w77e58 Winbond Electronics Corp America, w77e58 Datasheet - Page 18

• Manufacturer Part Number: w77e58
• Description: 8 Bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

SERIAL PORT CONTROL
SM0/FE: Serial port 0, Mode 0 bit or Framing Error Flag: The SMOD0 bit in PCON SFR determines
SM1:
SM2:
REN:
TB8:
RB8:
TI:
RI:
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 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. When set to 1, the serial clock become divide by 4 of
the oscillator clock. This results in faster synchronous serial communication.
This is the 9th bit to be transmitted in modes 2 and 3. This bit is set and cleared by software
as desired.
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 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 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.
Receive enable: When set to 1 serial reception is enabled, otherwise reception is disabled.
Serial port Mode bit 1:
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.
SM0
Mnemonic: SCON
0
0
1
1
Bit:
SM1
0
1
0
1
SM0/FE
7
Mode
0
1
2
3
SM1
6
Description
Synchronous
Asynchronous
Asynchronous
Asynchronous
SM2
- 18 -
5
REN
Length
10
11
11
4
8
Preliminary W77E58
TB8
3
Address: 98h
Baud rate
4/12 Tclk
variable
64/32 Tclk
variable
RB8
2
TI
1
RI
0