W925EP01 Datasheet, PDF (22/108 Pages) Winbond – 8-BIT CID MICROCONTROLLER

W925EP01/ W925EP01FG
SERIAL PORT0 CONTROL
(initial=00H)
Bit:
7
6
5
4
3
2
1
0
SM0/FE SM1 SM2 REN TB8 RB8
TI
RI
Mnemonic: SCON
Address: 98h
SM0/FE: Serial port0, Mode 0 bit or Framing Error Flag: The SMOD0 bit in PCON SFR 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.
SM1: Serial port0 Mode bit 1:
SM0
0
0
1
1
SM1
0
1
0
1
Mode
0
1
2
3
Description
Synchronous
Asynchronous
Asynchronous
Asynchronous
Length
8
10
11
11
Baud rate
4/12 Tclk
variable
16/32 Tclk
variable
SM2: In mode 2 or 3, if SM2 is set to 1, then RI will not be activated if the received 9th data bit (RB8)
is 0. In mode 0 and 1, bit SM2 can able to be changed by software. 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 port0 clock.
REN: Receive enable. When set to 1 serial reception is enabled, otherwise reception is disabled.
TB8: This is the 9th bit to be transmitted in modes 2 and 3. This bit is set and cleared by software as
desired.
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.
TI: Transmit interrupt flag: This flag is set by hardware at the end of the 8th bit time in mode 0, or at
the beginning of the stop bit in all other modes during serial transmission. This bit must be
cleared by software.
RI: Receive interrupt flag: This flag is set by hardware at the end of the 8th bit time in 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
(initial=XXH) Read Only
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
SBUF.7-0: Serial data on the serial port0 is read from or written to this location. It actually consists of
two separate internal 8-bit registers. One is the receive register, and the other is the
transmit buffer. Any read access gets data from the receive data buffer, while write access
is to the transmit data buffer.
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