SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
3826 Group
33
Serial I/O2
The serial I/O2 function can be used only for clock synchronous
serial I/O.
For clock synchronous serial I/O2, the transmitter and the receiver
must use the same clock. When the internal clock is used, transfer
is started by a write signal to the serial I/O2 register.
When an internal clock is selected as the synchronous clock of the
serial I/O2, either P62 or P63 can be selected as an output pin of
the synchronous clock. In this case, the pin that is not selected as
an output pin of the synchronous clock functions as a port.
[Serial I/O2 Control Register (SIO2CON)] 001D16
The serial I/O2 control register contains 8 bits which control vari-
ous serial I/O2 functions.
Fig. 29 Structure of serial I/O2 control register
Fig. 30 Block diagram of serial I/O2 function
Serial I/O2 control register
(SIO2CON : address 001D16)
b7
Internal synchronous clock select bits
0 0 0: f(XIN)/8
0 0 1: f(XIN)/16
0 1 0: f(XIN)/32
0 1 1: f(XIN)/64
1 0 0:
1 0 1:
1 1 0: f(XIN)/128
1 1 1: f(XIN)/256
Serial I/O2 port selection bit
0: I/O port
1: SOUT2,SCLK21/SCLK22 signal output
P61/SOUT2 P-channel output disable bit
0: CMOS output (in output mode)
1: N-channel open-drain output
(in output mode)
Transfer direction selection bit
0: LSB first
1: MSB first
Synchronous clock selection bit
0: External clock
1: Internal clock
Synchronous clock output pin selection bit
0: SCLK21
1: SCLK22
b0
b2 b1 b0
Do not set
XIN
“1”
“0”
“1”
“0”
“1”
S
CLK2
(Note)
1/8
1/16
1/32
1/64
1/128
1/256
Data bus
Serial I/O2
interrupt request
Serial I/O2 port selection bit
Serial I/O counter 2 (3)
Serial I/O shift register 2 (8)
Synchronous circuit
Synchronous clock
selection bit
External clock
Internal synchronous
clock select bits
Divider
P63 latch
P63/SCLK22
P62/SCLK21
P61/SOUT2
P60/SIN2
P62 latch
P61 latch
(Note)
Note: It is selected by the synchronous clock selection bit, the synchronous
clock output pin selection bit, and the serial I/O port selection bit.