M38203M4 Datasheet, PDF (244/344 Pages) Mitsubishi Electric Semiconductor – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.7 LCD drive control circuit
(2) Ports P0, P1 and P3
When pins P30/SEG16–P37/SEG23, P00/SEG24–P07/SEG31, P10/SEG32–P17/SEG39 are not used as
segment outputs, they can be used as input port P3 and as I/O ports P0 and P1.
Table 2.7.4 shows the setting of input port P3 and I/O ports P0, P1.
Table 2.7.4 Setting of input port P3 and I/O ports P0, P1
Ports
Setting
P30–P37
By setting bit 0 of segment output enable register (address 003816) to “0”
P00, P01
By setting bit 1 of segment output enable register (address 003816) to “0”
P02–P07
P10, P11
By setting bit 2 of segment output enable register (address 003816) to “0”
By setting bit 3 of segment output enable register (address 003816) to “0”
P12
P13–P17
By setting bit 4 of segment output enable register (address 003816) to “0”
By setting bit 5 of segment output enable register (address 003816) to “0”
(3) P3, P1 and P0 pull-down pins
When pins P30/SEG16–P37/SEG23, P00/SEG24–P07/SEG31, P10/SEG32–P17/SEG39 are not used as
ports, it is possible to exert pull-down control. Table 2.7.5 shows the setting of pull-down pins.
Table 2.7.5 Setting of pull-down pins
Pins
Setting
P30/SEG16–
P37/SEG23
By setting bit 0 of the segment output enable register (address 003816) to “0,” then
setting bit 3 of PULL register A (address 001616) to “1.”
P00/SEG24–
P07/SEG31
P10/SEG32–
P17/SEG39
By setting bits 1 and 2 of the segment output enable register (address 003816) to “0,”
next setting bit 0 of the port P0 direction register (address 000116) to “0,” then setting
bit 0 of PULL register A (address 001616) to “1.”
By setting bits 3 to 5 of the segment output enable register (address 003816) to “0,”
next setting bit 1 of the port P1 direction register (address 000316) to “0,” then setting
bit 1 of PULL register A (address 001616) to “1.”
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3820 GROUP USER’S MANUAL