH(M)
tSCKH(S)
tcyc –35
1/2 tcyc –35
64 tcyc
—
4
5
6
7
ns
ns
Clock (SPSCK) low time
Master
Slave
tSCKL(M)
tSCKL(S)
tcyc –35
1/2 tcyc –35
64 tcyc
—
ns
ns
Data setup time (inputs)
Master
Slave
tSU(M)
tSU(S)
40
40
—
—
ns
ns
Data hold time (inputs)
Master
Slave
tH(M)
tH(S)
40
40
—
—
ns
ns
Access time, slave(3)
CPHA = 0
CPHA = 1
tA(CP0)
tA(CP1)
8
9
0
0
50
50
ns
ns
Disable time, slave(4)
tDIS(S)
—
50
ns
Data valid time, after enable edge
Master
Slave(5)
tV(M)
tV(S)
10
—
—
60
60
ns
ns
Data hold time, outputs, after enable edge
Master
Slave
tHO(M)
tHO(S)
11
0
0
—
—
ns
ns
1. Numbers refer to dimensions in Figure 20-2 and Figure 20-3.
2. All timing is shown with respect to 20% VDD and 70% VDD, unless noted; 100 pF load on all SPI pins.
3. Time to data active from high-impedance state
4. Hold time to high-impedance state
5. With 100 pF on all SPI pins
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
289
Electrical Specifications
SS
INPUT
SS PIN OF MASTER HELD HIGH
1
5
4
SPSCK OUTPUT
CPOL = 0
NOTE
4
5
SPSCK OUTPUT
CPOL = 1
NOTE
6
7
MISO
MSB IN
BITS 6–1
BITS 6–1
LSB IN
INPUT
11
MASTER MSB OUT
10
11
MOSI
OUTPUT
MASTER LSB OUT
Note: This first clock edge is generated internally, but is not seen at the SPSCK pin.
a) SPI Master Timing (CPHA = 0)
SS
INPUT
SS PIN OF MASTER HELD HIGH
1
SPSCK OUTPUT
CPOL = 0
5
NOTE
NOTE
4
SPSCK OUTPUT
CPOL = 1
5
4
6
7
MISO
MSB IN
BITS 6–1
BITS 6–1
LSB IN
INPUT
11
10
10
MOSI
OUTPUT
MASTER MSB OUT
MASTER LSB OUT
Note: This last clock edge is generated internally, but is not seen at the SPSCK pin.
b) SPI Master Timing (CPHA = 1)
Figure 20-2. SPI Master Timing
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
290
3.3-Volt 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
OUTPUT
MSB IN
LSB IN
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
INPUT
MSB IN
LSB IN
Note: Not defined but normally LSB of character previously transmitted
b) SPI Slave Timing (CPHA = 1)
Figure 20-3. SPI Slave Timing
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
291
Electrical Specifications
20.14 Timer Interface Module Characteristics
Characteristic
Timer input capture pulse width
Timer input capture period
Symbol
tTH, TL
Min
Max
—
Unit
t
tcyc
2
Note(1)
tcyc + 5
tTLTL
tcyc
ns
—
tTCL, tTCH
Timer input clock pulse width
—
1. The minimum period is the number of cycles it takes to execute the interrupt service routine plus 1 tcyc
.
tTLTL
tTH
INPUT CAPTURE
RISING EDGE
tTLTL
tTL
INPUT CAPTURE
FALLING EDGE
tTLTL
tTH
tTL
INPUT CAPTURE
BOTH EDGES
tTCH
TCLK
tTCL
Figure 20-4. Timer Input Timing
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
292
Memory Characteristics
20.15 Memory Characteristics
Characteristic
RAM data retention voltage
Symbol
Min
1.3
1
Typ
—
Max
—
Unit
V
VRDR
FLASH program bus clock frequency
FLASH read bus clock frequency
—
—
—
MHz
Hz
(1)
0
—
8 M
fRead
FLASH page erase time
<1 k cycles
>1 k cycles
tErase
0.9
3.6
1
4
1.1
5.5
ms
tMErase
tNVS
FLASH mass erase time
4
10
5
—
—
—
—
—
—
—
—
—
—
—
—
40
—
ms
μs
μs
μs
μs
μs
μs
FLASH PGM/ERASE to HVEN setup time
FLASH high-voltage hold time
FLASH high-voltage hold time (mass erase)
FLASH program hold time
tNVH
tNVHL
tPGS
100
5
tPROG
FLASH program time
30
1
(2)
FLASH return to read time
tRCV
(3)
FLASH cumulative program HV period
—
10 k
15
—
4
ms
tHV
FLASH endurance(4)
—
—
100 k
100
—
—
Cycles
Years
FLASH data retention time(5)
1. fRead is defined as the frequency range for which the FLASH memory can be read.
2. tRCV is defined as the time it needs before the FLASH can be read after turning off the high voltage charge pump, by clear-
ing HVEN to 0.
3. tHV is defined as the cumulative high voltage programming time to the same row before next erase.
tHV must satisfy this condition: tNVS + tNVH + tPGS + (tPROG x 32) ≤ tHV maximum.
4. Typical endurance was evaluated for this product family. For additional information on how Freescale Semiconductor
defines Typical Endurance, please refer to Engineering Bulletin EB619.
5. Typical data retention values are based on intrinsic capability of the technology measured at high temperature and de-rated
to 25°C using the Arrhenius equation. For additional information on how Freescale Semiconductor defines Typical Data
Retention, please refer to Engineering Bulletin EB618.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
293
Electrical Specifications
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
294
Chapter 21
Ordering Information and Mechanical Specifications
21.1 Introduction
This section contains ordering numbers for the MC68HC908GR60A and gives the dimensions for:
•
•
•
32-pin low-profile quad flat pack (case 873A)
48-pin low-profile quad flat pack (case 932-03)
64-pin quad flat pack (case 840B)
The following figures show the latest package drawings at the time of this publication. To make sure that
you have the latest package specifications, contact your local Freescale Semiconductor Sales Office.
21.2 MC Order Numbers
Table 21-1. MC Order Numbers
Operating
MC Order Number
MC908GR60ACFJ
Package
Temperature Range
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
32-pin low-profile
quad flat package
(LQFP)
MC908GR60AVFJ
MC908GR60AMFJ
MC908GR60ACFA
MC908GR60AVFA
MC908GR60AMFA
MC908GR60ACFU
MC908GR60AVFU
MC908GR60AMFU
48-pin low-profile
quad flat package
(LQFP)
64-pin quad flat
package
(QFP)
Temperature designators:
C = –40°C to +85°C
V = –40°C to +105°C
M = –40°C to +125°C
M C 9 0 8 G R X X A X XX E
Pb FREE
FAMILY
PACKAGE DESIGNATOR
TEMPERATURE RANGE
Figure 21-1. Device Numbering System
21.3 Package Dimensions
Refer to the following pages for detailed package dimensions.
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
295
Appendix A
MC68HC908GR48A
A.1 Introduction
The MC68HC908GR48A is a member of the low-cost, high-performance M68HC08 Family of 8-bit
microcontroller units (MCUs). 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.
The information contained in this document pertains to the MC68HC908GR48A with the exceptions
shown in this appendix.
A.2 Block Diagram
See Figure A-1.
A.3 Memory
The MC68HC908GR48A can address 48 Kbytes of memory space. The memory map, shown in
Figure A-2, includes:
•
•
•
48 Kbytes of user FLASH memory
1536 bytes of random-access memory (RAM)
52 bytes of user-defined vectors
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
Freescale Semiconductor
305
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 48,640 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
USER RAM — 1536 BYTES
MONITOR ROM — 304 BYTES
2-CHANNEL TIMER INTERFACE
MODULE
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure A-1. MC68HC908GR48A Block Diagram
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
306
Freescale Semiconductor
$FE03
$FE04
$FE05
$FE06
$FE07
$FE08
$FE09
$FE0A
$FE0B
$FE0C
$FE0D
$FE0E
$FE0F
SIM BREAK FLAG CONTROL REGISTER (BFCR)
INTERRUPT STATUS REGISTER 1 (INT1)
INTERRUPT STATUS REGISTER 2 (INT2)
INTERRUPT STATUS REGISTER 3 (INT3)
INTERRUPT STATUS REGISTER 4 (INT4)
FLASH-2 CONTROL REGISTER (FL2CR)
BREAK ADDRESS REGISTER HIGH (BRKH)
BREAK ADDRESS REGISTER LOW (BRKL)
BREAK STATUS AND CONTROL REGISTER (BRKSCR)
LVI STATUS REGISTER (LVISR)
$0000
↓
$003F
I/O REGISTERS
64 BYTES
$0040
↓
$043F
RAM-1
1024 BYTES
$0440
↓
$0461
I/O REGISTERS
34 BYTES
$0462
↓
$057F
RESERVED
FLASH-2 TEST CONTROL REGISTER (FLTCR2)
FLASH-1 TEST CONTROL REGISTER (FLTCR1)
UNIMPLEMENTED
$0580
↓
$077F
RAM-2
512 BYTES
UNIMPLEMENTED
16 BYTES
RESERVED FOR COMPATIBILITY WITH MONITOR CODE
FOR A-FAMILY PART
$FE10
↓
$FE1F
$0780
↓
$1DFF
RESERVED
$FE20
↓
$FF7F
MONITOR ROM
352 BYTES
$1E00
↓
$1E0F
MONITOR ROM
16 BYTES
$FF80
$FF81
FLASH-1 BLOCK PROTECT REGISTER (FL1BPR)
FLASH-2 BLOCK PROTECT REGISTER (FL2BPR)
$1E10
↓
$3FFF
$FF82
↓
$FF87
RESERVED
RESERVED
FLASH-1 CONTROL REGISTER (FL1CR)
RESERVED
$FF88
$4000
↓
$7FFF
FLASH-2
16,384 BYTES
$FF89
↓
$FFCB
$8000
↓
$FDFF
FLASH-1
32,256 BYTES
$FFCC
↓
FLASH-1 VECTORS
52 BYTES
$FFFF(1)
$FE00
$FE01
$FE02
SIM BREAK STATUS REGISTER (BSR)
SIM RESET STATUS REGISTER (SRSR)
RESERVED
1. $FFF6–$FFFD used for eight security bytes
Figure A-2. MC68HC908GR48A Memory Map
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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307
A.4 Ordering Information
Table A-1. MC Order Numbers
Operating
Temperature Range
MC Order Number
Package
MC908GR48ACFJ
MC908GR48AVFJ
MC908GR48AMFJ
MC908GR48ACFA
MC908GR48AVFA
MC908GR48AMFA
MC908GR48ACFU
MC908GR48AVFU
MC908GR48AMFU
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
32-pin low-profile
quad flat package
(LQFP)
48-pin low-profile
quad flat package
(LQFP)
64-pin quad flat
package
(QFP)
Temperature designators:
C = –40°C to +85°C
V = –40°C to +105°C
M = –40°C to +125°C
M C 9 0 8 G R X X A X XX E
Pb FREE
FAMILY
PACKAGE DESIGNATOR
TEMPERATURE RANGE
Figure A-3. Device Numbering System
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308
Appendix B
MC68HC908GR32A
B.1 Introduction
The MC68HC908GR32A is a member of the low-cost, high-performance M68HC08 Family of 8-bit
microcontroller units (MCUs). 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.
The information contained in this document pertains to the MC68HC908GR32A with the exceptions
shown in this appendix.
B.2 Block Diagram
See Figure B-1.
B.3 Memory
The MC68HC908GR32A can address 32 Kbytes of memory space. The memory map, shown in
Figure B-2, includes:
•
•
•
32 Kbytes of user FLASH memory
1536 bytes of random-access memory (RAM)
52 bytes of user-defined vectors
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309
INTERNAL BUS
M68HC08 CPU
PTA7/KBD7/AD15–
PTA0/KBD0/AD8(2)
PROGRAMMABLE TIMEBASE
MODULE
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
SINGLE BREAKPOINT BREAK
MODULE
CONTROL AND STATUS REGISTERS — 64 BYTES
USER FLASH — 32,256 BYTES
PTB7/AD7–PTB0/AD0
DUAL VOLTAGE
LOW-VOLTAGE INHIBIT MODULE
PTC6(2)
PTC5(2)
PTC4(2, 3)
PTC3(2, 3)
PTC2(2, 3)
PTC1(2, 3)
PTC0(2, 3)
8-BIT KEYBOARD
INTERRUPT MODULE
USER RAM — 1536 BYTES
MONITOR ROM — 304 BYTES
2-CHANNEL TIMER INTERFACE
MODULE
USER FLASH VECTOR SPACE — 52 BYTES
CLOCK GENERATOR MODULE
6-CHANNEL TIMER INTERFACE
MODULE
PTD7/T2CH1(2)
PTD6/T2CH0(2)
PTD5/T1CH1(2)
PTD4/T1CH0(2)
PTD3/SPSCK(2)
PTD2/MOSI(2)
ENHANCED SERIAL
COMMUNICATIONS
INTERFACE MODULE
OSC1
1–8 MHz OSCILLATOR
OSC2
PHASE LOCKED LOOP
CGMXFC
COMPUTER OPERATING
PROPERLY MODULE
PTD1/MISO(2)
PTD0/SS/MCLK(2)
SERIAL PERIPHERAL
INTERFACE MODULE
SYSTEM INTEGRATION
RST(1)
MODULE
PTE5–PTE2
PTE1/RxD
PTE0/TxD
MONITOR MODE ENTRY
MODULE
SINGLE EXTERNAL
IRQ(1)
INTERRUPT MODULE
SECURITY
MODULE
VDDAD/VREFH
PTF7/T2CH5
PTF6/T2CH4
PTF5/T2CH3
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
VSSAD/VREFL
MEMORY MAP
MODULE
POWER-ON RESET
MODULE
PTF4/T2CH2
PTF3–PFT0(3)
VDD
VSS
VDDA
CONFIGURATION REGISTER 1–2
MODULE
POWER
PTG7/AD23–
PTG0/AD16
VSSA
1. Pin contains integrated pullup device.
2. Ports are software configurable with pullup device if input port or pullup/pulldown device for keyboard input.
3. Higher current drive port pins
Figure B-1. MC68HC908GR32A Block Diagram
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
310
Freescale Semiconductor
$FE04
$FE05
$FE06
$FE07
$FE08
$FE09
$FE0A
$FE0B
$FE0C
$FE0D
$FE0E
$FE0F
INTERRUPT STATUS REGISTER 1 (INT1)
INTERRUPT STATUS REGISTER 2 (INT2)
INTERRUPT STATUS REGISTER 3 (INT3)
INTERRUPT STATUS REGISTER 4 (INT4)
UNIMPLEMENTED
$0000
↓
$003F
I/O REGISTERS
64 BYTES
$0040
↓
$043F
RAM-1
1024 BYTES
BREAK ADDRESS REGISTER HIGH (BRKH)
BREAK ADDRESS REGISTER LOW (BRKL)
BREAK STATUS AND CONTROL REGISTER (BRKSCR)
LVI STATUS REGISTER (LVISR)
$0440
↓
$0461
I/O REGISTERS
34 BYTES
UNIMPLEMENTED
$0462
↓
$057F
RESERVED
FLASH-1 TEST CONTROL REGISTER (FLTCR1)
UNIMPLEMENTED
UNIMPLEMENTED
16 BYTES
RESERVED FOR COMPATIBILITY WITH MONITOR CODE
FOR A-FAMILY PART
$0580
↓
$077F
$FE10
↓
$FE1F
RAM-2
512 BYTES
$0780
↓
$1DFF
$FE20
↓
$FF7F
MONITOR ROM
352 BYTES
RESERVED
$FF80
FLASH-1 BLOCK PROTECT REGISTER (FL1BPR)
RESERVED
$1E00
↓
$1E0F
MONITOR ROM
16 BYTES
$FF81
↓
$FF87
$1E10
↓
$7FFF
RESERVED
$FF88
FLASH-1 CONTROL REGISTER (FL1CR)
RESERVED
$FF89
↓
$FFCB
$8000
↓
$FDFF
FLASH-1
32,256 BYTES
$FFCC
↓
FLASH-1 VECTORS
52 BYTES
$FE00
$FE01
$FE02
$FE03
SIM BREAK STATUS REGISTER (BSR)
SIM RESET STATUS REGISTER (SRSR)
RESERVED
$FFFF(1)
SIM BREAK FLAG CONTROL REGISTER (7BFCR)
1. $FFF6–$FFFD used for eight security bytes
Figure B-2. MC68HC908GR32A Memory Map
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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311
B.4 Ordering Information
Table B-1. MC Order Numbers
Operating
Temperature Range
MC Order Number
Package
MC908GR32ACFJ
MC908GR32AVFJ
MC908GR32AMFJ
MC908GR32ACFA
MC908GR32AVFA
MC908GR32AMFA
MC908GR32ACFU
MC908GR32AVFU
MC908GR32AMFU
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
–40°C to +85°C
–40°C to +105°C
–40°C to +125°C
32-pin low-profile
quad flat package
(LQFP)
48-pin low-profile
quad flat package
(LQFP)
64-pin quad flat
package
(QFP)
Temperature designators:
C = –40°C to +85°C
V = –40°C to +105°C
M = –40°C to +125°C
M C 9 0 8 G R X X A X XX E
Pb FREE
FAMILY
PACKAGE DESIGNATOR
TEMPERATURE RANGE
Figure B-3. Device Numbering System
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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312
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MC68HC908GR60A
Rev. 5, 04/2007
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