LAUNCHXL-CC2640R2: Waveform Generation

Thank you for the response!

A fixed-frequency 40kHz square pulse will work just fine, so I can go with that. Would you be able to guide me to some resources on how to implement this through PWM? Would I have to use Sensor Controller Studio or any other module?

Thanks!

Thank you very much for the help.

I am now trying to modify the pwmled2 example project to fit my specifications. Below is my modified code so far in the main thread of pwmled2.c. Everything else is in the example project is the same as how I downloaded it.

I am trying to generate a burst of pulses at 50% duty cycle for a short amount of time (time_fast) and then have it stay idle at a duty cycle of 0 for a longer period of time (time_slow). However, the duty cycle never changes from 0 to anything else in my while loop even though I am using  PWM_setDuty(). I tried different values but it always stays at 0 (or whatever value it is initialized to outside the while loop). How can I fix this?

void *mainThread(void *arg0)

{

    /* Period and duty in microseconds */

    uint16_t   pwmPeriod = 25;

    uint16_t   duty = 0;

    /* Sleep time in microseconds */

    uint32_t   time_slow = 100000; // delay between stages of LED

    uint32_t   time_fast = 1000;

    PWM_Handle pwm1 = NULL;

    PWM_Params params;

    /* Call driver init functions. */

    PWM_init();

    PWM_Params_init(&params);

    params.dutyUnits = PWM_DUTY_FRACTION;

    params.dutyValue = 0;

    params.periodUnits = PWM_PERIOD_US;

    params.periodValue = pwmPeriod;

    pwm1 = PWM_open(Board_PWM0, &params);

    if (pwm1 == NULL) {

        /* Board_PWM0 did not open */

        while (1);

    }

    PWM_start(pwm1);

    /* Loop forever incrementing the PWM duty */

    while (1) {

        printf("duty first %d\n", duty);

        if (duty == 0) {

            printf("duty slow %d\n", duty);

            usleep(time_slow);

            PWM_setDuty(pwm1, 0.5);

        }

        else if (duty != 0) {

            printf("duty fast %d\n", duty);

            usleep(time_fast);

            PWM_setDuty(pwm1, 0);

            printf("DUTY SET %d\n", duty);

        }

        else {

            printf("wrong duty %d\n", duty);

        }

    }

}

Thank you!

I am able to generate a signal that turns on and off intermittently. However, I am not yet able to control the time duration the signal is on and off for. Using usleep() (commented out below) does not seem to have any effect on the time duration. Is there another way to control the time duration the pulse stays on and off? For example, outputting burst for 1ms and staying idle for 100ms.

Additionally, would it be possible to control the number of pulses? For example, generate 5 40kHz square pulses every 100ms. I realize I can use a counter to just increment the number of pulses to 5, but I do not know how to generate just one single pulse. Currently, the signal produces bunch of square waves for the amount of time it is on.

void *mainThread(void *arg0)

{

    /* Period and duty */

    uint16_t   pwmPeriod = 40000; // in Hz

    uint32_t   duty;

    /* Sleep time in microseconds */

//    uint32_t   time_slow = 10000000; // idle duration

//    uint32_t   time_fast = 1000; // burst duration

    PWM_Handle pwm1 = NULL;

    PWM_Params params;

    /* Call driver init functions. */

    PWM_init();

    PWM_Params_init(&params);

    params.dutyUnits = PWM_DUTY_FRACTION;

    params.dutyValue = 0;

    params.periodUnits = PWM_PERIOD_HZ;

    params.periodValue = pwmPeriod;

    pwm1 = PWM_open(Board_PWM0, &params);

    if (pwm1 == NULL) {

        /* Board_PWM0 did not open */

        while (1);

    }

    PWM_start(pwm1);

    /* Loop forever incrementing the PWM duty */

    while (1) {

        printf("duty first %d\n", duty);

        if (duty == 0) {

            duty = (uint32_t) (((uint64_t) PWM_DUTY_FRACTION_MAX * 50) / 100);

//            usleep(time_slow);

        }

        else if (duty != 0) {

            duty = (uint32_t) (((uint64_t) PWM_DUTY_FRACTION_MAX * 0));

//            usleep(time_fast);

            PWM_setDuty(pwm1, duty);

            printf("DUTY SET %d\n", duty);

        }

        else {

            printf("wrong duty %d\n", duty);

        }

    }

}

Thank you. I will take a look. Is there an example project I could look at that incorporates this?

What about just controlling the time duration? Not the number of pulses. Like I mentioned, usleep() did not have any effect on the time duration of how long the LED stayed on/off. Is there another way that I am missing?