MSP430-Digital Input

digital input using the P1.3 (pull down resistor required)
      .include “msp430g2x31.inc”
      org 0xf800                           
      mov.w #(WDTPW|WDTHOLD), &WDTCTL
      CLR.B P1OUT
      CLR R5  
      mov.b #0x41, &P1DIR 
L1:   MOV.b &P1IN,  r5
      AND.b #0x8,r5
      tst r5
      JZ L1
      mov.b #0x41, &P1OUT 
L3:   jmp L3
      org 0xfffe
      dw 0xf800