M38203M4 Datasheet, PDF (250/344 Pages) Mitsubishi Electric Semiconductor – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.7 LCD drive control circuit
(4) Port P1 direction register (P1D)
When it is specified that pins P10/SEG32–P17/SEG39 are used as I/O ports by bits 3 to 5 of the
segment output enable register (address 003816), the setting of the port P1 direction register (address
000316) is valid.
When bit 0 of the port P1 direction register (address 000316) is set to “1,” port P1 is an output port.
When this bit is set to “0,” the port is an input port, so that the setting of bit 1 of the PULL register
A (address 001616) becomes valid. At reset, bit 0 of the port P1 direction register is set to “0.”
Figure 2.7.5 shows the structure of the port P1 direction register.
Port P1 direction register
b7 b6 b5 b4 b3 b2 b1 b0
Port P1 direction register (P1D) [Address 0316]
B
Name
Functions
At reset R W
0 ^{Port P1 direction}
register
0: All bits are input mode
1: All bits are output mode
1 Nothing is allocated. These bits cannot be
to written to and be read out.
7
0^×
0 ^××
Fig. 2.7.5 Structure of port P1 direction register
2–164
3820 GROUP USER’S MANUAL