PWM glitch/duty inversion when rapidly changing duty cycle

RE: PWM glitch/duty inversion when rapidly changing duty cycle

martin-ve — Fri, 12 Dec 2014 15:09:56 GMT

Hi All,

I have a similar problem. I have a nRF51 dongle, using SDK 7.1.0 without SD. I'm using two channels. One seems fine, the other one sometimes seems to miss an event, causing the signal to change polarity. I.e. when I set 15% duty it is actually 85%

I've also tried the nrf_pwm_noglitch driver. However, then only one channel is working. The one that is working, seems to work fine.

This is my code:

#include <stdbool.h>
#include <stdint.h>
#include "nrf.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "nrf_pwm.h"
#include "boards.h"
    
int main(void)
{
    uint32_t counter = 0;
    
    nrf_pwm_config_t pwm_config = PWM_DEFAULT_CONFIG;

	 /* This config will generate a frequency of 20kHz */
    pwm_config.mode             = PWM_MODE_MTR_100;
    pwm_config.num_channels     = 2;
    pwm_config.gpio_num[0]      = 15;
    pwm_config.gpio_num[1]      = 16;
    
    nrf_pwm_init(&pwm_config);
	
	 /* Change the resolution from 100 to 1000, resulting in a 
	 * PWM frequency of 2kHz with a resolution from 0-1000 */
	 nrf_pwm_set_max_value(1000);

    while (true)
    {
	    nrf_pwm_set_value(0, counter);
        nrf_pwm_set_value(1, counter);
			
        counter = (counter + 10) % 1000;
        
        nrf_delay_us(1000);
    }
}

RE: PWM glitch/duty inversion when rapidly changing duty cycle

michael — Wed, 10 Dec 2014 13:09:00 GMT

Hi Torbjorn, I'm using sdk version 6.1.0 and SoftDevice s110 7.1.0. I've created a support case in which I attached source for the nRF6310+PCA10004 DK that demonstrate the issue by fading LED 1 on the board in and out.

RE: PWM glitch/duty inversion when rapidly changing duty cycle

ovrebekk — Tue, 09 Dec 2014 13:32:19 GMT

Hi Michael

Which SDK and SoftDevice version are you using?

Also, are you able to share your code project? If yes, please just zip the project folder, including source and project files.

Regards Torbjørn