RE: nrf52832 pwm interrupt at end of period

L.B. — Thu, 16 Jul 2020 12:15:31 GMT

OK, so there is no legal way to do it, because the event NRF_PWM_EVENT_PWMPERIODEND is not being used by the driver.

Here is how I did it, with combined approach driver API + register access:

#include "nrf_drv_pwm.h"
#include "nrfx_pwm.h"

static nrf_drv_pwm_t m_pwm1 = NRF_DRV_PWM_INSTANCE(1);

static nrf_drv_pwm_config_t config1 = {
       .output_pins = {
               3, // channel 0
               NRF_DRV_PWM_PIN_NOT_USED, // channel 1
               NRF_DRV_PWM_PIN_NOT_USED, // channel 2
               NRF_DRV_PWM_PIN_NOT_USED // channel 3
       },
       .irq_priority = APP_IRQ_PRIORITY_LOWEST,
       .base_clock   = NRF_PWM_CLK_16MHz,
       .count_mode   = NRF_PWM_MODE_UP_AND_DOWN,
       .top_value    = 116, //~70kHz
       .load_mode    = NRF_PWM_LOAD_INDIVIDUAL,
       .step_mode    = NRF_PWM_STEP_AUTO
};

static nrf_pwm_values_individual_t /*const*/ seq_values[] = {
       {0x4D}
};

static nrf_pwm_sequence_t const pwm_seq_settings = {
       .values.p_individual = seq_values,
       .length              = NRF_PWM_VALUES_LENGTH(seq_values),
       .repeats             = 0,
       .end_delay           = 0
};

void user_touch_pwm_handler(nrf_drv_pwm_evt_type_t event_type){
   static uint32_t count = 0;

   if(count == 9){
       nrf_drv_pwm_uninit(&m_pwm1);
   }

   count++;
}

void user_touch_pwm_init(void){
   nrf_drv_pwm_init(&m_pwm1, &config1, user_touch_pwm_handler);
   m_pwm1.p_registers->INTENSET |= NRF_PWM_INT_PWMPERIODEND_MASK;
   nrf_drv_pwm_simple_playback(&m_pwm1, &pwm_seq_settings, 1, NRF_DRV_PWM_FLAG_LOOP);
}

This program will generate 10 pulses on P0.03 with 70 kHz frequency and will stop.

Regards,

L. B.

RE: nrf52832 pwm interrupt at end of period

haakonsh — Thu, 16 Jul 2020 12:06:01 GMT

You'll have to port the code to use the Timer driver API's. Afterwards, what you need to do to enable the interrupt is to call nrf_drv_timer_compare_int_enable(). The event handler provided to nrf_drv_timer_init will be called on any interrupt generated by that timer instance, so you'll have to determine what event it was, see:

nrf_drv_timer_init, nrf_timer_event_handler_t, and nrf_timer_event_t.