DS89C420-QCL Datasheet, PDF (117/139 Pages) Maxim Integrated Products – Ultra-High-Speed Flash Microcontroller User’s Guide

Ultra-High-Speed Flash
Microcontroller User’s Guide
SBUF
OUTPUT SHIFT REGISTER
SYSTEM CLOCK
S0
P3.0
LATCH
RXD
PIN
DIVIDE-
BY-12
0
DIVIDE-
BY-4
1
SM2=
SMS2C= ONx.5
SCONx.5
LDSBUF
RDSBUF
LOAD
SHIFT
SERIAL
READ
BUFFER
SERIAL
BAUD
BUFFER
CLOCK
RECEIVE
BUFFER
DATA
LOAD
CLOCK
T1
FLAG =
SCONx.1
R1
FLAG =
SCONx.0
SERIAL
INTERRUPT
DATA BUS
RD RECEIVE DATA BUFFER WR
SI
RECEIVE SHIFT REGISTER
TRANSMIT TIMING
LDSBUF
SHIFT
RXD
(DATA OUT)
TXD
(DATA CLOCK)
TI
RECEIVE TIMING
RDSBUF
SHIFT
RXD
(DATA IN)
TXD
(DATA CLOCK)
RI
TXD
PIN
WRITE TO SBUF
D0
D1
D2
D3
D4
D5
D6 D7
WRITE TO SCON (CLEAR RI)
D0
D1
D2
D3
D4
D5
D6
D7
Figure 12-1. Serial Port Mode 0
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