Texas Instruments MSP430x1xx - Manual (Page 130)

Ports P3, P4, P5, P6
8-10
Table 8–3. Port P3–P6 Registers
Register Short Form Address Register Type Initial State
Input P3IN 018h Read only – – – – –
P4IN 01Ch Read only – – – – –
P5IN 030h Read only – – – – –
P6IN 034h Read only – – – – –
Output P3OUT 019h Read/write Unchanged
P4OUT 01Dh Read/write Unchanged
P5OUT 031h Read/write Unchanged
P6OUT 035h Read/write Unchanged
Direction P3DIR 01Ah Read/write Reset
P4DIR 01Eh Read/write Reset
P5DIR 032h Read/write Reset
P6DIR 036h Read/write Reset
Port Select P3SEL 01Bh Read/write Reset
P4SEL 01Fh Read/write Reset
P5SEL 033h Read/write Reset
P6SEL 037h Read/write Reset
8.3.1.1 Input Registers
The input registers are read-only registers that reflect the signal at the I/O pins.
Note: Writing to Read-Only Register
Any attempt to write to these read-only registers results in an increased
current consumption while the write attempt is active.
8.3.1.2 Output Registers
The output registers show the information of the output buffers. The output
buffers can be modified by all instructions that write to a destination. If read,
the contents of the output buffer are independent of the pin direction. A
direction change does not modify the output buffer contents.
8.3.1.3 Direction Registers
The direction registers contain eight independent bits that define the direction
of each I/O pin. All bits are reset by the PUC signal.
When:
Bit = 0: The port pin is switched to input direction
Bit = 1: The port pin is switched to output direction