Port Configuration - NEC UPD789426 Series User Manual

Pin Name I/O
Note
P80, P81 I/O
Note
P90 to P97 I/O
µ
Note PD789426, 789436 Subseries only

4.2 Port Configuration

Ports have the following hardware configuration.
Item
Control registers
µ
PD789426, 789436
Ports
Subseries
µ
PD789446, 789456
Subseries
µ
PD789426, 789436
Pull-up
resistors Subseries
µ
PD789446, 789456
Subseries
CHAPTER 4 PORT FUNCTIONS
Table 4-1. Port Functions (2/2)
Function
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 setting pull-up resistor option
register B8 (PUB8).
Port 9.
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 setting pull-up resistor option
register B9 (PUB9).
Table 4-2. Configuration of Port
Port mode register (PMm: m = 0 to 3, 5, 7 to 9)
Pull-up resistor option register (PU0, PUB2, PUB3, PUB7 to PUB9)
Total: 40 (CMOS I/O: 30, CMOS input: 6, N-ch open-drain I/O: 4)
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)
User's Manual U15075EJ2V1UD
After Reset
Input
Input
Configuration
Alternate Function
−
−
79