
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
3825 Group
28
SERIAL I/O
Serial I/O can be used as either clock synchronous or asynchro-
nous (UART) serial I/O. A dedicated timer (baud rate generator) is
also provided for baud rate generation.
(1) Clock Synchronous Serial I/O Mode
Clock synchronous serial I/O mode can be selected by setting the
mode selection bit of the serial I/O control register to “1”.
For clock synchronous serial I/O, the transmitter and the receiver
must use the same clock. If an internal clock is used, transfer is
started by a write signal to the TB/RB (address 0018
16).
Fig. 23 Block diagram of clock synchronous serial I/O
Fig. 24 Operation of clock synchronous serial I/O function
4
6/
C
L
K
4
7/
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D
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4/
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6
Receive shift register
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Frequency division ratio 1/(n+1)
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count source se
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Clock control circuit
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ata
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.
3
:
T
h
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(
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g
(
R
B
F
)
b
e
c
o
m
e
s
“
1
”
.
7
0
1
2
3
4
5
6
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