Texas Instruments MSP430x1xx - Manual (Page 124)

Ports P1, P2
8-4
8.2.1 Port P1, Port P2 Control Registers
The seven control registers give maximum digital input/output configuration
flexibility:
- All individual I/O bits are independently programmable.
- Any combination of input, output, and interrupt condition is possible.
- Interrupt processing of external events is fully implemented for all eight
bits of ports P1 and P2.
The seven registers for port P1 and the seven registers for port P2 are shown
in Table 8–1 and Table 8–2, respectively.
Table 8–1. Port P1 Registers
Register
Short
Form Register
Type
Address Initial State
Input P1IN Read only 020h – – – – –
Output P1OUT Read/write 021h Unchanged
Direction P1DIR Read/write 022h Reset
Interrupt flags P1IFG Read/write 023h Reset
Interrupt edge select P1IES Read/write 024h Unchanged
Interrupt enable P1IE Read/write 025h Reset
Function select P1SEL Read/write 026h Reset
Table 8–2. Port P2 Registers
Register
Short
Form Register
Type
Address Initial State
Input P2IN Read only 028h – – – – –
Output P2OUT Read/write 029h Unchanged
Direction P2DIR Read/write 02Ah Reset
Interrupt flags P2IFG Read/write 02Bh Reset
Interrupt edge select P2IES Read/write 02Ch Unchanged
Interrupt enable P2IE Read/write 02Dh Reset
Function select P2SEL Read/write 02Eh Reset
These registers contain eight bits, and should be accessed using byte
instructions in absolute-address mode.
8.2.1.1 Input Registers P1IN, P2IN
Both Input registers are read-only registers that reflect the signals at the I/O
pins.
Note: Writing to Read-Only Registers P1IN, P2IN
Writing to these read-only registers results in increased current consumption
while the write attempt is active.