Preliminary W79E225A/227A Data Sheet
Publication Release Date: December 14, 2007
- 48 -
Revision A2.0
SERIAL PORT CONTROL 1
Bit:
7
6
5
4
3
2
1
0
SM0_1/FE_1 SM1_1
SM2_1
REN_1
TB8_1
RB8_1
TI_1
RI_1
Mnemonic: SCON1
Address: C0h
BIT
NAME
FUNCTION
7
SM0_1/
FE_1
Serial Port 1 mode select bit 0 or Framing Error Flag: This bit is controlled by the
SMOD0 bit in the PCON register.
(SM0) See table below.
(FE) This bit indicates an invalid stop bit. It must be manually cleared by software.
6
SM1_1
Serial Port 1 mode select bit 1. See table below.
5
SM2_1
Serial Port Clock or Multi-Processor Communication.
(Mode 0) This bit controls the serial port clock. If set to zero, the serial port runs at a
divide-by-12 clock of the oscillator. This is compatible with the standard 8051/52. If
set to one, the serial clock is a divide-by-4 clock of the oscillator.
(Mode 1) If SM2_1 is set to one, RI_1 is not activated if a valid stop bit is not
received.
(Modes 2 / 3) This bit enables multi-processor communication. If SM2_1 is set to
one, RI_1 is not activated if RB8_1, the ninth data bit, is zero.
4
REN_1
Receive enable:
1: Enable serial reception.
0: Disable serial reception.
3
TB8_1
(Modes 2 / 3) This is the 9th bit to transmit. This bit is set by software.
2
RB8_1
(Mode 0) No function.
(Mode 1) If SM2_1 = 0, RB8_1 is the stop bit that was received.
(Modes 2 / 3) This is the 9th bit that was received.
1
TI_1
Transmit interrupt flag: This flag is set by the hardware at the end of the 8th bit in
mode 0 or at the beginning of the stop bit in the other modes during serial
transmission. This bit must be cleared by software.
0
RI_1
Receive interrupt flag: This flag is set by the hardware at the end of the 8th bit in
mode 0 or halfway through the stop bits in the other modes during serial reception.
However, SM2_1 can restrict this behavior. This bit can only be cleared by
software.
SM1_1, SM0_1: Mode Select bits:
SM0_1
SM1_1
MODE
DESCRIPTION
LENGTH
BAUD RATE
0
0
0
Synchronous
8
Tclk divided by 4 or 12
0
1
1
Asynchronous
10
Variable
1
0
2
Asynchronous
11
Tclk divided by 32 or 64
1
1
3
Asynchronous
11
Variable