2.11 Input Capture and Compare Timer

The below example demonstrates how to use the Input Capture and Compare Timer peripheral in capture mode. A PWM signal is generated and fed as input to the input capture module. The input capture module is configured to generate an interrupt on falling edge of the input signal. The demo calculates and displays the frequency of the input signal on to the console.

volatile uint32_t capTimerCnt = 0;
volatile uint32_t diffCnt = 0;
volatile bool capInterrupt = false;
uint32_t freq = 0;

void cct_capture_callback(uintptr_t context)
{
    uint32_t timerCnt = CCT_FreeRunningTimerGet();
    if (timerCnt > capTimerCnt)
    {
        diffCnt = timerCnt - capTimerCnt;
    }
    else
    {
        diffCnt = (0xFFFFFFFF - capTimerCnt) + timerCnt;
    }
    capTimerCnt = timerCnt;
    capInterrupt = true;
}

int main ( void )
{
    /* Initialize all modules */
    SYS_Initialize ( NULL );
    
    printf("\n\r---------------------------------------------------------");
    printf("\n\r                    CCT Capture Demo                     ");
    printf("\n\r---------------------------------------------------------\n\r");
    
    CCT_Capture0CallbackRegister(cct_capture_callback, 0);
    
    CCT_FreeRunningTimerStart();
    
    PWM0_Start();

    while ( true )
    {
        if (capInterrupt == true)
        {
            freq = CCT_FrequencyGet()/diffCnt;
            printf("Frequency : %ld Hz\r\n", freq);
            capInterrupt = false;
        }
    }

    /* Execution should not come here during normal operation */

    return ( EXIT_FAILURE );
}