CHAPTER 4 PORT FUNCTIONS
Table 4-1. Port Functions (2/2)
Pin Name
I/O
Function
After Reset
Input
Alternate Function
P80, P81Note
I/O
I/O
Port 8.
−
2-bit I/O port.
Input/output can be specified in 1-bit units.
When used as an input port, an on-chip pull-up resistor
can be specified by means of pull-up resistor option
register B8 (PUB8).
P90 to P97Note
Port 9.
Input
−
8-bit I/O port.
Input/output can be specified in 1-bit units.
When used as an input port, an on-chip pull-up resistor
can be specified by means of pull-up resistor option
register B9 (PUB9).
Note µPD789426, 789436 Subseries only
4.2 Port Configuration
Ports have the following hardware configuration.
Table 4-2. Configuration of Port
Item
Configuration
Control registers
Port mode register (PMm: m = 0 to 3, 5, 7 to 9)
Pull-up resistor option register (PU0, PUB2, PUB3, PUB7 to PUB9)
Ports
µPD789426, 789436
Total: 40 (CMOS I/O: 30, CMOS input: 6, N-ch open-drain I/O: 4)
Subseries
µPD789446, 789456
Total: 30 (CMOS I/O: 20, CMOS input: 6, N-ch open-drain I/O: 4)
Total: 34 (software control: 30, mask option specification: 4)
Total: 24 (software control: 20, mask option specification: 4)
Subseries
Pull-up
µPD789426, 789436
resistors
Subseries
µPD789446, 789456
Subseries
80
User’s Manual U15075EJ1V0UM00
NEC [ NEC ]
