6.11 Digital I/O
Two I/O ports are implemented: 8-bit port P1 and 3-bit port P2.
- All individual I/O bits are independently programmable.
- Any combination of input, output, and interrupt condition is possible.
- Edge-selectable interrupt input capability for all eight bits of port P1 and three bits of port P2.
- Read and write access to port-control registers is supported by all instructions.
- Each I/O has an individually programmable pullup or pulldown resistor.
Because there are only three I/O pins implemented from port P2, bits [5:1] of all port P2 registers read as 0, and write data is ignored.