M37544G Mitsubishi Electric, M37544G Datasheet - Page 13

• Manufacturer Part Number: M37544G
• Description: Single-Chip 8-Bit CMOS Microcomputer
• Manufacturer: Mitsubishi Electric

I/O Ports
[Direction registers] PiD
The I/O ports have direction registers which determine the input/
output direction of each pin. Each bit in a direction register corre-
sponds to one pin, and each pin can be set to be input or output.
When “1” is set to the bit corresponding to a pin, this pin becomes
an output port. When “0” is set to the bit, the pin becomes an in-
put port.
When data is read from a pin set to output, not the value of the pin
itself but the value of port latch is read. Pins set to input are float-
ing, and permit reading pin values.
If a pin set to input is written to, only the port latch is written to and
the pin remains floating.
Fig. 13 Structure of pull-up control register
Fig. 14 Structure of port P1P3 control register
Note : Pins set to output ports are disconnected from pull-up control.
b7
b7
b0
b0
Port P1P3 control register
Pull-up control register
(P1P3C: address 0017
(PULL: address 0016
P3
P3
P1
Disable
P0
P0
P0
P0
P3
P3
Disable
P3
7
4
0
/INT
/INT
,P1
0
1
2
4
0
4
7
0 : CMOS level
1 : TTL level
0 : CMOS level
1 : TTL level
0 : CMOS level
1 : TTL level
, P0
– P0
– P3
pull-up control bit
pull-up control bit
pull-up control bit
pull-up control bit
2
0
1
input level selection bit
input level selection bit
input level selection bit
3
7
3
pull-up control bit
[Pull-up control register] PULL
By setting the pull-up control register (address 0016
and P3 can exert pull-up control by program. However, pins set to
output are disconnected from this control and cannot exert pull-up
control.
[Port P1P3 control register] P1P3C
By setting the port P1P3 control register (address 0017
CMOS input level or a TTL input level can be selected for ports
P1
pull-up control bit
pull-up control bit
0
, P1
2
16
, P3
16
, initial value: 00
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
, initial value: 00
4
and P3
7
MITSUBISHI MICROCOMPUTERS
0 : Pull-up Off
1 : Pull-up On
by program.
16
16
)
)
7544 Group
16
), ports P0
16
), a
13