cant not use capture timer interrupt msp430g2553

[MSPLife 2]

#define IRout BIT0
int main(void)
{
	WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
	BCSCTL1 = CALBC1_1MHZ;                    // Set DCO
	DCOCTL = CALDCO_1MHZ;

	P2DIR &= ~IRout;
	P2SEL |= IRout;
	P2SEL2 &= ~IRout;
	
	TA1CCTL0 = CM_2 + CCIS_0 + CAP + CCIE + SCS;		// Capture on falling edge, CCI0A, interrupt Enable
	TA1CTL = TASSEL_2 + MC_2 + TACLR + ID_0;		//

	__bis_SR_register(LPM0_bits+GIE);					// Go to sleep while waiting for trigger
	
	 while (true) {
  }
}
  
  #pragma vector=TIMER1_A0_VECTOR
__interrupt void Timer1A0(void)
{
	__bic_SR_register_on_exit(LPM0_bits);
}

Hi guys,

Below is my program, it's can not detect a falling edge. I set a break point at line "while true", it can not jump to that position.

What I was wrong?

Thank in advance!

[roadrunner84 466]

IIRC there are TWO interrupt vectors associated with the timer, are you using the right one? Also, the timer does have an interrupt of itself, using the TAIE flag. It is off by one clocktick with respect to CCR0 though.

[tripwire 139]

Your code works for me if I add the following two lines to the pin setup:

    P2OUT |= IRout;
    P2REN |= IRout;

That enables the pullup resistor on P2.0 so that when you ground it there's a definite transition from high to low.