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SC28L198A1BE,557

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54P55-P57
Philips Semiconductors Product data sheet
SC28L198Octal UART for 3.3 V and 5 V supply voltage
2006 Aug 10
19
Table 3. MR0– Mode Register 0
Bit 7 Bit 6 Bit 5:4 Bit 3:2 Bit 1:0
Xon/Xoff * transparency
Address Recognition *
transparency
TxiNT In–band flow control mode
Address Recognition
control
0 – flow control characters
received are pushed onto
the
RxFIFO
1 – flow control characters
received are not pushed
onto the RxFIFO
0 – Address characters
received are pushed to
RxFIFO
1 – Address characters
received are not pushed
onto the RxFIFO
TxFIFO
interrupt
level
control
00 – empty
01 – 3/4 empty
10 – 1/2 empty
11 – not full
00 – host mode, only the host CPU
may initiate flow control actions
through the CR
01 – Auto Transmitter flow control
10 – Auto Receiver flow control
11 – Auto Receiver and Transmitter
flow control
00 – none
01 – Auto wake
10 – Auto doze
11 – Auto wake and
auto doze
* If these bits are not 0 the characters will be stripped regardless of
bits (3:2) or (1:0)
MR0[7:6] – Control the handling of recognized Xon/Xoff or Address
characters. If set, the character codes are placed on the RxFIFO
along with their status bits just as ordinary characters are. If the
character is not pushed onto the RxFIFO, its received status will be
lost unless the receiver is operating in the block error mode, see
MR1[5] and the general discussion on receiver error handling.
Interrupt processing is not effected by the setting of these bits. See
Character recognition section.
MR0[5:4] – Controls the fill level at which a transmitter begins to
present its interrupt number to the interrupt arbitration logic. Use of
a low fill level minimizes the number of interrupts generated and
maximizes the number of transmit characters per interrupt cycle. It
also increases the probability that the transmitter will go idle for lack
of characters in the TxFIFO.
MR0[3:2] – Controls the Xon/Xoff processing logic. Auto
Transmitter flow control allows the gating of Transmitter activity by
Xon/Xoff characters received by the Channel’s receiver. Auto
Receiver flow control causes the Transmitter to emit an Xoff
character when the RxFIFO has loaded to a depth of 12 characters.
Draining the RxFIFO to a level of 8 or less causes the Transmitter to
emit an Xon character. All transmissions require no host
involvement. A setting other than b’00 in this field precludes the use
of the command register to transmit Xon/Xoff characters.
Note: Interrupt generation in Xon/Xoff processing is controlled by the
IMR (Interrupt Mask Register) of the individual channels. The
interrupt may be cleared by a read of the XISR, the Xon/Xoff
Interrupt Status Register. Receipt of a flow control character will
always generate an interrupt if the IMR is so programmed. The
MR0[3:2] bits have effect on the automatic aspects of flow control
only, not the interrupt generation.
MR0[1:0] – This field controls the operation of the Address
recognition logic. If the device is not operating in the special or
“wake–up” mode, this hardware may be used as a general purpose
character detector by choosing any combination except b’00.
Interrupt generation is controlled by the channel IMR. The interrupt
may be cleared by a read of the XISR, the Xon/Xoff Interrupt Status
Register. See further description in the section on the Wake Up
mode.
Table 4. MR1 – Mode Register 1
Bit 7 Bit 6 Bit 5 Bit 4:3 Bit 2 Bit 1:0
RxRTS
Control
ISR Read Mode Error Mode Parity Mode Parity Type Bits per Charac-
ter
0 – off
1 – on
0 – ISR unmasked
1 – ISR masked
0 = Character
1 = Block
00 – With Parity
01 – Force parity
10 – No parity
11 – Special Mode
0 = Even
1 = Odd
00 – 5
01 – 6
10 – 7
11 – 8
MR1[7]: Receiver Request to Send Control
This bit controls the deactivation of the RTSN output (I/O2) by the
receiver. This output is asserted and negated by commands applied
via the command register. MR1[7] = 1 causes RTSN to be
automatically negated upon receipt of a valid start bit if the receiver
FIFO is
full or greater. RTSN is reasserted when an the FIFO fill
level falls below
full. This constitutes a change from previous
members of Philips (Signets)’ UART families where the RTSN
function triggered on FIFO full. This behavior caused problems with
PC UARTs that could not stop transmission at the proper time. .
The RTSN feature can be used to prevent overrun in the receiver, by
using the RTSN output signal, to control the CTSN input of the
transmitting device.
MR1[6]: Interrupt Status Masking
This bit controls the readout mode of the Interrupt Status Register,
ISR. If set, the ISR reads the current status masked by the IMR, i.e.
only interrupt sources enabled in the IMR can ever show a ’1’ in the
ISR. If cleared, the ISR shows the current status of the interrupt
source without regard to the Interrupt Mask setting.
MR1[5]: Error Mode Select
This bit selects the operating mode of the three FIFOed status bits
(FE, PE, received break). In the character mode, status is provided
on a character by character basis; the status applies only to the
character at. the bottom of the FIFO. In the block mode, the status
provided in the SR for these bits is the accumulation (logical OR) of
Philips Semiconductors Product data sheet
SC28L198Octal UART for 3.3 V and 5 V supply voltage
2006 Aug 10
20
the status for all characters coming to the top of the FIFO, since the
last reset error command was issued.
MR1[4:3]: Parity Mode Select
If ’with parity’ or ’force parity’ is selected, a parity bit is added to the
transmitted character and the receiver performs a parity check on
incoming data. MR1[4:3] = 11 selects the channel to operate in the
special wake up mode.
MR1[2]: Parity Type Select
This bit sets the parity type (odd or even) if the ’with parity’ mode is
programmed by MR1[4:3], and the polarity of the forced parity bit if
the ’force parity’ mode is programmed. It has no effect if the ’no
parity’ mode is programmed. In the special ’wake up’ mode, it
selects the polarity of the A/D bit. The parity bit is used to an
address or data byte in the ’wake up’ mode.
MR1[1:0]: Bits per Character Select
This field selects the number of data bits per character to be
transmitted and received. This number does not include the start,
parity, or stop bits.
Table 5. MR2 – Mode Register 2
The MR2 register provides basic channel setup control that may need more frequent updating.
Bits 7:6 Bit 5 Bit 4 Bit 3:2 Bit 1:0
Channel Mode TxRTS Control CTSN Enable Tx RxINT Stop Length
00 = normal
01 = Auto echo
10 = Local loop
11 = Remote loop
0 = No
1 = Yes
0 = No
1 = Yes
00 = RRDY
01 = Half Full
10 = 3/4 Full
11 = Full
00 = 1.0
01 = 1.5
10 = 2.0
11 = 9/16
MR2[7:6] – Mode Select
The Octal UART can operate in one of four modes: MR2[7:6] = b’00
is the normal mode, with the transmitter and receiver operating
independently.
MR2[7:6] = b’01 places the channel in the automatic echo mode,
which automatically re transmits the received data. The following
conditions are true while in automatic echo mode:
Received data is re–clocked and re–transmitted on the TxD
output.
The receive clock is used for the transmitter.
The receiver must be enabled, but the transmitter need not be
enabled.
The TxRDY and TxEMT status bits are inactive.
The received parity is checked, but is not regenerated for
transmission,
i.e., transmitted parity bit is as received.
Character framing is checked, but the stop bits are re-transmitted
as received.
A received break is echoed as received until the next valid start
bit is detected
. CPU to receiver communication continues normally, but the CPU
to transmitter link is disabled.
Two diagnostic modes can also be selected.
MR2[7:6] = b’10 selects local loop back mode. In this mode:
The transmitter output is internally connected to the receiver
input.
The transmit clock is used for the receiver.
The TxD output is held high.
The RxD input is ignored.
The transmitter must be enabled, but the receiver need not be
enabled.
CPU to transmitter and receiver communications continue
normally.
The second diagnostic mode is the remote loop back mode,
selected by MR2[7:6] = b’11. In this mode:
Received data is re–clocked and re–transmitted on the TxD
output.
The receive clock is used for the transmitter.
Received data is not sent to the local CPU, and the error status
conditions are inactive.
The received parity is not checked and is not regenerated for
transmission, i.e., the transmitted parity bit is as received.
The receiver must be enabled, but the transmitter need not be
enabled.
Character framing is not checked, and the stop bits are
re-transmitted as received.
A received break is echoed as received until the next valid start
bit is detected.
MR2[5] – Transmitter Request to Send Control
This bit controls the deactivation of the RTSN output (I/O2) by the
transmitter. This output is manually asserted and negated by
appropriate commands issued via the command register. MR2[5] =
1 causes RTSN to be reset automatically one bit time after the
characters in the transmit shift register and in the TxFIFO (if any)
are completely transmitted (includes the programmed number of
stop bits if the transmitter is not enabled). This feature can be used
to automatically terminate the transmission of a message as follows:
Program auto reset mode: MR2[5]= 1.
Enable transmitter.
Assert RTSN via command.
Send message.
After the last character of the message is loaded to the TxFIFO,
disable the transmitter. Before disabling the transmitter be sure
the Status Register TxEMT bit is NOT set (i.e., the transmitter is
not underrun). The underrun condition is indicated by the
TxEMT bit in the SR being set. The condition occurs
immediately upon enabling the transmitter and persists until a
character is loaded to the TxFIFO. The Underrun condition will
not be a problem as long as the controlling processor keeps up
with the transmitter data flow. The proper operation of this
feature assumes that the transmitter is busy (not underrun) when
the disable is issued.
The last character will be transmitted and RTSN will be reset one
bit time after the last stop bit.
NOTE: When the transmitter controls the RTSN pin, the meaning of
the pin is COMPLETELY changed. It has nothing to do with the
normal RTSN/CTSN “handshaking”. It is usually used to mean “end
of message” and to “turn the line around” in simplex
communications.
MR2[4] – Clear to Send Control
The state of this bit determines if the CTSN input (I/O0) controls the
operation of the transmitter. If this bit is 0, CTSN has no effect on
Philips Semiconductors Product data sheet
SC28L198Octal UART for 3.3 V and 5 V supply voltage
2006 Aug 10
21
the transmitter. If this bit is a 1, the transmitter checks the state of
CTSN each time it is ready to begin sending a character. If it is
asserted (low), the character is transmitted. If it is negated (high),
the TxD output remains in the marking state and the transmission is
delayed until CTSN goes low. Changes in CTSN, while a character
is being transmitted, do not affect the transmission of that character.
This feature can be used to prevent overrun of a remote receiver.
MR2[3:2] – RxINT control field
Controls when interrupt arbitration for a receiver begins based on
RxFIFO fill level. This field allows interrupt arbitration to begin when
the RxFIFO is full, 3/4 full, 1/2 full or when it contains at least 1
character.
MR2[1:0] – Stop Bit Length Select
This field programs the length of the stop bit appended to the
transmitted character. Stop bit lengths of 9/16, 1, 1.5 and 2 bits can
be programmed for character lengths of 6, 7, and 8 bits. For a
character length of 5 bits, 1, 1.5 and 2 stop bits can be programmed.
In all cases, the receiver only checks for a mark condition at the
center of the first stop bit position (one bit time after the last data bit,
or after the parity bit if parity is enabled). If an external 1X clock is
used for the transmitter, MR2[1] = 0 selects one stop bit and MR2[1]
= 1 selects two stop bits to be transmitted.
Table 6. RxCSR and TxCSR – Receiver and Transmitter Clock Select Registers
Both registers consist of single 5 bit field that selects the clock source for the receiver and transmitter, respectively. The unused bits in this
register read b’111. The baud rates shown in the table below are based on the x1 crystal frequency of 3.6864MHz. The baud rates shown
below will vary as the X1 crystal clock varies. For example, if the X1 rate is changed to 7.3728 MHz all the rates below will double.
Bits 7:5 Bits 4:0
Reserved Transmitter/Receiver Clock select code, (see Clock Mux Table below)
Table 7. Data Clock Mux
CCLK maximum rate is 8MHz. Data clock rates will follow exactly the ratio of CCLK to 3.6864MHz.
Clock Select Code
CSR (4:0)
Clock selection,
CCLK = 3.6864 MHz
Clock Select Code
Clock selection,
CCLK = 3.6864 MHz
00000 BRG – 50 10000 BRG – 19.2K
00001 BRG – 75 10001 BRG – 28.8K
00010 BRG – 150 10010 BRG – 38.4K
00011 BRG – 200 10011 BRG – 57.6K
00100 BRG – 300 10100 BRG – 115.2K
00101 BRG – 450 10101 BRG – 230.4K
00110 BRG – 600 10110 G
IN
0
00111 BRG – 900 10111 G
IN
1
01000 BRG – 1200 11000 BRG C/T 0
01001 BRG – 1800 11001 BRG C/T 1
01010 BRG – 2400 11010 Reserved
01011 BRG – 3600 11011 I/O2 rcvr, I/O3 xmit –16x
01100 BRG – 4800 11100 I/O2 rcvr, I/O3 xmit–1x
01101 BRG – 7200 11101 Reserved
01110 BRG – 9600 11110 Reserved
01111 BRG – 14.4K 11111 Reserved
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54P55-P57

SC28L198A1BE,557

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Buy SC28L198A1BE,557
Manufacturer:
NXP Semiconductors
Description:
UART Interface IC 3V-5V 8CH UART
Lifecycle:
New from this manufacturer.
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