PHILIPS SC16C2552IA44

SC16C2552
Dual UART with 16-byte transmit and receive FIFOs
Rev. 03 — 20 June 2003
Product data
1. Description
The SC16C2552 is a two channel Universal Asynchronous Receiver and Transmitter
(UART) used for serial data communications. Its principal function is to convert
parallel data into serial data, and vice versa. The UART can handle serial data rates
up to 5 Mbits/s.
The SC16C2552 is pin compatible with the PC16C552 and ST16C2552. It will
power-up to be functionally equivalent to the 16C2450. The SC16C2552 provides
enhanced UART functions with 16 byte FIFOs, modem control interface, DMA mode
data transfer and concurrent writes to control registers of both channels. The DMA
mode data transfer is controlled by the FIFO trigger levels and the RXRDY and
TXRDY signals. On-board status registers provide the user with error indications and
operational status. System interrupts and modem control features may be tailored by
software to meet specific user requirements. An internal loop-back capability allows
on-board diagnostics. Independent programmable baud rate generators are provided
to select transmit and receive baud rates.
The SC16C2552 operates at 5 V, 3.3 V and 2.5 V, and the Industrial temperature
range, and is available in a plastic PLCC44 package.
2. Features
■
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■
■
■
■
■
■
■
■
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Industrial temperature range (−40 °C to +85 °C)
5 V, 3.3 V and 2.5 V operation
Pin-to-pin and functionally compatible to PC16C552, ST16C2552
Software compatible with INS8250, NS16C550
Up to 5 Mbits/s data rate at 5 V and 3 V, and 3 Mbits/s at 2.5 V
16-byte transmit FIFO
16-byte receive FIFO with error flags
Independent transmit and receive UART control
Four selectable Receive FIFO interrupt trigger levels; fixed XMIT FIFO interrupt
trigger level
Modem control signals (CTS, RTS, DSR, DTR, RI, CD)
DMA operation and DMA monitoring via package I/O pins, TXRDY/RXRDY
UART internal register sections A and B may be written to concurrently
Multi-function output allows more package functions with fewer I/O pins
Programmable character lengths (5, 6, 7, 8), with even, odd, or no parity
SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
3. Ordering information
Table 1:
Ordering information
Type number
SC16C2552IA44
Package
Name
Description
Version
PLCC44
plastic leaded chip carrier; 44 leads
SOT187-2
4. Block diagram
SC16C2552
A0–A2
CS
CHSEL
TRANSMIT
SHIFT
REGISTER
TXA, TXB
RECEIVE
FIFO
REGISTERS
RECEIVE
SHIFT
REGISTER
RXA, RXB
DATA BUS
AND
CONTROL LOGIC
REGISTER
SELECT
LOGIC
INTERCONNECT BUS LINES
AND
CONTROL SIGNALS
D0–D7
IOR
IOW
RESET
TRANSMIT
FIFO
REGISTERS
DTRA, DTRB
RTSA, RTSB
MFA, MFB
MODEM
CONTROL
LOGIC
INTA, INTB
TXRDYA, TXRDYB
RXRDYA, RXRDYB
INTERRUPT
CONTROL
LOGIC
CTSA, CTSB
RIA, RIB
CDA, CDB
DSRA, DSRB
CLOCK AND
BAUD RATE
GENERATOR
002aaa123
XTAL1
XTAL2
Fig 1. SC16C2552 block diagram.
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9397 750 11636
Product data
Rev. 03 — 20 June 2003
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
5. Pinning information
40 CTSA
41 DSRA
42 CDA
43 RIA
44 VCC
1 TXRDYA
2 D0
3 D1
4 D2
5 D3
6 D4
5.1 Pinning
D5
7
39 RXA
D6
8
38 TXA
D7
9
37 DTRA
A0 10
36 RTSA
XTAL1 11
35 MFA
SC16C2552IA44
GND 12
34 INTA
XTAL2 13
33 Vcc
A1 14
32 TXRDYB
A2 15
31 RIB
CHSEL 16
30 CDB
CTSB 28
DTRB 27
TXB 26
RXB 25
IOR 24
RTSB 23
GND 22
RESET 21
IOW 20
MFB 19
29 DSRB
CS 18
INTB 17
002aaa124
Fig 2. PLCC44 pin configuration.
5.2 Pin description
Table 2:
Pin description
Symbol
Pin
Type
Description
A2-A0
10, 14,
15
I
Register select. A0-A2 are used during read and write operations to select the UART
register to read from or write to.
CHSEL
16
I
Channel Select. UART channel A or B is selected by the logical state of this pin when
the CS is a logic 0. A logic 0 on CHSEL selects the UART channel ‘B’, while a logic 1
selects UART channel ‘A’.
CS
18
I
Chip Select (Active-LOW). This function is selects channel ‘A’ or ‘B’, in accordance
with the logical state of the CHSEL pin. This allows data to be transferred between the
user CPU and the SC16C2552, or the SC16C2552 and the CPU for a channel selected
by CHSEL. MF[0] overrides CHSEL while in the write cycle mode, allowing the user to
write both channel registers simultaneously with one write cycle.
D0-D7
2-9
I/O
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.
GND
12, 22
I
Signal and power ground.
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9397 750 11636
Product data
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
Table 2:
Pin description…continued
Symbol
Pin
Type
Description
INTA, INTB
34, 17
O
Interrupt A, B (Active-HIGH). This function is associated with individual channel
interrupts, INTA, INTB. INTA, INTB are enabled when MCR bit 3 is set to a logic 1,
interrupts are enabled in the interrupt enable register (IER), and when an interrupt
condition exists. Interrupt conditions include: receiver errors, available receiver buffer
data, transmit buffer empty, or when a modem status flag is detected.
IOR
24
I
Read strobe (Active-LOW). A logic 0 transition on this pin will load the contents of an
internal register defined by address bits A0-A2 onto the SC16C2552 data bus (D0-D7)
for access by external CPU.
IOW
20
I
Write strobe (Active-LOW). A logic 0 transition on this pin 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.
MFA, MFB
35, 19
O
Multi-Function A, B. This function is associated with an individual channel function, ‘A’
or ‘B’. User programmable bits 1-2 of the Alternate Function Register (AFR), selects a
signal function or output on these pins. OP2 (interrupt enable), BAUDOUT, and RXRDY
are signal functions that may be selected by the AFR. These signal functions are
described as follows:
OP2. When OP2 (interrupt output enable function) is selected, the MF pin is a logic 1
when INTA, INTB is set to the 3-State mode (disabled), or a logic 0 when INTA, INTB
is enabled. (See MCR[3].) A logic 1 is the default signal condition that is available
following a master reset or power-up.
BAUDOUT. When BAUDOUT function is selected, the 16× baud rate clock output is
available at this pin.
RXRDY. RXRDY is primarily intended for monitoring DMA mode 1 transfers for the
receive data FIFOs. A logic 0 indicates there is receive data to read/unload, i.e.,
receive ready status with one or more RX characters available in the FIFO/RHR. This
pin is a logic 1 when the FIFO/RHR is empty or when the programmed trigger level
has not been reached. This signal can also be used for single mode transfers (DMA
mode 0).
RESET
21
I
Reset (Active-HIGH). A logic 1 on 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. (See Section 7.11 “SC16C2552 external reset conditions” for initialization
details.)
TXRDYA,
TXRDYB
1, 32
O
Transmit Ready A, B (Active-LOW). These outputs provide the TX FIFO/THR status
for individual transmit channels (A-B). TXRDYn is primarily intended for monitoring
DMA mode 1 transfers for the transmit data FIFOs. An individual channel’s TXRDYA,
TXRDYB buffer ready status is indicated by logic 0, i.e., at least one location is empty
and available in the FIFO or THR. This pin goes to a logic 1 when there are no more
empty locations in the FIFO or THR. This signal can also be used for single mode
transfers (DMA mode 0).
VCC
33, 44
I
Power supply input.
XTAL1
11
I
Crystal or external clock input. Functions as a crystal input or as an external clock
input. A crystal can be connected between this pin and XTAL2 to form an internal
oscillator circuit. Alternatively, an external clock can be connected to this pin to provide
custom data rates. (See Section 6.5 “Programmable baud rate generator”.)
XTAL2
13
O
Output of the crystal oscillator or buffered clock. (See also XTAL1.) Crystal
oscillator output or buffered clock output. Should be left open if an external clock is
connected to XTAL1.
CDA, CDB
42, 30
I
Carrier Detect (Active-LOW). These inputs are associated with individual UART
channels A through B. A logic 0 on this pin indicates that a carrier has been detected by
the modem for that channel.
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
9397 750 11636
Product data
Rev. 03 — 20 June 2003
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
Table 2:
Pin description…continued
Symbol
Pin
Type
Description
CTSA, CTSB
40, 28
I
Clear to Send (Active-LOW). These inputs are associated with individual UART
channels, A through B. A logic 0 on the CTS pin indicates the modem or data set is
ready to accept transmit data from the SC16C2552. Status can be tested by reading
MSR[4].
DSRA, DSRB 41, 29
I
Data Set Ready (Active-LOW). These inputs are associated with individual UART
channels, A through B. A logic 0 on this pin indicates the modem or data set is
powered-on and is ready for data exchange with the UART.
DTRA, DTRB
37, 27
O
Data Terminal Ready (Active-LOW). These outputs are associated with individual
UART channels, A through B. A logic 0 on this pin indicates that the SC16C2552 is
powered-on and ready. This pin can be controlled via the modem control register.
Writing a logic 1 to MCR[0] will set the DTR output to logic 0, enabling the modem. This
pin will be a logic 1 after writing a logic 0 to MCR[0], or after a reset.
RIA, RIB
43, 31
I
Ring Indicator (Active-LOW). These inputs are associated with individual UART
channels, A through B. A logic 0 on this pin indicates the modem has received a ringing
signal from the telephone line. A logic 1 transition on this input pin will generate an
interrupt.
RTSA, RTSB
36, 23
O
Request to Send (Active-LOW). These outputs are associated with individual UART
channels, A through B. A logic 0 on the RTS pin indicates the receiver is ready to
receive data. Writing a logic 1 in the modem control register MCR[1] will set this pin to a
logic 0, indicating that the receiver is ready to receive data. After a reset this pin will be
set to a logic 1.
RXA, RXB
39, 25
I
Receive data A, B. These inputs are associated with individual serial channel data to
the SC16C2552 receive input circuits, A-B. The RX signal will be a logic 1 during reset,
idle (no data), or when the transmitter is disabled. During the local loop-back mode, the
RX input pin is disabled and TX data is connected to the UART RX input, internally.
TXA, TXB
38, 26
O
Transmit data A, B. These outputs are associated with individual serial transmit
channel data from the SC16C2552. The TX signal will be a logic 1 during reset, idle (no
data), or when the transmitter is disabled. During the local loop-back mode, the TX
output pin is disabled and TX data is internally connected to the UART RX input.
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
9397 750 11636
Product data
Rev. 03 — 20 June 2003
5 of 38
SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
6. Functional description
The SC16C2552 provides serial asynchronous receive data synchronization,
parallel-to-serial and serial-to-parallel data conversions for both the transmitter and
receiver sections. These functions are necessary for converting the serial data
stream into parallel data that is required with digital data systems. Synchronization for
the serial data stream is accomplished by adding start and stop bits to the transmit
data to form a data character. Data integrity is insured by attaching a parity bit to the
data character. The parity bit is checked by the receiver for any transmission bit
errors. The SC16C2552 is fabricated with an advanced CMOS process.
The SC16C2552 is an upward solution that provides a dual UART capability with
16 bytes of transmit and receive FIFO memory, instead of none in the 16C450. The
SC16C2552 is designed to work with high speed modems and shared network
environments that require fast data processing time. Increased performance is
realized in the SC16C2552 by the transmit and receive FIFOs. This allows the
external processor to handle more networking tasks within a given time. In addition,
the four selectable receive FIFO trigger interrupt levels are uniquely provided for
maximum data throughput performance especially when operating in a multi-channel
environment. The FIFO memory greatly reduces the bandwidth requirement of the
external controlling CPU, increases performance, and reduces power consumption.
The SC16C2552 is capable of operation to 1.5 Mbits/s with a 24 MHz. With a crystal
or external clock input of 7.3728 MHz, the user can select data rates up to
460.8 kbits/s.
The rich feature set of the SC16C2552 is available through internal registers.
Selectable receive FIFO trigger levels, selectable TX and RX baud rates, and modem
interface controls are all standard features.
6.1 UART A-B functions
The UART provides the user with the capability to bi-directionally transfer information
between an external CPU, the SC16C2552 package, and an external serial device. A
logic 0 on chip select pin CS, and a logic 1 on CHSEL allows the user to configure,
send data, and/or receive data via UART channel A. A logic 0 on chip select pin CS
and a logic 0 on CHSEL allows the user to configure, send data, and/or receive data
via UART channel B. Individual channel select functions are shown in Table 3.
Table 3:
Serial port selection
Chip Select
Function
CS = 1
none
CS = 0
UART channel selected as follows:
CHSEL = 1: UART Channel A
CHSEL = 0: UART Channel B
During a write mode cycle, the setting of AFR[0] to a logic 1 will override the CHSEL
selection and allow a simultaneous write to both UART channel sections. This
functional capability allow the registers in both UART channels to be modified
concurrently, saving individual channel initialization time. Caution should be
considered, however, when using this capability. Any in-process serial data transfer
may be disrupted by changing an active channel’s mode.
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9397 750 11636
Product data
Rev. 03 — 20 June 2003
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
6.2 Internal registers
The SC16C2552 provides two sets of internal registers (A and B) consisting of
12 registers each for monitoring and controlling the functions of each channel of the
UART. These registers are shown in Table 4. The UART registers function as data
holding registers (THR/RHR), interrupt status and control registers (IER/ISR), a FIFO
control register (FCR), line status and control registers (LCR/LSR), modem status
and control registers (MCR/MSR), programmable data rate (clock) control registers
(DLL/DLM), a user accessible scratchpad register (SPR), and an Alternate Function
Register (AFR).
Table 4:
A2
Internal registers decoding
A1
A0
READ mode
WRITE mode
General register set (THR/RHR, IER/ISR, MCR/MSR, FCR, LSR, SPR)[1]
0
0
0
Receive Holding Register
0
0
1
0
1
0
0
1
1
Line Control Register
1
0
0
Modem Control Register
1
0
1
Line Status Register
n/a
1
1
0
Modem Status Register
n/a
1
1
1
Scratchpad Register
Scratchpad Register
Interrupt Enable Register
Interrupt Status Register
FIFO Control Register
Register set 2
(DLL/DLM/AFR)[2]
0
0
0
LSB of Divisor Latch
LSB of Divisor Latch
0
0
1
MSB of Divisor Latch
MSB of Divisor Latch
0
1
0
Alternate Function Register
Alternate Function Register
[1]
[2]
The General Register sets are accessible only when CS is a logic 0 and LCR[7] is a logic 0.
The Baud Rate register and AFR register sets are accessible only when CS is a logic 0 and LCR[7] is
a logic 1 for the register set (A/B) being accessed.
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9397 750 11636
Product data
Transmit Holding Register
Rev. 03 — 20 June 2003
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
6.3 FIFO operation
The 16 byte transmit and receive data FIFOs are enabled by the FIFO Control
Register (FCR) bit 0. The user can set the receive trigger level via FCR bits 6-7, but
not the transmit trigger level. The transmit interrupt trigger level is set to 16 following a
reset. The receiver FIFO section includes a time-out function to ensure data is
delivered to the external CPU. An interrupt is generated whenever the Receive
Holding Register (RHR) has not been read following the loading of a character or the
receive trigger level has not been reached.
6.4 Time-out interrupts
The interrupts are enabled by IER[0-3]. Care must be taken when handling these
interrupts. Following a reset the transmitter interrupt is enabled, the SC16C2552 will
issue an interrupt to indicate that Transmit Holding Register is empty. This interrupt
must be serviced prior to continuing operations. The LSR register provides the
current singular highest priority interrupt only. It could be noted that CTS and RTS
interrupts have lowest interrupt priority. A condition can exist where a higher priority
interrupt may mask the lower priority CTS/RTS interrupt(s). Only after servicing the
higher pending interrupt will the lower priority CTS/RTS interrupt(s) be reflected in the
status register. Servicing the interrupt without investigating further interrupt conditions
can result in data errors.
When two interrupt conditions have the same priority, it is important to service these
interrupts correctly. Receive Data Ready and Receive Time Out have the same
interrupt priority (when enabled by IER[0]). The receiver issues an interrupt after the
number of characters have reached the programmed trigger level. In this case, the
SC16C2552 FIFO may hold more characters than the programmed trigger level.
Following the removal of a data byte, the user should re-check LSR[0] for additional
characters. A Receive Time Out will not occur if the receive FIFO is empty. The
time-out counter is reset at the center of each stop bit received or each time the
receive holding register (RHR) is read. The actual time-out value is 4 character time.
6.5 Programmable baud rate generator
The SC16C2552 supports high speed modem technologies that have increased input
data rates by employing data compression schemes. For example, a 33.6 kbit/s
modem that employs data compression may require a 115.2 kbit/s input data rate.
A 128.0 kbit/s ISDN modem that supports data compression may need an input
data rate of 460.8 kbit/s.
A baud rate generator is provided for each UART channel, allowing independent
TX/RX channel control. The programmable Baud Rate Generator is capable of
accepting an input clock up to 80 MHz, as required for supporting a 5 Mbits/s data
rate. The SC16C2552 can be configured for internal or external clock operation. For
internal clock oscillator operation, an industry standard microprocessor crystal is
connected externally between the XTAL1 and XTAL2 pins. Alternatively, an external
clock can be connected to the XTAL1 pin to clock the internal baud rate generator for
standard or custom rates (see Table 5).
The generator divides the input 16× clock by any divisor from 1 to 216 − 1. The
SC16C2552 divides the basic external clock by 16. The basic 16× clock provides
table rates to support standard and custom applications using the same system
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9397 750 11636
Product data
Rev. 03 — 20 June 2003
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
design. The rate table is configured via the DLL and DLM internal register functions.
Customized Baud Rates can be achieved by selecting the proper divisor values for
the MSB and LSB sections of baud rate generator.
X1
1.8432 MHz
C1
47 pF
XTAL2
XTAL1
XTAL2
XTAL1
Programming the Baud Rate Generator Registers DLM (MSB) and DLL (LSB)
provides a user capability for selecting the desired final baud rate. The example in
Table 5 shows the selectable baud rate table available when using a 1.8432 MHz
external clock input.
X1
1.8432 MHz
C2
100 pF
C1
22 pF
1.5 kΩ
C2
47 pF
002aaa169
Fig 3. Crystal oscillator connection.
Table 5:
Baud rate generator programming table using a 1.8432 MHz clock
Output
baud rate
Output
16× clock divisor
(decimal)
User
16× clock divisor
(HEX)
DLM
program value
(HEX)
DLL
program value
(HEX)
50
2304
900
09
00
75
1536
600
06
00
150
768
300
03
00
300
384
180
01
80
600
192
C0
00
C0
1200
96
60
00
60
2400
48
30
00
30
4800
24
18
00
18
7200
16
10
00
10
9600
12
0C
00
0C
19.2 k
6
06
00
06
38.4 k
3
03
00
03
57.6 k
2
02
00
02
115.2 k
1
01
00
01
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9397 750 11636
Product data
Rev. 03 — 20 June 2003
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
6.6 DMA operation
The SC16C2552 FIFO trigger level provides additional flexibility to the user for block
mode operation. LSR[5,6] provide an indication when the transmitter is empty or has
an empty location(s). The user can optionally operate the transmit and receive FIFOs
in the DMA mode (FCR[3]). When the transmit and receive FIFOs are enabled and
the DMA mode is de-activated (DMA Mode 0), the SC16C2552 activates the interrupt
output pin for each data transmit or receive operation. When DMA mode is activated
(DMA Mode 1), the user takes the advantage of block mode operation by loading or
unloading the FIFO in a block sequence determined by the receive trigger level and
the transmit FIFO. In this mode, the SC16C2552 sets the interrupt output pin when
characters in the transmit FIFO is below 16, or the characters in the receive FIFOs
are above the receive trigger level.
6.7 Loop-back mode
The internal loop-back capability allows on-board diagnostics. In the loop-back mode,
the normal modem interface pins are disconnected and reconfigured for loop-back
internally. MCR[0-3] register bits are used for controlling loop-back diagnostic testing.
In the loop-back mode, INT enable and MCR[2] in the MCR register (bits 2-3) control
the modem RI and CD inputs, respectively. MCR signals DTR and RTS (bits 0-1) are
used to control the modem CTS and DSR inputs, respectively. The transmitter output
(TX) and the receiver input (RX) are disconnected from their associated interface
pins, and instead are connected together internally (see Figure 4). The CTS, DSR,
CD, and RI are disconnected from their normal modem control inputs pins, and
instead are connected internally to DTR, RTS, INT enable, and MCR[2]. Loop-back
test data is entered into the transmit holding register via the user data bus interface,
D0-D7. The transmit UART serializes the data and passes the serial data to the
receive UART via the internal loop-back connection. The receive UART converts the
serial data back into parallel data that is then made available at the user data
interface D0-D7. The user optionally compares the received data to the initial
transmitted data for verifying error-free operation of the UART TX/RX circuits.
In this mode, the receiver and transmitter interrupts are fully operational. The Modem
Control Interrupts are also operational. However, the interrupts can only be read
using lower four bits of the Modem Status Register (MSR[0-3]) instead of the four
Modem Status Register bits 4-7. The interrupts are still controlled by the IER.
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9397 750 11636
Product data
Rev. 03 — 20 June 2003
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
SC16C2552
TRANSMIT
FIFO
REGISTERS
D0–D7
IOR
IOW
RESET
TRANSMIT
SHIFT
REGISTER
TXA, TXB
DATA BUS
AND
CONTROL LOGIC
A0–A2
CS
CHSEL
REGISTER
SELECT
LOGIC
INTERCONNECT BUS LINES
AND
CONTROL SIGNALS
MCR[4] = 1
RECEIVE
FIFO
REGISTERS
RECEIVE
SHIFT
REGISTER
RXA, RXB
RTSA, RTSB
DSRA, DSRB
DTRA, DTRB
MODEM
CONTROL
LOGIC
CTSA, CTSB
OP1A, OP1B
INTA, INTB
TXRDYA, TXRDYB
RXRDYA, RXRDYB
INTERRUPT
CONTROL
LOGIC
RIA, RIB
CLOCK AND
BAUD RATE
GENERATOR
OP2A, OP2B
CDA, CDB
002aaa126
XTAL1
XTAL2
Fig 4. Internal loop-back mode diagram.
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
9397 750 11636
Product data
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SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
7. Register descriptions
Table 6 details the assigned bit functions for the SC16C2552 internal registers. The
assigned bit functions are further defined in Section 7.1 through Section 7.11.
Table 6:
A2
A1
SC16C2552 internal registers
A0
Register
General Register
Default[1] Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Set[2]
0
0
0
RHR
XX
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
0
0
0
THR
XX
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
0
0
1
IER
00
0
0
0
0
modem
status
interrupt
receive
line
status
interrupt
transmit
holding
register
interrupt
receive
holding
register
0
1
0
FCR
00
RCVR
trigger
(MSB)
RCVR
trigger
(LSB)
0
0
DMA
mode
select
XMIT
FIFO
reset
RCVR
FIFO
reset
FIFO
enable
0
1
0
ISR
01
FIFOs
enabled
FIFOs
enabled
0
0
INT
priority
bit 2
INT
priority
bit 1
INT
priority
bit 0
INT
status
0
1
1
LCR
00
divisor
latch
enable
set
break
set parity even
parity
parity
enable
stop bits
word
length
bit 1
word
length
bit 0
1
0
0
MCR
00
0
0
0
loop
back
OP A/B,
INT A/B
enable
OP1
RTS
DTR
1
0
1
LSR
60
FIFO
data
error
THR and THR
TSR
empty
empty
break
interrupt
framing
error
parity
error
overrun
error
receive
data
ready
1
1
0
MSR
X0
CD
RI
DSR
CTS
∆CD
∆RI
∆DSR
∆CTS
1
1
1
SPR
FF
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
Special Register
Set[3]
0
0
0
DLL
XX
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
0
0
1
DLM
XX
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
0
1
0
AFR
00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
[1]
[2]
[3]
The value shown in represents the register’s initialized HEX value; X = n/a.
The General Register sets are accessible only when CS is a logic 0 and LCR[7] is a logic 0. Set A is accessible when CHSEL is a
logic 1, and set is accessible when CHSEL is a logic 0.
The Baud Rate register and AFR register sets are accessible only when CS is a logic 0 and LCR[7] is a logic 1 for the register set (A/B)
being accessed.
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Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
7.1 Transmit (THR) and Receive (RHR) Holding Registers
The serial transmitter section consists of an 8-bit Transmit Hold Register (THR) and
Transmit Shift Register (TSR). The status of the THR is provided in the Line Status
Register (LSR). Writing to the THR transfers the contents of the data bus (D7-D0) to
the TSR and UART via the THR, providing that the THR is empty. The THR empty
flag in the LSR register will be set to a logic 1 when the transmitter is empty or when
data is transferred to the TSR. Note that a write operation can be performed when the
THR empty flag is set (logic 0 = FIFO full; logic 1 = at least one FIFO location
available).
The serial receive section also contains an 8-bit Receive Holding Register (RHR) and
a Receive Serial Shift Register (RSR). Receive data is removed from the SC16C2552
and receive FIFO by reading the RHR register. The receive section provides a
mechanism to prevent false starts. On the falling edge of a start or false start bit, an
internal receiver counter starts counting clocks at the 16× clock rate. After 7-1⁄2
clocks, the start bit time should be shifted to the center of the start bit. At this time the
start bit is sampled, and if it is still a logic 0 it is validated. Evaluating the start bit in
this manner prevents the receiver from assembling a false character. Receiver status
codes will be posted in the LSR.
7.2 Interrupt Enable Register (IER)
The Interrupt Enable Register (IER) masks the interrupts from receiver ready,
transmitter empty, line status and modem status registers. These interrupts would
normally be seen on the INTA, INTB output pins.
Table 7:
Interrupt Enable Register bits description
Bit
Symbol
Description
7-4
IER[7-4]
Not used; initialized to logic 0.
3
IER[3]
Modem Status Interrupt. This interrupt will be issued whenever
there is a modem status change as reflected in MSR[0-3].
Logic 0 = Disable the modem status register interrupt (normal
default condition).
Logic 1 = Enable the modem status register interrupt.
2
IER[2]
Receive Line Status interrupt. This interrupt will be issued
whenever a receive data error condition exists as reflected in
LSR[1-4].
Logic 0 = Disable the receiver line status interrupt (normal
default condition).
Logic 1 = Enable the receiver line status interrupt.
1
IER[1]
Transmit Holding Register interrupt. In the 16C450 mode, this
interrupt will be issued whenever the THR is empty, and is
associated with LSR[5]. In the FIFO modes, this interrupt will be
issued whenever the FIFO and THR are empty.
Logic 0 = Disable the Transmit Holding Register Empty (TXRDY)
interrupt (normal default condition).
Logic 1 = Enable the TXRDY (ISR level 3) interrupt.
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Dual UART with 16-byte transmit and receive FIFOs
Table 7:
Interrupt Enable Register bits description…continued
Bit
Symbol
Description
0
IER[0]
Receive Holding Register. In the 16C450 mode, this interrupt will
be issued when the RHR has data, or is cleared when the RHR is
empty. In the FIFO mode, this interrupt will be issued when the
FIFO has reached the programmed trigger level or is cleared when
the FIFO drops below the trigger level.
Logic 0 = Disable the receiver ready (ISR level 2, RXRDY)
interrupt (normal default condition).
Logic 1 = Enable the RXRDY (ISR level 2) interrupt.
7.2.1
IER versus Transmit/Receive FIFO interrupt mode operation
When the receive FIFO (FCR[0] = logic 1), and receive interrupts (IER[0] = logic 1)
are enabled, the receive interrupts and register status will reflect the following:
• The receive RXRDY interrupt (Level 2 ISR interrupt) is issued to the external CPU
when the receive FIFO has reached the programmed trigger level. It will be cleared
when the receive FIFO drops below the programmed trigger level.
• Receive FIFO status will also be reflected in the user accessible ISR register when
the receive FIFO trigger level is reached. Both the ISR register receive status bit
and the interrupt will be cleared when the FIFO drops below the trigger level.
• The receive data ready bit (LSR[0]) is set as soon as a character is transferred
from the shift register (RSR) to the receive FIFO. It is reset when the FIFO is
empty.
• When the Transmit FIFO and interrupts are enabled, an interrupt is generated
when the transmit FIFO is empty due to the unloading of the data by the TSR and
UART for transmission via the transmission media. The interrupt is cleared either
by reading the ISR register, or by loading the THR with new data characters.
7.2.2
IER versus Receive/Transmit FIFO polled mode operation
When FCR[0] = logic 1, resetting IER[0-3] enables the SC16C2552 in the FIFO
polled mode of operation. In this mode, interrupts are not generated and the user
must poll the LSR register for TX and/or RX data status. Since the receiver and
transmitter have separate bits in the LSR either or both can be used in the polled
mode by selecting respective transmit or receive control bit(s).
•
•
•
•
LSR[0] will be a logic 1 as long as there is one byte in the receive FIFO.
LSR[1-4] will provide the type of receive errors, or a receive break, if encountered.
LSR[5] will indicate when the transmit FIFO is empty.
LSR[6] will indicate when both the transmit FIFO and transmit shift register are
empty.
• LSR[7] will show if any FIFO data errors occurred.
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Dual UART with 16-byte transmit and receive FIFOs
7.3 FIFO Control Register (FCR)
This register is used to enable the FIFOs, clear the FIFOs, set the receive FIFO
trigger levels, and select the DMA mode.
7.3.1
DMA mode
Mode 0 (FCR bit 3 = 0): Set and enable the interrupt for each single transmit or
receive operation, and is similar to the 16C450 mode. Transmit Ready (TXRDY) will
go to a logic 0 whenever an empty transmit space is available in the Transmit Holding
Register (THR). Receive Ready (RXRDY) at the MF pin will go to a logic 0 whenever
the Receive Holding Register (RHR) is loaded with a character and the MF register is
set to the RXRDY mode.
Mode 1 (FCR bit 3 = 1): Set and enable the interrupt in a block mode operation. The
transmit interrupt is set when the transmit FIFO has at least one empty location.
TXRDY remains a logic 0 as long as one empty FIFO location is available. The
receive interrupt is set when the receive FIFO fills to the programmed trigger level.
However, the FIFO continues to fill regardless of the programmed level until the FIFO
is full. RXRDY at the MF pin remains a logic 0 as long as the FIFO fill level is above
the programmed trigger level, and the MF register is set to the RXRDY mode.
7.3.2
FIFO mode
Table 8:
FIFO Control Register bits description
Bit
Symbol
Description
7-6
FCR[7]
(MSB),
FCR[6]
(LSB)
RCVR trigger. These bits are used to set the trigger level for the
receive FIFO interrupt.
5-4
FCR[5-4]
Not used; initialized to logic 0.
3
FCR[3]
DMA mode select.
An interrupt is generated when the number of characters in the
FIFO equals the programmed trigger level. However, the FIFO will
continue to be loaded until it is full. Refer to Table 9.
Logic 0 = Set DMA mode ‘0’ (normal default condition).
Logic 1 = Set DMA mode ‘1’
Transmit operation in mode ‘0’: When the SC16C2552 is in the
16C450 mode (FIFOs disabled; FCR[0] = logic 0) or in the FIFO
mode (FIFOs enabled; FCR[0] = logic 1; FCR[3] = logic 0), and
when there are no characters in the transmit FIFO or transmit
holding register, the TXRDY pin will be a logic 0. Once active, the
TXRDY pin will go to a logic 1 after the first character is loaded into
the transmit holding register.
Receive operation in mode ‘0’: When the SC16C2552 is in
16C450 mode, or in the FIFO mode (FCR[0] = logic 1;
FCR[3] = logic 0) and there is at least one character in the receive
FIFO, the RXRDY signal at the MF pin will be a logic 0. Once
active, the RXRDY signal at the MF pin will go to a logic 1 when
there are no more characters in the receiver. NOTE: The AFR
register must be set to the RXRDY mode prior to any possible
reading of the RXRDY signal.
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Dual UART with 16-byte transmit and receive FIFOs
Table 8:
Bit
FIFO Control Register bits description…continued
Symbol
3
(continued)
Description
Transmit operation in mode ‘1’: When the SC16C2552 is in
FIFO mode (FCR[0] = logic 1; FCR[3] = logic 1), the TXRDY pin
will be a logic 1 when the transmit FIFO is completely full. It will be
a logic 0 if one or more FIFO locations are empty.
Receive operation in mode ‘1’: When the SC16C2552 is in FIFO
mode (FCR[0] = logic 1; FCR[3] = logic 1) and the trigger level has
been reached, or a Receive Time-Out has occurred, the RXRDY
signal at the MF pin will go to a logic 0. Once activated, it will go to
a logic 1 after there are no more characters in the FIFO.
NOTE: The AFR register must be set to the RXRDY mode prior to
any possible reading of the RXRDY signal.
2
FCR[2]
XMIT FIFO reset.
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
FCR[1]
RCVR FIFO reset.
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.
0
FCR[0]
FIFOs enabled.
Logic 0 = Disable the transmit and receive FIFO (normal default
condition).
Logic 1 = Enable the transmit and receive FIFO. This bit must
be a ‘1’ when other FCR bits are written to, or they will not
be programmed.
Table 9:
RCVR trigger levels
FCR[7]
FCR[6]
RX FIFO trigger level
0
0
01
0
1
04
1
0
08
1
1
14
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Dual UART with 16-byte transmit and receive FIFOs
7.4 Interrupt Status Register (ISR)
The SC16C2552 provides four levels of prioritized interrupts to minimize external
software interaction. The Interrupt Status Register (ISR) provides the user with four
interrupt status bits. Performing a read cycle on the ISR will provide the user with the
highest pending interrupt level to be serviced. No other interrupts are acknowledged
until the pending interrupt is serviced. Whenever the interrupt status register is read,
the interrupt status is cleared. However, it should be noted that only the current
pending interrupt is cleared by the read. A lower level interrupt may be seen after
re-reading the interrupt status bits. Table 10 “Interrupt source” shows the data values
(bits 0-3) for the four prioritized interrupt levels and the interrupt sources associated
with each of these interrupt levels.
Table 10:
Interrupt source
Priority
level
ISR[3]
ISR[2]
ISR[1]
ISR[0]
Source of the interrupt
1
0
1
1
0
LSR (Receiver Line Status Register)
2
0
1
0
0
RXRDY (Received Data Ready)
2
1
1
0
0
RXRDY (Receive Data time-out)
3
0
0
1
0
TXRDY (Transmitter Holding Register Empty)
4
0
0
0
0
MSR (Modem Status Register)
Table 11:
Interrupt Status Register bits description
Bit
Symbol
Description
7-6
ISR[7-6]
FIFOs enabled. These bits are set to a logic 0 when the FIFOs are
not being used in the 16C450 mode. They are set to a logic 1
when the FIFOs are enabled in the SC16C2552 mode.
5-4
ISR[5-4]
Not used; initialized to a logic 0.
Logic 0 or cleared = default condition.
Logic 0 or cleared = default condition.
3-1
ISR[3-1]
INT priority bits 2-0. These bits indicate the source for a pending
interrupt at interrupt priority levels 1, 2, and 3 (see Table 10).
Logic 0 or cleared = default condition.
0
ISR[0]
INT status.
Logic 0 = An interrupt is pending and the ISR contents may be
used as a pointer to the appropriate interrupt service routine.
Logic 1 = No interrupt pending (normal default condition).
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Dual UART with 16-byte transmit and receive FIFOs
7.5 Line Control Register (LCR)
The Line Control Register is used to specify the asynchronous data communication
format. The word length, the number of stop bits, and the parity are selected by
writing the appropriate bits in this register.
Table 12:
Line Control Register bits description
Bit
Symbol
Description
7
LCR[7]
Divisor latch enable. The internal baud rate counter latch and
Enhance Feature mode enable.
Logic 0 = Divisor latch disabled (normal default condition).
Logic 1 = Divisor latch enabled.
6
LCR[6]
Set break. 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 for
alerting the remote receiver to a line break condition.
5-3
LCR[5-3]
Programs the parity conditions (see Table 13).
2
LCR[2]
Stop bits. The length of stop bit is specified by this bit in
conjunction with the programmed word length (see Table 14).
Logic 0 or cleared = default condition.
1-0
LCR[1-0]
Word length bits 1, 0. These two bits specify the word length to be
transmitted or received (see Table 15).
Logic 0 or cleared = default condition.
Table 13:
LCR[5] parity selection
LCR[5]
LCR[4]
LCR[3]
Parity selection
X
X
0
no parity
X
0
1
ODD parity
0
1
1
EVEN parity
0
0
1
force parity ‘1’
1
1
1
forced parity ‘0’
Table 14:
LCR[2] stop bit length
LCR[2]
Word length
Stop bit length (bit times)
0
5, 6, 7, 8
1
1
5
1-1⁄2
1
6, 7, 8
2
Table 15:
LCR[1-0] word length
LCR[1]
LCR[0]
Word length
0
0
5
0
1
6
1
0
7
1
1
8
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Dual UART with 16-byte transmit and receive FIFOs
7.6 Modem Control Register (MCR)
This register controls the interface with the modem or a peripheral device.
Table 16:
Modem Control Register bits description
Bit
Symbol
Description
7-5
MCR[7-5]
Not used; initialized to a logic 0.
4
MCR[4]
Loop-back. Enable the local loop-back mode (diagnostics). In this
mode the transmitter output TX and the receiver input RX, CTS, DSR,
CD, and RI are disconnected from the SC16C2552 I/O pins.
Internally the modem data and control pins are connected into a
loop-back data configuration (see Figure 4). In this mode, the receiver
and transmitter interrupts remain fully operational. The Modem
Control Interrupts are also operational, but the interrupts’ sources are
switched to the lower four bits of the Modem Control. Interrupts
continue to be controlled by the IER register.
Logic 0 = Disable loop-back mode (normal default condition).
Logic 1 = Enable local loop-back mode (diagnostics).
3
MCR[3]
OP2, INTA/INTB enable. Used to control the modem CD signal in the
loop-back mode.
Logic 0 = Forces INT (A-B) outputs to the 3-State mode and sets
OP2 to a logic 1 (normal default condition). In the loop-back mode,
sets CD internally to a logic 1.
Logic 1 = Forces the INT (A-B outputs to the active mode and sets
OP2 to a logic 0. In the loop-back mode, sets CD internally to a
logic 0.
2
MCR[2]
OP1. This bit is used in the Loop-back mode only. In the loop-back
mode, this bit is used to write the state of the modem RI interface
signal.
1
MCR[1]
RTS
Logic 0 = Force RTS output to a logic 1 (normal default condition).
Logic 1 = Force RTS output to a logic 0.
0
MCR[0]
DTR
Logic 0 = Force DTR output to a logic 1 (normal default condition).
Logic 1 = Force DTR output to a logic 0.
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Dual UART with 16-byte transmit and receive FIFOs
7.7 Line Status Register (LSR)
This register provides the status of data transfers between the SC16C2552 and
the CPU.
Table 17:
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 current FIFO data. This bit is cleared when LSR register is read.
6
LSR[6]
THR and TSR empty. This bit is the Transmit Empty indicator. This bit is
set to a logic 1 whenever the transmit holding register and the transmit
shift register are both empty. It is reset to logic 0 whenever either the THR
or TSR contains a data character. In the FIFO mode, this bit is set to ‘1’
whenever the transmit FIFO and transmit shift register are both empty.
5
LSR[5]
THR empty. This bit is the Transmit Holding Register Empty indicator.
This bit indicates that the UART is ready to accept a new character for
transmission. In addition, this bit causes the UART to issue an interrupt to
CPU when the THR interrupt enable is set. The THR bit is set to a logic 1
when a character is transferred from the transmit holding register into the
transmitter shift register. The bit is reset to a logic 0 concurrently with the
loading of the transmitter holding register by the CPU. In the FIFO mode,
this bit is set when the transmit FIFO is empty; it is cleared when at least
1 byte is written to the transmit FIFO.
4
LSR[4]
Break interrupt.
Logic 0 = No break condition (normal default condition).
Logic 1 = The receiver received a break signal (RX was a logic 0 for
one character frame time). In the FIFO mode, only one break character
is loaded into the FIFO.
3
LSR[3]
Framing error.
Logic 0 = No framing error (normal default condition).
Logic 1 = Framing error. The receive character did not have a valid stop
bit(s). In the FIFO mode, this error is associated with the character at
the top of the FIFO.
2
LSR[2]
Parity error.
Logic 0 = No parity error (normal default condition).
Logic 1 = Parity error. The receive character does not have correct
parity information and is suspect. In the FIFO mode, this error is
associated with the character at the top of the FIFO.
1
LSR[1]
Overrun error.
Logic 0 = No overrun error (normal default condition).
Logic 1 = Overrun error. A data overrun error occurred in the receive
shift register. This happens when additional data arrives while the FIFO
is full. In this case, the previous data in the shift register is overwritten.
Note that under this condition, the data byte in the receive shift register
is not transferred into the FIFO, therefore the data in the FIFO is not
corrupted by the error.
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Dual UART with 16-byte transmit and receive FIFOs
Table 17:
Line Status Register bits description…continued
Bit
Symbol
Description
0
LSR[0]
Receive data ready.
Logic 0 = No data in receive holding register or FIFO (normal default
condition).
Logic 1 = Data has been received and is saved in the receive holding
register or FIFO.
7.8 Modem Status Register (MSR)
This register provides the current state of the control interface signals from the
modem, or other peripheral device to which the SC16C2552 is connected. Four bits
of this register are used to indicate the changed information. These bits are set to a
logic 1 whenever a control input from the modem changes state. These bits are set to
a logic 0 whenever the CPU reads this register.
Table 18:
Modem Status Register bits description
Bit
Symbol
Description
7
MSR[7]
Carrier Detect, CD. During normal operation, this bit is the complement
of the CD input. Reading this bit in the loop-back mode produces the
state of MCR[3] (OPA/OPB).
6
MSR[6]
Ring Indicator, RI. During normal operation, this bit is the complement of
the RI input. Reading this bit in the loop-back mode produces the state of
MCR[2] (OP1).
5
MSR[5]
Data Set Ready, DSR. During normal operation, this bit is the
complement of the DSR input. During the loop-back mode, this bit is
equivalent to MCR[0] (DTR).
4
MSR[4]
Clear To Send, CTS. During normal operation, this bit is the complement
of the CTS input. During the loop-back mode, this bit is equivalent to
MCR[1] (RTS).
3
MSR[3]
∆CD [1]
Logic 0 = No CD change (normal default condition).
Logic 1 = The CD input to the SC16C2552 has changed state since
the last time it was read. A modem Status Interrupt will be generated.
2
MSR[2]
∆RI [1]
Logic 0 = No RI change (normal default condition).
Logic 1 = The RI input to the SC16C2552 has changed from a logic 0
to a logic 1. A modem Status Interrupt will be generated.
1
MSR[1]
∆DSR [1]
Logic 0 = No DSR change (normal default condition).
Logic 1 = The DSR input to the SC16C2552 has changed state since
the last time it was read. A modem Status Interrupt will be generated.
0
MSR[0]
∆CTS [1]
Logic 0 = No CTS change (normal default condition).
Logic 1 = The CTS input to the SC16C2552 has changed state since
the last time it was read. A modem Status Interrupt will be generated.
[1]
Whenever any MSR bit 0-3 is set to logic 1, a Modem Status Interrupt will be generated.
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Dual UART with 16-byte transmit and receive FIFOs
7.9 Scratchpad Register (SPR)
The SC16C2552 provides a temporary data register to store 8 bits of user
information.
7.10 Alternate Function Register (AFR)
This is a read/write register used to select specific modes of MF operation and to
allow both UART register’s sets to be written concurrently.
Table 19:
Alternate Function Register bits description
Bit
Symbol
Description
7-3
AFR[7-3]
Not used. All are initialized to logic 0.
2-1
AFR[2-1]
Selects a signal function for output on the MFA, MFB pins. These
signal functions are described as: OP2 (interrupt enable),
BAUDOUT, or TXRDY. Only one signal function can be selected
at a time. See Table 20.
0
AFR[0]
When this bit is set, CPU can write concurrently to the same
register in both UARTs. This function is intended to reduce the
dual UART initialization time. It can be used by CPU when both
channels are initialized to the same state. The external CPU can
set or clear this bit by accessing either register set. When this bit
is set, the Channel Select pin still selects the channel to be
accessed during read operation. Setting or clearing this bit has no
effect on read operations. The user should ensure that LCR[7] of
both channels are in the same state before executing a
concurrent write to the registers at address 0, 1, or 2.
Logic 0 = No concurrent write (normal default condition).
Logic 1 = Register set A and B are written concurrently with a
single external CPU I/O write operation.
Table 20:
MFA, MFB function selection
AFR[2]
AFR[1]
MF function
0
0
OP2
0
1
BAUDOUT
1
0
RXRDY
1
1
reserved
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Dual UART with 16-byte transmit and receive FIFOs
7.11 SC16C2552 external reset conditions
Table 21:
Reset state for registers
Register
Reset state
IER
IER[7-0] = 0
ISR
ISR[7-1] = 0; ISR[0] = 1
LCR
LCR[7-0] = 0
MCR
MCR[7-0] = 0
LSR
LSR[7] = 0; LSR[6-5] = 1; LSR[4-0] = 0
MSR
MSR[7-4] = input signals; MSR[3-0] = 0
FCR
FCR[7-0] = 0
AFR
AFR[7-0] = 0
Table 22:
Reset state for outputs
Output
Reset state
TXA, TXB
HIGH
OP2A, OP2B
HIGH
RTSA, RTSB
HIGH
DTRA, DTRB
HIGH
INTA, INTB
LOW
TXRDYA, TXRDYB
LOW
8. Limiting values
Table 23: Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol
Parameter
Min
Max
Unit
VCC
supply voltage
Conditions
-
7
V
Vn
voltage at any pin
GND − 0.3
VCC + 0.3
V
Tamb
operating temperature
−40
+85
°C
Tstg
storage temperature
−65
+150
°C
Ptot(pack)
total power dissipation per
package
-
500
mW
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Dual UART with 16-byte transmit and receive FIFOs
9. Static characteristics
Table 24: DC 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
Min
Max
3.3 V
Min
Max
5.0 V
Min
Unit
Max
VIL(CK)
LOW-level clock input voltage
−0.3
0.45
−0.3
0.6
−0.5
0.6
V
VIH(CK)
HIGH-level clock input voltage
1.8
VCC
2.4
VCC
3.0
VCC
V
VIL
LOW-level input voltage
(except X1 clock)
−0.3
0.65
−0.3
0.8
−0.5
0.8
V
VIH
HIGH-level input voltage
(except X1 clock)
1.6
-
2.0
-
2.2
-
V
VOL
LOW-level output voltage
on all outputs[1]
IOL = 5 mA
(databus)
-
-
-
-
-
0.4
V
IOL = 4 mA
(other outputs)
-
-
-
0.4
-
-
V
IOL = 2 mA
(databus)
-
0.4
-
-
-
-
V
IOL = 1.6 mA
(other outputs)
-
0.4
-
-
-
-
V
IOH = −5 mA
(databus)
-
-
-
-
2.4
-
V
IOH = −1 mA
(other outputs)
-
-
2.0
-
-
-
V
IOH = −800 µA
(data bus)
1.85
-
-
-
-
-
V
IOH = −400 µA
(other outputs)
1.85
-
-
-
-
-
V
VOH
HIGH-level output voltage
ILIL
LOW-level input leakage
current
-
±10
-
±10
-
±10
µA
ICL
clock leakage
-
±30
-
±30
-
±30
µA
ICC
supply current
Ci
input capacitance
[1]
f = 5 MHz
-
3.5
-
4.5
-
4.5
mA
-
5
-
5
-
5
pF
Except x2, VOL = 1 V typical.
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Dual UART with 16-byte transmit and receive FIFOs
10. Dynamic characteristics
Table 25: 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
3.3 V
5.0 V
Unit
Min
Max
Min
Max
Min
Max
10
-
6
-
6
-
ns
-
48
-
80
80
MHz
t1w, t2w
clock pulse duration
t3w
oscillator/clock frequency
t6s
address set-up time
0
-
0
-
0
-
ns
t6h
address hold time
0
-
0
-
0
-
ns
t7d
IOR delay from chip select
10
-
10
-
10
-
ns
t7w
IOR strobe width
77
-
26
-
23
-
ns
t7h
chip select hold time from IOR
0
-
0
-
0
-
ns
t9d
read cycle delay
25 pF load
20
-
20
-
20
-
ns
[1]
25 pF load
t12d
delay from IOR to data
25 pF load
-
77
-
26
-
23
ns
t12h
data disable time
25 pF load
-
15
-
15
-
15
ns
t13d
IOW delay from chip select
10
-
10
-
10
-
ns
20
-[2]
20
-[2]
15
-[2]
ns
0
-
0
-
0
-
ns
25
-
25
-
20
-
ns
t13w
IOW strobe width
t13h
chip select hold time from IOW
t15d
write cycle delay
t16s
data set-up time
20
-
20
-
15
-
ns
t16h
data hold time
15
-
5
-
5
-
ns
t17d
delay from IOW to output
25 pF load
-
100
-
33
-
29
ns
t18d
delay to set interrupt from Modem
input
25 pF load
-
100
-
24
-
23
ns
t19d
delay to reset interrupt from IOR
25 pF load
-
100
-
24
-
23
ns
-
1
-
1
-
1
Rclk
25 pF load
-
100
-
29
-
28
ns
[3]
t20d
delay from stop to set interrupt
t21d
delay from IOR to reset interrupt
t22d
delay from start to set interrupt
-
100
-
45
-
40
ns
t23d
delay from IOW to transmit start
8
24
8
24
8
24
Rclk
t24d
delay from IOW to reset interrupt
-
100
-
45
-
40
ns
t25d
delay from stop to set RXRDY
-
1
-
1
-
1
Rclk
t26d
delay from IOR to reset RXRDY
-
100
-
45
-
40
ns
t27d
delay from IOW to set TXRDY
-
100
-
45
-
40
ns
t28d
delay from start to reset TXRDY
-
8
-
8
-
8
Rclk
tRESET
Reset pulse width
200
-
40
-
40
-
ns
N
baud rate divisor
1
216 − 1
1
216 − 1
1
216 − 1
Rclk
[1]
Applies to external clock, crystal oscillator max 24 MHz.
[2]
1
IOWstrobe max = -------------------------------------2 ( Baudrate max )
[3]
= 333 ns (for Baudratemax = 1.5 Mbits/s)
= 1 µs (for Baudratemax = 460.8 kbits/s)
= 4 µs (for Baudratemax = 115.2 kbits/s)
When in both DMA mode 0 and FIFO enable mode, the write cycle delay should be larger than one x1, clock cycle.
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Dual UART with 16-byte transmit and receive FIFOs
10.1 Timing diagrams
t6h
VALID
ADDRESS
A0–A2
CHSEL
t6s
t13h
ACTIVE
CS
t13d
t15d
t13w
IOW
ACTIVE
t16h
t16s
D0–D7
DATA
002aaa128
Fig 5. General write timing.
t6h
VALID
ADDRESS
A0–A2
CHSEL
t6s
t7h
ACTIVE
CS
t7d
t9d
t7w
IOR
ACTIVE
t12h
t12d
D0–D7
DATA
002aaa127
Fig 6. General read timing.
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Dual UART with 16-byte transmit and receive FIFOs
IOW
ACTIVE
t17d
RTS
DTR
CHANGE OF STATE
CHANGE OF STATE
CD
CHANGE OF STATE
CTS
CHANGE OF STATE
DSR
t18d
INT
t18d
ACTIVE
ACTIVE
ACTIVE
t19d
IOR
ACTIVE
ACTIVE
ACTIVE
t18d
RI
CHANGE OF STATE
002aaa352
Fig 7. Modem input/output timing.
t 2w
t 1w
EXTERNAL
CLOCK
002aaa112
t 3w
Fig 8. External clock timing.
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Dual UART with 16-byte transmit and receive FIFOs
PARITY
BIT
START
BIT
STOP
BIT
NEXT
DATA
START
BIT
DATA BITS (5-8)
RX
D0
D1
D2
D3
D4
D5
D6
D7
5 DATA BITS
6 DATA BITS
t20d
7 DATA BITS
ACTIVE
INT
t21d
ACTIVE
IOR
16 BAUD RATE CLOCK
002aaa113
Fig 9. Receive timing.
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Dual UART with 16-byte transmit and receive FIFOs
PARITY
BIT
START
BIT
STOP
BIT
NEXT
DATA
START
BIT
DATA BITS (5–8)
RX
D0
D1
D2
D3
D4
D5
D6
D7
t25d
ACTIVE
DATA
READY
RXRDY
t26d
ACTIVE
IOR
002aaa114
Fig 10. Receive ready timing in non-FIFO mode.
START
BIT
PARITY
BIT
STOP
BIT
DATA BITS (5–8)
RX
D0
D1
D2
D3
D4
D5
D6
D7
FIRST BYTE THAT
REACHES THE
TRIGGER LEVEL
t25d
ACTIVE
DATA
READY
RXRDY
t26d
ACTIVE
IOR
002aaa115
Fig 11. Receive ready timing in FIFO mode.
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Dual UART with 16-byte transmit and receive FIFOs
PARITY
BIT
START
BIT
STOP
BIT
NEXT
DATA
START
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
t22d
t24d
t23d
IOW
ACTIVE
ACTIVE
16 BAUD RATE CLOCK
002aaa116
Fig 12. Transmit timing.
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Dual UART with 16-byte transmit and receive FIFOs
START
BIT
TX
DATA BITS (5–8)
D0
IOW
ACTIVE
D0–D7
BYTE #1
PARITY
BIT
D1
D2
D3
D4
D5
D6
STOP
BIT
NEXT
DATA
START
BIT
D7
TRANSMITTER READY
t28d
t27d
ACTIVE
TXRDY
TRANSMITTER
NOT READY
002aaa345
Fig 13. Transmit ready timing in non-FIFO mode.
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Dual UART with 16-byte transmit and receive FIFOs
START
BIT
PARITY
BIT
STOP
BIT
DATA BITS (5-8)
TX
D0
D1
D2
D3
D4
D5
D6
D7
5 DATA BITS
6 DATA BITS
7 DATA BITS
IOW
ACTIVE
t28d
D0–D7
BYTE #16
t27d
TXRDY
FIFO FULL
002aaa346
Fig 14. Transmit ready timing in FIFO mode (DMA mode ‘1’).
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Dual UART with 16-byte transmit and receive FIFOs
11. Package outline
PLCC44: plastic leaded chip carrier; 44 leads
SOT187-2
eD
eE
y
X
39
A
29
28
40
bp
ZE
b1
w M
44
1
E
HE
pin 1 index
A
A4 A1
e
(A 3)
6
β
18
Lp
k
7
detail X
17
e
v M A
ZD
D
B
HD
v M B
0
5
10 mm
scale
DIMENSIONS (mm dimensions are derived from the original inch dimensions)
A4
A1
UNIT A
A3
D(1) E(1)
e
eD
eE
HD
bp b1
max.
min.
4.57
4.19
mm
inches
0.81
0.66
HE
k
16.66 16.66
16.00 16.00 17.65 17.65 1.22
1.27
16.51 16.51
14.99 14.99 17.40 17.40 1.07
0.51
0.25
3.05
0.53
0.33
0.180
0.02
0.165
0.01
0.12
0.021 0.032 0.656 0.656
0.05
0.013 0.026 0.650 0.650
0.63
0.59
0.63
0.59
Lp
v
w
y
1.44
1.02
0.18
0.18
0.1
ZD(1) ZE(1)
max. max.
2.16
β
2.16
45 o
0.695 0.695 0.048 0.057
0.007 0.007 0.004 0.085 0.085
0.685 0.685 0.042 0.040
Note
1. Plastic or metal protrusions of 0.25 mm (0.01 inch) maximum per side are not included.
REFERENCES
OUTLINE
VERSION
IEC
JEDEC
JEITA
SOT187-2
112E10
MS-018
EDR-7319
EUROPEAN
PROJECTION
ISSUE DATE
99-12-27
01-11-14
Fig 15. PLCC44 package outline (SOT187-2).
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Dual UART with 16-byte transmit and receive FIFOs
12. Soldering
12.1 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.
12.2 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.
12.3 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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Dual UART with 16-byte transmit and receive FIFOs
• 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.
12.4 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.
12.5 Package related soldering information
Table 26:
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
LQFP, QFP, TQFP
not recommended[5][6]
suitable
SSOP, TSSOP, VSO, VSSOP
[1]
[2]
suitable
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.
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.
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
9397 750 11636
Product data
not
recommended[7]
Rev. 03 — 20 June 2003
35 of 38
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Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
[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.
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.
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.
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.
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.
[4]
[5]
[6]
[7]
13. Revision history
Table 27:
Revision history
Rev Date
03
20030620
CPCN
Description
-
Product data (9397 750 11636). ECN 853-2375 30034 of 16 June 2003.
Modifications:
•
Figure 3 “Crystal oscillator connection.” on page 9: changed capacitors’ values and
added connection with oscillator.
02
20030313
-
Product data (9397 750 11205). ECN 853-2375 29620 of 07 March 2003.
01
20020910
-
Product data (9397 750 08936). ECN 853-2375 28891 of 10 September 2002.
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Dual UART with 16-byte transmit and receive FIFOs
14. 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]
Please consult the most recently issued data sheet before initiating or completing a design.
[2]
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.
15. Definitions
16. 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.
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.
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.
Contact information
For additional information, please visit http://www.semiconductors.philips.com.
For sales office addresses, send e-mail to: [email protected].
Product data
Fax: +31 40 27 24825
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
9397 750 11636
Rev. 03 — 20 June 2003
37 of 38
SC16C2552
Philips Semiconductors
Dual UART with 16-byte transmit and receive FIFOs
Contents
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2
3
4
5
5.1
5.2
6
6.1
6.2
6.3
6.4
6.5
6.6
6.7
7
7.1
7.2
7.2.1
7.2.2
7.3
7.3.1
7.3.2
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Ordering information . . . . . . . . . . . . . . . . . . . . . 2
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Pinning information . . . . . . . . . . . . . . . . . . . . . . 3
Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 3
Functional description . . . . . . . . . . . . . . . . . . . 6
UART A-B functions . . . . . . . . . . . . . . . . . . . . . 6
Internal registers. . . . . . . . . . . . . . . . . . . . . . . . 7
FIFO operation . . . . . . . . . . . . . . . . . . . . . . . . . 8
Time-out interrupts . . . . . . . . . . . . . . . . . . . . . . 8
Programmable baud rate generator . . . . . . . . . 8
DMA operation . . . . . . . . . . . . . . . . . . . . . . . . 10
Loop-back mode . . . . . . . . . . . . . . . . . . . . . . . 10
Register descriptions . . . . . . . . . . . . . . . . . . . 12
Transmit (THR) and Receive (RHR)
Holding Registers . . . . . . . . . . . . . . . . . . . . . 13
Interrupt Enable Register (IER) . . . . . . . . . . . 13
IER versus Transmit/Receive FIFO interrupt
mode operation . . . . . . . . . . . . . . . . . . . . . . . 14
IER versus Receive/Transmit FIFO polled
mode operation . . . . . . . . . . . . . . . . . . . . . . . 14
FIFO Control Register (FCR) . . . . . . . . . . . . . 15
DMA mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
FIFO mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Interrupt Status Register (ISR) . . . . . . . . . . . . 17
Line Control Register (LCR) . . . . . . . . . . . . . . 18
Modem Control Register (MCR) . . . . . . . . . . . 19
Line Status Register (LSR) . . . . . . . . . . . . . . . 20
Modem Status Register (MSR). . . . . . . . . . . . 21
Scratchpad Register (SPR) . . . . . . . . . . . . . . 22
Alternate Function Register (AFR) . . . . . . . . . 22
SC16C2552 external reset conditions . . . . . . 23
© 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: 20 June 2003
Document order number: 9397 750 11636
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9
10
10.1
11
12
12.1
12.2
12.3
12.4
12.5
13
14
15
16
Limiting values . . . . . . . . . . . . . . . . . . . . . . . .
Static characteristics . . . . . . . . . . . . . . . . . . .
Dynamic characteristics . . . . . . . . . . . . . . . . .
Timing diagrams. . . . . . . . . . . . . . . . . . . . . . .
Package outline . . . . . . . . . . . . . . . . . . . . . . . .
Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction to soldering surface mount
packages . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reflow soldering. . . . . . . . . . . . . . . . . . . . . . .
Wave soldering. . . . . . . . . . . . . . . . . . . . . . . .
Manual soldering . . . . . . . . . . . . . . . . . . . . . .
Package related soldering information . . . . . .
Revision history . . . . . . . . . . . . . . . . . . . . . . .
Data sheet status. . . . . . . . . . . . . . . . . . . . . . .
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . .
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