SC16C754IA68 [NXP]
Quad UART with 64-byte FIFO; 四通道UART,具有64字节FIFO型号: | SC16C754IA68 |
厂家: | NXP |
描述: | Quad UART with 64-byte FIFO |
文件: | 总49页 (文件大小:572K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
SC16C754
Quad UART with 64-byte FIFO
Rev. 04 — 19 June 2003
Product data
1. Description
The SC16C754 is a quad universal asynchronous receiver/transmitter (UART) with
64-byte FIFOs, automatic hardware/software flow control, and data rates up to
5 Mbits/s (3.3 V and 5 V). The SC16C754 offers enhanced features. It has a
transmission control register (TCR) that stores receiver FIFO threshold levels to
start/stop transmission during hardware and software flow control. With the FIFO
RDY register, the software gets the status of TXRDY/RXRDY for all four ports in one
access. On-chip status registers provide the user with error indications, operational
status, and modem interface control. System interrupts may be tailored to meet user
requirements. An internal loop-back capability allows on-board diagnostics.
The UART transmits data, sent to it over the peripheral 8-bit bus, on the TX signal and
receives characters on the RX signal. Characters can be programmed to be 5, 6, 7, or
8 bits. The UART has a 64-byte receive FIFO and transmit FIFO and can be
programmed to interrupt at different trigger levels. The UART generates its own
desired baud rate based upon a programmable divisor and its input clock. It can
transmit even, odd, or no parity and 1, 1.5, or 2 stop bits. The receiver can detect
break, idle, or framing errors, FIFO overflow, and parity errors. The transmitter can
detect FIFO underflow. The UART also contains a software interface for modem
control operations, and has software flow control and hardware flow control
capabilities.
The SC16C754 is available in plastic LQFP80 and PLCC68 packages.
2. Features
■ Pin compatible with SC16C654IA68 and SC16C554IA68 with additional
enhancements
■ Up to 5 Mbits/s baud rate (at 3.3 V and 5 V; at 2.5 V maximum baud rate is
3 Mbits/s)
■ 64-byte transmit FIFO
■ 64-byte receive FIFO with error flags
■ Programmable and selectable transmit and receive FIFO trigger levels for DMA
and interrupt generation
■ Software/hardware flow control
◆ Programmable Xon/Xoff characters
◆ Programmable auto-RTS and auto-CTS
■ Optional data flow resume by Xon any character
■ DMA signalling capability for both received and transmitted data
■ Supports 5 V, 3.3 V and 2.5 V operation
■ Software selectable baud rate generator
SC16C754
Quad UART with 64-byte FIFO
Philips Semiconductors
■ Prescaler provides additional divide-by-4 function
■ Fast databus access time
■ Programmable sleep mode
■ Programmable serial interface characteristics
◆ 5, 6, 7, or 8-bit characters
◆ Even, odd, or no parity bit generation and detection
◆ 1, 1.5, or 2 stop bit generation
■ False start bit detection
■ Complete status reporting capabilities in both normal and sleep mode
■ Line break generation and detection
■ Internal test and loop-back capabilities
■ Fully prioritized interrupt system controls
■ Modem control functions (CTS, RTS, DSR, DTR, RI, and CD).
3. Ordering information
Table 1:
Ordering information
Type number
Package
Name
Description
Version
SC16C754IB80
SC16C754IA68
LQFP80
PLCC68
plastic low profile quad flat package; 80 leads; body 12 × 12 × 1.4 mm
plastic leaded chip carrier; 68 leads
SOT315-1
SOT188-2
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Product data
Rev. 04 — 19 June 2003
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SC16C754
Quad UART with 64-byte FIFO
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4. Block diagram
SC16C754
TRANSMIT
FIFO
TRANSMIT
SHIFT
TXA-TXD
REGISTERS
REGISTER
D0–D7
IOR
IOW
DATA BUS
AND
CONTROL LOGIC
RESET
FLOW
CONTROL
LOGIC
RECEIVE
FIFO
RECEIVE
SHIFT
RXA-RXD
REGISTERS
REGISTER
FLOW
CONTROL
LOGIC
REGISTER
SELECT
LOGIC
A0–A2
CSA-CSD
DTRA-DTRD
RTSA-RTSD
MODEM
CONTROL
LOGIC
INTA-INTD
TXRDY
RXRDY
CTSA-CTSD
RIA-RID
CDA-CDD
CLOCK AND
BAUD RATE
GENERATOR
INTERRUPT
CONTROL
LOGIC
DSRA-DSRD
INTSEL
002aaa206
XTAL1 XTAL2
CLKSEL
Fig 1. Block diagram.
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SC16C754
Quad UART with 64-byte FIFO
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5. Pinning information
5.1 Pinning
NC
NC
1
2
3
4
5
6
7
8
9
60 NC
59 DSRD
58 CTSD
57 DTRD
56 GND
55 RTSD
54 INTD
53 CSD
52 TXD
51 IOR
DSRA
CTSA
DTRA
V
CC
RTSA
INTA
CSA
TXA 10
IOW 11
TXB 12
CSB 13
INTB 14
RTSB 15
GND 16
DTRB 17
CTSB 18
DSRB 19
NC 20
SC16C754IB80
50 TXC
49 CSC
48 INTC
47 RTSC
46
V
CC
45 DTRC
44 CTSC
43 DSRC
42 NC
41 NC
002aaa366
Fig 2. LQFP80 pin configuration.
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Rev. 04 — 19 June 2003
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SC16C754
Quad UART with 64-byte FIFO
Philips Semiconductors
DSRA 10
CTSA 11
DTRA 12
60 DSRD
59 CDSD
58 DTRD
57 GND
56 RTSD
55 INTD
54 CSD
53 TXD
52 IOR
V
13
CC
RTSA 14
INTA 15
CSA 16
TXA 17
IOW 18
TXB 19
SC16C754IA68
51 TXC
50 CSC
49 INTC
48 RTSC
CSB 20
INTB 21
RTSB 22
GND 23
DTRB 24
CTSB 25
DSRB 26
47
V
CC
46 DTRC
45 CTSC
44 DSRC
002aaa367
Fig 3. PLCC68 pin configuration.
5.2 Pin description
Table 2:
Symbol
Pin description
Pin
Type
Description
LQFP80 PLCC68
A0
A1
A2
30
29
28
34
33
32
I
I
I
I
Address 0 select bit. Internal registers address selection.
Address 1 select bit. Internal registers address selection.
Address 2 select bit. Internal registers address selection.
CDA, CDB,
CDC, CDD
79, 23, 9, 27,
39, 63 43, 61
Carrier Detect (Active-LOW). These inputs are associated with individual
UART channels A through D. A logic LOW on these pins indicates that a
carrier has been detected by the modem for that channel. The state of these
inputs is reflected in the modem status register (MSR).
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SC16C754
Quad UART with 64-byte FIFO
Philips Semiconductors
Table 2:
Symbol
Pin description…continued
Pin
Type
Description
LQFP80 PLCC68
CLKSEL
26
30
I
Clock Select. CLKSEL selects the divide-by-1 or divide-by-4 prescalable
clock. During the reset, a logic 1 (VCC) on CLKSEL selects the divide-by-1
prescaler. A logic 0 (GND) on CLKSEL selects the divide-by-4 prescaler.
The value of CLKSEL is latched into MCR[7] at the trailing edge of RESET.
A logic 1(VCC) on CLKSEL will latch a 0 into MCR[7]. A logic 0 (GND) on
CLKSEL will latch a 1 into MCR[7]. MCR[7] can be changed after RESET to
alter the prescaler value.
CSA, CSB,
CSC, CSD
9, 13,
49, 53
16, 20,
50, 54
I
I
Chip Select (Active-LOW). These pins enable data transfers between the
user CPU and the SC16C754 for the channel(s) addressed. Individual
UART sections (A, B, C, D) are addressed by providing a logic LOW on the
respective CSA through CSD pins.
CTSA, CTSB,
CTSC, CTSD
4, 18,
44, 58
11, 25,
45, 59
Clear to Send (Active-LOW). These inputs are associated with individual
UART channels A through D. A logic 0 (LOW) on the CTS pins indicates the
modem or data set is ready to accept transmit data from the SC16C754.
Status can be tested by reading MSR[4]. These pins only affect the transmit
and receive operations when Auto-CTS function is enabled via the
Enhanced Feature Register EFR[7] for hardware flow control operation.
D0-D2,
D3-D7
68-70,
71-75
66-68,
1-5
I/O
I
Data bus (bi-directional). These pins are the 8-bit, 3-state data bus for
transferring information to or from the controlling CPU. D0 is the least
significant bit and the first data bit in a transmit or receive serial data stream.
DSRA, DSRB, 3, 19,
DSRC, DSRD
10, 26,
44, 60
Data Set Ready (Active-LOW). These inputs are associated with individual
UART channels A through D. A logic 0 (LOW) on these pins indicates the
modem or data set is powered-on and is ready for data exchange with the
UART. The state of these inputs is reflected in the modem status register
(MSR).
43, 59
DTRA, DTRB,
DTRC, DTRD
5, 17,
45, 57
12, 24,
46, 58
O
Data Terminal Ready (Active-LOW). These outputs are associated with
individual UART channels A through D. A logic 0 (LOW) on these pins
indicates that the SC16C754 is powered-on and ready. These pins can be
controlled via the modem control register. Writing a logic 1 to MCR[0] will
set the DTR output to logic 0 (LOW), enabling the modem. The output of
these pins will be a logic 1 after writing a logic 0 to MCR[0], or after a reset.
GND
16, 36, 6, 23,
I
Signal and power ground.
56, 76
40, 57
INTA, INTB,
INTC, INTD
8, 14,
48, 54
15, 21,
49, 55
O
Interrupt A, B, C, and D (Active-HIGH). These pins provide individual
channel interrupts INTA through INTD. INTA through INTD are enabled
when MCR[3] is set to a logic 1, interrupt sources are enabled in the
interrupt enable register (IER). Interrupt conditions include: receiver errors,
available receiver buffer data, available transmit buffer space, or when a
modem status flag is detected. INTA-INTD are in the high-impedance state
after reset.
INTSEL
67
51
65
52
I
I
Interrupt select (Active-HIGH with internal pull-down). INTSEL can be
used in conjunction with MCR[3] to enable or disable the 3-STate interrupts
INTA-INTD or override MCR[3] and force continuous interrupts. Interrupt
outputs are enabled continuously by making this pin a logic 1. Driving this
pin LOW allows MCR[3] to control the 3-State interrupt output. In this mode,
MCR[3] is set to a logic 1 to enable the 3-State outputs.
IOR
Input/Output Read strobe (Active-LOW). A HIGH-to-LOW transition on
IOR will load the contents of an internal register defined by address bits
A0-A2 onto the SC16C754 data bus (D0-D7) for access by external CPU.
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SC16C754
Quad UART with 64-byte FIFO
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Table 2:
Symbol
Pin description…continued
Pin
Type
Description
LQFP80 PLCC68
IOW
NC
11
18
I
Input/Output Write strobe (Active-LOW). A LOW-to-HIGH transition on
IOW will transfer the contents of the data bus (D0-D7) from the external
CPU to an internal register that is defined by address bits A0-A2 and CSA
and CSD.
1, 2, 20, 31
21, 22,
-
Not connected.
27, 40,
41, 42,
60, 61,
62, 80
RESET
33
37
I
I
Reset. This pin will reset the internal registers and all the outputs. The
UART transmitter output and the receiver input will be disabled during reset
time. RESET is an active-HIGH input.
RIA, RIB,
RIC, RID
78, 24, 8, 28,
38, 64
Ring Indicator (Active-LOW). These inputs are associated with individual
UART channels, A through D. A logic 0 on these pins indicates the modem
has received a ringing signal from the telephone line. A LOW-to-HIGH
transition on these input pins generates a modem status interrupt, if
enabled. The state of these inputs is reflected in the modem status register
(MSR).
42, 62
RTSA, RTSB,
RTSC, RTSD
7, 15,
47, 55
14, 22,
48, 56
O
Request to Send (Active-LOW). These outputs are associated with
individual UART channels, A through D. A logic 0 on the RTS pin indicates
the transmitter has data ready and waiting to send. Writing a logic 1 in the
modem control register MCR[1] will set this pin to a logic 0, indicating data
is available. After a reset these pins are set to a logic 1. These pins only
affect the transmit and receive operations when Auto-RTS function is
enabled via the Enhanced Feature Register (EFR[6]) for hardware flow
control operation.
RXA, RXB,
RXC, RXD
77, 25, 7, 29,
I
Receive data input. These inputs are associated with individual serial
channel data to the SC16C754. During the local loop-back mode, these RX
input pins are disabled and TX data is connected to the UART RX input
internally.
37, 65
41, 63
RXRDY
34
38
O
O
O
Receive Ready (Active-LOW). RXRDY contains the wire-ORed status of
all four receive channel FIFOs, RXRDY A-D. It goes LOW when the trigger
level has been reached or a time-out interrupt occurs. It goes HIGH when all
RX FIFOs are empty and there is an error in RX FIFO.
TXA, TXB,
TXC, TCD
10, 12, 17, 19,
50, 52
Transmit data. These outputs are associated with individual serial transmit
channel data from the SC16C754. During the local loop-back mode, the TX
output pin is disabled and TX data is internally connected to the UART RX
input.
51, 53
TXRDY
35
39
Transmit Ready (Active-LOW). TXRDY contains the wire-ORed status of
all four transmit channel FIFOs, TXRDY A-D. It goes LOW when there are a
trigger level number of spaces available. It goes HIGH when all four TX
buffers are full.
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Rev. 04 — 19 June 2003
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SC16C754
Quad UART with 64-byte FIFO
Philips Semiconductors
Table 2:
Symbol
Pin description…continued
Pin
Type
Description
LQFP80 PLCC68
VCC
6, 46, 66 13, 47,
64
I
I
Power supply input.
XTAL1
31
35
Crystal or external clock input. Functions as a crystal input or as an
external clock input. A crystal can be connected between XTAL1 and XTAL2
to form an internal oscillator circuit (see Figure 13). Alternatively, an
external clock can be connected to this pin to provide custom data rates.
XTAL2
32
36
O
Output of the crystal oscillator or buffered clock. (See also XTAL1.)
XTAL2 is used as a crystal oscillator output or a buffered clock output.
6. Functional description
The SC16C754 UART is pin-compatible with the SC16C554 and SC16C654 UARTs.
It provides more enhanced features. All additional features are provided through a
special enhanced feature register.
The UART will perform serial-to-parallel conversion on data characters received from
peripheral devices or modems, and parallel-to-parallel conversion on data characters
transmitted by the processor. The complete status of each channel of the SC16C754
UART can be read at any time during functional operation by the processor.
The SC16C754 can be placed in an alternate mode (FIFO mode) relieving the
processor of excessive software overhead by buffering received/transmitted
characters. Both the receiver and transmitter FIFOs can store up to 64 bytes
(including three additional bits of error status per byte for the receiver FIFO) and have
selectable or programmable trigger levels. Primary outputs RXRDY and TXRDY allow
signalling of DMA transfers.
The SC16C754 has selectable hardware flow control and software flow control.
Hardware flow control significantly reduces software overhead and increases system
efficiency by automatically controlling serial data flow using the RTS output and CTS
input signals. Software flow control automatically controls data flow by using
programmable Xon/Xoff characters.
The UART includes a programmable baud rate generator that can divide the timing
reference clock input by a divisor between 1 and (216 − 1).
6.1 Trigger levels
The SC16C754 provides independent selectable and programmable trigger levels for
both receiver and transmitter DMA and interrupt generation. After reset, both
transmitter and receiver FIFOs are disabled and so, in effect, the trigger level is the
default value of one byte. The selectable trigger levels are available via the FCR. The
programmable trigger levels are available via the TLR.
6.2 Hardware flow control
Hardware flow control is comprised of Auto-CTS and Auto-RTS. Auto-CTS and
Auto-RTS can be enabled/disabled independently by programming EFR[7:6].
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Rev. 04 — 19 June 2003
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SC16C754
Quad UART with 64-byte FIFO
Philips Semiconductors
With Auto-CTS, CTS must be active before the UART can transmit data.
Auto-RTS only activates the RTS output when there is enough room in the FIFO to
receive data and de-activates the RTS output when the RX FIFO is sufficiently full.
The halt and resume trigger levels in the TCR determine the levels at which RTS is
activated/deactivated.
If both Auto-CTS and Auto-RTS are enabled, when RTS is connected to CTS, data
transmission does not occur unless the receiver FIFO has empty space. Thus,
overrun errors are eliminated during hardware flow control. If not enabled, overrun
errors occur if the transmit data rate exceeds the receive FIFO servicing latency.
UART 1
UART 2
RX
TX
SERIAL-TO-
PARALLEL
PARALLEL-
TO-SERIAL
RX
TX
FIFO
FIFO
RTS
CTS
FLOW
FLOW
CONTROL
CONTROL
D7-D0
D7-D0
TX
RX
PARALLEL-
TO-SERIAL
SERIAL-TO-
PARALLEL
TX
FIFO
RX
FIFO
CTS
RTS
FLOW
FLOW
CONTROL
CONTROL
002aaa228
Fig 4. Autoflow control (Auto-RTS and Auto-CTS) example.
6.2.1 Auto-RTS
Auto-RTS data flow control originates in the receiver block (see Figure 1 “Block
diagram.” on page 3). Figure 5 shows RTS functional timing. The receiver FIFO
trigger levels used in Auto-RTS are stored in the TCR. RTS is active if the RX FIFO
level is below the halt trigger level in TCR[3:0]. When the receiver FIFO halt trigger
level is reached, RTS is deasserted. The sending device (e.g., another UART) may
send an additional byte after the trigger level is reached (assuming the sending UART
has another byte to send) because it may not recognize the deassertion of RTS until
it has begun sending the additional byte. RTS is automatically reasserted once the
receiver FIFO reaches the resume trigger level programmed via TCR[7:4]. This
reassertion allows the sending device to resume transmission.
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SC16C754
Quad UART with 64-byte FIFO
Philips Semiconductors
RX
START
BYTE N
STOP
START
BYTE N + 1
STOP
START
RTS
1
2
N
N+1
IOR
002aaa226
(1) N = receiver FIFO trigger level.
(2) The two blocks in dashed lines cover the case where an additional byte is sent, as described in Section 6.2.1.
Fig 5. RTS functional timing.
6.2.2 Auto-CTS
The transmitter circuitry checks CTS before sending the next data byte. When CTS is
active, the transmitter sends the next byte. To stop the transmitter from sending the
following byte, CTS must be deasserted before the middle of the last stop bit that is
currently being sent. The auto-CTS function reduces interrupts to the host system.
When flow control is enabled, CTS level changes do not trigger host interrupts
because the device automatically controls its own transmitter. Without auto-CTS, the
transmitter sends any data present in the transmit FIFO and a receiver overrun error
may result.
START
BYTE 0-7
STOP
TX
START
BYTE 0-7
STOP
CTS
002aaa227
(1) When CTS is LOW, the transmitter keeps sending serial data out.
(2) When CTS goes HIGH before the middle of the last stop bit of the current byte, the transmitter finishes sending the current
byte, but is does not send the next byte.
(3) When CTS goes from HIGH to LOW, the transmitter begins sending data again.
Fig 6. CTS functional timing.
6.3 Software flow control
Software flow control is enabled through the enhanced feature register and the
modem control register. Different combinations of software flow control can be
enabled by setting different combinations of EFR[3:0]. Table 3 shows software flow
control options.
Table 3:
Software flow control options (EFR[0:3])
EFR[3] EFR[2] EFR[1] EFR[0] TX, RX software flow controls
0
1
0
1
0
0
1
1
X
X
X
X
X
X
X
X
no transmit flow control
transmit Xon1, Xoff1
transmit Xon2, Xoff2
transmit Xon1, Xon2, Xoff1, Xoff2
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SC16C754
Quad UART with 64-byte FIFO
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Table 3:
Software flow control options (EFR[0:3])…continued
EFR[3] EFR[2] EFR[1] EFR[0] TX, RX software flow controls
X
X
X
1
X
X
X
0
0
1
0
1
0
0
1
1
no receive flow control
receiver compared Xon1, Xoff1
receiver compares Xon2, Xoff2
transmit Xon1, Xoff1
receiver compares Xon1 and Xon2, Xoff1 and Xoff2
transmit Xon2, Xoff2
0
1
1
1
1
1
1
1
receiver compares Xon1 and Xon2, Xoff1 and Xoff2
transmit Xon1, Xon2, Xoff1, Xoff2
receiver compares Xon1 and Xon2, Xoff1 and Xoff2
Remark: When using software flow control, the Xon/Xoff characters cannot be used
for data characters.
There are two other enhanced features relating to software flow control:
• Xon Any function (MCR[5]): Operation will resume after receiving any character
after recognizing the Xoff character. It is possible that an Xon1 character is
recognized as an Xon Any character, which could cause an Xon2 character to be
written to the RX FIFO.
• Special character (EFR[5]): Incoming data is compared to Xoff2. Detection of the
special character sets the Xoff interrupt (IIR[4]) but does not halt transmission. The
Xoff interrupt is cleared by a read of the IIR. The special character is transferred to
the RX FIFO.
6.3.1 RX
When software flow control operation is enabled, the SC16C754 will compare
incoming data with Xoff1,2 programmed characters (in certain cases, Xoff1 and Xoff2
must be received sequentially). When the correct Xoff character are received,
transmission is halted after completing transmission of the current character. Xoff
detection also sets IIR[4] (if enabled via IER[5]) and causes INT to go HIGH.
To resume transmission, an Xon1,2 character must be received (in certain cases
Xon1 and Xon2 must be received sequentially). When the correct Xon characters are
received, IIR[4] is cleared, and the Xoff interrupt disappears.
6.3.2 TX
Xoff1/2 character is transmitted when the RX FIFO has passed the HALT trigger level
programmed in TCR[3:0].
Xon1/2 character is transmitted when the RX FIFO reaches the RESUME trigger
level programmed in TCR[7:4].
The transmission of Xoff/Xon(s) follows the exact same protocol as transmission of
an ordinary byte from the FIFO. This means that even if the word length is set to be 5,
6, or 7 characters, then the 5, 6, or 7 least significant bits of Xoff1,2/Xon1,2 will be
transmitted. (Note that the transmission of 5, 6, or 7 bits of a character is seldom
done, but this functionality is included to maintain compatibility with earlier designs.)
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SC16C754
Quad UART with 64-byte FIFO
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It is assumed that software flow control and hardware flow control will never be
enabled simultaneously. Figure 7 shows an example of software flow control.
6.3.3 Software flow control example
UART1
UART2
TRANSMIT FIFO
RECEIVE FIFO
DATA
PARALLEL-TO-SERIAL
SERIAL-TO-PARALLEL
Xon-1 WORD
SERIAL-TO-PARALLEL
PARALLEL-TO-SERIAL
Xon-1 WORD
Xoff–Xon–Xoff
Xon-2 WORD
Xon-2 WORD
Xoff-1 WORD
Xoff-1 WORD
COMPARE
PROGRAMMED
Xon-Xoff
Xoff-2 WORD
Xoff-2 WORD
CHARACTERS
002aaa229
Fig 7. Software flow control example.
Assumptions: UART1 is transmitting a large text file to UART2. Both UARTs are
using software flow control with single character Xoff (0F) and Xon (0D) tokens. Both
have Xoff threshold (TCR[3:0] = F) set to 60, and Xon threshold (TCR[7:4] = 8) set to
32. Both have the interrupt receive threshold (TLR[7:4] = D) set to 52.
UART 1 begins transmission and sends 52 characters, at which point UART2 will
generate an interrupt to its processor to service the RCV FIFO, but assume the
interrupt latency is fairly long. UART1 will continue sending characters until a total of
60 characters have been sent. At this time, UART2 will transmit a 0F to UART1,
informing UART1 to halt transmission. UART1 will likely send the 61st character while
UART2 is sending the Xoff character. Now UART2 is serviced and the processor
reads enough data out of the RX FIFO that the level drops to 32. UART2 will now
send a 0D to UART1, informing UART1 to resume transmission.
6.4 Reset
Table 4 summarizes the state of register after reset.
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SC16C754
Quad UART with 64-byte FIFO
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Table 4:
Register
Register reset functions
Reset control
RESET
RESET
RESET
RESET
RESET
RESET
RESET
RESET
RESET
RESET
RESET
RESET
Reset state
Interrupt enable register
Interrupt identification register
FIFO control register
All bits cleared.
Bit 0 is set. All other bits cleared.
All bits cleared.
Line control register
Reset to 00011101 (1D hex).
All bits cleared.
Modem control register
Line status register
Bits 5 and 6 set. All other bits cleared.
Bits 0-3 cleared. Bits 4-7 input signals.
All bits cleared.
Modem status register
Enhanced feature register
Receiver holding register
Transmitter holding register
Transmission control register
Trigger level register
Pointer logic cleared.
Pointer logic cleared.
All bits cleared.
All bits cleared.
[1] Registers DLL, DLH, SPR, Xon1, Xon2, Xoff1, Xoff2 are not reset by the top-level reset signal
RESET, i.e., they hold their initialization values during reset.
Table 5 summarizes the state of registers after reset.
Table 5:
Signal
TX
Signal RESET functions
Reset control
Reset state
high
RESET
RESET
RESET
RESET
RESET
RTS
high
DTR
high
RXRDY
TXRDY
high
low
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6.5 Interrupts
The SC16C754 has interrupt generation and prioritization (six prioritized levels of
interrupts) capability. The interrupt enable register (IER) enables each of the six types
of interrupts and the INT signal in response to an interrupt generation. The IER can
also disable the interrupt system by clearing bits 0-3, 5-7. When an interrupt is
generated, the IIR indicates that an interrupt is pending and provides the type of
interrupt through IIR[5;0]. Table 6 summarizes the interrupt control functions.
Table 6:
IIR[5:0]
Interrupt control functions
Priority
level
Interrupt type
Interrupt source
Interrupt reset method
000001
000110
None
1
none
none
none
receiver line status
OE, FE, PE, or BI errors occur in
characters in the RX FIFO
FE, PE, BI: all erroneous
characters are read from the
RX FIFO.
OE: read LSR
read RHR
001100
000100
2
2
RX time-out
stale data in RX FIFO
DRDY (data ready)
(FIFO disable)
RHR interrupt
read RHR
RX FIFO above trigger level
(FIFO enable)
000010
3
THR interrupt
TFE (THR empty)
(FIFO disable)
read IIR or a write to the THR
TX FIFO passes above trigger level
(FIFO enable)
000000
010000
4
5
modem status
Xoff interrupt
MSR[3:0] = 0
read MSR
receive Xoff character(s)/special
character
receive Xon character(s)/Read of
IIR
100000
6
CTS, RTS
RTS pin or CTS pin change state from read IIR
active (LOW) to inactive (HIGH)
It is important to note that for the framing error, parity error, and break conditions,
LSR[7] generates the interrupt. LSR[7] is set when there is an error anywhere in the
RX FIFO, and is cleared only when there are no more errors remaining in the FIFO.
LSR[4:2] always represent the error status for the received character at the top of the
RX FIFO. Reading the RX FIFO updates LSR[4:2] to the appropriate status for the
new character at the top of the FIFO. If the RX FIFO is empty, then LSR[4:2] are all
zeros.
For the Xoff interrupt, if an Xoff flow character detection caused the interrupt, the
interrupt is cleared by an Xon flow character detection. If a special character
detection caused the interrupt, the interrupt is cleared by a read of the LSR.
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6.5.1 Interrupt mode operation
In interrupt mode (if any bit of IER[3:0] is 1) the processor is informed of the status of
the receiver and transmitter by an interrupt signal, INT. Therefore, it is not necessary
to continuously poll the line status register (LSR) to see if any interrupt needs to be
serviced. Figure 8 shows interrupt mode operation.
IIR
IOW / IOR
INT
PROCESSOR
IER
1
1
1
1
THR
RHR
002aaa230
Fig 8. Interrupt mode operation.
6.5.2 Polled mode operation
In polled mode (IER[3:0] = 0000) the status of the receiver and transmitter can be
checked by polling the line status register (LSR). This mode is an alternative to the
FIFO interrupt mode of operation where the status of the receiver and transmitter is
automatically known by means of interrupts sent to the CPU. Figure 9 shows FIFO
polled mode operation.
LSR
IOW / IOR
PROCESSOR
IER
0
0
0
0
THR
RHR
002aaa231
Fig 9. FIFO polled mode operation.
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6.6 DMA operation
There are two modes of DMA operation, DMA mode 0 or DMA mode 1, selected by
FCR[3].
In DMA mode 0 or FIFO disable (FCR[0] = 0) DMA occurs in single character
transfers. In DMA mode 1, multi-character (or block) DMA transfers are managed to
relieve the processor for longer periods of time.
6.6.1 Single DMA transfers (DMA mode 0/FIFO disable)
Figure 10 shows TXRDY and RXRDY in DMA mode 0/FIFO disable.
TX
RX
TXRDY
RXRDY
wrptr
rdptr
AT LEAST ONE
AT LEAST ONE
LOCATION FILLED
LOCATION FILLED
TXRDY
RXRDY
FIFO EMPTY
FIFO EMPTY
wrptr
rdptr
002aaa232
Fig 10. TXRDY and RXRDY in DMA mode 0/FIFO disable.
Transmitter: When empty, the TXRDY signal becomes active. TXRDY will go inactive
after one character has been loaded into it.
Receiver: RXRDY is active when there is at least one character in the FIFO. It
becomes inactive when the receiver is empty.
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6.6.2 Block DMA transfers (DMA mode 1)
Figure 11 shows TXRDY and RXRDY in DMA mode 1.
TX
RX
wrptr
TRIGGER
LEVEL
TXRDY
rdptr
RXRDY
AT LEAST ONE
LOCATION FILLED
FIFO FULL
TRIGGER
LEVEL
TXRDY
RXRDY
wrptr
FIFO EMPTY
rdptr
002aaa234
Fig 11. TXRDY and RXRDY in DMA mode 1.
Transmitter: TXRDY is active when there is a trigger level number of spaces
available. It becomes inactive when the FIFO is full.
Receiver: RXRDY becomes active when the trigger level has been reached, or when
a time-out interrupt occurs. It will go inactive when the FIFO is empty or an error in
the RX FIFO is flagged by LSR[7].
6.7 Sleep mode
Sleep mode is an enhanced feature of the SC16C754 UART. It is enabled when
EFR[4], the enhanced functions bit, is set and when IER[4] is set. Sleep mode is
entered when:
• The serial data input line, RX, is idle (see Section 6.8 “Break and time-out
conditions”).
• The TX FIFO and TX shift register are empty.
• There are no interrupts pending except THR and time-out interrupts.
Remark: Sleep mode will not be entered if there is data in the RX FIFO.
In sleep mode, the UART clock and baud rate clock are stopped. Since most registers
are clocked using these clocks, the power consumption is greatly reduced. The UART
will wake up when any change is detected on the RX line, when there is any change
in the state of the modem input pins, or if data is written to the TX FIFO.
Remark: Writing to the divisor latches, DLL and DLH, to set the baud clock, must not
be done during sleep mode. Therefore, it is advisable to disable sleep mode using
IER[4] before writing to DLL or DLH.
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6.8 Break and time-out conditions
An RX idle condition is detected when the receiver line, RX, has been HIGH for
4 character time. The receiver line is sampled midway through each bit.
When a break condition occurs, the TX line is pulled LOW. A break condition is
activated by setting LCR[6].
6.9 Programmable baud rate generator
The SC16C754 UART contains a programmable baud generator that takes any clock
input and divides it by a divisor in the range between 1 and (216 − 1). An additional
divide-by-4 prescaler is also available and can be selected by MCR[7], as shown in
Figure 12. The output frequency of the baud rate generator is 16× the baud rate. The
formula for the divisor is:
XTAL1 crystal input frequency
---------------------------------------------------------------------------
prescaler
divisor =
--------------------------------------------------------------------------------
(desired baud rate × 16)
Where:
prescaler = 1, when MCR[7] is set to 0 after reset (divide-by-1 clock selected)
prescaler = 4, when MCR[7] is set to 1 after reset (divide-by-4 clock selected).
Remark: The default value of prescaler after reset is divide-by-1.
Figure 12 shows the internal prescaler and baud rate generator circuitry.
PRESCALER
MCR[7] = 0
LOGIC
(DIVIDE-BY-1)
INTERNAL
XTAL1
XTAL2
BAUD RATE
CLOCK FOR
TRANSMITTER
AND
INTERNAL
OSCILLATOR
LOGIC
BAUD RATE
GENERATOR
LOGIC
INPUT CLOCK
REFERENCE
CLOCK
RECEIVER
PRESCALER
LOGIC
(DIVIDE-BY-4)
MCR[7] = 1
002aaa233
Fig 12. Prescaler and baud rate generator block diagram.
DLL and DLH must be written to in order to program the baud rate. DLL and DLH are
the least significant and most significant byte of the baud rate divisor. If DLL and DLH
are both zero, the UART is effectively disabled, as no baud clock will be generated.
Remark: The programmable baud rate generator is provided to select both the
transmit and receive clock rates.
Table 7 and Table 8 show the baud rate and divisor correlation for crystal with
frequency 1.8432 MHz and 3.072 MHz, respectively.
Figure 13 shows the crystal clock circuit reference.
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Table 7:
Baud rates using a 1.8432 MHz crystal
Desired baud rate
Divisor used to generate
Percent error difference
16 × clock
between desired and actual
50
2304
1536
1047
857
768
384
192
96
75
110
0.026
0.058
134.5
150
300
600
1200
1800
2000
2400
3600
4800
7200
9600
19200
38400
56000
64
58
0.69
48
32
24
16
12
6
3
2
2.86
Table 8:
Baud rates using a 3.072 MHz crystal
Desired baud rate
Divisor used to generate
Percent error difference
16 × clock
between desired and actual
50
3840
2560
1745
1428
1280
640
320
160
107
96
75
110
0.026
0.034
134.5
150
300
600
1200
1800
2000
2400
3600
4800
7200
9600
19200
38400
0.312
80
53
0.628
1.23
40
27
20
10
5
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1.5 kΩ
X1
X1
1.8432 MHz
1.8432 MHz
C1
47 pF
C2
100 pF
C1
22 pF
C2
47 pF
002aaa169
Fig 13. Crystal oscillator connection.
7. Register descriptions
Each register is selected using address lines A0, A1, A2, and in some cases, bits
from other registers. The programming combinations for register selection are shown
in Table 9.
Table 9:
Register map - read/write properties
A2 A1 A0 Read mode
Write mode
0
0
0
0
1
1
1
1
0
0
0
1
1
1
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
0
0
1
1
1
1
1
0
1
0
1
0
1
0
1
0
1
0
0
1
0
1
0
1
1
receive holding register (RHR)
interrupt enable register (IER)
interrupt identification register (IIR)
line control register (LCR)
modem control register (MCR)[1]
line status register (LSR)
modem status register (MSR)
scratchpad register (SPR)
divisor latch LSB (DLL)[2], [3]
divisor latch MSB (DLH)[2], [3]
enhanced feature register (EFR)[2], [4]
Xon1 word[2], [4]
transmit holding register (THR)
interrupt enable register
FIFO control register (FCR)
line control register
modem control register[1]
scratchpad register
divisor latch LSB[2], [3]
divisor latch MSB[2], [3]
enhanced feature register[2], [4]
Xon1 word[2], [4]
Xon2 word[2], [4]
Xoff1 word[2], [4]
Xoff2 word[2], [4]
Xon2 word[2], [4]
Xoff1 word[2], [4]
Xoff2 word[2], [4]
transmission control register (TCR)[2], [5] transmission control register[2], [5]
trigger level register (TLR)[2], [5]
FIFO ready register[2], [6]
trigger level register[2], [5]
[1] MCR[7] can only be modified when EFR[4] is set.
[2] Accessed by a combination of address pins and register bits.
[3] Accessible only when LCR[7] is logic 1.
[4] Accessible only when LCR is set to 10111111 (xBF).
[5] Accessible only when EFR[4] = 1 and MCR[6] = 1, i.e., EFR[4] and MCR[6] are read/write enables.
[6] Accessible only when CSA - CSD = 0, MCR[2] = 1, and loop-back is disabled (MCR[4] = 0).
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Table 10 lists and describes the SC16C754 internal registers.
Table 10: SC16C754 internal registers
Read/
Write
A2 A1 A0 Register Bit 7
General Register Set[1]
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
1
RHR
THR
IER
bit 7
bit 6
bit 5
bit 4
bit 4
bit 3
bit 3
bit 2
bit 2
bit 1
bit 1
THR
bit 0
bit 0
R
bit 7
bit 6
bit 5
0/Xoff[2]
W
0/CTS
interrupt interrupt
enable[2] enable[2]
0/RTS
0/X sleep modem receive
mode[2]
Rx data R/W
available
status
interrupt interrupt
line status empty
interrupt interrupt
RX FIFO FIFO
reset enable
0
1
0
FCR
RX
trigger
level
RX trigger 0/TX
level (LSB) trigger
level
0/TX
trigger
level
DMA
mode
select
TX FIFO
reset
W
(MSB)
(MSB)[2] (LSB)[2]
0
0
1
1
1
1
0
0
0
1
0
1
IIR
FCR[0]
FCR[0]
0/CTS,
RTS
0/Xoff
interrupt interrupt
interrupt interrupt
R
priority
bit 2
priority
bit 1
priority
bit 0
status
LCR
MCR
LSR
DLAB
break
control bit
set parity paritytype parity
select enable
number of word
stop bits
word
length
bit 0
R/W
R/W
R
length
bit 1
1× or
1×/4
clock
TCR and
TLR
enable
0/Xon
Any
0/enable IRQ
loop-back enable
OP
FIFO
ready
enable
RTS
DTR
0/error in THR and
THR
break
framing parity error overrun data in
RX FIFO TSR empty empty
interrupt
error
∆CD
bit 3
bit 3
bit 3
0
error
∆DSR
bit 1
receiver
∆CTS
bit 0
1
1
1
1
1
1
1
1
1
1
0
1
0
1
1
MSR
SPR
TCR
TLR
CD
bit 7
bit 7
bit 7
0
RI
DSR
bit 5
bit 5
bit 5
CTS
bit 4
bit 4
bit 4
∆RI
bit 2
bit 2
bit 2
0
R
bit 6
bit 6
bit 6
0
R/W
R/W
R/W
R
bit 1
bit 0
bit 1
bit 0
FIFO
Rdy
RX FIFO RX FIFO
B status A status
TX FIFO TX FIFO
B status A status
Special Register Set[3]
0
0
0
DLL
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 9
bit 0
bit 8
R/W
R/W
0
0
1
DLH
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
Enhanced Register Set[4]
0
1
0
EFR
Auto CTS Auto RTS Special
Enable
software software
software software R/W
character enhanced flow
flow
flow
flow
detect
functions control
control
bit 2
control
bit 1
control
bit 0
[2]
bit 3
1
1
1
1
0
0
1
1
0
1
0
1
Xon1
Xon2
Xoff1
Xoff2
bit 7
bit 7
bit 7
bit 7
bit 6
bit 6
bit 6
bit 6
bit 5
bit 5
bit 5
bit 5
bit 4
bit 4
bit 4
bit 4
bit 3
bit 3
bit 3
bit 3
bit 2
bit 2
bit 2
bit 2
bit 1
bit 1
bit 1
bit 1
bit 0
bit 0
bit 0
bit 0
R/W
R/W
R/W
R/W
[1] These registers are accessible only when LCR[7] = 0.
[2] The shaded bits in the above table can only be modified if register bit EFR[4] is enabled, i.e., if enhanced functions are enabled.
[3] The Special Register set is accessible only when LCR[7] is set to a logic 1.
[4] Enhanced Feature Register; Xon-1,2 and Xoff-1,2 are accessible only when LCR is set to ‘BFHex’.
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Remark: Refer to the notes under Table 9 for more register access information.
7.1 Receiver holding register (RHR)
The receiver section consists of the receiver holding register (RHR) and the receiver
shift register (RSR). The RHR is actually a 64-byte FIFO. The RSR receives serial
data from the RX terminal. The data is converted to parallel data and moved to the
RHR. The receiver section is controlled by the line control register. If the FIFO is
disabled, location zero of the FIFO is used to store the characters.
Remark: In this case, characters are overwritten if overflow occurs.
If overflow occurs, characters are lost. The RHR also stores the error status bits
associated with each character.
7.2 Transmit holding register (THR)
The transmitter section consists of the transmit holding register (THR) and the
transmit shift register (TSR). The THR is actually a 64-byte FIFO. The THR receives
data and shifts it into the TSR, where it is converted to serial data and moved out on
the TX terminal. If the FIFO is disabled, the FIFO is still used to store the byte.
Characters are lost if overflow occurs.
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7.3 FIFO control register (FCR)
This is a write-only register that is used for enabling the FIFOs, clearing the FIFOs,
setting transmitter and receiver trigger levels, and selecting the type of DMA
signalling. Table 11 shows FIFO control register bit settings.
Table 11: FIFO Control Register bits description
Bit
Symbol
Description
7-6
FCR[7]
(MSB),
FCR[6]
(LSB)
RCVR trigger. Sets the trigger level for the RX FIFO.
00 - 8 characters
01 - 16 characters
10 - 56 characters
11 - 60 characters
5-4
FCR[5]
(MSB),
FCR[4]
(LSB)
TX trigger. Sets the trigger level for the TX FIFO.
00 - 8 spaces
01 - 16 spaces
10 - 32 spaces
11 - 56 spaces
FCR[5-4] can only be modified and enabled when EFR[4] is set. This is
because the transmit trigger level is regarded as an enhanced function.
3
2
FCR[3]
FCR[2]
DMA mode select.
Logic 0 = Set DMA mode ‘0’
Logic 1 = Set DMA mode ‘1’
Reset TX FIFO.
Logic 0 = No FIFO transmit reset (normal default condition).
Logic 1 = Clears the contents of the transmit FIFO and resets the
FIFO counter logic (the transmit shift register is not cleared or
altered). This bit will return to a logic 0 after clearing the FIFO.
1
0
FCR[1]
FCR[0]
Reset RX FIFO.
Logic 0 = No FIFO receive reset (normal default condition).
Logic 1 = Clears the contents of the receive FIFO and resets the FIFO
counter logic (the receive shift register is not cleared or altered). This
bit will return to a logic 0 after clearing the FIFO.
FIFO enable.
Logic 0 = Disable the transmit and receive FIFO (normal default
condition).
Logic 1 = Enable the transmit and receive FIFO.
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7.4 Line control register (LCR)
This register controls the data communication format. The word length, number of
stop bits, and parity type are selected by writing the appropriate bits to the LCR.
Table 12 shows the line control register bit settings.
Table 12: Line Control Register bits description
Bit
Symbol
Description
7
LCR[7]
Divisor latch enable.
Logic 0 = Divisor latch disabled (normal default condition).
Logic 1 = Divisor latch enabled.
6
5
LCR[6]
LCR[5]
Break control bit. When enabled, the Break control bit causes a break
condition to be transmitted (the TX output is forced to a logic 0 state).
This condition exists until disabled by setting LCR[6] to a logic 0.
Logic 0 = no TX break condition (normal default condition).
Logic 1 = forces the transmitter output (TX) to a logic 0 to alert the
communication terminal to a line break condition.
Set parity. LCR[5] selects the forced parity format (if LCR[3] = 1).
Logic 0 = parity is not forced (normal default condition).
LCR[5] = logic 1 and LCR[4] = logic 0: parity bit is forced to a logical 1
for the transmit and receive data.
LCR[5] = logic 1 and LCR[4] = logic 1: parity bit is forced to a logical 0
for the transmit and receive data.
4
3
LCR[4]
LCR[3]
Parity type select.
Logic 0 = ODD Parity is generated (if LCR[3] = 1).
Logic 1 = EVEN Parity is generated (if LCR[3] = 1).
Parity enable.
Logic 0 = no parity (normal default condition).
Logic 1 = a parity bit is generated during transmission and the
receiver checks for received parity.
2
LCR[2]
Number of Stop bits. Specifies the number of stop bits.
0 = 1 stop bit (word length = 5, 6, 7, 8)
1 = 1.5 stop bits (word length = 5)
1 = 2 stop bits (word length = 6, 7, 8)
1-0
LCR[1-0]
Word length bits 1, 0. These two bits specify the word length to be
transmitted or received.
00 - 5 bits
01 - 6 bits
10 - 7 bits
11 - 8 bits
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7.5 Line status register (LSR)
Table 13 shows the line status register bit settings.
Table 13: Line Status Register bits description
Bit
Symbol
Description
7
LSR[7]
FIFO data error.
Logic 0 = No error (normal default condition).
Logic 1 = At least one parity error, framing error, or break indication is
in the receiver FIFO. This bit is cleared when no more errors are
present in the FIFO.
6
5
LSR[6]
LSR[5]
THR and TSR empty. This bit is the Transmit Empty indicator.
Logic 0 = Transmitter hold and shift registers are not empty.
Logic 1 = Transmitter hold and shift registers are empty.
THR empty. This bit is the Transmit Holding Register Empty indicator.
Logic 0 = Transmit hold register is not empty.
Logic 1 = Transmit hold register is empty. The processor can now load
up to 64 bytes of data into the THR if the TX FIFO is enabled.
4
3
LSR[4]
LSR[3]
Break interrupt.
Logic 0 = No break condition (normal default condition).
Logic 1 = A break condition occurred and associated byte is 00, i.e.,
RX was LOW for one character time frame.
Framing error.
Logic 0 = No framing error in data being read from RX FIFO (normal
default condition).
Logic 1 = Framing error occurred in data being read from RX FIFO, i.e.,
received data did not have a valid stop bit.
2
1
0
LSR[2]
LSR[1]
LSR[0]
Parity error.
Logic 0 = No parity error (normal default condition).
Logic 1 = Parity error in data being read from RX FIFO.
Overrun error.
Logic 0 = No overrun error (normal default condition).
Logic 1 = Overrun error has occurred.
Data in receiver.
Logic 0 = No data in receive FIFO (normal default condition).
Logic 1 = At least one character in the RX FIFO.
When the LSR is read, LSR[4:2] reflect the error bits (BI, FE, PE) of the character at
the top of the RX FIFO (next character to be read). The LSR[4:2] registers do not
physically exist, as the data read from the RX FIFO is output directly onto the output
data bus, DI[4:2], when the LSR is read. Therefore, errors in a character are identified
by reading the LSR and then reading the RHR.
LSR[7] is set when there is an error anywhere in the RX FIFO, and is cleared only
when there are no more errors remaining in the FIFO.
Reading the LSR does not cause an increment of the RX FIFO read pointer. The
RX FIFO read pointer is incremented by reading the RHR.
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7.6 Modem control register (MCR)
The MCR controls the interface with the mode, data set, or peripheral device that is
emulating the modem. Table 14 shows modem control register bit settings.
Table 14: Modem Control Register bits description
Bit
Symbol
MCR[7] [1] Clock select.
Logic 0 = Divide-by-1 clock input.
Logic 1 = Divide-by-4 clock input.
MCR[6] [1] TCR and TLR enable.
Description
7
6
5
4
Logic 0 = no action.
Logic 1 = Enable access to the TCR and TLR registers.
MCR[5] [1] Xon Any.
Logic 0 = Disable Xon Any function.
Logic 1 = Enable Xon Any function.
Enable loop-back.
MCR[4]
MCR[3]
Logic 0 = Normal operating mode.
Logic 1 = Enable local loop-back mode (internal). In this mode the
MCR[3:0] signals are looped back into MSR[7:4] and the TX output
is looped back to the RX input internally.
3
IRQ enable OP.
Logic 0 = Forces INTA-INTB outputs to the 3-State mode and OP
output to HIGH state.
Logic 1 = Forces the INTA-INTB outputs to the active state and OP
output to LOW state. In loop-back mode, controls MSR[7].
2
1
MCR[2]
MCR[1]
FIFO Ready enable.
Logic 0 = Disable the FIFO Rdy register.
Logic 1 = Enable the FIFO Rdy register.
In loop-back mode, controls MSR[6].
RTS
Logic 0 = Force RTS output to inactive (HIGH).
Logic 1 = Force RTS output to active (LOW).
In loop-back mode, controls MSR[4]. If Auto-RTS is enabled, the
RTS output is controlled by hardware flow control.
0
MCR[0]
DTR
Logic 0 = Force DTR output to inactive (HIGH).
Logic 1 = Force DTR output to active (LOW).
In loop-back mode, controls MSR[5].
[1] MCR[7:5] can only be modified when EFR[4] is set, i.e., EFR[4] is a write enable.
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7.7 Modem status register (MSR)
This 8-bit register provides information about the current state of the control lines
from the mode, data set, or peripheral device to the processor. It also indicates when
a control input from the modem changes state. Table 15 shows modem status
register bit settings per channel.
Table 15: Modem Status Register bits description
Bit
Symbol
Description
7
MSR[7]
CD (Active-HIGH, logical 1). This bit is the complement of the CD input
during normal mode. During internal loop-back mode, it is equivalent to
MCR[3].
6
5
4
MSR[6]
MSR[5]
MSR[4]
RI (Active-HIGH, logical 1). This bit is the complement of the RI input
during normal mode. During internal loop-back mode, it is equivalent to
MCR[2].
DSR (Active-HIGH, logical 1). This bit is the complement of the DSR
input during normal mode. During internal loop-back mode, it is
equivalent MCR[0].
CTS (Active-HIGH, logical 1). This bit is the complement of the CTS
input during normal mode. During internal loop-back mode, it is
equivalent to MCR[1].
3
2
1
0
MSR[3]
MSR[2]
MSR[1]
MSR[0]
∆CD. Indicates that CD input (or MCR[3] in loop-back mode) has
changed state. Cleared on a read.
∆RI. Indicates that RI input (or MCR[2] in loop-back mode) has changed
state from LOW to HIGH. Cleared on a read.
∆DSR. Indicates that DSR input (or MCR[0] in loop-back mode) has
changed state. Cleared on a read.
∆CTS. Indicates that CTS input (or MCR[1] in loop-back mode) has
changed state. Cleared on a read.
[1] The primary inputs RI, CD, CTS, DSR are all Active-LOW, but their registered equivalents in the MSR
and MCR (in loop-back) registers are Active-HIGH.
7.8 Interrupt enable register (IER)
The interrupt enable register (IER) enables each of the six types of interrupt, receiver
error, RHR interrupt, THR interrupt, Xoff received, or CTS/RTS change of state from
LOW to HIGH. The INT output signal is activated in response to interrupt generation.
Table 16 shows interrupt enable register bit settings.
Table 16: Interrupt Enable Register bits description
Bit
Symbol
IER[7] [1] CTS interrupt enable.
Logic 0 = Disable the CTS interrupt (normal default condition).
Logic 1 = Enable the CTS interrupt.
IER[6] [1] RTS interrupt enable.
Description
7
6
5
Logic 0 = Disable the RTS interrupt (normal default condition).
Logic 1 = Enable the RTS interrupt.
IER[5] [1] Xoff interrupt.
Logic 0 = Disable the Xoff interrupt (normal default condition).
Logic 1 = Enable the Xoff interrupt.
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Table 16: Interrupt Enable Register bits description…continued
Bit
Symbol
IER[4] [1] Sleep mode.
Logic 0 = Disable sleep mode (normal default condition).
Description
4
Logic 1 = Enable sleep mode. See Section 6.7 “Sleep mode” for details.
Modem Status Interrupt.
3
2
IER[3]
Logic 0 = Disable the modem status register interrupt (normal default
condition).
Logic 1 = Enable the modem status register interrupt.
Receive Line Status interrupt.
IER[2]
Logic 0 = Disable the receiver line status interrupt (normal default
condition).
Logic 1 = Enable the receiver line status interrupt.
Transmit Holding Register interrupt.
1
0
IER[1]
IER[0]
Logic 0 = Disable the THR interrupt (normal default condition).
Logic 1 = Enable the THR interrupt.
Receive Holding Register interrupt.
Logic 0 = Disable the RHR interrupt (normal default condition).
Logic 1 = Enable the RHR interrupt.
[1] IER[7:4] can only be modified if EFR[4] is set, i.e., EFR[4] is a write enable. Re-enabling IER[1] will
not cause a new interrupt if the THR is below the threshold.
7.9 Interrupt identification register (IIR)
The IIR is a read-only 8-bit register which provides the source of the interrupt in a
prioritized manner. Table 17 shows interrupt identification register bit settings.
Table 17: Interrupt Identification Register bits description
Bit
7-6
5
Symbol
IIR[7:6]
IIR[5]
Description
Mirror the contents of FCR[0].
RTS/CTS LOW-to-HIGH change of state.
1 = Xoff/Special character has been detected.
3-bit encoded interrupt. See Table 18.
Interrupt status.
4
IIR[4]
3-1
0
IIR[3:1]
IIR[0]
Logic 0 = An interrupt is pending.
Logic 1 = No interrupt is pending.
The interrupt priority list is shown in Table 18.
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Table 18: Interrupt priority list
Priority IIR[5]
IIR[4]
IIR[3]
IIR[2]
IIR[1]
IIR[0]
Source of the interrupt
level
1
2
2
3
4
5
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
1
1
1
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
Receiver Line Status error
Receiver time-out interrupt
RHR interrupt
THR interrupt
Modem interrupt
Received Xoff signal/
special character
6
1
0
0
0
0
0
CTS, RTS change of state
from active (LOW) to
inactive (HIGH)
7.10 Enhanced feature register (EFR)
This 8-bit register enables or disables the enhanced features of the UART. Table 19
shows the enhanced feature register bit settings.
Table 19: Enhanced Feature Register bits description
Bit
Symbol
Description
7
EFR[7]
CTS flow control enable.
Logic 0 = CTS flow control is disabled (normal default condition).
Logic 1 = CTS flow control is enabled. Transmission will stop when a
HIGH signal is detected on the CTS pin.
6
5
EFR[6]
EFR[5]
EFR[4]
RTS flow control enable.
Logic 0 = RTS flow control is disabled (normal default condition).
Logic 1 = RTS flow control is enabled. The RTS pin goes HIGH when
the receiver FIFO HALT trigger level TCR[3:0] is reached, and goes
LOW when the receiver FIFO RESUME transmission trigger level
TCR[7:4] is reached.
Special character detect.
Logic 0 = Special character detect disabled (normal default condition).
Logic 1 = Special character detect enabled. Received data is
compared with Xoff-2 data. If a match occurs, the received data is
transferred to FIFO and IIR[4] is set to a logical 1 to indicate a special
character has been detected.
4
Enhanced functions enable bit.
Logic 0 = Disables enhanced functions and writing to IER[7:4],
FCR[5:4], MCR[7:5].
Logic 1 = Enables the enhanced function IER[7:4], FCR[5:4], and
MCR[7:5] can be modified, i.e., this bit is therefore a write enable.
3-0
EFR[3:0] Combinations of software flow control can be selected by programming
these bits. See Table 3 “Software flow control options (EFR[0:3])” on
page 10.
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7.11 Divisor latches (DLL, DLH)
These are two 8-bit registers which store the 16-bit divisor for generation of the baud
clock in the baud rate generator. DLH stores the most significant part of the divisor.
DLL stores the least significant part of the divisor.
Note that DLL and DLH can only be written to before sleep mode is enabled, i.e.,
before IER[4] is set.
7.12 Transmission control register (TCR)
This 8-bit register is used to store the RX FIFO threshold levels to stop/start
transmission during hardware/software flow control. Table 20 shows transmission
control register bit settings.
Table 20: Transmission Control Register bits description
Bit
7-4
3-0
Symbol
Description
TCR[7:4] RX FIFO trigger level to resume transmission (0-60).
TCR[3:0] RX FIFO trigger level to halt transmission (0-60).
TCR trigger levels are available from 0-60 bytes with a granularity of four.
Remark: TCR can only be written to when EFR[4] = 1 and MCR[6] = 1. The
programmer must program the TCR such that TCR[3:0] > TCR[7:4]. There is no
built-in hardware check to make sure this condition is met. Also, the TCR must be
programmed with this condition before Auto-RTS or software flow control is enabled
to avoid spurious operation of the device.
7.13 Trigger level register (TLR)
This 8-bit register is pulsed to store the transmit and received FIFO trigger levels
used for DMA and interrupt generation. Trigger levels from 4-60 can be programmed
with a granularity of 4. Table 21 shows trigger level register bit settings.
Table 21: Trigger Level Register bits description
Bit
7-4
3-0
Symbol
Description
TLR[7:4] RX FIFO trigger levels (4-60), number of characters available.
TLR[3:0] TX FIFO trigger levels (4-60), number of spaces available.
Remark: TLR can only be written to when EFR[4] = 1 and MCR[6] = 1. If TLR[3:0] or
TLR[7:4] are logical 0, the selectable trigger levels via the FIFO control register (FCR)
are used for the transmit and receive FIFO trigger levels. Trigger levels from 4-60
bytes are available with a granularity of four. The TLR should be programmed for N⁄4,
where N is the desired trigger level.
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7.14 FIFO ready register
The FIFO ready register provides real-time status of the transmit and receive FIFOs
of both channels.
Table 22: FIFO Ready Register bits description
Bit
Symbol
Description
7-4
FIFO Rdy[7:4]
0 = There are less than a RX trigger level number of characters
in the RX FIFO.
1 = The RX FIFO has more than a RX trigger level number of
characters available for reading or a time-out condition has
occurred.
3-0
FIFO Rdy[3:0]
0 = There are less than a TX trigger level number of spaces
available in the TX FIFO.
1 = There are at least a TX trigger level number of spaces
available in the TX FIFO.
The FIFO Rdy register is a read-only register that can be accessed when any of the
two UARTs is selected CSA - CSD = 0, MCR[2] (FIFO Rdy Enable) is a logic 1, and
loop-back is disabled. The address is 111.
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8. Programmer’s guide
The base set of registers that is used during high-speed data transfer have a
straightforward access method. The extended function registers require special
access bits to be decoded along with the address lines. The following guide will help
with programming these registers. Note that the descriptions below are for individual
register access. Some streamlining through interleaving can be obtained when
programming all the registers.
Table 23: Register programming guide
Command
Actions
Read LCR (03), save in temp
Set baud rate to VALUE1, VALUE2
Set LCR (03) to 80
Set DLL (00) to VALUE1
SET DLM (01) to VALUE2
Set LCR (03) to temp
Set Xoff-1, Xon-1 to VALUE1, VALUE2
Set Xoff-2, Xon-2 to VALUE1, VALUE2
Read LCR (03), save in temp
Set LCR (03) to BF
Set Xoff-1 (06) to VALUE1
SET Xon-1 (04) to VALUE2
Set LCR (03) to temp
Read LCR (03), save in temp
Set LCR (03) to BF
Set Xoff-2 (07) to VALUE1
SET Xon-2 (05) to VALUE2
Set LCR (03) to temp
Set software flow control mode to
VALUE
Read LCR (03), save in temp
Set LCR (03) to BF
Set EFR (02) to VALUE
Set LCR (03) to temp
Set flow control threshold to VALUE
Read LCR (03), save in temp1
Set LCR (03) to BF
Read EFR (02), save in temp2
Set EFR (02) to 10 + temp2
Set LCR (03) to 00
Read MCR (04), save in temp3
Set MCR (04) to 40 + temp3
Set TCR (06) to VALUE
Set MCR (04) to temp3
Set LCR (03) to BF
Set EFR (02) to temp2
Set LCR (03) to temp1
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Table 23: Register programming guide…continued
Command Actions
Read LCR (03), save in temp1
Set TX FIFO and RX FIFO thresholds
to VALUE
Set LCR (03) to BF
Read EFR (02), save in temp2
Set EFR (02) to 10 + temp2
Set LCR (03) to 00
Read MCR (04), save in temp3
Set MCR (04) to 40 + temp3
Set TLR (07) to VALUE
Set MCR (04) to temp3
Set LCR (03) to BF
Set EFR (02) to temp2
Set LCR (03) to temp1
Read FIFO Rdy register
Read MCR (04), save in temp1
Set temp2 = temp1 × EF [1]
Set MCR (04) = 40 + temp2
Read FFR (07), save in temp2
Pass temp2 back to host
Set MCR (04) to temp1
Read LCR (03), save in temp1
Set LCR (03) to BF
Set prescaler value to divide-by-1
Read EFR (02), save in temp2
Set EFR (02) to 10 + temp2
Set LCR (03) to 00
Read MCR (04), save in temp3
Set MCR (04) to temp3 × 7F [1]
Set LCR (03) to BF
Set EFR (02) to temp2
Set LCR (03) to temp1
Set prescaler value to divide-by-4
Read LCR (03), save in temp1
Set LCR (03) to BF
Read EFR (02), save in temp2
Set EFR (02) to 10 + temp2
Set LCR (03) to 00
Read MCR (04), save in temp3
Set MCR (04) to temp3 + 80
Set LCR (03) to BF
Set EFR (02) to temp2
Set LCR (03) to temp1
[1] × sign here means bit-AND.
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9. Limiting values
Table 24: Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol
VCC
VI
Parameter
Conditions
Min
-
Max
Unit
V
supply voltage
7
input voltage
−0.3
−0.3
−40
−65
VCC + 0.3
VCC + 0.3
+85
V
VO
output voltage
V
Tamb
Tstg
operating ambient temperature
storage temperature
in free-air
°C
°C
+150
[1] Stresses beyond those listed under Limiting values may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is
not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
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10. Static characteristics
Table 25: DC electrical characteristics
VCC = 2.5 V, 3.3 V ±10% or 5 V ±10%.
Symbol Parameter
Conditions
2.5 V
3.3 V and 5 V
Nom Max
Unit
Min
Nom Max
Min
VCC
VI
supply voltage
input voltage
V
CC − 10% VCC
VCC + 10% VCC − 10% VCC
VCC + 10% V
0
-
-
VCC
VCC
0
-
-
VCC
VCC
V
V
[1]
[1]
VIH
HIGH-level input
voltage
1.6
2.0
VIL
LOW-level input
voltage
-
-
0.65
-
-
0.8
V
[2]
[4]
[5]
[4]
[5]
[4]
[5]
[4]
[5]
VO
output voltage
0
-
VCC
0
-
VCC
V
VOH
HIGH-level output IOH = −8 mA
voltage
-
-
-
2.0
-
-
V
IOH = −4 mA
-
-
-
2.0
-
-
V
IOH = −800 µA
IOH = −400 µA
1.85
-
-
-
-
-
V
1.85
-
-
-
-
-
V
VOL
LOW-level output IOL = 8 mA
voltage[7]
-
-
-
-
-
0.4
0.4
-
V
IOL = 4 mA
-
-
-
-
-
V
IOL = 2 mA
IOL = 1.6 mA
-
-
0.4
0.4
18
85
-
-
V
-
-
-
-
-
V
Ci
input capacitance
-
-
-
-
18
85
pF
°C
Tamb
operating ambient
temperature
−40
25
−40
25
[3]
[8]
Tj
junction
temperature
0
25
125
0
25
125
°C
clock speed
-
-
-
-
-
50
-
-
-
-
-
-
80
-
MHz
%
clock duty cycle
50
-
50
-
[6]
ICC
supply current
f = 5 MHz
4.5
-
6
-
mA
mA
ICCsleep sleep current[9]
1
1
[1] Meets TTL levels, VIO(min) = 2 V and VIH(max) = 0.8 V on non-hysteresis inputs.
[2] Applies for external output buffers.
[3] These junction temperatures reflect simulated conditions. Absolute maximum junction temperature is 150 °C. The customer is
responsible for verifying junction temperature.
[4] These parameters apply for D7-D0.
[5] These parameters apply for DTRA, DTRB, INIA, INTB, RTSA, RTSB, RXRDYA, RXRDYB, TXRDYA, TXRDYB, TXA, TXB.
[6] Measurement condition, normal operation other than sleep mode:
VCC = 3.3 V; Tamb = 25 °C. Full duplex serial activity on all two serial (UART) channels at the clock frequency specified in the
recommended operating conditions with divisor of 1.
[7] Except x2, VOL = 1 V typical.
[8] Applies to external clock; crystal oscillator max. 24 MHz.
[9] When using crystal oscillator. The use of an external clock will increase the sleep current.
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11. Dynamic characteristics
Table 26: AC electrical characteristics
Tamb = −40 °C to +85 °C; VCC = 2.5 V, 3.3 V or 5.0 V ±10%, unless otherwise specified.
Symbol Parameter
Conditions
2.5 V
Max
3.3 V
Max
5.0 V
Unit
Min
10
-
Min
6
Min Max
t1w, t2w
t3w
clock pulse duration
-
-
6
-
ns
[1]
oscillator/clock frequency
address set-up time
address hold time
48
-
80
-
80
-
MHz
ns
t6s
0
-
0
0
t6h
0
-
0
-
0
-
ns
t7d
IOR delay from chip select
IOR strobe width
10
90
0
-
10
26
0
-
10
23
0
-
ns
t7w
25 pF load
-
-
-
ns
t7h
chip select hold time from IOR
read cycle delay
-
-
-
ns
t9d
25 pF load
25 pF load
25 pF load
20
-
-
20
-
-
20
-
-
ns
t12d
t12h
t13d
t13w
t13h
t15d
t16s
t16h
t17d
t18d
t19d
t20d
t21d
t22d
t23d
t24d
t25d
t26d
t27d
t28d
tRESET
N
delay from IOR to data
data disable time
90
15
-
26
15
-
23
15
-
ns
-
-
-
ns
IOW delay from chip select
IOW strobe width
10
20
0
10
20
0
10
15
0
ns
[2]
[3]
-
-
-
ns
chip select hold time from IOW
write cycle delay
-
-
-
ns
25
20
15
-
-
25
15
5
-
20
15
5
-
ns
data set-up time
-
-
-
ns
data hold time
-
-
-
ns
delay from IOW to output
25 pF load
100
100
100
1
-
33
24
24
1
-
29
23
23
1
ns
delay to set interrupt from Modem input 25 pF load
-
-
-
ns
delay to reset interrupt from IOR
delay from stop to set interrupt
delay from IOR to reset interrupt
delay from start to set interrupt
delay from IOW to transmit start
delay from IOW to reset interrupt
delay from stop to set RXRDY
delay from IOR to reset RXRDY
delay from IOW to set TXRDY
delay from start to reset TXRDY
Reset pulse width
25 pF load
-
-
-
ns
-
-
-
Rclk
ns
25 pF load
-
100
100
24
100
1
-
29
45
24
45
1
-
28
40
24
40
1
-
-
-
ns
8
8
8
Rclk
ns
-
-
-
-
-
-
Rclk
ns
-
100
100
8
-
45
45
8
-
40
40
8
-
-
-
ns
-
-
-
Rclk
200
1
-
200
-
200
-
ns
baud rate divisor
216 − 1 1
216 − 1 1
216 − 1 Rclk
[1] Applies to external clock, crystal oscillator max 24 MHz.
1
[2] IOWstrobemax
=
--------------------------------------
2(Baudratemax
)
= 333 ns (for Baudratemax = 1.5 Mbits/s)
= 1 µs (for Baudratemax = 460.8 kbits/s)
= 4 µs (for Baudratemax = 115.2 kbits/s)
[3] When in both DMA mode 0 and FIFO enable mode, the write cycle delay should be larger than one x1, clock cycle.
9397 750 11618
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Quad UART with 64-byte FIFO
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11.1 Timing diagrams
t
t
6h
VALID
ADDRESS
A0–A2
t
6s
13h
ACTIVE
CSx
t
13d
t
15d
t
13w
IOW
ACTIVE
t
16h
t
16s
D0–D7
DATA
002aaa109
Fig 14. General write timing.
t
t
6h
VALID
ADDRESS
A0–A2
t
6s
7h
ACTIVE
CSx
IOR
t
7d
t
9d
t
7w
ACTIVE
t
12h
t
12d
D0–D7
DATA
002aaa110
Fig 15. General read timing.
9397 750 11618
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Quad UART with 64-byte FIFO
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IOW
ACTIVE
t
17d
RTS
DTR
CHANGE OF STATE
CHANGE OF STATE
CD
CTS
DSR
CHANGE OF STATE
CHANGE OF STATE
t
t
18d
18d
INT
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
t
19d
IOR
ACTIVE
t
18d
RI
CHANGE OF STATE
002aaa352
Fig 16. Modem input/output timing.
t
t
1w
2w
EXTERNAL
CLOCK
002aaa112
t
3w
Fig 17. External clock timing.
9397 750 11618
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NEXT
DATA
START
BIT
PARITY STOP START
BIT
BIT
BIT
DATA BITS (5-8)
RX
D0
D1
D2
D3
D4
D5
D6
D7
5 DATA BITS
6 DATA BITS
7 DATA BITS
t
20d
ACTIVE
INT
t
21d
ACTIVE
IOR
16 BAUD RATE CLOCK
002aaa113
Fig 18. Receive timing.
NEXT
DATA
START
BIT
PARITY STOP START
BIT BIT
BIT
DATA BITS (5–8)
RX
D0
D1
D2
D3
D4
D5
D6
D7
t
25d
ACTIVE
DATA
READY
RXRDY
t
26d
ACTIVE
IOR
002aaa114
Fig 19. Receive ready timing in non-FIFO mode.
9397 750 11618
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Product data
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Quad UART with 64-byte FIFO
Philips Semiconductors
START
BIT
PARITY STOP
BIT
BIT
DATA BITS (5–8)
RX
D0
D1
D2
D3
D4
D5
D6
D7
FIRST BYTE THAT
REACHES THE
TRIGGER LEVEL
t
25d
ACTIVE
DATA
READY
RXRDY
t
26d
ACTIVE
IOR
002aaa115
Fig 20. Receive ready timing in FIFO mode.
NEXT
DATA
START
BIT
PARITY STOP START
BIT BIT
BIT
DATA BITS (5–8)
TX
D0
D1
D2
D3
D4
D5
D6
D7
5 DATA BITS
6 DATA BITS
7 DATA BITS
ACTIVE TX READY
INT
t
22d
t
24d
t
23d
ACTIVE
ACTIVE
IOW
16 BAUD RATE CLOCK
002aaa116
Fig 21. Transmit timing.
9397 750 11618
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Quad UART with 64-byte FIFO
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NEXT
DATA
START
BIT
PARITY STOP START
BIT
BIT
BIT
DATA BITS (5-8)
TX
D0
D1
D2
D3
D4
D5
D6
D7
ACTIVE
IOW
D0–D7
TXRDY
BYTE #1
t
27d
ACTIVE
TRANSMITTER READY
TRANSMITTER
NOT READY
002aaa117
Fig 22. Transmit ready timing in non-FIFO mode.
9397 750 11618
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Product data
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Quad UART with 64-byte FIFO
Philips Semiconductors
START
BIT
PARITY STOP
BIT
BIT
DATA BITS (5-8)
TX
D0
D1
D2
D3
D4
D5
D6
D7
5 DATA BITS
6 DATA BITS
7 DATA BITS
ACTIVE
IOW
D0–D7
TXRDY
t
28d
BYTE #32
t
27d
FIFO FULL
002aaa365
Fig 23. Transmit ready timing in FIFO mode (DMA mode ‘1’).
9397 750 11618
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12. Package outline
LQFP80: plastic low profile quad flat package; 80 leads; body 12 x 12 x 1.4 mm
SOT315-1
y
X
A
60
41
Z
61
40
E
e
H
A
E
2
E
A
(A )
3
A
1
w M
p
θ
b
L
p
L
pin 1 index
80
21
detail X
1
20
Z
D
v
M
A
e
w M
b
p
D
B
H
v
M
B
D
0
5
10 mm
scale
DIMENSIONS (mm are the original dimensions)
A
(1)
(1)
(1)
(1)
UNIT
A
A
A
b
c
D
E
e
H
H
L
L
v
w
y
Z
Z
θ
1
2
3
p
D
E
p
D
E
max.
7o
0o
0.16 1.5
0.04 1.3
0.27 0.18 12.1 12.1
0.13 0.12 11.9 11.9
14.15 14.15
13.85 13.85
0.75
0.30
1.45 1.45
1.05 1.05
mm
1.6
0.25
0.5
1
0.2 0.15 0.1
Note
1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.
REFERENCES
OUTLINE
EUROPEAN
PROJECTION
ISSUE DATE
VERSION
IEC
JEDEC
JEITA
00-01-19
03-02-25
SOT315-1
136E15
MS-026
Fig 24. LQFP80 package outline (SOT315-1).
9397 750 11618
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PLCC68: plastic leaded chip carrier; 68 leads
SOT188-2
e
e
D
E
y
X
A
60
44
Z
E
43
61
b
p
b
1
w
M
68
1
H
E
E
pin 1 index
A
e
A
1
A
4
(A )
3
L
p
9
k
27
β
detail X
10
26
v
M
A
e
Z
D
D
B
H
v
M
B
D
0
5
10 mm
scale
DIMENSIONS (mm dimensions are derived from the original inch dimensions)
(1)
(1)
A
A
Z
Z
E
4
1
(1)
(1)
D
UNIT
mm
A
A
b
D
E
e
e
e
H
H
k
L
p
v
w
y
β
b
3
1
D
E
D
E
p
max.
min.
max. max.
4.57
4.19
0.81 24.33 24.33
0.66 24.13 24.13
23.62 23.62 25.27 25.27 1.22 1.44
22.61 22.61 25.02 25.02 1.07 1.02
0.53
0.33
0.51 0.25
3.3
1.27
0.05
0.18 0.18
0.1
2.16 2.16
o
45
0.180
0.165
0.032 0.958 0.958
0.026 0.950 0.950
0.93 0.93 0.995 0.995 0.048 0.057
0.89 0.89 0.985 0.985 0.042 0.040
0.021
0.013
inches
0.02 0.01 0.13
0.007 0.007 0.004 0.085 0.085
Note
1. Plastic or metal protrusions of 0.25 mm (0.01 inch) maximum per side are not included.
REFERENCES
OUTLINE
EUROPEAN
PROJECTION
ISSUE DATE
VERSION
IEC
JEDEC
JEITA
99-12-27
01-11-14
SOT188-2
112E10
MS-018
EDR-7319
Fig 25. PLCC68 package outline (SOT188-2).
9397 750 11618
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13. Soldering
13.1 Introduction to soldering surface mount packages
This text gives a very brief insight to a complex technology. A more in-depth account
of soldering ICs can be found in our Data Handbook IC26; Integrated Circuit
Packages (document order number 9398 652 90011).
There is no soldering method that is ideal for all IC packages. Wave soldering can still
be used for certain surface mount ICs, but it is not suitable for fine pitch SMDs. In
these situations reflow soldering is recommended. In these situations reflow
soldering is recommended.
13.2 Reflow soldering
Reflow soldering requires solder paste (a suspension of fine solder particles, flux and
binding agent) to be applied to the printed-circuit board by screen printing, stencilling
or pressure-syringe dispensing before package placement. Driven by legislation and
environmental forces the worldwide use of lead-free solder pastes is increasing.
Several methods exist for reflowing; for example, convection or convection/infrared
heating in a conveyor type oven. Throughput times (preheating, soldering and
cooling) vary between 100 and 200 seconds depending on heating method.
Typical reflow peak temperatures range from 215 to 270 °C depending on solder
paste material. The top-surface temperature of the packages should preferably be
kept:
• below 220 °C (SnPb process) or below 245 °C (Pb-free process)
– for all BGA and SSOP-T packages
– for packages with a thickness ≥ 2.5 mm
– for packages with a thickness < 2.5 mm and a volume ≥ 350 mm3 so called
thick/large packages.
• below 235 °C (SnPb process) or below 260 °C (Pb-free process) for packages with
a thickness < 2.5 mm and a volume < 350 mm3 so called small/thin packages.
Moisture sensitivity precautions, as indicated on packing, must be respected at all
times.
13.3 Wave soldering
Conventional single wave soldering is not recommended for surface mount devices
(SMDs) or printed-circuit boards with a high component density, as solder bridging
and non-wetting can present major problems.
To overcome these problems the double-wave soldering method was specifically
developed.
If wave soldering is used the following conditions must be observed for optimal
results:
• Use a double-wave soldering method comprising a turbulent wave with high
upward pressure followed by a smooth laminar wave.
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• For packages with leads on two sides and a pitch (e):
– larger than or equal to 1.27 mm, the footprint longitudinal axis is preferred to be
parallel to the transport direction of the printed-circuit board;
– smaller than 1.27 mm, the footprint longitudinal axis must be parallel to the
transport direction of the printed-circuit board.
The footprint must incorporate solder thieves at the downstream end.
• For packages with leads on four sides, the footprint must be placed at a 45° angle
to the transport direction of the printed-circuit board. The footprint must
incorporate solder thieves downstream and at the side corners.
During placement and before soldering, the package must be fixed with a droplet of
adhesive. The adhesive can be applied by screen printing, pin transfer or syringe
dispensing. The package can be soldered after the adhesive is cured.
Typical dwell time of the leads in the wave ranges from 3 to 4 seconds at 250 °C or
265 °C, depending on solder material applied, SnPb or Pb-free respectively.
A mildly-activated flux will eliminate the need for removal of corrosive residues in
most applications.
13.4 Manual soldering
Fix the component by first soldering two diagonally-opposite end leads. Use a low
voltage (24 V or less) soldering iron applied to the flat part of the lead. Contact time
must be limited to 10 seconds at up to 300 °C.
When using a dedicated tool, all other leads can be soldered in one operation within
2 to 5 seconds between 270 and 320 °C.
13.5 Package related soldering information
Table 27: Suitability of surface mount IC packages for wave and reflow soldering
methods
Package[1]
Soldering method
Wave
Reflow[2]
BGA, LBGA, LFBGA, SQFP, SSOP-T[3],
TFBGA, VFBGA
not suitable
suitable
DHVQFN, HBCC, HBGA, HLQFP, HSQFP,
HSOP, HTQFP, HTSSOP, HVQFN, HVSON,
SMS
not suitable[4]
suitable
PLCC[5], SO, SOJ
suitable
suitable
suitable
suitable
LQFP, QFP, TQFP
not recommended[5][6]
not recommended[7]
SSOP, TSSOP, VSO, VSSOP
[1] For more detailed information on the BGA packages refer to the (LF)BGA Application Note
(AN01026); order a copy from your Philips Semiconductors sales office.
[2] All surface mount (SMD) packages are moisture sensitive. Depending upon the moisture content, the
maximum temperature (with respect to time) and body size of the package, there is a risk that internal
or external package cracks may occur due to vaporization of the moisture in them (the so called
popcorn effect). For details, refer to the Drypack information in the Data Handbook IC26; Integrated
Circuit Packages; Section: Packing Methods.
9397 750 11618
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[3] These transparent plastic packages are extremely sensitive to reflow soldering conditions and must
on no account be processed through more than one soldering cycle or subjected to infrared reflow
soldering with peak temperature exceeding 217 °C ± 10 °C measured in the atmosphere of the reflow
oven. The package body peak temperature must be kept as low as possible.
[4] These packages are not suitable for wave soldering. On versions with the heatsink on the bottom
side, the solder cannot penetrate between the printed-circuit board and the heatsink. On versions with
the heatsink on the top side, the solder might be deposited on the heatsink surface.
[5] If wave soldering is considered, then the package must be placed at a 45° angle to the solder wave
direction. The package footprint must incorporate solder thieves downstream and at the side corners.
[6] Wave soldering is suitable for LQFP, QFP and TQFP packages with a pitch (e) larger than 0.8 mm; it
is definitely not suitable for packages with a pitch (e) equal to or smaller than 0.65 mm.
[7] Wave soldering is suitable for SSOP and TSSOP packages with a pitch (e) equal to or larger than
0.65 mm; it is definitely not suitable for packages with a pitch (e) equal to or smaller than 0.5 mm.
14. Revision history
Table 28: Revision history
Rev Date
CPCN Description
04 20030619
-
Product data (9397 750 11618); ECN 853-2411 30036 of 16 June 2003.
Modifications:
• Figure 13 “Crystal oscillator connection.” on page 20: changed capacitors’ values and added
connection with resistor.
• Table 25 “DC electrical characteristics” on page 35: ICCsleep: change all values to 1 mA nom.
• Table 26 “AC electrical characteristics”: add Table note 2, its reference to parameter ‘IOW
strobe width’, and re-number subsequent note.
03 20030415
02 20030314
01 20030124
-
-
-
Product data (9397 750 11374); ECN 853-2411 29796 of 11 April 2003.
Product data (9397 750 11192); ECN 853-2411 29625 of 07 March 2003.
Product data (9397 750 10891); ECN 853-2411 29395 of 16 January 2003.
9397 750 11618
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SC16C754
Quad UART with 64-byte FIFO
Philips Semiconductors
15. Data sheet status
Level Data sheet status[1]
Product status[2][3]
Definition
I
Objective data
Development
This data sheet contains data from the objective specification for product development. Philips
Semiconductors reserves the right to change the specification in any manner without notice.
II
Preliminary data
Qualification
This data sheet contains data from the preliminary specification. Supplementary data will be published
at a later date. Philips Semiconductors reserves the right to change the specification without notice, in
order to improve the design and supply the best possible product.
III
Product data
Production
This data sheet contains data from the product specification. Philips Semiconductors reserves the
right to make changes at any time in order to improve the design, manufacturing and supply. Relevant
changes will be communicated via a Customer Product/Process Change Notification (CPCN).
[1]
[2]
Please consult the most recently issued data sheet before initiating or completing a design.
The product status of the device(s) described in this data sheet may have changed since this data sheet was published. The latest information is available on the Internet at
URL http://www.semiconductors.philips.com.
[3]
For data sheets describing multiple type numbers, the highest-level product status determines the data sheet status.
16. Definitions
17. Disclaimers
Short-form specification — The data in a short-form specification is
extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.
Life support — These products are not designed for use in life support
appliances, devices, or systems where malfunction of these products can
reasonably be expected to result in personal injury. Philips Semiconductors
customers using or selling these products for use in such applications do so
at their own risk and agree to fully indemnify Philips Semiconductors for any
damages resulting from such application.
Limiting values definition — Limiting values given are in accordance with
the Absolute Maximum Rating System (IEC 60134). Stress above one or
more of the limiting values may cause permanent damage to the device.
These are stress ratings only and operation of the device at these or at any
other conditions above those given in the Characteristics sections of the
specification is not implied. Exposure to limiting values for extended periods
may affect device reliability.
Right to make changes — Philips Semiconductors reserves the right to
make changes in the products - including circuits, standard cells, and/or
software - described or contained herein in order to improve design and/or
performance. When the product is in full production (status ‘Production’),
relevant changes will be communicated via a Customer Product/Process
Change Notification (CPCN). Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no
licence or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are
free from patent, copyright, or mask work right infringement, unless otherwise
specified.
Application information — Applications that are described herein for any
of these products are for illustrative purposes only. Philips Semiconductors
make no representation or warranty that such applications will be suitable for
the specified use without further testing or modification.
Contact information
For additional information, please visit http://www.semiconductors.philips.com.
For sales office addresses, send e-mail to: sales.addresses@www.semiconductors.philips.com.
Fax: +31 40 27 24825
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
48 of 49
9397 750 11618
Product data
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Quad UART with 64-byte FIFO
Philips Semiconductors
Contents
1
2
3
4
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Ordering information. . . . . . . . . . . . . . . . . . . . . 2
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 3
9
Limiting values . . . . . . . . . . . . . . . . . . . . . . . . 34
Static characteristics . . . . . . . . . . . . . . . . . . . 35
Dynamic characteristics. . . . . . . . . . . . . . . . . 36
Timing diagrams. . . . . . . . . . . . . . . . . . . . . . . 37
Package outline . . . . . . . . . . . . . . . . . . . . . . . . 43
10
11
11.1
12
5
5.1
5.2
Pinning information. . . . . . . . . . . . . . . . . . . . . . 4
Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 5
13
13.1
Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Introduction to soldering surface mount
packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Reflow soldering. . . . . . . . . . . . . . . . . . . . . . . 45
Wave soldering. . . . . . . . . . . . . . . . . . . . . . . . 45
Manual soldering . . . . . . . . . . . . . . . . . . . . . . 46
Package related soldering information. . . . . . 46
6
6.1
6.2
6.2.1
6.2.2
6.3
6.3.1
6.3.2
6.3.3
6.4
Functional description . . . . . . . . . . . . . . . . . . . 8
Trigger levels. . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Hardware flow control. . . . . . . . . . . . . . . . . . . . 8
Auto-RTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Auto-CTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Software flow control . . . . . . . . . . . . . . . . . . . 10
RX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
TX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Software flow control example . . . . . . . . . . . . 12
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Interrupt mode operation . . . . . . . . . . . . . . . . 15
Polled mode operation . . . . . . . . . . . . . . . . . . 15
DMA operation . . . . . . . . . . . . . . . . . . . . . . . . 16
Single DMA transfers (DMA mode 0/FIFO
13.2
13.3
13.4
13.5
14
15
16
17
Revision history . . . . . . . . . . . . . . . . . . . . . . . 47
Data sheet status. . . . . . . . . . . . . . . . . . . . . . . 48
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.5
6.5.1
6.5.2
6.6
6.6.1
disable) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Block DMA transfers (DMA mode 1). . . . . . . . 17
Sleep mode. . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Break and time-out conditions . . . . . . . . . . . . 18
Programmable baud rate generator . . . . . . . . 18
6.6.2
6.7
6.8
6.9
7
Register descriptions . . . . . . . . . . . . . . . . . . . 20
Receiver holding register (RHR). . . . . . . . . . . 22
Transmit holding register (THR) . . . . . . . . . . . 22
FIFO control register (FCR) . . . . . . . . . . . . . . 23
Line control register (LCR) . . . . . . . . . . . . . . . 24
Line status register (LSR). . . . . . . . . . . . . . . . 25
Modem control register (MCR) . . . . . . . . . . . . 26
Modem status register (MSR). . . . . . . . . . . . . 27
Interrupt enable register (IER) . . . . . . . . . . . . 27
Interrupt identification register (IIR) . . . . . . . . 28
Enhanced feature register (EFR) . . . . . . . . . . 29
Divisor latches (DLL, DLH) . . . . . . . . . . . . . . . 30
Transmission control register (TCR) . . . . . . . . 30
Trigger level register (TLR) . . . . . . . . . . . . . . . 30
FIFO ready register. . . . . . . . . . . . . . . . . . . . . 31
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
7.13
7.14
8
Programmer’s guide . . . . . . . . . . . . . . . . . . . . 32
© Koninklijke Philips Electronics N.V. 2003.
Printed in the U.S.A
All rights are reserved. Reproduction in whole or in part is prohibited without the prior
written consent of the copyright owner.
The information presented in this document does not form part of any quotation or
contract, is believed to be accurate and reliable and may be changed without notice. No
liability will be accepted by the publisher for any consequence of its use. Publication
thereof does not convey nor imply any license under patent- or other industrial or
intellectual property rights.
Date of release: 19 June 2003
Document order number: 9397 750 11618
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