External Interrupt At PORT 1

External interrupt at port 1

Basic Steps

1)Enable global interrupt(eint)

2)Enable external interrupt (on p1.4--P1IE  )

3)select interrupt edge (IP1IES)

4)clear P1IFG flag starting the program

5)clear P1IFG flag in your interrupt service routine

.include "msp430g2x31.inc"

      org 0xf800                 

      mov.w #(WDTPW|WDTHOLD), &WDTCTL

      mov.w #0x280, SP

      mov.b #0x10, P1REN

      CLR.B P1OUT

      mov.b   #001h,&P1DIR           

      bis.b   #010h,&P1IE        ;enable interrupt on p1.4   

      bis.b   #010h,&P1IES       ;select -ve edge

      bic.b   #010h,&P1IFG       ;clear interuupt flag       
      eint ;enables interrup

      gg:jmp gg   

P1ISR:    mov.b   #001h,&P1OUT          

          bic.b   #010h,&P1IFG           

          reti                          

          ORG     0FFE4h                 

          DW      P1ISR    

          ORG     0FFFEh                 

          DW      0xf800