MSM80C154S/83C154S/85C154HVS
122
SBUF (R)
INPUT SHIFT REG.
INTERNAL BUS
RI
SBUF (T)
START
START
INTERNAL BUS
TI
RXD
SAMPLE
LOGIC
1/16
COUTER
TXD
RXD
WRITE
TO SBUF
SERIAL PORT
INTERRUPT
REN
SM2
RECEIVE DATA
NEGLECT LOGIC
SERR
BAUD RATE
CLOCK
RCLK
RCLK=1
RCLK=0
1/16
COUTER
BAUD RATE
CLOCK
TCLK
TCLK=1
TCLK=0
TIMER/COUNTER2
OVERFLOW
SMOD
SMOD=1
SMOD=0
1/2
TIMER/COUNTER1
OVERFLOW
Figure 4-35 Serial port (mode 3)