24
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
38C8 Group
SERIAL I/O
Serial I/O can be used as either clock synchronous or asynchronous
(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 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 transmit/receive buffer registers.
Fig. 20 Block diagram of clock synchronous serial I/O
Fig. 21 Operation of clock synchronous serial I/O function
4
6
/
CLK
4
7
/
R
D
4
4
/
X
4
5
/
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1/4
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Clock control circuit
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Transmit buffer register
Transmit shift register
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verrun error
detection
otes 1:
e transm
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nterrupt
can
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er reg
ster
as empt
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=1
or a
ter
the transmit shift operation has ended (TSC=1), by setting the transmit interrupt source selection bit (TIC) of the serial
I/O control register.
2: If data is written to the transmit buffer register when TSC=0, the transmit clock is generated continuously and serial data
is output continuously from the T
X
D pin.
3: The receive interrupt (RI) is set when the receive buffer full flag (RBF) becomes “1” .
7
0
1
2
3
4
5
6
(11 strony)
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