TM4C123GH6PM: Timer Match Interrupt Not Firing

Rohin Malhotra

Part Number: TM4C123GH6PM

Hi,

I have the Tiva C Series TM4C123G Launchpad. I have been trying to configure the Compare Match interrupt for Timer0 but am unable to make it fire. Will be glad if anyone can help me out. Below is my code.

void Timer0AIntHandler(void)
{
    // Clear the timer interrupt
    TimerIntClear(TIMER0_BASE, TIMER_CAPA_MATCH);

    GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1, GPIO_PIN_1 );

}

void timer_init0()
{

        SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);
        TimerConfigure( TIMER0_BASE, TIMER_CFG_PERIODIC );

        TimerLoadSet(TIMER0_BASE, TIMER_A, 8000 );
        TimerMatchSet(TIMER0_BASE, TIMER_A, 5000 );

        IntEnable(INT_TIMER0A);

        TimerIntEnable(TIMER0_BASE, TIMER_CAPA_MATCH);
        IntMasterEnable();

        TimerIntRegister(TIMER0_BASE, TIMER_A, Timer0AIntHandler);

        TimerEnable(TIMER0_BASE, TIMER_A);

}

Also I've been unable to understand what is prescalar and prescalar match. My experience tells me that prescalar is used for getting a different clock frequency for the timer than the system clock. And is prescalar match the Timer Match when using the prescalar?

over 7 years ago

0 Charles Tsai over 7 years ago

TI__Guru**** 170356 points

Hi,
Can you change to TimerConfigure( TIMER0_BASE, TIMER_CFG_SPLIT_PAIR | TIMER_CFG_A_PERIODIC )?

0 Rohin Malhotra over 7 years ago in reply to Charles Tsai

Prodigy 30 points

Already tried. Does not work.

0 Rohin Malhotra over 7 years ago

Prodigy 30 points

Okay, I guess I've found quite a big gaping hole in TivaWare for TM4C123GH6PM. The Timer API has no function argument defined for setting up the Timer for Compare Match. Same goes for the interrupt for compare match.

You will have to set up the hardware registers manually to make this work.

// Enabling Timer1 compare match interrupt
TIMER1_IMR_R |= 0x10 ;

// Clearing Timer1 compare match interrupt
TIMER1_ICR_R = 16 ;

0 Charles Tsai over 7 years ago in reply to Rohin Malhotra

TI__Guru**** 170356 points

Hi Rohin,
Sorry, I was out of office yesterday. As I mentioned to you in our private message, I also couldn't get it to work as the API only has TIMER_CAPA_MATCH and among others to choose from which do not include the real timer compare match interrupt unless you directly write to the register to enable the corresponding interrupt. This is a shortcoming in the API and we will take note of it and see what we can do about it.

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TM4C123GH6PM: Timer Match Interrupt Not Firing