w77e58 Winbond Electronics Corp America, w77e58 Datasheet - Page 64

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

The TI flag is set high in C1 following the end of transmission of the last bit. The serial port will
receive data when REN is 1 and RI is zero. The shift clock (TxD) will be activated and the serial port
will latch data on the rising edge of shift clock. The external device should therefore present data on
the falling edge on the shift clock. This process continues till all the 8 bits have been received. The RI
flag is set in C1 following the last rising edge of the shift clock on TxD. This will stop reception, till the
RI is cleared by software.
MODE 1
In Mode 1, the full duplex asynchronous mode is used. Serial communication frames are made up of
10 bits transmitted on TXD and received on RXD. The 10 bits consist of a start bit (0), 8 data bits
(LSB first), and a stop bit (1). On receive, the stop bit goes into RB8 in the SFR SCON. The baud rate
in this mode is variable. The serial baud can be programmed to be 1/16 or 1/32 of the Timer 1
overflow. Since the Timer 1 can be set to different reload values, a wide variation in baud rates is
possible.
SM2
div. by 4
div. by 64
div. by 1024 osc/256
REN
Mode
12
Clock Source
RI
0
Iutput function
P3.0 Alternate
1
osc/1
osc/16
input
4
RXD
Write to
SBUF
TX START
TX CLOCK
RX
CLOCK
RX
START
CONTROLLE
SERIAL
LOAD SBUF
RX SHIFT
Data Bus
Internal
Figure 20. Serial Port Mode 1
TX SHIFT
CLOCK
SHIFT
TI
RI
Receive Shift Register
- 64 -
CLOCK
SIN
Transmit Shift Register
PAROUT
CLOCK
PARIN
LOAD
Preliminary W77E58
SOUT
SBUF
TXD
P3.1 Alternate
Output function
Serial Port Interrupt
RXD
P3.0 Alternate
Output Function
Read SBUF
SBUF
Data Bus
Internal