PWM skipping

[gaminn]

Hello, this is my PWM wrapper around nrf sdk pwm implementation:

#include "Pwm.h"
#include "app_pwm.h"

#define PIN    7

APP_PWM_INSTANCE(PWM1, 2);

static volatile TYesNo Ready = NO;

//-----------------------------------------------------------------------------

static void pwm_ready_callback(uint32_t pwm_id)    // PWM callback function
{
   Ready = YES;
}

void PwmInit( void)
// Initialisation
{
   app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_1CH(5000L, PIN);
   pwm1_cfg.pin_polarity[0] = APP_PWM_POLARITY_ACTIVE_HIGH;
   app_pwm_init(&PWM1,&pwm1_cfg,pwm_ready_callback);
   app_pwm_enable(&PWM1);
}

void PwmStart( byte Channel)
// Start PWM
{
}

void PwmDutySet( byte Channel, word Duty)
// Set PWM <Duty> cycle
{
   Ready = NO;
   while(app_pwm_channel_duty_set(&PWM1, Channel, Duty) == NRF_ERROR_BUSY);
   while(!Ready);
}

void PwmStop( byte Channel)
// Stop PWM
{
}

In main function I call:

PwmInit();
PwmDutySet(0, 50); // 50% duty on channel 0

It generates this:

The duty is OK, but the problem is that PWM is generated for 200 ms, then shuts off for another 200 ms. Why and how to fix it? Is anything bad with my PWM wrapper? I use softdevice S110. The MCU is not resetting as I'm able to connect to the application via BLE.

[Stefan Birnir Sverrisson]

Hi

I am actually not sure why you have such a periodic pause while using the PWM with the softdevice. Have you seen the PWM library on Github. I suspect that it would work better with the softdevice than the PWM example in the SDK.

[gaminn]

Unfortunately, I can't get the PWM library on Github working. I use nrf SDK 8 and the library is probably not compatible with it. At least I had to define nrf_gpiote_task_config and nrf_gpiote_unconfig functions which do not exist in nrf SDK 8. But the PWM still don't work. Is there another library which can generate 1 channel PWM. I don't need more.