CCS/MSP430F5529: Not getting GPIO interrupt for button press

Jacob Ignatius

Part Number: MSP430F5529

Tool/software: Code Composer Studio

Hi,

I am trying to toggle an LED on the MSP430F5529 Launchpad when a button is pressed. The button is on board the chip, connected to P1.1, and the LED is connected to 1.0.

I am not getting an interrupt for the button press.

My code is shown below. Can you tell me what is wrong?

#include <msp430.h> 


/**
 * main.c
 */
int main(void)
{
	WDTCTL = WDTPW | WDTHOLD;	// stop watchdog timer
	
	//Switch LED off
	P1DIR |= BIT0;    // P1.0 is output and the rest are input
	P1OUT &= ~0x01;
	P1IE  |= (BIT1);
	P1IES &= (~BIT1); // Falling Edge 1 -> 0
	P1IFG &= (~BIT1); // Clear interrupt flag for P2.1

	while (1)
    {
        __bis_SR_register(LPM0_bits + GIE);   // Enter LPM0 and wait for an interrupt
        __no_operation();                     // Set breakpoint >>here<< and read
    }

	return 0;
}

#pragma vector = PORT1_VECTOR
__interrupt void InterruptVectorPort1()
{
    P1OUT ^= 0x01;  // Toggle P1.0
    P1IFG &= ~BIT1; // Clear Interrupt Flag
}

over 7 years ago

0 Jeff Hastings over 7 years ago

Intellectual 820 points

turn on the pull up for P1.1

0 Jacob Ignatius over 7 years ago in reply to Jeff Hastings

Intellectual 300 points

I tried that:

#include <msp430.h> 


/**
 * main.c
 */
int main(void)
{
	WDTCTL = WDTPW | WDTHOLD;	// stop watchdog timer
	
	//Switch LED off
	P1DIR |= BIT0;    // P1.0 is output and the rest are input
	P1OUT &= ~0x01;
	P1IE  |= (BIT1);
	P1IES &= (~BIT1); // Falling Edge 1 -> 0
	P1IFG &= (~BIT1); // Clear interrupt flag for P2.1
	P1REN |= BIT1;

	while (1)
    {
        __bis_SR_register(LPM0_bits + GIE);   // Enter LPM0 and wait for an interrupt
        __no_operation();                     // Set breakpoint >>here<< and read
    }

	return 0;
}

#pragma vector = PORT1_VECTOR
__interrupt void InterruptVectorPort1()
{
    P1OUT ^= 0x01;  // Toggle P1.0
    P1IFG &= ~BIT1; // Clear Interrupt Flag
}

but I still don't get an interrupt.

0 Bruce McKenney over 7 years ago in reply to Jacob Ignatius

Guru 95350 points

How do you know you're not getting an interrupt?
A debugger breakpoint in the ISR is a reliable indicator. The LED is less so, due to switch bounce. A breakpoint at the __no_operation() in main will never be reached (see also LPM0_EXIT).

0 Jacob Ignatius over 7 years ago in reply to Bruce McKenney

Intellectual 300 points

I already have a breakpoint in my ISR and the debugger never gets there.

Are there any jumpers I need to remove?

0 Bruce McKenney over 7 years ago in reply to Jacob Ignatius

Guru 95350 points

Your code acts as expected -- I hit a breakpoint in the ISR, and the LED responds (modulo switch bounce) -- on my F5529 Launchpad.

[LP Rev 1.6. All the "eZ-FET" jumpers are installed except 5V, RTS, and CTS. JP8 (LED1) jumper is installed. Nothing else is connected. CCS 6.2.0.]

If you Pause (double vertical bars in the toolbar), where is it executing?

0 Bruce McKenney over 7 years ago in reply to Bruce McKenney

Guru 95350 points

..and then I power cycled it, and saw your symptom. Add the line:

P1OUT |= BIT1; // Pull Up, not Down

0 Jacob Ignatius over 7 years ago in reply to Bruce McKenney

Intellectual 300 points

Thanks

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CCS/MSP430F5529: Not getting GPIO interrupt for button press