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

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