MSP430F5418 port interrupt occurs for both high-to-low and low-to-high transitions

I had set MSP430F5418 P2.5 for high to low transition. But I am getting interrupts for both low-to-high and high-to-low transitions. Please my code snippet below.

    P2OUT |= BIT5   /* Enable P2.5 internal resistances */
    P2REN |= BIT5   /* Set up P2.5 as pull-Up resistances */

    P2IES |= BIT5;    
    P2IE  |= BIT5;    
    P2IFG &= ~BIT5;   /* P2.5 IFG cleared */


#pragma vector=PORT2_VECTOR
__interrupt void port2_interrupt (void)
{
    switch (P2IV)
   开发者_开发知识库 {
        case 0x0CU:
        {
            /* Do something here */
            P2IFG &= ~BIT5;
            break;
        }
        default:
        {
            /* No Action */
            break;
        }
    }
}

Hans, I am not using a switch to assert the pin. It is actually done by another processor. I got a reply In TI (Texas instruments) forum that there could be a hidden high-to-low signal within a low-to-high transition and vice versa.

So, I modified my code as follows and it worked fine.

...

 P2OUT |= BIT5 ;   /* Enable P2.5 internal resistance */
 P2REN |= BIT5;    /* Set up P2.5  as pull-up resistance */

 P2IES |= BIT5;    /* Sets P2IFG for high to low transition */
 P2IE  |= BIT5;    /* P2.5 interrupt enabled */
 P2IFG &= ~BIT5;   /* P2.5 IFG cleared */
...

#pragma vector=PORT2_VECTOR
__interrupt void port2_isr (void)
{
    switch (P2IV)
    {
        case 0x0CU:
        {
            TA1CCTL0 &= ~CCIE;
            TA1CCR0 = 0U;
            TA1CCTL0 |= CCIE;
            TA1CCTL0 &= ~CCIFG;
            TA1CCR0 = TA1R + 15U;
            P2IFG &= ~BIT5;
            break;
        }
        ...
        ...
    }
}

#pragma vector = TIMER1_A0_VECTOR    /*  Timer1_A3 CC0 */
static __interrupt void _timer1_ao_isr (void)
{
    TA1CCTL0 &= ~CCIE;
    if ((P2IN & BIT5) == 0U)
    {
       // Got a valid high-to-low assert here!!!
    }
}

Not actually an answer, just a suggestion, rename your variables to something more meaningful, two months from now you won't remember that BIT5 is the pin that you check for a high-to-low transition. You can use a define to rename BIT5 to say, HIGH_TO_LOW_PIN. You can do the same thing with the timer setup, refactor it to something more meaningful.