W79E201 Datasheet, PDF (16/87 Pages) Winbond – 8-BIT MICROCONTROLLER

W79E201
Serial Port Control
Bit:
7
6
5
4
3
2
1
0
SM0/FE SM1 SM2 REN TB8 RB8
TI
RI
Mnemonic: SCON
Address: 98h
BIT NAME
FUNCTION
Serial port, Mode 0 bit or Framing Error Flag: The SMOD0 bit in PCON SFR
7
SM0/FE
determines whether this bit acts as SM0 or as FE. The operation of SM0 is
described below. When used as FE, this bit will be set to indicate an invalid stop
bit. This bit must be manually cleared in software to clear the FE condition.
Serial port Mode bit 1:
Mode: SM0 SM1 Description
Length Baud rate
6 SM1 ⁰
1
2
0 0 Synchronous
0 1 Asynchronous
1 0 Asynchronous
8
4/12 Tclk
10 Variable
11 64/32 Tclk
3
1 1 Asynchronous
11 Variable
Multiple processors communication. Setting this bit to 1 enables the multiprocessor
communication feature in mode 2 and 3. In mode 2 or 3, if SM2 is set to 1, then RI
5
SM2
will not be activated if the received 9th data bit (RB8) is 0. In mode 1, if SM2 = 1,
then RI will not be activated if a valid stop bit was not received. In mode 0, the SM2
bit controls the serial port clock. If set to 0, then the serial port runs at a divide by
12 clock of the oscillator. This gives compatibility with the standard 8052.
4
REN
Receive enable: When set to 1 serial reception is enabled, otherwise reception is
disabled.
3
TB8
This is the 9th bit to be transmitted in modes 2 and 3. This bit is set and cleared by
software as desired.
2
RB8
In modes 2 and 3 this is the received 9th data bit. In mode 1, if SM2 = 0, RB8 is the
stop bit that was received. In mode 0 it has no function.
Transmit interrupt flag: This flag is set by hardware at the end of the 8th bit time in
1
TI mode 0, or at the beginning of the stop bit in all other modes during serial
transmission. This bit must be cleared by software.
Receive interrupt flag: This flag is set by hardware at the end of the 8th bit time in
0
RI
mode 0, or halfway through the stop bits time in the other modes during serial
reception. However the restrictions of SM2 apply to this bit. This bit can be cleared
only by software.
Serial Data Buffer
Bit:
7
6
5
4
3
2
1
0
SBUF.7 SBUF.6 SBUF.5 SBUF.4 SBUF.3 SBUF.2 SBUF.1 SBUF.0
Mnemonic: SBUF
Address: 99h
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