Data Sheet

SC16C850
2.5 V to 3.3 V UART, 5 Mbit/s (max.) with 128-byte FIFOs,
infrared (IrDA), and 16 mode or 68 mode parallel bus interface
Rev. 2 — 11 November 2010
Product data sheet
1. General description
The SC16C850 is a 2.5 V to 3.3 V, low power, single 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 Mbit/s. The SC16C850 is functionally (software) compatible with
the SC16C650B. SC16C850 can be programmed to operate in extended mode (see
Section 6.2) where additional advanced UART features are available. The SC16C850
UART provides enhanced UART functions with 128-byte FIFOs, modem control interface,
and IrDA encoder/decoder. 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 loopback capability
allows on-board diagnostics.
The SC16C850IBS with Intel (16 mode) or Motorola (68 mode) bus host interface
operates at 2.5 V to 3.3 V and is available in a very small (Micro-UART) HVQFN32
package.
The SC16C850IET with Intel (16 mode) bus host interface operates at 2.5 V to 3.3 V and
is available in a very small TFBGA36 package.
2. Features and benefits
„
„
„
„
„
„
„
„
„
„
„
„
„
„
„
Single channel high performance UART
Intel or Motorola bus interface selectable using 16/68 pin
2.5 V to 3.3 V operation
Up to 5 Mbit/s data rate
128-byte transmit FIFO to reduce the bandwidth requirement of the external CPU
128-byte receive FIFO with error flags to reduce the bandwidth requirement of the
external CPU
128 programmable Receive and Transmit FIFO interrupt trigger levels
128 Receive and Transmit FIFO reporting levels (level counters)
Automatic software (Xon/Xoff) and hardware (RTS/CTS or DTR/DSR) flow control
Industrial temperature range (−40 °C to +85 °C)
128 hardware and software trigger levels
Automatic 9-bit mode (RS-485) address detection
Automatic RS-485 driver turn-around with programmable delay
UART software reset
High resolution clock prescaler, from 0 to 15 with granularity of 1⁄16 to allow
non-standard UART clock to be used
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
„
„
„
„
„
„
„
„
Programmable Xon/Xoff characters
Software selectable baud rate generator
Support IrDA version 1.0 (up to 115.2 kbit/s)
Standard modem interface or infrared IrDA encoder/decoder interface
Enhanced Sleep mode and low power feature
Modem control functions (CTS, RTS, DSR, DTR, RI, CD)
Independent transmitter and receiver enable/disable
Pb-free, RoHS compliant package offered
3. Ordering information
Table 1.
Ordering information
Type number
Package
Name
Description
Version
SC16C850IBS
HVQFN32
plastic thermal enhanced very thin quad flat package; no leads;
32 terminals; body 5 × 5 × 0.85 mm
SOT617-1
SC16C850IBS/Q900
HVQFN32
plastic thermal enhanced very thin quad flat package; no leads;
32 terminals; body 5 × 5 × 0.85 mm
SOT617-1
SC16C850IET
TFBGA36
plastic thin fine-pitch ball grid array package; 36 balls;
body 3.5 × 3.5 × 0.8 mm
SOT912-1
[1]
SC16C850IBS/Q900 is AEC-Q100 compliant. Contact [email protected] for PPAP.
SC16C850
Product data sheet
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Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
2 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
4. Block diagram
SC16C850
D0 to D7
IOR
IOW
RESET
TRANSMIT
FIFO
REGISTER
LOWPWR
INT
TX
DATA BUS
AND
CONTROL
LOGIC
INTERCONNECT BUS LINES
AND
CONTROL SIGNALS
FLOW
CONTROL
LOGIC
A0 to A2
CS
TRANSMIT
SHIFT
REGISTER
REGISTER
SELECT
LOGIC
RECEIVE
FIFO
REGISTER
FLOW
CONTROL
LOGIC
IR
ENCODER
RECEIVE
SHIFT
REGISTER
RX
IR
DECODER
POWER-DOWN
CONTROL
DTR
RTS
CLOCK AND
BAUD RATE
GENERATOR
INTERRUPT
CONTROL
LOGIC
MODEM
CONTROL
LOGIC
CTS
RI
CD
DSR
002aad020
XTAL1
Fig 1.
XTAL2
Block diagram of SC16C850 (16 mode)
SC16C850
Product data sheet
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Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
3 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
SC16C850
TRANSMIT
FIFO
REGISTER
D0 to D7
R/W
RESET
LOWPWR
IRQ
TX
DATA BUS
AND
CONTROL
LOGIC
INTERCONNECT BUS LINES
AND
CONTROL SIGNALS
FLOW
CONTROL
LOGIC
A0 to A2
CS
TRANSMIT
SHIFT
REGISTER
REGISTER
SELECT
LOGIC
RECEIVE
FIFO
REGISTER
FLOW
CONTROL
LOGIC
IR
ENCODER
RECEIVE
SHIFT
REGISTER
RX
IR
DECODER
POWER-DOWN
CONTROL
DTR
RTS
CLOCK AND
BAUD RATE
GENERATOR
INTERRUPT
CONTROL
LOGIC
MODEM
CONTROL
LOGIC
CTS
RI
CD
DSR
002aad021
XTAL1
Fig 2.
XTAL2
Block diagram of SC16C850 (68 mode)
SC16C850
Product data sheet
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Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
4 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
5. Pinning information
5.1 Pinning
SC16C850IET
ball A1
index area
1
2
3
4
5
6
A
B
C
D
E
F
002aad022
Transparent top view
Fig 3.
Pin configuration for TFBGA36
1
2
3
4
5
6
A
VDD
n.c.
IOR
n.c.
XTAL2
XTAL1
B
A2
n.c.
n.c.
IOW
LOWPWR
CS
C
A0
VSS
A1
VSS
TX
RX
D
INT
RTS
CTS
VDD
D7
D6
E
DTR
n.c.
CD
D1
D3
D5
F
RESET
DSR
RI
D0
D2
D4
002aad023
Transparent top view.
Fig 4.
SC16C850
Product data sheet
Ball mapping for TFBGA36
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Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
5 of 55
SC16C850
NXP Semiconductors
25 DSR
26 CD
27 RI
28 VDD
29 D0
D4
1
24 CTS
D4
1
24 CTS
16
2
23 RESET
68
2
23 RESET
D5
3
22 DTR
D5
3
D6
4
21 RTS
D6
4
D7
5
20 INT
D7
5
RX
6
19 A0
RX
6
19 A0
TX
7
18 A1
TX
7
18 A1
CS
8
17 A2
CS
8
17 A2
20 IRQ
n.c. 16
n.c. 15
VDD 14
VSS 13
R/W 12
XTAL2 11
9
002aad024
21 RTS
(68 mode)
XTAL1 10
n.c. 16
n.c. 15
IOR 14
VSS 13
IOW 12
XTAL2 11
9
LOWPWR
XTAL1 10
(16 mode)
22 DTR
SC16C850IBS
SC16C850IBS/Q900
LOWPWR
SC16C850IBS
SC16C850IBS/Q900
Transparent top view
002aad025
Transparent top view
a. 16 mode
Fig 5.
30 D1
32 D3
terminal 1
index area
31 D2
25 DSR
26 CD
27 RI
28 VDD
29 D0
30 D1
32 D3
terminal 1
index area
31 D2
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
b. 68 mode
Pin configuration for HVQFN32
5.2 Pin description
Table 2.
Symbol
16/68
Pin description
Pin
TFBGA36
HVQFN32
-
2
Type
Description
I
Bus select. Intel or Motorola bus select.
When 16/68 pin is at logic 1 or left unconnected (internally pulled-up) the
device will operate in Intel bus (16 mode) type of interface.
When 16/68 pin is at logic 0, the device will operate in Motorola bus (68 mode)
type of interface.
A0
C1
19
I
Address 0 select bit. Internal register address selection.
A1
C3
18
I
Address 1 select bit. Internal register address selection.
A2
B1
17
I
Address 2 select bit. Internal register address selection.
CD
E3
26
I
Carrier Detect (active LOW). A logic 0 on this pin indicates that a carrier has
been detected by the modem. Status can be tested by reading MSR[7].
CS
B6
8
I
Chip Select (active LOW). In 16 mode or 68 mode, this input is chip select for
the UART.
CTS
D3
24
I
Clear to Send (active LOW). A logic 0 on the CTS pin indicates the modem
or data set is ready to accept transmit data from the SC16C850. Status can be
tested by reading MSR[4].
DSR
F2
25
I
Data Set Ready (active LOW). A logic 0 on this pin indicates the modem or
data set is powered-on and is ready for data exchange with the UART. Status
can be tested by reading MSR[5].
DTR
E1
22
O
Data Terminal Ready (active LOW). A logic 0 on this pin indicates that the
SC16C850 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.
SC16C850
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
6 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 2.
Symbol
Pin description …continued
Pin
Type
Description
29
I/O
30
I/O
Data bus (bidirectional). 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.
TFBGA36
HVQFN32
D0
F4
D1
E4
D2
F5
31
I/O
D3
E5
32
I/O
D4
F6
1
I/O
D5
E6
3
I/O
D6
D6
4
I/O
D7
D5
5
I/O
INT
-
20
O
(IRQ)
When 16/68 pin is at logic 1 or unconnected, this output becomes active HIGH
interrupt output. The output state is defined by the user through the software
setting of MCR[5]. INT is set to the active mode when MCR[5] is set to a
logic 1. INT is set to the open-source mode when MCR[5] is set to a logic 0.
When 16/68 pin is at logic 0, this output becomes device interrupt output
(active LOW, open-drain). An external pull-up resistor to VDD is required.
INT
D1
-
O
Interrupt output (active HIGH). The output state is defined by the user
through the software setting of MCR[5]. INT is set to the active mode when
MCR[5] is set to a logic 1. INT is set to the open-source mode when MCR[5] is
set to a logic 0.
IOR
-
14
I
When 16/68 pin is at logic 1, this input becomes the read strobe (active LOW).
When 16/68 pin is at logic 0, this input pin is not used and should be
connected to VDD.
IOR
A3
-
I
Read strobe (active LOW).
IOW
-
12
I
When 16/68 pin is at logic 1 or unconnected, this input becomes the write
strobe (active LOW).
(VDD)
(R/W)
When 16/68 pin is at logic 0, this input becomes read strobe when it is at logic
HIGH, and write strobe when it is at logic LOW.
B4
-
I
Write strobe (active LOW).
LOWPWR B5
9
I
Low Power. When asserted (active HIGH), the device immediately goes into
low power mode. The oscillator is shut-off and some host interface pins are
isolated from the host’s bus to reduce power consumption. The device only
returns to normal mode when the LOWPWR pin is de-asserted. On the
negative edge of a de-asserting LOWPWR signal, the device is automatically
reset and all registers return to their default reset states. This pin has a 22 kΩ
internal pull-down resistor, therefore, it can be left unconnected (refer to
Section 6.12 “Low power feature”).
23
I
Master Reset. When 16/68 pin is at logic 1 or unconnected, this input
becomes the RESET pin (active HIGH).
IOW
RESET
-
(RESET)
When 16/68 pin is at logic LOW, this input pin becomes RESET (active LOW).
(See Section 7.23 “SC16C850 external reset condition and software reset” for
initialization details.)
RESET
F1
-
I
Reset input (active HIGH). See Section 7.23 “SC16C850 external reset
condition and software reset” for initialization details.
RI
F3
27
I
Ring Indicator (active LOW). 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 if modem status interrupt is enabled. Status
can be tested by reading MCR[6].
SC16C850
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
7 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 2.
Symbol
Pin description …continued
Pin
Type
Description
21
O
Request to Send (active LOW). 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 this pin will be set to a logic 1.
C6
6
I
UART receive data. The RX signal will be a logic 1 during reset, idle (no
data), or when not receiving data. During the local loopback mode, the RX
input pin is disabled and TX data is connected to the UART RX input,
internally.
TX
C5
7
O
UART transmit data. The TX signal will be a logic 1 during reset, idle (no
data), or when the transmitter is disabled. During the local loopback mode, the
TX output pin is disabled and TX data is internally connected to the UART RX
input.
VDD
A1, D4
28
I
Power supply input.
VSS
C2, C4
13[1]
I
Signal and power ground.
XTAL1
A6
10
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 6.9 “Programmable baud
rate generator”). See Figure 8.
XTAL2
A5
11
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.
TFBGA36
HVQFN32
RTS
D2
RX
[1]
HVQFN32 package die supply ground is connected to both VSS pin and exposed center pad. VSS pin must be connected to supply
ground for proper device operation. For enhanced thermal, electrical, and board level performance, the exposed pad needs to be
soldered to the board using a corresponding thermal pad on the board and for proper heat conduction through the board, thermal vias
need to be incorporated in the PCB in the thermal pad region.
SC16C850
Product data sheet
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Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
8 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
6. Functional description
The SC16C850 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 (character orientated protocol). Data integrity is ensured by attaching a parity bit
to the data character. The parity bit is checked by the receiver for any transmission bit
errors. The electronic circuitry to provide all these functions is fairly complex, especially
when manufactured on a single integrated silicon chip. The SC16C850 represents such
an integration with greatly enhanced features. The SC16C850 is fabricated with an
advanced CMOS process.
The SC16C850 is an upward solution to the SC16C650B that provides a single UART
capability with 128 bytes of transmit and receive FIFO memory, instead of 32 bytes for the
SC16C650B and 16 bytes in the SC16C550B. The SC16C850 is designed to work with
high speed modems and shared network environments that require fast data processing
time. Increased performance is realized in the SC16C850 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 and transmit FIFO trigger interrupt levels are
provided in 16C650 mode, or 128 programmable levels are provided in the extended
mode for maximum data throughput performance especially when operating in a
multi-channel environment (see Section 6.2 “Extended mode (128-byte FIFO)”). The FIFO
memory greatly reduces the bandwidth requirement of the external controlling CPU and
increases performance. A low power pin (LOWPWR) is provided to further reduce power
consumption by isolating the host bus interface.
The SC16C850 is capable of operation up to 5 Mbit/s with an external 80 MHz clock. With
a crystal, the SC16C850 is capable of operation up to 1.5 Mbit/s.
The rich feature set of the SC16C850 is available through internal registers. These
features are: selectable and programmable receive and transmit FIFO trigger levels,
selectable TX and RX baud rates, and modem interface controls, and are all standard
features. Following a power-on reset, an external reset, or a software reset, the
SC16C850 is software compatible with the previous generation, SC16C550B, and
SC16C650B.
6.1 UART selection
The UART provides the user with the capability to bidirectionally transfer information
between an external CPU, the SC16C850 package, and an external serial device. A
logic 0 (LOW) on chip select pin CS allows the user to configure, send data, and/or
receive data via the UART. Refer to Table 3 and Table 4.
Table 3.
Serial port selection (Intel interface)
H = HIGH; L = LOW.
SC16C850
Product data sheet
Chip Select
Function
CS = H
none
CS = L
UART select
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Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
9 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 4.
Serial port selection (Motorola interface)
H = HIGH; L = LOW.
Chip Select
Function
CS = H
none
CS = L
UART select
6.2 Extended mode (128-byte FIFO)
The device is in the extended mode when any of these four registers contains any value
other than 0: FLWCNTH, FLWCNTL, TXINTLVL, RXINTLVL.
6.3 Internal registers
The SC16C850 provides a set of 25 internal registers for monitoring and controlling the
functions of the UART. These registers are shown in Table 5.
Table 5.
Internal registers decoding
A2
A0
A1
Read mode
Write mode
General register set (THR/RHR, IER/ISR, MCR/MSR, FCR, LCR/LSR, EFCR, SPR)[1]
0
0
0
Receive Holding Register
Transmit Holding Register
0
0
1
Interrupt Enable Register
Interrupt Enable Register
0
1
0
Interrupt Status Register
FIFO Control Register
0
1
1
Line Control Register
Line Control Register
1
0
0
Modem Control Register
Modem Control Register
1
0
1
Line Status Register
Extra Feature Control Register (EFCR)
1
1
0
Modem Status Register
n/a
1
1
1
Scratchpad Register
Scratchpad Register
Baud rate register set
(DLL/DLM)[2]
0
0
0
LSB of Divisor Latch
LSB of Divisor Latch
0
0
1
MSB of Divisor Latch
MSB of Divisor Latch
Second special register set
(TXLVLCNT/RXLVLCNT)[3]
0
1
1
Transmit FIFO Level Count
n/a
1
0
0
Receive FIFO Level Count
n/a
Enhanced feature register set (EFR, Xon1/Xon2, Xoff1/Xoff2)[4]
0
1
0
Enhanced Feature Register
Enhanced Feature Register
1
0
0
Xon1 word
Xon1 word
1
0
1
Xon2 word
Xon2 word
1
1
0
Xoff1 word
Xoff1 word
1
1
1
Xoff2 word
Xoff2 word
First extra feature register set (TXINTLVL/RXINTLVL, FLWCNTH/FLWCNTL)[5]
SC16C850
Product data sheet
0
1
0
Transmit FIFO Interrupt Level
Transmit FIFO Interrupt Level
1
0
0
Receive FIFO Interrupt Level
Receive FIFO Interrupt Level
1
1
0
Flow Control Count High
Flow Control Count High
1
1
1
Flow Control Count Low
Flow Control Count Low
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Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
10 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 5.
Internal registers decoding …continued
A2
A0
A1
Read mode
Write mode
Second extra feature register set (CLKPRES, RS485TIME, AFCR2, AFCR1)[6]
0
1
0
Clock Prescaler
Clock Prescaler
1
0
0
RS-485 turn-around Timer
RS-485 turn-around Timer
1
1
0
Additional Feature Control Register 2
Additional Feature Control Register 2
1
1
1
Additional Feature Control Register 1
Additional Feature Control Register 1
[1]
These registers are accessible only when LCR[7] is a logic 0.
[2]
These registers are accessible only when LCR[7] is a logic 1.
[3]
Second Special registers are accessible only when EFCR[0] = 1.
[4]
Enhanced Feature Registers are only accessible when LCR = 0xBF.
[5]
First Extra Feature Registers are only accessible when EFCR[2:1] = 01b.
[6]
Second Extra Feature Registers are only accessible when EFCR[2:1] = 10b.
6.4 FIFO operation
6.4.1 32-byte FIFO mode
When all four of these registers (TXINTLVL, RXINTLVL, FLWCNTH, FLWCNTL) in the
‘first extra feature register set’ are empty (0x00) the transmit and receive trigger levels are
set by FCR[7:4]. In this mode the transmit and receive trigger levels are backward
compatible to the SC16C650B (see Table 6), and the FIFO sizes are 32 entries. The
transmit and receive data FIFOs are enabled by the FIFO Control Register bit 0 (FCR[0]).
It should be noted that the user can set the transmit trigger levels by writing to the FCR,
but activation will not take place until EFR[4] is set to a logic 1. The receiver FIFO section
includes a time-out function to ensure data is delivered to the external CPU (see
Section 6.8). Please refer to Table 11 and Table 12 for the setting of FCR[7:4].
Table 6.
Interrupt trigger level and flow control mechanism
FCR[7:6]
FCR[5:4]
INT pin activation
RX
TX
Negate RTS or
send Xoff
8
Assert RTS or
send Xon
0
00
00
8
16
01
01
16
8
16
7
10
10
24
24
24
15
11
11
28
30
28
23
6.4.2 128-byte FIFO mode
When either TXINTLVL, RXINTLVL, FLWCNTH or FLWCNTL in the ‘first extra feature
register set’ contains any value other than 0x00, the transmit and receive trigger levels are
set by TXINTLVL and RXINTLVL registers. TXINTLVL sets the trigger levels for the
transmit FIFO, and the transmit trigger levels can be set to any value between 1 and 128
with granularity of 1. RXINTLVL sets the trigger levels for the receive FIFO, the receive
trigger levels can be set to any value between 1 and 128 with granularity of 1.
When the effective FIFO size changes (that is, when FCR[0] toggles or when the
combined content of TXINTLVL, RXINTLVL, FLWCNTH and FLWCNTL changes between
equal and unequal to 0x00), both RX FIFO and TX FIFO will be reset (data in the FIFO will
be lost).
SC16C850
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
11 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
6.5 Hardware flow control
When automatic hardware flow control is enabled, the SC16C850 monitors the CTS pin
for a remote buffer overflow indication and controls the RTS pin for local buffer overflows.
Automatic hardware flow control is selected by setting EFR[6] (RTS) and EFR[7] (CTS) to
a logic 1. If CTS transitions from a logic 0 to a logic 1 indicating a flow control request,
ISR[5] will be set to a logic 1 (if enabled via IER[7:6]), and the SC16C850 will suspend TX
transmissions as soon as the stop bit of the character in process is shifted out.
Transmission is resumed after the CTS input returns to a logic 0, indicating more data
may be sent.
When AFCR1[2] is set to logic 1 then the function of CTS pin is mapped to the DSR pin,
and the function of RTS is mapped to DTR pin. DSR and DTR pins will behave as
described above for CTS and RTS.
With the automatic hardware flow control function enabled, an interrupt is generated when
the receive FIFO reaches the programmed trigger level. The RTS (or DTR) pin will not be
forced to a logic 1 (RTS off), until the receive FIFO reaches the next trigger level.
However, the RTS (or DTR) pin will return to a logic 0 after the receive buffer (FIFO) is
unloaded to the next trigger level below the programmed trigger level. Under the above
described conditions, the SC16C850 will continue to accept data until the receive FIFO is
full.
When the TXINTLVL, RXINTLVL, FLWCNTH and FLWCNTL in the ‘first extra feature
register set’ are all zeroes, the hardware and software flow control trigger levels are set by
FCR[7:4]; see Table 6.
When the TXINTLVL, RXINTLVL, FLWCNTH or FLWCNTL in the ‘first extra feature
register set’ contain any value other than 0x00, the hardware and software flow control
trigger levels are set by FLWCNTH and FLWCNTL. The content in FLWCNTH determines
how many bytes are in the receive FIFO before RTS (or DTR) is de-asserted or Xoff is
sent. The content in FLWCNTL determines how many bytes are in the receive FIFO
before RTS (or DTR) is asserted, or Xon is sent.
In 128-byte FIFO mode, hardware and software flow control trigger levels can be set to
any value between 1 and 128 in granularity of 1. The value of FLWCNTH should always
be greater than FLWCNTL. The UART does not check for this condition automatically, and
if this condition is not met, spurious operation of the device might occur. When using
FLWCNTH and FLWCNTL, these registers must be initialized to proper values before
hardware or software flow control is enabled via the EFR register.
6.6 Software flow control
When software flow control is enabled, the SC16C850 compares one or two sequentially
received data characters with the programmed Xon or Xoff character value(s). If the
received character(s) match the programmed Xoff values, the SC16C850 will halt
transmission (TX) as soon as the current character(s) has completed transmission. When
a match occurs, ISR bit 4 will be set (if enabled via IER[5]) and the interrupt output pin (if
receive interrupt is enabled) will be activated. Following a suspension due to a match of
the Xoff characters’ values, the SC16C850 will monitor the receive data stream for a
match to the Xon1/Xon2 character value(s). If a match is found, the SC16C850 will
resume operation and clear the flags (ISR[4]).
SC16C850
Product data sheet
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12 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Reset initially sets the contents of the Xon/Xoff 8-bit flow control registers to a logic 0.
Following reset, the user can write any Xon/Xoff value desired for software flow control.
Different conditions can be set to detect Xon/Xoff characters and suspend/resume
transmissions (see Table 24). When double 8-bit Xon/Xoff characters are selected, the
SC16C850 compares two consecutive receive characters with two software flow control
8-bit values (Xon1, Xon2, Xoff1, Xoff2) and controls TX transmissions accordingly. Under
the above described flow control mechanisms, flow control characters are not placed
(stacked) in the receive FIFO. When using software flow control, the Xon/Xoff characters
cannot be used for data transfer.
In the event that the receive buffer is overfilling, the SC16C850 automatically sends an
Xoff character (when enabled) via the serial TX output to the remote UART. The
SC16C850 sends the Xoff1/Xoff2 characters as soon as the number of received data in
the receive FIFO passes the programmed trigger level. To clear this condition, the
SC16C850 will transmit the programmed Xon1/Xon2 characters as soon as the number of
characters in the receive FIFO drops below the programmed trigger level.
6.7 Special character detect
A special character detect feature is provided to detect an 8-bit character when EFR[5] is
set. When an 8-bit character is detected, it will be placed on the user-accessible data
stack along with normal incoming RX data. This condition is selected in conjunction with
EFR[3:0] (see Table 24). Note that software flow control should be turned off when using
this special mode by setting EFR[3:0] to all zeroes.
The SC16C850 compares each incoming receive character with Xoff2 data. If a match
occurs, the received data will be transferred to the FIFO, and ISR[4] will be set to indicate
detection of a special character. Although Table 8 “SC16C850 internal registers” shows
Xon1, Xon2, Xoff1, Xoff2 with eight bits of character information, the actual number of bits
is dependent on the programmed word length. Line Control Register bits LCR[1:0] define
the number of character bits, that is, either 5 bits, 6 bits, 7 bits or 8 bits. The word length
selected by LCR[1:0] also determines the number of bits that will be used for the special
character comparison. Bit 0 in Xon1, Xon2, Xoff1, Xoff2 corresponds with the LSB bit for
the received character.
6.8 Interrupt priority and time-out interrupts
The interrupts are enabled by IER[7:0]. Care must be taken when handling these
interrupts. Following a reset, if Interrupt Enable Register (IER) bit 1 = 1, the SC16C850
will issue a Transmit Holding Register interrupt. This interrupt must be serviced prior to
continuing operations. The ISR indicates the current singular highest priority interrupt
only. A condition can exist where a higher priority interrupt masks the lower priority
interrupt(s) (see Table 13). Only after servicing the higher pending interrupt will the lower
priority interrupt(s) be reflected in the status register. Servicing the interrupt without
investigating further interrupt conditions can result in data errors.
Receive Data Ready and Receive Time-Out have the same interrupt priority (when
enabled by IER[0]), and it is important to serve these interrupts correctly. The receiver
issues an interrupt after the number of characters have reached the programmed trigger
level. In this case, the SC16C850 FIFO may hold more characters than the programmed
trigger level. Following the removal of a data byte, the user should re-check LSR[0] to see
if there are any 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
SC16C850
Product data sheet
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Rev. 2 — 11 November 2010
© NXP B.V. 2010. All rights reserved.
13 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
each time the Receive Holding Register (RHR) is read. The actual time-out value is
4 character time, including data information length, start bit, parity bit, and the size of stop
bit, that is, 1×, 1.5×, or 2× bit times.
6.9 Programmable baud rate generator
The SC16C850 UART contains a programmable rational baud rate generator that takes
any clock input and divides it by a divisor in the range between 1 and (216 − 1). The
SC16C850 offers the capability of dividing the input frequency by rational divisor. The
fractional part of the divisor is controlled by the CLKPRES register in the ‘first extra feature
register set’.
f XTAL1
baud rate = ------------------------------------------------------------------M
MCR [ 7 ] × 16 × ⎛⎝ N + ------⎞⎠
16
(1)
where:
N is the integer part of the divisor in DLL and DLM registers;
M is the fractional part of the divisor in CLKPRES register;
fXTAL1 is the clock frequency at XTAL1 pin.
Prescaler = 1 when MCR[7] is set to 0.
Prescaler = 4 when MCR[7] is set to 1.
CLKPRES
[3:0]
DIVIDE-BY-1
MCR[7] = 0
XTAL1
XTAL2
BAUD RATE
GENERATOR
(DLL, DLM)
OSCILLATOR
DIVIDE-BY-4
transmitter and
receiver clock
MCR[7] = 1
002aac645
Fig 6.
Prescalers and baud rate generator block diagram
A single baud rate generator is provided for the transmitter and receiver. The
programmable Baud Rate Generator is capable of operating with a frequency of up to
80 MHz. To obtain maximum data rate, it is necessary to use full rail swing on the clock
input. The SC16C850 can be configured for internal or external clock operation. For
internal clock operation, an industry standard crystal is connected externally between the
XTAL1 and XTAL2 pins (see Figure 7). Alternatively, an external clock can be connected
to the XTAL1 pin (see Figure 8) to clock the internal baud rate generator for standard or
custom rates (see Table 7).
The generator divides the input 16× clock by any divisor from 1 to (216 − 1). The
SC16C850 divides the basic external clock by 16. The baud rate is configured via the
CLKPRES, 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 the baud
rate generator.
SC16C850
Product data sheet
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Rev. 2 — 11 November 2010
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14 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Programming the baud rate generator registers CLKPRES, DLM (MSB) and DLL (LSB)
provides a user capability for selecting the desired final baud rate. The example in Table 7
shows the selectable baud rate table available when using a 1.8432 MHz external clock
input when MCR[7] = 0, and CLKPRES = 0x00.
XTAL1
XTAL2
XTAL1
X1
1.8432 MHz
XTAL2
X1
1.8432 MHz
C1
22 pF
C2
33 pF
C1
22 pF
1.5 kΩ
C2
47 pF
002aaa870
Fig 7.
Crystal oscillator connection
XTAL1
fXTAL1
XTAL2
100 pF
002aac630
If fXTAL1 frequency is greater than 50 MHz, then a DC blocking capacitor is required.
XTAL2 pin should be left unconnected when an external clock is used.
Fig 8.
External clock connection
Table 7.
SC16C850
Product data sheet
Baud rate generator programming table using a 1.8432 MHz clock when
MCR[7] = 0 and CLKPRES[3:0] = 0
Output
baud rate
(bit/s)
Output
16× clock divisor
(decimal)
Output
16× clock divisor
(hexadecimal)
DLM
program value
(hexadecimal)
DLL
program value
(hexadecimal)
50
2304
900
09
00
75
1536
600
06
00
110
1047
417
04
17
150
768
300
03
00
300
384
180
01
80
600
192
C0
00
C0
1.2 k
96
60
00
60
2.4 k
48
30
00
30
3.6 k
32
20
00
20
4.8 k
24
18
00
18
7.2 k
16
10
00
10
9.6 k
12
0C
00
0C
19.2 k
6
06
00
06
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 7.
Baud rate generator programming table using a 1.8432 MHz clock when
MCR[7] = 0 and CLKPRES[3:0] = 0 …continued
Output
baud rate
(bit/s)
Output
16× clock divisor
(decimal)
Output
16× clock divisor
(hexadecimal)
DLM
program value
(hexadecimal)
DLL
program value
(hexadecimal)
38.4 k
3
03
00
03
57.6 k
2
02
00
02
115.2 k
1
01
00
01
6.10 Loopback mode
The internal loopback capability allows on-board diagnostics. In the Loopback mode, the
normal modem interface pins are disconnected and reconfigured for loopback internally
(see Figure 9). MCR[3:0] register bits are used for controlling loopback diagnostic testing.
In the Loopback mode, the transmitter output (TX) and the receiver input (RX) are
disconnected from their associated interface pins, and instead are connected together
internally. The CTS, DSR, CD, and RI are disconnected from their normal modem control
input pins, and instead are connected internally to RTS, DTR, MCR[3] (OP2) and MCR[2]
(OP1). Loopback test data is entered into the transmit holding register via the user data
bus interface, D[7:0]. The transmit UART serializes the data and passes the serial data to
the receive UART via the internal loopback connection. The receive UART converts the
serial data back into parallel data that is then made available at the user data interface
D[7:0]. 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 interrupt pin is 3-stated, therefore, the software must use the polling
method (see Section 7.2.2) to send and receive data.
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
SC16C850
D0 to D7
IOR
IOW
RESET
TRANSMIT
SHIFT
REGISTER
DATA BUS
AND
CONTROL
LOGIC
INTERCONNECT BUS LINES
AND
CONTROL SIGNALS
FLOW
CONTROL
LOGIC
A0 to A2
CS
TX
REGISTER
SELECT
LOGIC
RECEIVE
FIFO
REGISTERS
IR
ENCODER
MCR[4] = 1
TRANSMIT
FIFO
REGISTERS
RECEIVE
SHIFT
REGISTER
FLOW
CONTROL
LOGIC
RX
IR
DECODER
RTS
LOWPWR
CTS
POWERDOWN
CONTROL
DTR
MODEM
CONTROL
LOGIC
INT
(IRQ)
INTERRUPT
CONTROL
LOGIC
DSR
OP1
CLOCK AND
BAUD RATE
GENERATOR
RI
OP2
CD
002aad026
XTAL1 XTAL2
Fig 9.
Internal Loopback mode diagram
SC16C850
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
6.11 Sleep mode
Sleep mode is an enhanced feature of the SC16C850 UART. It is enabled when EFR[4],
the enhanced functions bit, is set and when IER[4] bit is set.
6.11.1 Conditions to enter Sleep mode
Sleep mode is entered when:
• Modem input pins are not toggling.
• The serial data input line, RX, is idle for 4 character time (logic HIGH) and AFCR1[4]
is logic 0. When AFCR1[4] is logic 1 the device will go to sleep regardless of the state
of the RX pin (see Section 7.21 for the description of AFCR1 bit 4).
• The TX FIFO and TX shift register are empty.
• There are no interrupts pending.
• The RX FIFO is empty.
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.
Remark: Writing to the divisor latches, DLL and DLM, 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 DLM.
6.11.2 Conditions to resume normal operation
SC16C850 resumes normal operation by any of the following:
• Receives a start bit on RX pin.
• Data is loaded into transmit FIFO.
• A change of state on any of the modem input pins
If the device is awakened by one of the conditions described above, it will return to the
Sleep mode automatically after all the conditions described in Section 6.11.1 are met. The
device will stay in Sleep mode until it is disabled by setting any channel’s IER bit 4 to a
logic 0.
When the SC16C850 is in Sleep mode and the host data bus (D[7:0], A[2:0], IOW, IOR,
CS) remains in steady state, either HIGH or LOW, the Sleep mode supply current will be
in the μA range as specified in Table 36 “Static characteristics”. If any of these signals is
toggling or floating then the sleep current will be higher.
6.12 Low power feature
A low power feature is provided by the SC16C850 to prevent the switching of the host
data bus from influencing the sleep current. When the pin LOWPWR is activated (logic
HIGH), the device immediately and unconditionally goes into Low power mode. All clocks
are stopped and most host interface pins are isolated to reduce power consumption. The
device only returns to normal mode when the LOWPWR pin is de-asserted. The pin can
be left unconnected because it has an internal pull-down resistor.
SC16C850
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
6.13 RS-485 features
6.13.1 Auto RS-485 RTS control
Normally the RTS pin is controlled by MCR[1], or if hardware flow control is enabled, the
logic state of the RTS pin is controlled by the hardware flow control circuitry. AFCR2[4] will
take the precedence over the other two modes; once this bit is set, the transmitter will
control the state of the RTS pin. The transmitter automatically asserts the RTS pin
(logic 0) once the host writes data to the transmit FIFO, and de-asserts RTS pin (logic 1)
once the last bit of the data has been transmitted.
To use the auto RS-485 RTS mode the software would have to disable the hardware
flow control function.
6.13.2 RS-485 RTS inversion
AFCR2[5] reverses the polarity of the RTS pin if the UART is in auto RS-485 RTS mode.
When the transmitter has data to be sent it will de-asserts the RTS pin (logic 1), and when
the last bit of the data has been sent out the transmitter asserts the RTS pin (logic 0).
6.13.3 Auto 9-bit mode (RS-485)
AFCR2[0] is used to enable the 9-bit mode (Multi-drop or RS-485 mode). In this mode of
operation, a ‘master’ station transmits an address character followed by data characters
for the addressed ‘slave’ stations. The slave stations examine the received data and
interrupt the controller if the received character is an address character (parity bit = 1).
To use the automatic 9-bit mode, the software would have to disable the hardware and
software flow control functions.
6.13.3.1
Normal Multi-drop mode
The 9-bit Mode in AFCR2[0] is enabled, but not Special Character Detect (EFR[5]). The
receiver is set to Force Parity 0 (LCR[5:3] = 111) in order to detect address bytes.
With the receiver initially disabled, it ignores all the data bytes (parity bit = 0) until an
address byte is received (parity bit = 1). This address byte will cause the UART to set the
parity error. The UART will generate a line status interrupt (IER[2] must be set to ‘1’ at this
time), and at the same time puts this address byte in the RX FIFO. After the controller
examines the byte it must make a decision whether or not to enable the receiver; it should
enable the receiver if the address byte addresses its ID address, and must not enable the
receiver if the address byte does not address its ID address.
If the controller enables the receiver, the receiver will receive the subsequent data until
being disabled by the controller after the controller has received a complete message
from the ‘master’ station. If the controller does not disable the receiver after receiving a
message from the ‘master’ station, the receiver will generate a parity error upon receiving
another address byte. The controller then determines if the address byte addresses its ID
address, if it is not, the controller then can disable the receiver. If the address byte
addresses the ‘slave’ ID address, the controller takes no further action, and the receiver
will receive the subsequent data.
SC16C850
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
6.13.3.2
Auto address detection
If Special Character Detect is enabled (EFR[5] is set and the Xoff2 register contains the
address byte) the receiver will try to detect an address byte that matches the programmed
character in the Xoff2 register. If the received byte is a data byte or an address byte that
does not match the programmed character in the Xoff2 register, the receiver will discard
these data. Upon receiving an address byte that matches the Xoff2 character, the receiver
will be automatically enabled if not already enabled, and the address character is pushed
into the RX FIFO along with the parity bit (in place of the parity error bit). The receiver also
generates a line status interrupt (IER[2] must be set to ‘1’ at this time). The receiver will
then receive the subsequent data from the ‘master’ station until being disabled by the
controller after having received a message from the ‘master’ station.
If another address byte is received and this address byte does not match the Xoff2
character, the receiver will be automatically disabled and the address byte is ignored. If
the address byte matches the Xoff2 character, the receiver will put this byte in the RX
FIFO along with the parity bit in the parity error bit (LSR bit 2).
7. Register descriptions
Table 8 details the assigned bit functions for the SC16C850 internal registers. The
assigned bit functions are more fully defined in Section 7.1 through Section 7.23.
SC16C850
Product data sheet
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20 of 55
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx x x x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xx xx xxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxx x x
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx xxx
NXP Semiconductors
SC16C850
Product data sheet
Table 8.
SC16C850 internal registers
A2 A1 A0 Register
General register
Default[1]
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R/W
set[2]
0
0
RHR
0xXX
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R
0
0
0
THR
0xXX
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
W
0
0
1
IER
0x00
CTS
interrupt[3]
RTS
interrupt[3]
Xoff
interrupt[3]
Sleep
mode[3]
modem
status
interrupt
receive line
status
interrupt
transmit
holding
register
interrupt
receive
holding
register
interrupt
R/W
0
1
0
FCR
0x00
RCVR
trigger
(MSB)
RCVR
TX trigger
trigger (LSB) (MSB)[3]
TX trigger
(LSB)[3]
reserved
XMIT FIFO
reset
RCVR FIFO FIFOs
reset
enable
W
0
1
0
ISR
0x01
FIFOs
enabled
FIFOs
enabled
INT priority
bit 4
INT priority
bit 3
INT priority
bit 2
INT priority
bit 1
INT priority
bit 0
INT status
R
0
1
1
LCR
0x00
divisor latch
enable
set break
set parity
even parity
parity
enable
stop bits
word length
bit 1
word length
bit 0
R/W
1
0
0
MCR
0x00
clock
select[3]
IrDA enable
INT type
loopback
OP2
OP1
RTS
DTR
R/W
1
0
1
LSR
0x60
FIFO data
error
THR and
TSR empty
THR empty
break
interrupt
framing
error
parity error
overrun
error
receive data R
ready
1
0
1
EFCR
0x00
reserved
reserved
reserved
reserved
reserved
Enable extra Enable extra Enable
W
feature bit 1 feature bit 0 TXLVLCNT/
RXLVLCNT
1
1
0
MSR
0xX0
CD
RI
DSR
CTS
ΔCD
ΔRI
ΔDSR
ΔCTS
R
1
1
1
SPR
0xFF
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
Special register
set[4]
0
0
0
DLL
0xXX
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
0
0
1
DLM
0xXX
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
R/W
Second special register set[6]
1
1
TXLVLCNT
0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R
1
0
0
RXLVLCNT
0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R
SC16C850
21 of 55
© NXP B.V. 2010. All rights reserved.
0
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Rev. 2 — 11 November 2010
All information provided in this document is subject to legal disclaimers.
0
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx x x x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xx xx xxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxx x x
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx xxx
SC16C850 internal registers …continued
A2 A1 A0 Register
Default[1]
Enhanced feature register
set[5]
0
1
0
EFR
1
0
0
1
0
1
1
1
1
1
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
R/W
0x00
Auto CTS
Auto RTS
special
character
select
Enable
IER[7:4],
ISR[5:4],
FCR[5:4],
MCR[7:5]
Cont-3 TX,
RX Control
Cont-2 TX,
RX Control
Cont-1 TX,
RX Control
Cont-0 TX,
RX Control
R/W
Xon1
0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
Xon2
0x00
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
R/W
0
Xoff1
0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
1
Xoff2
0x00
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
R/W
0
1
0
TXINTLVL
0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
1
0
0
RXINTLVL
0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
1
1
0
FLWCNTH
0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
1
1
1
FLWCNTL
0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
reserved
reserved
reserved
reserved
bit 3
bit 2
bit 1
bit 0
R/W
bit 4
bit 3
bit 2
bit 1
bit 0
R/W
Second extra feature register set[8]
0
1
0
CLKPRES
0x00
1
0
0
RS485TIME 0x00
bit 7
bit 6
bit 5
1
1
0
AFCR2
0x00
reserved
reserved
RS485 RTS Auto RS485 RS485
Invert
RTS
RTS/DTR
Transmitter
Disable
Receiver
Disable
9-bit Enable R/W
1
1
1
AFCR1
0x00
reserved
reserved
reserved
RTS/CTS
mapped to
DTR/DSR
Software
Reset
TSR
Interrupt
The value shown represents the register’s initialized HEX value; X = not applicable.
[2]
Accessible only when LCR[7] is logic 0, and EFCR[2:0] are logic 000b.
[3]
This bit is only accessible when EFR[4] is set.
[4]
Baud rate registers accessible only when LCR[7] is logic 1.
reserved
22 of 55
© NXP B.V. 2010. All rights reserved.
[5]
Enhanced Feature Register, Xon1/Xon2 and Xoff1/Xoff2 are accessible only when LCR is set to 0xBF, and EFCR[2:1] are logic 0.
[6]
Second Special registers are accessible only when EFCR[0] = 1, and EFCR[2:1] are logic 0.
[7]
First extra feature register set is only accessible when EFCR[2:1] = 01b.
[8]
Second extra feature register set is only accessible when EFCR[2:1] = 10b.
R/W
SC16C850
[1]
Sleep
RXLow
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Rev. 2 — 11 November 2010
All information provided in this document is subject to legal disclaimers.
First extra feature register
set[7]
NXP Semiconductors
SC16C850
Product data sheet
Table 8.
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
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 to D0) to the
transmit FIFO. The THR empty flag in the LSR will be set to a logic 1 when the transmit
FIFO is empty or when data is transferred to the TSR.
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 SC16C850
receive FIFO by reading the RHR. 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 71⁄2 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 INT output pin.
Table 9.
Interrupt Enable Register bits description
Bit
Symbol Description
7
IER[7]
CTS interrupt.
logic 0 = disable the CTS interrupt (normal default condition)
logic 1 = enable the CTS interrupt. The SC16C850 issues an interrupt when
the CTS pin transitions from a logic 0 to a logic 1.
6
IER[6]
RTS interrupt.
logic 0 = disable the RTS interrupt (normal default condition)
logic 1 = enable the RTS interrupt. The SC16C850 issues an interrupt when
the RTS pin transitions from a logic 0 to a logic 1.
5
IER[5]
Xoff interrupt.
logic 0 = disable the software flow control, receive Xoff interrupt (normal default
condition)
logic 1 = enable the receive Xoff interrupt
4
IER[4]
Sleep mode.
logic 0 = disable Sleep mode (normal default condition)
logic 1 = enable Sleep mode
3
IER[3]
Modem Status Interrupt. This interrupt will be issued whenever there is a modem
status change as reflected in MSR[3:0].
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[4:1].
logic 0 = disable the receiver line status interrupt (normal default condition)
logic 1 = enable the receiver line status interrupt
SC16C850
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SC16C850
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 9.
Interrupt Enable Register bits description …continued
Bit
Symbol Description
1
IER[1]
Transmit Holding Register interrupt. In the non-FIFO 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 is empty.
logic 0 = disable the Transmit Holding Register Empty (TXRDY) interrupt
(normal default condition)
logic 1 = enable the TXRDY (ISR level 3) interrupt
0
IER[0]
Receive Holding Register interrupt. In the non-FIFO 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 is enabled (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, 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, setting IER[3:0] puts the SC16C850 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).
•
•
•
•
•
SC16C850
Product data sheet
LSR[0] will be a logic 1 as long as there is one byte in the receive FIFO.
LSR[4:1] 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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SC16C850
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
7.3 FIFO Control Register (FCR)
This register is used to enable the FIFOs, clear the FIFOs, and set the receive FIFO
trigger levels.
7.3.1 FIFO mode
Table 10.
FIFO Control Register bits description
Bit
Symbol
Description
7:6
FCR[7:6]
Receive trigger level in 32-byte FIFO mode[1].
These bits are used to set the trigger levels for receive FIFO interrupt and flow
control. The SC16C850 will issue a receive ready interrupt when the number of
characters in the receive FIFO reaches the selected trigger level. Refer to
Table 11.
5:4
FCR[5:4]
Transmit trigger level in 32-byte FIFO mode[2].
These bits are used to set the trigger level for the transmit FIFO interrupt and
flow control. The SC16C850 will issue a transmit empty interrupt when the
number of characters in FIFO drops below the selected trigger level. Refer to
Table 12.
3
FCR[3]
reserved
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. 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. This bit will return to a logic 0 after clearing the FIFO.
0
FCR[0]
FIFO enable.
logic 0 = disable the transmit and receive FIFO (normal default condition)
logic 1 = enable the transmit and receive FIFO
[1]
For 128-byte FIFO mode, refer to Section 7.16, Section 7.17, Section 7.18.
[2]
For 128-byte FIFO mode, refer to Section 7.15, Section 7.17, Section 7.18.
Table 11.
FCR[6]
RX FIFO trigger level (bytes) in 32-byte FIFO mode[1]
0
0
8
0
1
16
1
0
24
1
1
28
[1]
SC16C850
Product data sheet
RCVR trigger levels
FCR[7]
When RXINTLVL, TXINTLVL, FLWCNTL or FLWCNTH contains any value other than 0x00, receive and
transmit trigger levels are set by RXINTLVL, TXINTLVL registers (see Section 6.4 “FIFO operation”).
All information provided in this document is subject to legal disclaimers.
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 12.
TX FIFO trigger levels
FCR[5]
FCR[4]
TX FIFO trigger level (bytes) in 32-byte FIFO mode[1]
0
0
16
0
1
8
1
0
24
1
1
30
[1]
When RXINTLVL, TXINTLVL, FLWCNTL or FLWCNTH contains any value other than 0x00, receive and
transmit trigger levels are set by RXINTLVL, TXINTLVL registers (see Section 6.4 “FIFO operation”).
7.4 Interrupt Status Register (ISR)
The SC16C850 provides six levels of prioritized interrupts to minimize external software
interaction. The Interrupt Status Register (ISR) provides the user with six 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. A lower level interrupt may be seen after servicing the higher level
interrupt and re-reading the interrupt status bits. Table 13 “Interrupt source” shows the
data values (bits 5:0) for the six prioritized interrupt levels and the interrupt sources
associated with each of these interrupt levels.
Table 13.
Interrupt source
Priority ISR[5]
level
ISR[4]
ISR[3]
ISR[2]
ISR[1]
ISR[0]
Source of the interrupt
1
0
0
0
1
1
0
LSR (Receiver Line Status
Register)
2
0
0
0
1
0
0
RXRDY (Received Data Ready)
2
0
0
1
1
0
0
RXRDY (Receive Data time-out)
3
0
0
0
0
1
0
TXRDY (Transmitter Holding
Register Empty)
4
0
0
0
0
0
0
MSR (Modem Status Register)
5
0
1
0
0
0
0
RXRDY (Received Xoff signal)/
Special character
6
1
0
0
0
0
0
CTS, RTS change of state
Table 14.
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 non-FIFO mode. They are set to a logic 1 when the FIFOs are
enabled in the SC16C850 mode.
logic 0 or cleared = default condition
5:4
ISR[5:4]
INT priority bits 4:3. These bits are enabled when EFR[4] is set to a logic 1.
ISR[4] indicates that matching Xoff character(s) have been detected. ISR[5]
indicates that CTS, RTS have been generated. Note that once set to a
logic 1, the ISR[4] bit will stay a logic 1 until Xon character(s) are received.
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 13).
logic 0 or cleared = default condition
SC16C850
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SC16C850
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 14.
Interrupt Status Register bits description …continued
Bit
Symbol
Description
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)
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 15.
Line Control Register bits description
Bit
Symbol
Description
7
LCR[7]
Divisor latch enable. The internal baud rate counter latch and Enhanced
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 16).
2
LCR[2]
Stop bits. The length of stop bit is specified by this bit in conjunction with the
programmed word length (see Table 17).
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 18).
logic 0 or cleared = default condition
SC16C850
Product data sheet
Table 16.
LCR[5:3] parity selection
LCR[5]
LCR[4]
LCR[3]
Parity selection
X
X
0
no parity
0
0
1
odd parity
0
1
1
even parity
1
0
1
forced parity ‘1’
1
1
1
forced parity ‘0’
Table 17.
LCR[2] stop bit length
LCR[2]
Word length (bits)
Stop bit length (bit times)
0
5, 6, 7, 8
1
1
5
11⁄2
1
6, 7, 8
2
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 18.
LCR[1:0] word length
LCR[1]
LCR[0]
Word length (bits)
0
0
5
0
1
6
1
0
7
1
1
8
7.6 Modem Control Register (MCR)
This register controls the interface with the modem or a peripheral device.
Table 19.
Modem Control Register bits description
Bit
Symbol
Description
7
MCR[7]
Clock select
logic 0 = divide-by-1 clock input
logic 1 = divide-by-4 clock input
6
MCR[6]
IR enable (see Figure 22).
logic 0 = enable the standard modem receive and transmit input/output
interface (normal default condition)
logic 1 = enable infrared IrDA receive and transmit inputs/outputs. While
in this mode, the TX/RX output/inputs are routed to the infrared
encoder/decoder. The data input and output levels will conform to the
IrDA infrared interface requirement. As such, while in this mode, the
infrared TX output will be a logic 0 during idle data conditions.
5
MCR[5]
Interrupt type (Intel mode only). In Intel mode (16/68 = 1), this pin
determines the interrupt output pin configuration.
logic 0 = CMOS output
logic 1 = open-source. A 300 Ω to 500 Ω pull-down resistor is required.
In Motorola mode (16/68 = 0), the output is always open-drain.
4
MCR[4]
Loopback. Enable the local loopback mode (diagnostics). In this mode the
transmitter output (TX) and the receiver input (RX), CTS, DSR, CD, and RI
are disconnected from the SC16C850 I/O pins. Internally the modem data
and control pins are connected into a loopback data configuration (see
Figure 9). 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 Loopback mode (normal default condition)
logic 1 = enable local Loopback mode (diagnostics)
3
MCR[3]
OP2. This bit is used for internal Loopback mode only. In Loopback mode,
this bit is used to write the state of the modem CD interface signal.
2
MCR[2]
OP1. This bit is used for internal Loopback mode only. In Loopback 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
SC16C850
Product data sheet
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SC16C850
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
7.7 Line Status Register (LSR)
This register provides the status of data transfers between the SC16C850 and the CPU.
Table 20.
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 there are no remaining error flags
associated with the remaining data in the FIFO.
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.
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
SC16C850
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SC16C850
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
7.8 Modem Status Register (MSR)
This register shares the same address as EFCR register. This is a read-only register and
it provides the current state of the control interface signals from the modem, or other
peripheral device to which the SC16C850 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.
When write, the data will be written to EFCR register.
Table 21.
Modem Status Register bits description
Bit
Symbol
Description
7
MSR[7]
CD. During normal operation, this bit is the complement of the CD input.
Reading this bit in the loopback mode produces the state of MCR[3] (OP2).
6
MSR[6]
RI. During normal operation, this bit is the complement of the RI input.
Reading this bit in the loopback mode produces the state of MCR[2] (OP1).
5
MSR[5]
DSR. During normal operation, this bit is the complement of the DSR input.
During the loopback mode, this bit is equivalent to MCR[0] (DTR).
4
MSR[4]
CTS. During normal operation, this bit is the complement of the CTS input.
During the loopback mode, this bit is equivalent to MCR[1] (RTS).
3
MSR[3]
ΔCD [1]
logic 0 = no CD change (normal default condition)
logic 1 = the CD input to the SC16C850 has changed state since the last
time it was read. A modem Status Interrupt will be generated.
2
MSR[2]
ΔRI [1]
logic 0 = no RI change (normal default condition)
logic 1 = the RI input to the SC16C850 has changed from a logic 0 to a
logic 1. A modem Status Interrupt will be generated.
1
MSR[1]
ΔDSR [1]
logic 0 = no DSR change (normal default condition)
logic 1 = the DSR input to the SC16C850 has changed state since the
last time it was read. A modem Status Interrupt will be generated.
0
MSR[0]
ΔCTS [1]
logic 0 = no CTS change (normal default condition)
logic 1 = the CTS input to the SC16C850 has changed state since the last
time it was read. A modem Status Interrupt will be generated.
[1]
SC16C850
Product data sheet
Whenever any MSR bit 3:0 is set to logic 1, a Modem Status Interrupt will be generated.
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
7.9 Extra Feature Control Register (EFCR)
This is a write-only register, and it allows the software access to these registers: ‘first extra
feature register set’, ‘second extra feature register set’, Transmit FIFO Level Counter
(TXLVLCNT), and Receive FIFO Level Counter (RXLVLCNT).
Table 22.
Extra Feature Control Register bits description
Bit
Symbol
Description
7:3
EFCR[7:3]
reserved
2:1
EFCR[2:1]
Enable Extra Feature Control bits
00 = General register set is accessible
01 = First extra feature register set is accessible
10 = Second extra feature register set is accessible
11 = reserved
0
EFCR[0]
Enable TXLVLCNT and RXLVLCNT access
0 = TXLVLCNT and RXLVLCNT are disabled
1 = TXLVLCNT and RXLVLCNT are enabled and can be read.
Remark: EFCR[2:1] has higher priority than EFCR[0]. TXLVLCNT and RXLVLCNT can
only be accessed if EFCR[2:1] are zeroes.
7.10 Scratchpad Register (SPR)
The SC16C850 provides a temporary data register to store 8 bits of user information.
7.11 Divisor Latch (DLL and DLM)
These are two 8-bit registers which store the 16-bit divisor for generation of the baud clock
in the baud rate generator. DLM, stores the most significant part of the divisor. DLL stores
the least significant part of the divisor.
7.12 Transmit FIFO Level Count (TXLVLCNT)
This register is a read-only register. It reports the number of spaces available in the
transmit FIFO.
7.13 Receive FIFO Level Count (RXLVLCNT)
This register is a read-only register. It reports the fill level of the receive FIFO (the number
of characters in the RX FIFO).
SC16C850
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
7.14 Enhanced Feature Register (EFR)
Enhanced features are enabled or disabled using this register.
Bits 0 through 4 provide single or dual character software flow control selection. When the
Xon1 and Xon2 and/or Xoff1 and Xoff2 modes are selected, the double 8-bit words are
concatenated into two sequential numbers.
Table 23.
Enhanced Feature Register bits description
Bit
Symbol
Description
7
EFR[7]
Automatic CTS flow control.
logic 0 = automatic CTS flow control is disabled (normal default condition)
logic 1 = enable automatic CTS flow control. Transmission will stop when
CTS goes to a logical 1. Transmission will resume when the CTS pin returns
to a logical 0.
6
EFR[6]
Automatic RTS flow control. Automatic RTS may be used for hardware flow
control by enabling EFR[6]. When Auto-RTS is selected, an interrupt will be
generated when the receive FIFO is filled to the programmed trigger level and
RTS will go to a logic 1 at the next trigger level. RTS will return to a logic 0 when
data is unloaded below the next lower trigger level (programmed trigger level 1).
The state of this register bit changes with the status of the hardware flow
control. RTS functions normally when hardware flow control is disabled.
logic 0 = automatic RTS flow control is disabled (normal default condition)
logic 1 = enable automatic RTS flow control
5
EFR[5]
Special Character Detect.
logic 0 = special character detect disabled (normal default condition)
logic 1 = special character detect enabled. The SC16C850 compares each
incoming receive character with Xoff2 data. If a match exists, the received
data will be transferred to FIFO and ISR[4] will be set to indicate detection of
special character. Bit 0 in the X-registers corresponds with the LSB bit for the
receive character. When this feature is enabled, the normal software flow
control must be disabled (EFR[3:0] must be set to a logic 0).
4
EFR[4]
Enhanced function control bit. The content of IER[7:4], ISR[5:4], FCR[5:4], and
MCR[7:5] can be modified and latched. After modifying any bits in the enhanced
registers, EFR[4] can be set to a logic 0 to latch the new values. This feature
prevents existing software from altering or overwriting the SC16C850 enhanced
functions.
logic 0 = disable/latch enhanced features[1]. (Normal default condition.)
logic 1 = enables the enhanced functions[1].
3:0
[1]
SC16C850
Product data sheet
EFR[3:0] Cont-3:0 TX, RX control. Logic 0 or cleared is the default condition.
Combinations of software flow control can be selected by programming these
bits. See Table 24.
Enhanced function control bits IER[7:4], ISR[5:4], FCR[5:4] and MCR[7:5].
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SC16C850
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Software flow control functions[1]
Table 24.
Cont-3
Cont-2
Cont-1
Cont-0
TX, RX software flow controls
0
0
X
X
No transmit flow control
1
0
X
X
Transmit Xon1/Xoff1
0
1
X
X
Transmit Xon2/Xoff2
1
1
X
X
Transmit Xon1 and Xon2/Xoff1 and Xoff2
X
X
0
0
No receive flow control
X
X
1
0
Receiver compares Xon1/Xoff1
X
X
0
1
Receiver compares Xon2/Xoff2
1
0
1
1
Transmit Xon1/Xoff1
Receiver compares Xon1 or Xon2, Xoff1 or Xoff2
0
1
1
1
Transmit Xon2/Xoff2
Receiver compares Xon1 or Xon2, Xoff1 or Xoff2
1
1
1
1
Transmit Xon1 and Xon2, Xoff1 and Xoff2
Receiver compares Xon1 and Xon2, Xoff1 and Xoff2
[1]
When using a software flow control the Xon/Xoff characters cannot be used for data transfer.
7.15 Transmit Interrupt Level Register (TXINTLVL)
This 8-bit register is used to store the transmit FIFO trigger levels used for interrupt
generation. Trigger levels from 1 to 128 can be programmed with a granularity of 1.
Table 25 shows the TXINTLVL register bit settings.
Table 25.
TXINTLVL register bits description
Bit
Symbol
Description
7:0
TXINTLVL[7:0]
This register stores the programmable transmit interrupt trigger levels
for 128-byte FIFO mode[1].
0x00 = trigger level is set to 1
0x01 = trigger level is set to 1
...
0x80 = trigger level is set to 128
[1]
For 32-byte FIFO mode, refer to Section 7.3.
7.16 Receive Interrupt Level Register (RXINTLVL)
This 8-bit register is used store the receive FIFO trigger levels used for interrupt
generation. Trigger levels from 1 to 128 can be programmed with a granularity of 1.
Table 26 shows the RXINTLVL register bit settings.
Table 26.
RXINTLVL register bits description
Bit
Symbol
Description
7:0
RXINTLVL[7:0]
This register stores the programmable receive interrupt trigger levels
for 128-byte FIFO mode[1].
0x00 = trigger level is set to 1
0x01 = trigger level is set to 1
...
0x80 = trigger level is set to 128
SC16C850
Product data sheet
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33 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
[1]
For 32-byte FIFO mode, refer to Section 7.3.
7.17 Flow Control Trigger Level High (FLWCNTH)
This 8-bit register is used to store the receive FIFO high threshold levels to start/stop
transmission during hardware/software flow control. Table 27 shows the FLWCNTH
register bit settings; see Section 6.5.
Table 27.
FLWCNTH register bits description
Bit
Symbol
Description
7:0
FLWCNTH[7:0]
This register stores the programmable HIGH threshold level for
hardware and software flow control for 128-byte FIFO mode[1].
0x00 = trigger level is set to 1
0x01 = trigger level is set to 1
...
0x80 = trigger level is set to 128
[1]
For 32-byte FIFO mode, refer to Section 7.3.
7.18 Flow Control Trigger Level Low (FLWCNTL)
This 8-bit register is used to store the receive FIFO low threshold levels to start/stop
transmission during hardware/software flow control. Table 28 shows the FLWCNTL
register bit settings; see Section 6.5.
Table 28.
FLWCNTL register bits description
Bit
Symbol
Description
7:0
FLWCNTL[7:0]
This register stores the programmable LOW threshold level for
hardware and software flow control for 128-byte FIFO mode[1].
0x00 = trigger level is set to 1
0x01 = trigger level is set to 1
...
0x80 = trigger level is set to 128
[1]
For 32-byte FIFO mode, refer to Section 7.3.
7.19 Clock Prescaler (CLKPRES)
This register hold values for the clock prescaler.
Table 29.
SC16C850
Product data sheet
Clock Prescaler register bits description
Bit
Symbol
Description
7:4
CLKPRES[7:4]
reserved
3:0
CLKPRES[3:0]
Clock Prescaler value. Reset to 0.
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
7.20 RS-485 Turn-around time delay (RS485TIME)
The value in this register controls the turn-around time of the external line transceiver in
bit time. In automatic 9-bit mode RTS or DTR pin is used to control the direction of the line
driver, after the last bit of data has been shifted out of the transmit shift register the UART
will count down the value in this register. When the count value reaches zero, the UART
will assert RTS or DTR pin (logic 0) to turn the external RS-485 transceiver around for
receiving.
Table 30.
RS-485 programmable turn-around time register bits description
Bit
Symbol
Description
7:0
RS485TIME[7:0]
External RS-485 transceiver turn-around time delay. The value
represents the bit time at the programmed baud rate.
7.21 Advanced Feature Control Register 2 (AFCR2)
Table 31.
Advanced Feature Control Register 2 register bits description
Bit
Symbol
Description
7:6
AFCR2[7:6]
reserved
5
AFCR2[5]
RTSInvert. Invert RTS or DTR signal in automatic 9-bit mode.
logic 0 = RTS or DTR is set to 0 by the UART during transmission,
and to 1 during reception
logic 1 = RTS or DTR is set to 1 by the UART during transmission,
and to 0 during reception
4
AFCR2[4]
RTSCon. Enable the transmitter to control RTS or DTR pin in
automatic 9-bit mode.
logic 0 = transmitter does not control RTS or DTR pin
logic 1 = transmitter controls RTS or DTR pin
3
AFCR2[3]
RS485 RTS/DTR. Select RTS or DTR pin to control the external
transceiver.
logic 0 = RTS pin is used to control the external transceiver
logic 1 = DTR pin is used to control the external transceiver
2
AFCR2[2]
TXDisable. Disable transmitter
logic 0 = transmitter is enabled
logic 1 = transmitter is disabled
1
AFCR2[1]
RXDisable. Disable receiver
logic 0 = receiver is enabled
logic 1 = receiver is disabled
0
AFCR2[0]
9-bitMode. Enable 9-bit mode or Multidrop (RS-485) mode
logic 0 = normal RS-232 mode
logic 1 = enable 9-bit mode
SC16C850
Product data sheet
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
7.22 Advanced Feature Control Register 1 (AFCR1)
Table 32.
Advanced Feature Control Register 1 register bits description
Bit
Symbol
Description
7:5
AFCR1[7:5]
reserved
4
AFCR1[4]
Sleep RXLow. Program RX input to be edge-sensitive or level-sensitive.
logic 0 = RX input is level-sensitive. If RX pin is LOW, the UART will
not go to sleep. Once the UART is in Sleep mode, it will wake up if RX
pin goes LOW.
logic 1 = RX input is edge-sensitive. UART will go to sleep even if RX
pin is LOW, and will wake up when RX pin toggles.
3
AFCR1[3]
reserved
2
AFCR1[2]
RTS/CTS mapped to DTR/DSR. Switch the function of RTS/CTS to
DTR/DSR.
logic 0 = RTS and CTS signals are used for hardware flow control.
logic 1 = DTR and DSR signals are used for hardware flow control.
RTS and CTS retain their functionality.
1
AFCR1[1]
SReset. Software Reset. A write to this bit will reset the UART. Once the
UART is reset this bit is automatically set to 0.[1]
0
AFCR1[0]
TSR Interrupt. Select TSR interrupt mode
logic 0 = transmit empty interrupt occurs when transmit FIFO falls
below the trigger level or becomes empty.
logic 1 = transmit empty interrupt occurs when transmit FIFO falls
below the trigger level, or becomes empty and the last stop bit has
been shifted out of the Transmit Shift Register.
[1]
SC16C850
Product data sheet
It takes 4 XTAL1 clocks to reset the device.
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
7.23 SC16C850 external reset condition and software reset
These two reset methods are identical and will reset the internal registers as indicated in
Table 33.
Table 33.
Reset state for registers
Register
Reset state
IER
IER[7:0] = 0
FCR
FCR[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
EFCR
EFCR[7:0] = 0
SPR
SPR[7:0] = 1
DLL
undefined
DLM
undefined
TXLVLCNT
TXLVLCNT[7:0] = 0
RXLVLCNT
RXLVLCNT[7:0] = 0
EFR
EFR[7:0] = 0
Xon1
undefined
Xon2
undefined
Xoff1
undefined
Xoff2
undefined
TXINTLVL
TXINTLVL[7:0] = 0
RXINTLVL
RXINTLVL[7:0] = 0
FLWCNTH
FLWCNTH[7:0] = 0
FLWCNTL
FLWCNTL[7:0] = 0
CLKPRES
CLKPRES[7:0] = 0
RS485TIME
RS485TIME[7:0] = 0
AFCR2
AFCR2[7:0] = 0
AFCR1
AFCR1[7:0] = 0
Table 34.
SC16C850
Product data sheet
Reset state for outputs
Output
Reset state
TX
logic 1
RTS
logic 1
DTR
logic 1
INT
logic 0
IRQ
open-drain
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
8. Limiting values
Table 35. Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol
Parameter
VDD
supply voltage
Vn
voltage on any other pin
Tamb
ambient temperature
Tstg
Ptot/pack
Conditions
Min
Max
Unit
-
7
V
VSS − 0.3
VDD + 0.3 V
−40
+85
°C
storage temperature
−65
+150
°C
total power dissipation per
package
-
500
mW
operating in free air
9. Static characteristics
Table 36. Static characteristics
Tamb = −40 °C to +85 °C; tolerance of VDD ± 10 %; unless otherwise specified.
Symbol
Parameter
Conditions
VDD = 2.5 V
VDD = 3.3 V
Min
Max
Min
Unit
Max
VIL(clk)
clock LOW-level input voltage
XTAL1 pin
−0.3
0.45
−0.3
0.6
V
VIH(clk)
clock HIGH-level input voltage
XTAL1 pin
1.8
VDD
2.4
VDD
V
VIL
LOW-level input voltage
except XTAL1 clock,
LOWPWR pin
−0.3
0.65
−0.3
0.8
V
−0.3
0.65
−0.3
0.8
V
1.6
-
2.0
-
V
VDD
2.2
VDD
V
LOWPWR pin
HIGH-level input voltage
VIH
except XTAL1 clock,
LOWPWR pin
LOW-level output voltage
VOL
VOH
[1]
HIGH-level output voltage
LOWPWR pin
[1]
1.6
IOL = 4 mA
[2]
-
-
-
0.4
V
IOL = 2 mA
[2]
-
0.4
-
-
V
IOH = −4 mA
[2]
-
-
2.2
-
V
IOH = −800 μA
[2]
1.85
-
-
-
V
ILIL
LOW-level input leakage current
-
10
-
10
μA
ILIH
HIGH-level input leakage current
-
10
-
10
μA
IL(clk)
clock leakage current
LOW-level
-
30
-
30
μA
HIGH-level
-
30
-
30
μA
IDD
supply current
-
3
-
3
mA
IDD(sleep)
sleep mode supply current
[3]
-
50
-
50
μA
IDD(lp)
low-power mode supply current
[4]
-
50
-
50
μA
Ci
input capacitance
-
5
-
5
pF
[1]
f = 5 MHz
Hysteresis input.
[2]
Except XTAL2; XTAL2 VOL is 1 V typical.
[3]
Sleep current might be higher if there is any activity on the UART data bus during Sleep mode.
[4]
Activated by LOWPWR pin.
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Product data sheet
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
10. Dynamic characteristics
Table 37. Dynamic characteristics - Intel or 16 mode
Tamb = −40 °C to +85 °C; tolerance of VDD ± 10 %; unless otherwise specified.
Symbol
Parameter
Conditions
VDD = 2.5 V
VDD = 3.3 V
Min
Max
Min
Max
Unit
tWH
pulse width HIGH
6
-
6
-
ns
tWL
pulse width LOW
6
-
6
-
ns
tw(clk)
clock pulse width
12.5
-
12.5
-
ns
-
80
-
80
[1][2]
fXTAL1
frequency on pin XTAL1
MHz
tsu(A)
address set-up time
10
-
5
-
ns
th(A)
address hold time
10
-
5
-
ns
td(CS-IOR)
delay time from CS to IOR
10
-
5
-
ns
tw(IOR)
IOR pulse width time
35
-
26
-
ns
th(IOR-CS)
hold time from IOR to chip select
0
-
0
-
ns
td(IOR)
IOR delay time
10
-
10
-
ns
td(IOR-Q)
delay time from IOR to data output
25 pF load
-
35
-
26
ns
tdis(IOR-QZ)
disable time from IOR to
high-impedance data output[3]
25 pF load
-
17
-
15
ns
td(CSL-IOWL)
delay time from CS LOW to
IOW LOW
10
-
5
-
ns
tw(IOW)
IOW pulse width time
15
-
20
-
ns
th(IOW-CS)
hold time from IOW to CS
0
-
0
-
ns
td(IOW)
IOW delay time
15
-
20
-
ns
tsu(D-IOWH)
set-up time from data input to
IOW HIGH
10
-
5
-
ns
th(IOWH-D)
data input hold time after IOW HIGH
10
-
5
-
ns
td(IOW-Q)
delay time from IOW to data output
25 pF load
-
40
-
33
ns
td(modem-INT)
delay time from modem to INT
25 pF load
-
35
-
24
ns
td(IOR-INTL)
delay time from IOR to INT LOW
25 pF load
-
35
-
24
ns
td(stop-INT)
delay time from stop to INT
25 pF load
[4]
-
1TRCLK
-
1TRCLK
s
td(start-INT)
delay time from start to INT
25 pF load
[4]
-
1TRCLK
-
1TRCLK
s
[4]
8TRCLK
24TRCLK
8TRCLK
-
55
-
td(IOW-TX)
delay time from IOW to TX
25 pF load
td(IOW-INTL)
delay time from IOW to INT LOW
25 pF load
24TRCLK s
45
ns
ns
tw(RESET)
pulse width on pin RESET
10
-
10
-
N
baud rate divisor
1
(216 − 1)
1
(216 − 1)
[1]
Applies to external clock, crystal oscillator max 24 MHz.
[2]
Maximum frequency = ---------------
1
t w ( clk )
[3]
10 % of the data bus output voltage level.
[4]
RCLK is an internal signal derived from Divisor Latch LSB (DLL) and Divisor Latch MSB (DLM) divisor latches.
SC16C850
Product data sheet
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Table 38. Dynamic characteristics - Motorola or 68 mode
Tamb = −40 °C to +85 °C; tolerance of VDD ± 10 %; unless otherwise specified.
Symbol
Parameter
Conditions
VDD = 2.5 V
Min
Max
Min
Max
tWH
pulse width HIGH
6
-
6
-
ns
tWL
pulse width LOW
6
-
6
-
ns
tw(clk)
clock pulse width
12.5
-
12.5
-
ns
[1][2]
VDD = 3.3 V
Unit
fXTAL1
frequency on pin XTAL1
-
80
-
80
tsu(A)
address set-up time
10
-
10
-
ns
th(A)
address hold time
15
-
15
-
ns
tsu(RWL-CSL)
set-up time from R/W LOW to CS LOW
10
-
10
-
ns
tsu(RWH-CSL)
set-up time from R/W HIGH to CS LOW
10
-
10
-
ns
tw(CS)
CS pulse width
25 pF load
50
-
20
-
ns
td(CS)
CS delay time
25 pF load
20
-
10
-
ns
td(CS-Q)
delay time from CS to data output
25 pF load
-
50
-
20
ns
tdis(CS-QZ)
disable time from CS to
high-impedance data output
25 pF load
-
20
-
20
ns
th(CS-RWH)
hold time from CS to R/W HIGH
10
-
10
-
ns
td(RW)
R/W delay time
10
-
10
-
ns
tsu(D-CSH)
set-up time from data input to CS HIGH
15
-
15
-
ns
th(CSH-D)
data input hold time after CS HIGH
15
-
15
-
ns
[3]
-
40
-
30
ns
read delay time from CS to IRQ HIGH
[3]
-
40
-
30
ns
td(stop-IRQL)
delay time from stop to IRQ LOW
[4]
-
1TRCLK
-
1TRCLK
s
td(CS-TX)W
write delay time from CS to TX
[4]
8TRCLK
24TRCLK
8TRCLK
td(start-IRQL)
delay time from start to IRQ LOW
[3][4]
-
1TRCLK
-
1TRCLK
s
[3]
-
55
-
45
ns
td(modem-IRQL) delay time from modem to IRQ LOW
td(CS-IRQH)R
MHz
24TRCLK s
td(CS-IRQH)W
write delay time from CS to IRQ HIGH
td(CS-Q)W
write delay time from CS to data output
-
40
-
33
ns
tw(RESET_N)
pulse width on pin RESET
10
-
10
-
ns
N
baud rate divisor
1
(216 − 1)
1
(216 − 1)
[1]
Applies to external clock, crystal oscillator max 24 MHz.
[2]
Maximum frequency = ---------------
[3]
1 kΩ pull-up resistor on IRQ pin.
[4]
RCLK is an internal signal derived from Divisor Latch LSB (DLL) and Divisor Latch MSB (DLM) divisor latches.
1
t w ( clk )
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
10.1 Timing diagrams
th(A)
valid
address
A0 to A2
tsu(A)
th(IOW-CS)
active
CS
td(CSL-IOWL)
tw(IOW)
IOW
td(IOW)
active
th(IOWH-D)
tsu(D-IOWH)
D0 to D7
data
002aac690
Fig 10. General write timing (16 mode)
A0 to A4
tsu(A)
th(A)
tw(CS)
CS
tsu(RWL-CSL)
td(RW)
th(CS-RWH)
R/W
tsu(D-CSH)
th(CSH-D)
D0 to D7
002aac408
Fig 11. General write timing (68 mode)
SC16C850
Product data sheet
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
th(A)
valid
address
A0 to A2
tsu(A)
th(IOR-CS)
active
CS
td(CS-IOR)
tw(IOR)
IOR
td(IOR)
active
td(IOR-Q)
tdis(IOR-QZ)
D0 to D7
data
002aac691
Fig 12. General read timing (16 mode)
th(A)
A0 to A4
tsu(A)
tw(CS)
td(CS)
CS
tsu(RWH-CSL)
tdis(CS-QZ)
R/W
td(CS-Q)
D0 to D7
002aac407
Fig 13. General read timing (68 mode)
tWL
tWH
external clock
tw(clk)
002aac357
1
f XTAL = --------------t w ( clk )
Fig 14. External clock timing
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Product data sheet
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SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
active
IOW
td(IOW-Q)
RTS
DTR
change of state
change of state
CD
CTS
DSR
change of state
change of state
td(modem-INT)
INT
td(modem-INT)
active
active
active
td(IOR-INTL)
active
IOR
active
active
td(modem-INT)
change of state
RI
002aac409
Fig 15. Modem input/output timing (16 mode)
CS (write)(1)
active
td(CS-Q)W
RTS
DTR
change of state
change of state
CD
CTS
DSR
change of state
td(modem-IRQL)
IRQ
change of state
td(modem-IRQL)
active
active
active
td(CS-IRQH)R
CS (read)(2)
active
active
active
td(modem-IRQL)
change of state
RI
002aac632
(1) CS timing during a write cycle. See Figure 11.
(2) CS timing during a read cycle. See Figure 13.
Fig 16. Modem input/output timing (68 mode)
SC16C850
Product data sheet
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NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
start
bit
RX
parity
bit
data bits (0 to 7)
D0
D1
D2
D3
D4
D5
D6
stop
bit
next data
start
bit
D7
5 data bits
6 data bits
td(stop-INT)
7 data bits
INT(1)(2)
active
td(IOR-INTL)
active
IOR
16 baud rate clock
002aac410
(1) INT is active when RX FIFO fills up to trigger level or a time-out condition happens (see Section 6.8).
(2) INT is cleared when RX FIFO drops below trigger level.
Fig 17. Receive timing in 16 mode
start
bit
RX
parity
bit
data bits (0 to 7)
D0
D1
D2
D3
D4
D5
D6
stop
bit
next data
start
bit
D7
5 data bits
6 data bits
td(stop-IRQL)
7 data bits
active
IRQ(1)(2)
td(CS-IRQH)R
CS (read)
active
16 baud rate clock
002aac633
(1) IRQ is active when RX FIFO fills up to trigger level or time-out condition happens (see Section 6.8).
(2) IRQ is cleared when RX FIFO drops below trigger level.
Fig 18. Receive timing in 68 mode
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Product data sheet
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NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
start
bit
TX
parity
bit
data bits (0 to 7)
D0
D1
D2
D3
D4
D5
D6
stop
bit
next data
start
bit
D7
5 data bits
6 data bits
7 data bits
INT(1)(2)
active
transmitter ready
td(start-INT)
td(IOW-TX)
IOW
td(IOW-INTL)
active
active
16 baud rate clock
002aac413
(1) INT is active when TX FIFO is empty or TX FIFO drops below trigger level.
(2) INT is cleared when ISR is read or TX FIFO fills up to trigger level.
Fig 19. Transmit timing in 16 mode
start
bit
data bits (0 to 7)
D0
TX
parity
bit
D1
D2
D3
D4
D5
D6
stop
bit
next data
start
bit
D7
5 data bits
6 data bits
7 data bits
active
TX ready
IRQ(1)(2)
td(start-IRQL)
td(CS-IRQH)W
td(CS-TX)W
CS (write)
active
active
16 baud rate clock
002aac634
(1) IRQ is active when TX FIFO is empty or TX FIFO drops below trigger level.
(2) IRQ is cleared when ISR is read or TX FIFO fills up to trigger level.
Fig 20. Transmit timing in 68 mode
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Product data sheet
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
UART frame
start
data bits
0
TX data
1
0
1
0
stop
0
1
1
0
1
IrDA TX data
1/ bit time
2
bit
time
3/ bit time
16
002aaa212
Fig 21. Infrared transmit timing
IrDA RX data
bit
time
RX data
0 to 1 16× clock delay
0
1
0
1
start
0
0
data bits
1
1
0
1
stop
UART frame
002aaa213
Fig 22. Infrared receive timing
SC16C850
Product data sheet
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NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
11. Package outline
HVQFN32: plastic thermal enhanced very thin quad flat package; no leads;
32 terminals; body 5 x 5 x 0.85 mm
A
B
D
SOT617-1
terminal 1
index area
A
A1
E
c
detail X
C
e1
e
1/2
e b
9
y
y1 C
v M C A B
w M C
16
L
17
8
e
e2
Eh
1/2
1
terminal 1
index area
e
24
32
25
X
Dh
0
2.5
5 mm
scale
DIMENSIONS (mm are the original dimensions)
UNIT
A(1)
max.
A1
b
c
D (1)
Dh
E (1)
Eh
e
e1
e2
L
v
w
y
y1
mm
1
0.05
0.00
0.30
0.18
0.2
5.1
4.9
3.25
2.95
5.1
4.9
3.25
2.95
0.5
3.5
3.5
0.5
0.3
0.1
0.05
0.05
0.1
Note
1. Plastic or metal protrusions of 0.075 mm maximum per side are not included.
REFERENCES
OUTLINE
VERSION
IEC
JEDEC
JEITA
SOT617-1
---
MO-220
---
EUROPEAN
PROJECTION
ISSUE DATE
01-08-08
02-10-18
Fig 23. Package outline SOT617-1 (HVQFN32)
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NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
TFBGA36: plastic thin fine-pitch ball grid array package; 36 balls; body 3.5 x 3.5 x 0.8 mm
B
D
SOT912-1
A
ball A1
index area
E
A
A2
A1
detail X
e1
1/2 e
e
v
w
b
F
M
M
C
C A B
C
y1 C
y
e
E
D
e2
C
B
1/2 e
A
ball A1
index area
1
2
3
4
5
6
X
0
2.5
5 mm
scale
DIMENSIONS (mm are the original dimensions)
UNIT
A
max
A1
A2
b
D
E
e
e1
e2
v
w
y
y1
mm
1.15
0.25
0.15
0.90
0.75
0.35
0.25
3.6
3.4
3.6
3.4
0.5
2.5
2.5
0.15
0.05
0.08
0.1
REFERENCES
OUTLINE
VERSION
IEC
JEDEC
JEITA
SOT912-1
---
---
---
EUROPEAN
PROJECTION
ISSUE DATE
05-08-09
05-09-01
Fig 24. Package outline SOT912-1 (TFBGA36)
SC16C850
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NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
12. Soldering of SMD packages
This text provides a very brief insight into a complex technology. A more in-depth account
of soldering ICs can be found in Application Note AN10365 “Surface mount reflow
soldering description”.
12.1 Introduction to soldering
Soldering is one of the most common methods through which packages are attached to
Printed Circuit Boards (PCBs), to form electrical circuits. The soldered joint provides both
the mechanical and the electrical connection. There is no single soldering method that is
ideal for all IC packages. Wave soldering is often preferred when through-hole and
Surface Mount Devices (SMDs) are mixed on one printed wiring board; however, it is not
suitable for fine pitch SMDs. Reflow soldering is ideal for the small pitches and high
densities that come with increased miniaturization.
12.2 Wave and reflow soldering
Wave soldering is a joining technology in which the joints are made by solder coming from
a standing wave of liquid solder. The wave soldering process is suitable for the following:
• Through-hole components
• Leaded or leadless SMDs, which are glued to the surface of the printed circuit board
Not all SMDs can be wave soldered. Packages with solder balls, and some leadless
packages which have solder lands underneath the body, cannot be wave soldered. Also,
leaded SMDs with leads having a pitch smaller than ~0.6 mm cannot be wave soldered,
due to an increased probability of bridging.
The reflow soldering process involves applying solder paste to a board, followed by
component placement and exposure to a temperature profile. Leaded packages,
packages with solder balls, and leadless packages are all reflow solderable.
Key characteristics in both wave and reflow soldering are:
•
•
•
•
•
•
Board specifications, including the board finish, solder masks and vias
Package footprints, including solder thieves and orientation
The moisture sensitivity level of the packages
Package placement
Inspection and repair
Lead-free soldering versus SnPb soldering
12.3 Wave soldering
Key characteristics in wave soldering are:
• Process issues, such as application of adhesive and flux, clinching of leads, board
transport, the solder wave parameters, and the time during which components are
exposed to the wave
• Solder bath specifications, including temperature and impurities
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NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
12.4 Reflow soldering
Key characteristics in reflow soldering are:
• Lead-free versus SnPb soldering; note that a lead-free reflow process usually leads to
higher minimum peak temperatures (see Figure 25) than a SnPb process, thus
reducing the process window
• Solder paste printing issues including smearing, release, and adjusting the process
window for a mix of large and small components on one board
• Reflow temperature profile; this profile includes preheat, reflow (in which the board is
heated to the peak temperature) and cooling down. It is imperative that the peak
temperature is high enough for the solder to make reliable solder joints (a solder paste
characteristic). In addition, the peak temperature must be low enough that the
packages and/or boards are not damaged. The peak temperature of the package
depends on package thickness and volume and is classified in accordance with
Table 39 and 40
Table 39.
SnPb eutectic process (from J-STD-020C)
Package thickness (mm)
Package reflow temperature (°C)
Volume (mm3)
< 350
≥ 350
< 2.5
235
220
≥ 2.5
220
220
Table 40.
Lead-free process (from J-STD-020C)
Package thickness (mm)
Package reflow temperature (°C)
Volume (mm3)
< 350
350 to 2000
> 2000
< 1.6
260
260
260
1.6 to 2.5
260
250
245
> 2.5
250
245
245
Moisture sensitivity precautions, as indicated on the packing, must be respected at all
times.
Studies have shown that small packages reach higher temperatures during reflow
soldering, see Figure 25.
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NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
maximum peak temperature
= MSL limit, damage level
temperature
minimum peak temperature
= minimum soldering temperature
peak
temperature
time
001aac844
MSL: Moisture Sensitivity Level
Fig 25. Temperature profiles for large and small components
For further information on temperature profiles, refer to Application Note AN10365
“Surface mount reflow soldering description”.
13. Abbreviations
Table 41.
SC16C850
Product data sheet
Abbreviations
Acronym
Description
CPU
Central Processing Unit
DLL
Divisor Latch LSB
DLM
Divisor Latch MSB
FIFO
First In, First Out
IrDA
Infrared Data Association
ISDN
Integrated Service Digital Network
LSB
Least Significant Bit
MSB
Most Significant Bit
PCB
Printed-Circuit Board
RoHS
Restriction of Hazardous Substances directive
UART
Universal Asynchronous Receiver/Transmitter
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2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
14. Revision history
Table 42.
Revision history
Document ID
Release date
Data sheet status
Change notice
Supersedes
SC16C850 v.2
20101111
Product data sheet
-
SC16C850 v.1
Modifications:
•
Table 1 “Ordering information”:
– added Type number SC16C850IBS/Q900
– added Table note [1]
•
•
Figure 5 “Pin configuration for HVQFN32”: added Type number SC16C850IBS/Q900
•
Table 8 “SC16C850 internal registers”, Table note [2] changed from “... and EFCR[2:1] are logic 0.”
to “... and EFCR2:0] are logic 000b.”
•
Table 16 “LCR[5:3] parity selection”:
Table 2 “Pin description”, description of pin LOWPWR changed from “This pin has an internal
pull-down resistor, ...” to “This pin has a 22 kΩ internal pull-down resistor, ...”
– second row changed from “X 0 1” to “0 0 1”
– fourth row changed from “0 0 1” to “1 0 1”
•
Table 36 “Static characteristics”:
– VIL(clk): added condition “XTAL1 pin”
– VIH(clk): added condition “XTAL1 pin”
– VIL, condition “except XTAL1 clock”: appended “LOWPWR pin”
– VIL: added condition “LOWPWR pin”
– VIH, condition “except XTAL1 clock”: appended “LOWPWR pin”
– VIH: added condition “LOWPWR pin”
– VOH Min value for condition IOH = −4 mA and under column VDD = 3.3 V is changed from “2.0 V” to
“2.2 V”
– IDD Max value (for both VDD = 2.5 V and VDD = 3.3 V) changed from “2 mA” to “3 mA”
– added (new) Table note [1]
SC16C850 v.1
SC16C850
Product data sheet
20080110
Product data sheet
-
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Rev. 2 — 11 November 2010
-
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52 of 55
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NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
15. Legal information
15.1 Data sheet status
Document status[1][2]
Product status[3]
Definition
Objective [short] data sheet
Development
This document contains data from the objective specification for product development.
Preliminary [short] data sheet
Qualification
This document contains data from the preliminary specification.
Product [short] data sheet
Production
This document contains the product specification.
[1]
Please consult the most recently issued document before initiating or completing a design.
[2]
The term ‘short data sheet’ is explained in section “Definitions”.
[3]
The product status of device(s) described in this document may have changed since this document was published and may differ in case of multiple devices. The latest product status
information is available on the Internet at URL http://www.nxp.com.
15.2 Definitions
Draft — The document is a draft version only. The content is still under
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included herein and shall have no liability for the consequences of
use of such information.
Short data sheet — A short data sheet is an extract from a full data sheet
with the same product type number(s) and title. A short data sheet is intended
for quick reference only and should not be relied upon to contain detailed and
full information. For detailed and full information see the relevant full data
sheet, which is available on request via the local NXP Semiconductors sales
office. In case of any inconsistency or conflict with the short data sheet, the
full data sheet shall prevail.
Product specification — The information and data provided in a Product
data sheet shall define the specification of the product as agreed between
NXP Semiconductors and its customer, unless NXP Semiconductors and
customer have explicitly agreed otherwise in writing. In no event however,
shall an agreement be valid in which the NXP Semiconductors product is
deemed to offer functions and qualities beyond those described in the
Product data sheet.
15.3 Disclaimers
Limited warranty and liability — Information in this document is believed to
be accurate and reliable. However, NXP Semiconductors does not give any
representations or warranties, expressed or implied, as to the accuracy or
completeness of such information and shall have no liability for the
consequences of use of such information.
In no event shall NXP Semiconductors be liable for any indirect, incidental,
punitive, special or consequential damages (including - without limitation - lost
profits, lost savings, business interruption, costs related to the removal or
replacement of any products or rework charges) whether or not such
damages are based on tort (including negligence), warranty, breach of
contract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, NXP Semiconductors’ aggregate and cumulative liability towards
customer for the products described herein shall be limited in accordance
with the Terms and conditions of commercial sale of NXP Semiconductors.
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors accepts no liability for inclusion and/or use of
NXP Semiconductors products in such equipment or applications and
therefore such inclusion and/or use is at the customer’s own risk.
Applications — Applications that are described herein for any of these
products are for illustrative purposes only. NXP Semiconductors makes no
representation or warranty that such applications will be suitable for the
specified use without further testing or modification.
Customers are responsible for the design and operation of their applications
and products using NXP Semiconductors products, and NXP Semiconductors
accepts no liability for any assistance with applications or customer product
design. It is customer’s sole responsibility to determine whether the NXP
Semiconductors product is suitable and fit for the customer’s applications and
products planned, as well as for the planned application and use of
customer’s third party customer(s). Customers should provide appropriate
design and operating safeguards to minimize the risks associated with their
applications and products.
NXP Semiconductors does not accept any liability related to any default,
damage, costs or problem which is based on any weakness or default in the
customer’s applications or products, or the application or use by customer’s
third party customer(s). Customer is responsible for doing all necessary
testing for the customer’s applications and products using NXP
Semiconductors products in order to avoid a default of the applications and
the products or of the application or use by customer’s third party
customer(s). NXP does not accept any liability in this respect.
Limiting values — Stress above one or more limiting values (as defined in
the Absolute Maximum Ratings System of IEC 60134) will cause permanent
damage to the device. Limiting values are stress ratings only and (proper)
operation of the device at these or any other conditions above those given in
the Recommended operating conditions section (if present) or the
Characteristics sections of this document is not warranted. Constant or
repeated exposure to limiting values will permanently and irreversibly affect
the quality and reliability of the device.
Terms and conditions of commercial sale — NXP Semiconductors
products are sold subject to the general terms and conditions of commercial
sale, as published at http://www.nxp.com/profile/terms, unless otherwise
agreed in a valid written individual agreement. In case an individual
agreement is concluded only the terms and conditions of the respective
agreement shall apply. NXP Semiconductors hereby expressly objects to
applying the customer’s general terms and conditions with regard to the
purchase of NXP Semiconductors products by customer.
Right to make changes — NXP Semiconductors reserves the right to make
changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
No offer to sell or license — Nothing in this document may be interpreted or
construed as an offer to sell products that is open for acceptance or the grant,
conveyance or implication of any license under any copyrights, patents or
other industrial or intellectual property rights.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in life support, life-critical or
safety-critical systems or equipment, nor in applications where failure or
Export control — This document as well as the item(s) described herein
may be subject to export control regulations. Export might require a prior
authorization from national authorities.
SC16C850
Product data sheet
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53 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
Non-automotive qualified products — Unless this data sheet expressly
states that this specific NXP Semiconductors product is automotive qualified,
the product is not suitable for automotive use. It is neither qualified nor tested
in accordance with automotive testing or application requirements. NXP
Semiconductors accepts no liability for inclusion and/or use of
non-automotive qualified products in automotive equipment or applications.
NXP Semiconductors’ specifications such use shall be solely at customer’s
own risk, and (c) customer fully indemnifies NXP Semiconductors for any
liability, damages or failed product claims resulting from customer design and
use of the product for automotive applications beyond NXP Semiconductors’
standard warranty and NXP Semiconductors’ product specifications.
In the event that customer uses the product for design-in and use in
automotive applications to automotive specifications and standards, customer
(a) shall use the product without NXP Semiconductors’ warranty of the
product for such automotive applications, use and specifications, and (b)
whenever customer uses the product for automotive applications beyond
15.4 Trademarks
Notice: All referenced brands, product names, service names and trademarks
are the property of their respective owners.
16. Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
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54 of 55
SC16C850
NXP Semiconductors
2.5 to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
17. Contents
1
General description . . . . . . . . . . . . . . . . . . . . . . 1
2
Features and benefits . . . . . . . . . . . . . . . . . . . . 1
3
Ordering information . . . . . . . . . . . . . . . . . . . . . 2
4
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5
Pinning information . . . . . . . . . . . . . . . . . . . . . . 5
5.1
Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 6
6
Functional description . . . . . . . . . . . . . . . . . . . 9
6.1
UART selection. . . . . . . . . . . . . . . . . . . . . . . . . 9
6.2
Extended mode (128-byte FIFO) . . . . . . . . . . 10
6.3
Internal registers . . . . . . . . . . . . . . . . . . . . . . . 10
6.4
FIFO operation . . . . . . . . . . . . . . . . . . . . . . . . 11
6.4.1
32-byte FIFO mode . . . . . . . . . . . . . . . . . . . . 11
6.4.2
128-byte FIFO mode . . . . . . . . . . . . . . . . . . . 11
6.5
Hardware flow control . . . . . . . . . . . . . . . . . . . 12
6.6
Software flow control . . . . . . . . . . . . . . . . . . . 12
6.7
Special character detect . . . . . . . . . . . . . . . . . 13
6.8
Interrupt priority and time-out interrupts . . . . . 13
6.9
Programmable baud rate generator . . . . . . . . 14
6.10
Loopback mode . . . . . . . . . . . . . . . . . . . . . . . 16
6.11
Sleep mode . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.11.1
Conditions to enter Sleep mode . . . . . . . . . . . 18
6.11.2
Conditions to resume normal operation . . . . . 18
6.12
Low power feature . . . . . . . . . . . . . . . . . . . . . 18
6.13
RS-485 features . . . . . . . . . . . . . . . . . . . . . . . 19
6.13.1
Auto RS-485 RTS control . . . . . . . . . . . . . . . . 19
6.13.2
RS-485 RTS inversion . . . . . . . . . . . . . . . . . . 19
6.13.3
Auto 9-bit mode (RS-485). . . . . . . . . . . . . . . . 19
6.13.3.1 Normal Multi-drop mode . . . . . . . . . . . . . . . . . 19
6.13.3.2 Auto address detection . . . . . . . . . . . . . . . . . . 20
7
Register descriptions . . . . . . . . . . . . . . . . . . . 20
7.1
Transmit (THR) and Receive (RHR)
Holding Registers . . . . . . . . . . . . . . . . . . . . . . 23
7.2
Interrupt Enable Register (IER) . . . . . . . . . . . 23
7.2.1
IER versus Transmit/Receive FIFO
interrupt mode operation . . . . . . . . . . . . . . . . 24
7.2.2
IER versus Receive/Transmit FIFO
polled mode operation . . . . . . . . . . . . . . . . . . 24
7.3
FIFO Control Register (FCR) . . . . . . . . . . . . . 25
7.3.1
FIFO mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.4
Interrupt Status Register (ISR) . . . . . . . . . . . . 26
7.5
Line Control Register (LCR) . . . . . . . . . . . . . . 27
7.6
Modem Control Register (MCR) . . . . . . . . . . . 28
7.7
Line Status Register (LSR) . . . . . . . . . . . . . . . 29
7.8
Modem Status Register (MSR) . . . . . . . . . . . . 30
7.9
Extra Feature Control Register (EFCR) . . . . . 31
7.10
Scratchpad Register (SPR) . . . . . . . . . . . . . . 31
7.11
7.12
7.13
7.14
7.15
7.16
7.17
7.18
7.19
7.20
7.21
7.22
7.23
8
9
10
10.1
11
12
12.1
12.2
12.3
12.4
13
14
15
15.1
15.2
15.3
15.4
16
17
Divisor Latch (DLL and DLM). . . . . . . . . . . . .
Transmit FIFO Level Count (TXLVLCNT) . . .
Receive FIFO Level Count (RXLVLCNT). . . .
Enhanced Feature Register (EFR) . . . . . . . .
Transmit Interrupt Level Register (TXINTLVL)
Receive Interrupt Level Register (RXINTLVL)
Flow Control Trigger Level High (FLWCNTH)
Flow Control Trigger Level Low (FLWCNTL) .
Clock Prescaler (CLKPRES) . . . . . . . . . . . . .
RS-485 Turn-around time delay (RS485TIME)
Advanced Feature Control Register 2
(AFCR2). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Advanced Feature Control Register 1
(AFCR1). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SC16C850 external reset condition and
software reset . . . . . . . . . . . . . . . . . . . . . . . .
Limiting values . . . . . . . . . . . . . . . . . . . . . . . .
Static characteristics . . . . . . . . . . . . . . . . . . .
Dynamic characteristics. . . . . . . . . . . . . . . . .
Timing diagrams. . . . . . . . . . . . . . . . . . . . . . .
Package outline. . . . . . . . . . . . . . . . . . . . . . . .
Soldering of SMD packages . . . . . . . . . . . . . .
Introduction to soldering. . . . . . . . . . . . . . . . .
Wave and reflow soldering. . . . . . . . . . . . . . .
Wave soldering . . . . . . . . . . . . . . . . . . . . . . .
Reflow soldering . . . . . . . . . . . . . . . . . . . . . .
Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . .
Revision history . . . . . . . . . . . . . . . . . . . . . . .
Legal information . . . . . . . . . . . . . . . . . . . . . .
Data sheet status . . . . . . . . . . . . . . . . . . . . . .
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . .
Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . .
Contact information . . . . . . . . . . . . . . . . . . . .
Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31
31
31
32
33
33
34
34
34
35
35
36
37
38
38
39
41
47
49
49
49
49
50
51
52
53
53
53
53
54
54
55
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in section ‘Legal information’.
© NXP B.V. 2010.
All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
Date of release: 11 November 2010
Document identifier: SC16C850
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