w77e58 Winbond Electronics Corp America, w77e58 Datasheet - Page 68

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

MODE 3
This mode is similar to Mode 2 in all respects, except that the baud rate is programmable. The user
must first initialize the Serial related SFR SCON before any communication can take place. This
involves selection of the Mode and baud rate. The Timer 1 should also be initialized if modes 1 and 3
are used. In all four modes, transmission is started by any instruction that uses SBUF as a destination
register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. This will generate a
clock on the TxD pin and shift in 8 bits on the RxD pin. Reception is initiated in the other modes by
the incoming start bit if REN = 1. The external device will start the communication by transmitting the
start bit.
Table 10. Serial Ports Modes
SM1
(SMOD_1)
0
0
1
1
SMOD=
Overflow
RCLK
TCLK
Timer 1
RXD
SM0
2
0
0
1
0
1
SAMPLE
0
0
1
Mode
(for Serial Port 0 only)
1
1
DETECTOR
0
1
2
3
Timer 2 Overflow
1-TO-0
16
16
Asynch.
Asynch.
Asynch.
Synch.
Type
Write to
SBUF
START
RX CLOCK
TX CLOCK
TX START
CONTROLLER
DETECTOR
RX
SERIAL
4 or 12 T
Timer 1 or 2
32 or 64
Timer 1 or 2
Figure 23. Serial Port Mode 3
BIT
Baud Clock
Data Bus
RX SHIFT
TX SHIFT
Internal
LOAD
SBUF
T
CLKS
- 68 -
CLKS
TI
RI
TB8
Receive Shift Register
CLOCK
SIN
Frame
10 bits
11 bits
11 bits
8 bits
PAROUT
size
Transmit Shift Register
STOP
LOAD
CLOCK
START
PARIN
D8
D8
Preliminary W77E58
SOUT
Start
SBUF
RB8
No
bit
1
1
1
Serial Port
Stop
SBUF
Interrupt
Read
No
bit
TXD
1
1
1
function
9th bit
Internal
None
None
0, 1
0, 1
Data
Bus