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CHAPTER 4 PORT FUNCTIONS
User’s Manual U19780EJ2V0UD
113
4.3 Registers Controlling Port Function
Port functions are controlled by the following four types of registers.
•
Port mode registers (PMxx)
•
Port registers (Pxx)
•
Pull-up resistor option registers (PUxx)
•
A/D port configuration register (ADPC)
(1) Port mode registers (PMxx)
These registers specify input or output mode for the port in 1-bit units.
These registers can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets these registers to FFH.
When port pins are used as alternate-function pins, set the port mode register by referencing
4.5 Settings of
Port Mode Register and Output Latch When Using Alternate Function
.
Figure 4-25. Format of Port Mode Register (1/2)
(1) 78K0/KB2-A
Symbol
7 6 5 4 3 2 1 0
Address
After
reset
R/W
PM1
1 1 1 1
PM13
PM12
PM11
PM10
FF21H
FFH
R/W
PM2
1
1
PM25 PM24 PM23 PM22 PM21 PM20 FF22H
FFH
R/W
PM3 1
1 PM35 1
1 PM32
PM31 1 FF23H FFH R/W
PM6
1 1 1 1 1 1
PM61
PM60
FF26H
FFH
R/W
PM8
1 1 1 1
PM83
PM82
PM81
PM80
FF28H
FFH
R/W
PM12
1 1 1 1 1
PM122
PM121
PM120
FF2CH
FFH
R/W
PMmn
Pmn pin I/O mode selection
(m = 1 to 3, 6, 8, 12; n = 0 to 5)
0
Output mode (output buffer on)
1
Input mode (output buffer off)
Caution Be sure to set bits 4 to 7 of PM1, bits 6 and 7 of PM2, bits 0, 3, 4, 6, and 7 of PM3, bits 2 to 7
of PM6, bits 4 to 7 of PM8, and bits 3 to 7 of PM12 to 1.