RE: Unable to generate PWM pulse

Stefan Birnir Sverrisson — Sun, 27 Sep 2015 07:57:45 GMT

Hi Ayan

I have included an answer on this thread which hopefully answers your question.

RE: Unable to generate PWM pulse

Ayan — Fri, 25 Sep 2015 07:33:41 GMT

Thanks Stefan. I too feel that it'll be best to use a standard pwm_library. I have downloaded nrf51-pwm-library from github, But I don't know how/where to start. Can you help me guiding on how to include the library in my project? I'm new to this.

RE: Unable to generate PWM pulse

Stefan Birnir Sverrisson — Wed, 23 Sep 2015 16:09:36 GMT

Hi Ayan

May I ask why you want to make your own pwm implementation? The basics of the pwm_library on Github is basically the same as you are proposing, i.e. a Timer using two CC registers, two PPIs and a single GPIOTE channel in Toggle mode. You can configure it for many PWM channels or just one PWM channel. You could configure it to a single PWM channel by defining your main function as e.g. :

int main(void)
{
	nrf_pwm_config_t pwm_config = PWM_DEFAULT_CONFIG;
	pwm_config.mode             = PWM_MODE_LED_255;
	pwm_config.num_channels     = 1;
	pwm_config.gpio_num[0]      = LED_1;

    nrf_pwm_init(&pwm_config);

	nrf_pwm_set_value(0, 150);
	nrf_delay_us(1000000);
	nrf_pwm_set_value(0, 180);
	nrf_delay_us(1000000);
	nrf_pwm_set_value(0, 210);
	nrf_delay_us(1000000);
	nrf_pwm_set_value(0, 240);

    while(true){}
}

where the duty cycle of the configured channel is set 4 times.

I recommend to use the pwm_library as it uses Timeslot API to safely update the pwm duty cycle, which is discussed on this thread a little.