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Code not working when compiled on Code Composer Studio but same code works with IAR

shivakumar wantamutte
Prodigy 150 points

Other Parts Discussed in Thread: MSP430G2553

Hi,

Below is the code to configure Timer0 on MSP430G2553 in up mode. On interrupt (i.e when timer value rolls over), I am toggling the LED. LED toggles when compiled and flashed with IAR but it doesnt work when compiled and flashed with CCS. Please help me with this issue.

#include <msp430.h>

/*
* main.c
*/
int main(void)

{

WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer


P1DIR |= 0x01;


TACTL=0x152;                         // Select Clock source, clock divider and enable timer interrupt

TACCTL0=CCIE;                     // Select compare mode and enable compare interrupt.

TACCR0=32768;                    // Timer Value register.

_EINT();                                   // Enable Global Interrupts.

for(;;)

{

}

}

#pragma vector=TIMER0_A0_VECTOR
__interrupt void TIMER0_ISR (void)
{
                  P1OUT ^= 0x01;                        // Toggle the LED each time the timer rolls over after max value.
}

Thanks and regards,
Shivakumar V W

  • 0
    Guru 58965 points

    What does the object code look like when compiled with CCS?

    Is the for (,,){} endless loop optimized out?

  • 0
    Guru 16361 points

    You've set the TAIE bit in TACTL, which enables the TAIFG interrupt request. You've also set CCIE in TACCTL0, which enables the CCIFG interrupt request.

    When TAR counts to the value in TACCR0, the TACCTL0.CCIFG flag will be set and that will result in the TIMER0_A0_VECTOR being called. That will toggle the state of P1.0 as you'd expect.

    On the next tick, TAR will "count" from the value in TACCR0 to zero, and TACTL.TAIFG will be set. That will cause the processor to try to run the TIMER0_A1_VECTOR which is not defined. On recent versions of CCS this will result in the trap ISR being called, and that will put your program into an infinite loop. I'm not sure what's happening on IAR, but it's possible that the MCU is resetting and restarting the program from the top. That would result in it looking like it was working correctly, as the IO output state is maintained across resets.

    Try changing the program to set TACTL = TASSEL_1 | ID_1 | MC_1, and it should work on both IAR and CCS.

  • 0 in reply to Robert Cowsill
    Prodigy 150 points
    I verified once again on IAR and its working fine i.e I was able to see breakpoint hit in the ISR. But anyways, your reply for not working with CCS worked fine for me. Yes it was entering Trap ISR and your suggestion helped me in fixing this issue. Thanks a lot.
  • 0 in reply to Robert Cowsill
    Guru 227245 points
    Robert, when in IAR there is a generic ISR (not an infinite loop) this will cause this ISR to be called continuously (TAIFG is not reset), but the CCR0 interrupt has higher priority, so it will be executed in-between. While main will stay frozen. While if the CPU is trapped inside the trap ISR (that never exit), even higher priority interrupts like the CCR0.CCIFG won't be executed.

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