
3874 Group User's Manual
APPLICATION
2-87
2.5 Serial I/O
Fig. 2.5.13 Example of control procedure
Set port P47 as input mode.
Set the baud rate generator.
Write the transmit data to the transmit buffer register.
Port P47 = “L” ?
Y
N
Set “1” to the serial I/O1 transmit interrupt enable bit.
Set “1” to the serial I/O1 receive interrupt enable bit.
Set “1” to the serial I/O1 transmit/receive interrupt
enable bit for each vector.
N O P
Set “0” to the serial I/O1 transmit/receive interrupt
enable bit of each vector.
Set “0” to the serial I/O1 transmit interrupt enable bit.
Set “0” to the serial I/O1 receive interrupt enable bit.
Set “0” to the serial I/O1 transmit/receive interrupt
request bit for each vector
Set “0” to the serial I/O1 transmit interrupt request bit.
Set “0” to the serial I/O1 receive interrupt request bit.
Select BRG count source
Synchronous clock
← External clock
SRDY1 output enabled
Select transmit interrupt factor
Transmit enabled (in full-duplex
communication)
Receive enabled
Clock synchronous serial I/O
Serial I/O1 enabled
Set serial I/O1 control register
Select BRG count source
Synchronous clock
← BRG output/4
SRDY1 output disabled
Select transmit interrupt factor
Transmit enabled
Receive enabled (in full-duplex
communication)
Clock synchronous serial I/O
Serial I/O1 enabled
N O P
Write the transmit data to the transmit buffer register.
(Write dummy data in half-duplex communication)
At this point, SRDY1
← “L”
Set serial I/O1 control register
Set “0” to the serial I/O1 transmit/receive interrupt
request bit for each vector.
Set “0” to the serial I/O1 transmit interrupt request bit.
Set “0” to the serial I/O1 receive interrupt request bit.
Set “1” to the serial I/O1 transmit interrupt enable bit.
Set “1” to the serial I/O1 receive interrupt enable bit.
Set “1” to the serial I/O1 transmit/receive interrupt
enable bit for each vector.
Set “0” to the serial I/O1 transmit/receive interrupt
enable bit of each vector.
Set “0” to the serial I/O1 transmit interrupt enable bit.
Set “0” to the serial I/O1 receive interrupt enable bit.
3874 group 1
3874 group 2
SIO1CON (address: 1A16)
11
1
10
0
SIO1CON (address: 1A16)
11
1
Serial I/O1 receive interrupt
Serial I/O1 transmit interrupt