How to start pwm sequence after particular time delay of gpio event?

[RAM_MS]

I am working on an application where I need to start pwm sequence after particular delay (accurate delay of multiple of 100us).

I am quite new to nordic environment.

Here is my code . Can please guide me what is wrong here??

#define    Period    20000 //20ms

const nrf_drv_timer_t TIMER_LED = NRF_DRV_TIMER_INSTANCE(0);

APP_PWM_INSTANCE(PWM1,1); 

static int gpio_flag =0;

void pwm_update(void)
{
      uint32_t value;
      value = duty_1;
      ready_flag = false;
      /* Set the duty cycle - keep trying until PWM is ready... */
      
      

      while ((app_pwm_channel_duty_set(&PWM1, 0, value))&(app_pwm_channel_duty_set(&PWM1, 1, value)) == NRF_ERROR_BUSY);
 
      /* ... or wait for callback. */
      while (!ready_flag);
      APP_ERROR_CHECK(app_pwm_channel_duty_set(&PWM1, 1, value));
      APP_ERROR_CHECK(app_pwm_channel_duty_set(&PWM1, 0, value));

}


void in_pin_handler(nrf_drv_gpiote_pin_t pin, nrf_gpiote_polarity_t action)
{
   gpio_flag =1;
   nrf_drv_timer_enable(&TIMER_LED);

   
}

void timer0_handler(nrf_timer_event_t event_type, void* p_context)
{
  switch (event_type)
    {
        case NRF_TIMER_EVENT_COMPARE0:
             timer_flg =1;
             nrf_drv_timer_clear(&TIMER_LED);
             gpio_flag=0;
             pwm_update();
            break;

        default:
            //Do nothing.
            break;
    }
}


void timer_init(void)
{
    uint32_t time_us = 500; 
    uint32_t time_ticks;
    uint32_t err_code = NRF_SUCCESS;

    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
    err_code = nrf_drv_timer_init(&TIMER_LED, &timer_cfg, timer0_handler);
    APP_ERROR_CHECK(err_code);

    time_ticks = nrf_drv_timer_us_to_ticks(&TIMER_LED, time_us);
    nrf_drv_timer_compare(
         &TIMER_LED, NRF_TIMER_CC_CHANNEL0, time_ticks, true);

    
}

[RAM_MS]

Hello Karl,

Karl Ylvisaker said:

This looks mostly correct, but I cant see that you have connected the GPIOTE IN EVENT to the TIMER's START task through PPI anywher

static void ppi_init(void)
{
    uint32_t err_code = NRF_SUCCESS;

    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);

    // Allocate the channel from the available PPI channels
    err_code = nrf_drv_ppi_channel_alloc(&ppi_channel_1);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_assign(ppi_channel_1,
                                          nrf_drv_gpiote_in_event_addr_get(PIN_IN),
                                          nrf_drv_timer_task_address_get(&PWM_DELAY_TIMER,
                                                                         NRF_TIMER_TASK_START));
    APP_ERROR_CHECK(err_code);


    err_code = nrf_drv_ppi_channel_alloc(&ppi_channel_2);
    APP_ERROR_CHECK(err_code);

    compare_event_addr = nrf_drv_timer_task_address_get(&PWM_DELAY_TIMER,NRF_TIMER_CC_CHANNEL0);
    pwm_task_addr =  nrf_drv_pwm_task_address_get(&m_pwm0,NRF_PWM_TASK_SEQSTART0);

    err_code = nrf_drv_ppi_channel_assign(ppi_channel_2, compare_event_addr,pwm_task_addr);
    APP_ERROR_CHECK(err_code);


    err_code = nrf_drv_ppi_channel_enable(ppi_channel_1);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_enable(ppi_channel_2);
    APP_ERROR_CHECK(err_code);
 }

static void gpio_init(void)
{
    ret_code_t err_code;
    

    err_code = nrf_drv_gpiote_init();
    APP_ERROR_CHECK(err_code);

    
    nrf_drv_gpiote_in_config_t in_config = GPIOTE_CONFIG_IN_SENSE_LOTOHI(true);
    in_config.pull = NRF_GPIO_PIN_PULLDOWN;

    err_code = nrf_drv_gpiote_in_init(PIN_IN, &in_config, in_pin_handler);
    APP_ERROR_CHECK(err_code);

    nrf_drv_gpiote_in_event_enable(PIN_IN, true);
}

void timers_init(void)
{
    uint32_t err_code;
    uint32_t timer_ticks;
    
    nrfx_timer_config_t timer_cfg = NRFX_TIMER_DEFAULT_CONFIG;
    timer_cfg.frequency = NRF_TIMER_FREQ_1MHz;
    err_code = nrfx_timer_init(&PWM_DELAY_TIMER, &timer_cfg,pwm_delay_timeout_handler);
    APP_ERROR_CHECK(err_code);

    timer_ticks = nrfx_timer_us_to_ticks(&PWM_DELAY_TIMER, PWM_DELAY_US);

    nrfx_timer_extended_compare(&PWM_DELAY_TIMER, 
                                  NRF_TIMER_CC_CHANNEL0, 
                                  timer_ticks,
                                  NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
                                  true);

   nrfx_timer_enable(&PWM_DELAY_TIMER);

}


static void pwm_init(void)
{
    nrf_drv_pwm_config_t const config0 =
    {
        .output_pins =
        {
            OUTPUT_PIN, // channel 0
            OUTPUT_PIN2,             // 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_1MHz,
        .count_mode   = NRF_PWM_MODE_UP,
        .top_value    = 20000,
        .load_mode    = NRF_PWM_LOAD_INDIVIDUAL,
        .step_mode    = NRF_PWM_STEP_AUTO
    };
    // Init PWM without error handler
    APP_ERROR_CHECK(nrf_drv_pwm_init(&m_pwm0, &config0, NULL));

    seq_values->channel_0 = duty ;
    seq_values->channel_1 = duty | 0x8000;
    
    APP_ERROR_CHECK(nrf_drv_pwm_simple_playback(&m_pwm0, &seq, 1,NRF_DRV_PWM_FLAG_LOOP|NRF_DRV_PWM_FLAG_START_VIA_TASK));
                
}

So this scenario needed two ppi connection .

1-> From GPIOTE  IN   EVENT to the TIMER START 

2->TIMER COMPATRE to PWM_TASK_SEQSTART .

I am implemented in this way ,Please verify is this connection is right now??

  

[Karl Ylvisaker]

RAM_MS said:

So this scenario needed two ppi connection .

1-> From GPIOTE  IN   EVENT to the TIMER START 

2->TIMER COMPATRE to PWM_TASK_SEQSTART .

Yes, your scenario requires two PPI connections.

RAM_MS said:

I am implemented in this way ,Please verify is this connection is right now??

Yes, I do not immediately spot anything wrong with this configuration.
What do you see when you now attempt to compile and run this program?

Best regards,
Karl

[RAM_MS]

Hello Karl,

Karl Ylvisaker said:

What do you see when you now attempt to compile and run this program?

compiled successfully with zero error but pwm output isn't coming , that means its not triggering.

But below error coming.

<error> app: Fatal error

<warning> app: System reset

Best regards,
 Ram

[Karl Ylvisaker]

Please make sure to have DEBUG defined in your preprocessor defines, like shown in the included image:

This will make the logger output a detailed error message whenever a non-NRF_SUCCESS error is passed to an APP_ERROR_CHECK.
Try this, and let me know what the logger says when this happens.

Best regards,
Karl

[RAM_MS]

Hello Karl,

Karl Ylvisaker said:

Try this, and let me know what the logger says when this happens.

<info> app: PPI example started.

<info> app: LED started.

<info> app: gpio started.

<info> app: timer started.

<error> app: ERROR 1073856524 [Unknown error code] at C:\Nordic\DeviceDownload\nRF5SDK1702d674dde\nRF5_SDK_17.0.2_d674dde\examples\my proj\pwm_common_mode\main.c:176

PC at: 0x00006BA5

<error> app: End of error report

And my main code is:

int main(void)
{

    uint32_t err_code;

    err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();
    ppi_init();
    NRF_LOG_INFO("PPI example started.");
    bsp_board_init(BSP_INIT_LEDS);
    NRF_LOG_INFO("LED started.");
    gpio_init();
    NRF_LOG_INFO("gpio started.");
    timers_init();
    NRF_LOG_INFO("timer  started.");
    pwm_init();
    
    NRF_LOG_INFO("pwm started.");
     
    unsigned int val;
    
    while (1)
    {
      
      
       
    }
}

This means Its coming from pwm_init() function.

Best regards,
 Ram