IC80C51
IC80C31
IC80C51/31 INTERNAL BUS
TB8
TIMER 1
OVERFLOW
WRITE
TO
SBUF
S
2
Q
D
SBUF
SMOD
= 1
TXD
CL
SMOD
= 0
ZERO DETECTOR
SHIFT
TX CONTROL
START
DATA
TX CLOCK
SEND
16
TI
SERIAL
PORT
INTERRUPT
16
SAMPLE
1-TO-0
LOAD
RI
RX CLOCK
START
SBUF
SHIFT
1FFH
RX CONTROL
TRANSITION
DETECTOR
BIT
DETECTOR
INPUT SHIFT REG.
(9 BITS)
RXD
LOAD
SBUF
SHIFT
SBUF
READ
SBUF
IC80C51/31 INTERNAL BUS
TX
CLOCK
WRITE TO SBUF
SEND
S1P1
DATA
TRANSMIT
SHIFT
START
BIT
D0
D1
D2
D3
D4
D5
D6
D7
TB8
TXD
TI
STOP BIT
STOP BIT GEN
RX
CLOCK
16 RESET
START
BIT
RXD
D0
D1
D2
D3
D4
D5
D6
RB8
D7
STOP
BIT
BIT DETECTOR SAMPLE TIMES
RECEIVE
SHIFT
RI
Figure 14. Serial Port Mode 3
Integrated Circuit Solution Inc.
MC001-0B
25
ICSI [ INTEGRATED CIRCUIT SOLUTION INC ]
