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);

    
}

[Karl Ylvisaker]

Hello,

I am quite new to nordic environment.

Welcome! Please do not hesitate to ask if you should have any questions.

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

Could you show me the entirety of your main.c code?
Right now I do not see where you setup your gpio for triggering the enabling of the timer, so I am not sure that the timer is ever started, for instance.

Could you also elaborate on what behavior you are seeing, and how this differs from what you would expect? Does the device reset for example, or is it just that 'nothing' is happening, for example?

Best regards,
Karl

[RAM_MS]

Hello Karl,

Karl Ylvisaker said:

Right now I do not see where you setup your gpio for triggering the enabling of the timer, so I am not sure that the timer is ever started, for instance.

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

   
}

Karl Ylvisaker said:

Could you also elaborate on what behavior you are seeing, and how this differs from what you would expect? Does the device reset for example, or is it just that 'nothing' is happening, for example?

I am not getting the delay I am expecting.

I think I have done some wrong configuration in linking to timer from gpio interrupt routine. 

Best regards,
Ram

[RAM_MS]

Hello Karl,

               sorry for the inconvenience.

              Please find below attached .zip file of the project .pwm_timer_based - Copy.zip

Best regards,
Ram

[Karl Ylvisaker]

Thank you for providing the .zip file.

The first thing I notice in your code is that you are both making use of the drivers / libraries, and manipulating the registers directly - you should only ever do one of the two, since direct modifying of registers while also using the drivers can break them or force them into invalid states with undefined behavior.

I will try to replicate the behavior you describe on my end with the constant 98 µs CC events - which SDK version are you using?

Best regards,
Karl

[RAM_MS]

Hello Karl,

Karl Ylvisaker said:

The first thing I notice in your code is that you are both making use of the drivers / libraries, and manipulating the registers directly - you should only ever do one of the two, since direct modifying of registers while also using the drivers can break them or force them into invalid states with undefined behavior.

 Okay .As I am quite new to Nordic environment ,so take multiple Nordic sdk example  into account to create my application.

 You can also suggest me ,how to implement this as complete scenario is known to you( I am expecting ).

Karl Ylvisaker said:

I will try to replicate the behavior you describe on my end with the constant 98 µs CC events - which SDK version are you using?

I am using SDK 17.02 version.

Please guide me to resolve this.

Best regards,
Ram

[RAM_MS]

Hello Karl,

               Waiting for your valuable inputs.

 

Thanks & regards,
Ram

[RAM_MS]

Hello Karl,

               Waiting for your response.

 

Thanks & regards,
Ram

[Karl Ylvisaker]

Hello again, Ram

Thank you for your continued patience with this. I am sorry that it has taken so long to get back to you on this.

RAM_MS said:

 Okay .As I am quite new to Nordic environment ,so take multiple Nordic sdk example  into account to create my application.

Welcome!
Absolutely, merging different examples could absolutely be a challenge if ones not already familiar with the SDK and how it works.

RAM_MS said:

You can also suggest me ,how to implement this as complete scenario is known to you( I am expecting ).

Yes, sure, I'll take a look at this today. I'll update you by the end of day.

Best regards,
Karl

[RAM_MS]

Hello Karl,

Karl Ylvisaker said:

Yes, sure, I'll take a look at this today. I'll update you by the end of day

Sure, I am eagerly waiting for your response.

 

Thanks & regards,
Ram

[Karl Ylvisaker]

Hello again, Ram

Attached you'll find an example that updates the PWM duty cycle using a button to start a timer that calls the pwm_update function when it expires. The delay is configurable and defined at the top of main.c
To test the example just flash it to a nRF52 DK and press button 1 on the DK -  after the configurable delay has passed it will call the (currently empty) pwm_update function.

I did not know exactly what you would like to update the PWM to, or what configuration you need to PWM to have wrt. frequency and polarity, so I used the default pwm configuration from the pwm_library example, and left the pwm_update function empty.
You could also reconfigure the input to be a non-button pin, if that's what you are going to use in your application.

Take a look and let me know if this was what you were looking for, or if you should have any questions! :) 

Best regards,
Karl

[Karl Ylvisaker]

Strange, it seems something went wrong with the previous upload.
I try again here:
5852.pwm_button_timer_demo.zip

I also forgot to mention: extract the .zip to your SDK17.0.2/examples/peripheral path.

[RAM_MS]

Hello Karl,

Karl Ylvisaker said:

ake a look and let me know if this was what you were looking for, or if you should have any questions!

I definitely tested this today and update you the status .

Advance thank you for valuable time and inputs. 

Thanks & regards,
Ram