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Chapter 3 Port Functions
45
Port Control Registers
3-2-2 I/O Port Control Registers
This section describes the special function registers that control the
MN101C117's I/O ports.
■ Data Registers
• PnOUT registers
Data registers to output to the ports.
Data written to these registers is output from the ports.
• PnIN registers
Data registers to input data from the ports.
The value of data at the pins can be input by reading these registers.
These are read-only registers.
Input and output registers are mapped to separate addresses.
To use these ports for I/O, configure them as I/O ports in the PnOMD/PnIMD registers,
described in this section.
■ Direction Control Registers
• PnDIR registers
These registers set the port for use as an input or output.
■ Pull-up/Pull-down Resistor Control Registers
• PnPLU registers
These register settings determine whether internal pull-up resistors are added to the ports.
• PnPLUD registers
These register settings determine whether internal pull-up or pull-down resistors are
added to the ports.
0
1
Low (Vss level) is output.
High (Vdd level) is output.
0
1
Pin is low.
Pin is high.
0
1
Input mode
Output mode
0
1
No pull-up / pull-down resistor
Pull-up / Pull down resistor
0
1
No pull-up / pull-down resistor
Pull-up / Pull down resistor