Low-power PWM library: PWM doesnt stop if low_power_pwm_stop is called from handler. Is this a bug?

Question

I am using SDK 12.0.0. 
 I am working with low_power_pwm_init() to initialise the pwm and I have passed a handler while initialising. I want to stop the pwm from the handler hence I am calling low_power_pwm_stop() from the handler. I observe that the pwm doesnt stop. 
 I tried to investigate the reason for this and found that pwm_timeout_handler() in low_power_pwm.c is restarting the pwm. Below is the snippet that is suspect. 
 if (p_pwm_instance->pwm_state == NRF_DRV_STATE_INITIALIZED)
{
 p_pwm_instance->pwm_state = NRF_DRV_STATE_POWERED_ON;
 err_code = app_timer_start(*p_pwm_instance->p_timer_id, p_pwm_instance->timeout_ticks, p_pwm_instance);
 APP_ERROR_CHECK(err_code);
}
 
 In low_power_pwm_stop(), p_pwm_instance->pwm_state is assigned NRF_DRV_STATE_INITIALIZED and in the above snippet the timer is started if the driver state is NRF_DRV_STATE_INITIALIZED, causing the pwm to be ON again. 
 Is this a bug?

FormerMember · Accepted Answer

I modified the low_power_pwm.c to fix. 
 static void pwm_timeout_handler(void * p_context)
{
 ret_code_t err_code;
 uint8_t duty_cycle;

 low_power_pwm_t * p_pwm_instance = (low_power_pwm_t *)p_context;

 if (p_pwm_instance->evt_type == LOW_POWER_PWM_EVENT_PERIOD)
 {
 duty_cycle = p_pwm_instance->duty_cycle;

 if (duty_cycle == p_pwm_instance->period) // Process duty cycle 100%
 {
 led_on(p_pwm_instance);
 p_pwm_instance->timeout_ticks = p_pwm_instance->period + APP_TIMER_MIN_TIMEOUT_TICKS;
 }
 else if (duty_cycle == 0) // Process duty cycle 0%
 {
 led_off(p_pwm_instance);
 p_pwm_instance->timeout_ticks = p_pwm_instance->period + APP_TIMER_MIN_TIMEOUT_TICKS;
 }
 else // Process any other duty cycle than 0 or 100%
 {
 led_on(p_pwm_instance);
 p_pwm_instance->timeout_ticks = ((duty_cycle * p_pwm_instance->period)>>8) +
 APP_TIMER_MIN_TIMEOUT_TICKS;
 // setting next state
 p_pwm_instance->evt_type = LOW_POWER_PWM_EVENT_DUTY_CYCLE;
 }

 if (p_pwm_instance->handler)
 {
 p_pwm_instance->handler(p_pwm_instance);
 }
 }
 else
 {
 led_off(p_pwm_instance);
 p_pwm_instance->evt_type = LOW_POWER_PWM_EVENT_PERIOD;
 p_pwm_instance->timeout_ticks = (((p_pwm_instance->period - p_pwm_instance->duty_cycle) * p_pwm_instance->period)>>8) +
 APP_TIMER_MIN_TIMEOUT_TICKS;
 }

 if (p_pwm_instance->pwm_state == NRF_DRV_STATE_POWERED_ON)
 {
 err_code = app_timer_start(*p_pwm_instance->p_timer_id, p_pwm_instance->timeout_ticks, p_pwm_instance);
 APP_ERROR_CHECK(err_code);
 }
}
 
 I hope it helps you.

Ole Bauck · Answer

Hi, 
 I can see that this will be the case and will report it internally. 
 You can set a flag in the event handler and call the stop routine in main. 
 Ole

Low-power PWM library: PWM doesnt stop if low_power_pwm_stop is called from handler. Is this a bug?

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