How to have a beep after another in a loop with PWM?

RE: How to have a beep after another in a loop with PWM?

builder01 — Sun, 18 Sep 2022 09:31:03 GMT

I ended up using this library to solve my problem:
sourceforge.net/.../

RE: How to have a beep after another in a loop with PWM?

builder01 — Tue, 12 Jul 2022 05:28:21 GMT

Hi,

Based on your suggestion I attempted the following:

static void buzzer_write_handler(ble_buzzer_service_t * p_buzzer_service, ble_buzzer_new_status_t * new_buzzer_status)
{
    
    buzzer_new_status_t new_status = new_buzzer_status->params_command.status_command_data;
    //ble_buzzer_service_t * p_buzz_serv = p_buzzer_service;
    //uint8_t const * p_data

    nrf_pwm_sequence_t const seq0 = 
    {
      .values.p_common = sequence_values,
      .length          = NRF_PWM_VALUES_LENGTH(sequence_values),
      .repeats         = 0x00,
      .end_delay       = 0,
    };

    NRF_LOG_INFO("write handler");
    while(new_status.p_data[0] == 0x01)
    {
      NRF_LOG_INFO("Buzzing!");
      (void)nrfx_pwm_simple_playback(&m_pwm0, &seq0, 3, NRFX_PWM_FLAG_STOP);
      nrf_delay_ms(500);
      
      //read p_data gain
      //new_status = new_buzzer_status->params_command.status_command_data;
    }
    
    (void)nrfx_pwm_stop(&m_pwm0, false);
    NRF_LOG_INFO("Quiet!");
    
}

However, it doesn't work because, at least within the scope of the while-loop, the new_status.pdata[0] will not change.

The question is: how can I make the application pass the new value I've written to the characteristic when it is inside this while-loop playing the PWM tone?

I tried calling the buzzer_write_handler() again within the while-loop, but that didn't work either.

RE: How to have a beep after another in a loop with PWM?

Kenneth — Mon, 11 Jul 2022 15:05:04 GMT

I don't see how your while(1) will ever exit? You need some logic to exit that while loop when you want to stop the pwm.

Kenneth

RE: How to have a beep after another in a loop with PWM?

builder01 — Mon, 11 Jul 2022 15:00:20 GMT

Hi Kenneth,

Thanks for your answer.

Setting the NRF_LOG_DEFERRED to 0 made the NRF_LOG_INFO() call work.

But also, as I expected, it's basically printing the NRF_LOG_INFO("Buzzing! within pwm_play") calls within the while-loop. If I write 0x00 to the characteristic, the function pwm_stop() is not called, because the application is stuck in the while-loop of the pwm_play() function.

It sounds to me that disabling the PWM won't work as the application insists on staying within the pwm_play() function.

Perhaps I'm misunderstanding something fundamental and this is the actual expected behavior.

If that's the case, do you care to suggest an alternative implementation to my code within the pwm_play function?

//..
  while(1){
    NRF_LOG_INFO("Buzzing! within pwm_play");
    (void)nrfx_pwm_simple_playback(&m_pwm0, &seq0, 3, NRFX_PWM_FLAG_STOP);
    nrf_delay_ms(500);
  }
//..

As I said, I know I can work around it by removing everything but the ..._simple_playback() function and use the NRFX_PWM_FLAG_LOOP, but that plays a constant tone (no silences in between beeps).

Best,

Ernesto

RE: How to have a beep after another in a loop with PWM?

Kenneth — Mon, 11 Jul 2022 08:44:02 GMT

It may be that you should change NRF_LOG_DEFERRED to 0 in sdk_config.h to ensure that it will print log statement directly when calling NRF_LOG() api instead of waiting for idle. Hopefully you should then be able to enable better debugging for you to find the problem.

Kenneth

RE: How to have a beep after another in a loop with PWM?

builder01 — Sat, 09 Jul 2022 11:13:44 GMT

HI Kenneth,

What I mean with "it's stuck in the for- or while-loop" is that it's stuck in the loop I implemented within the pwm_play() function. In other wors, the server remains beeping forever according to this while loop and it'll never stop, not even if I write 0x00 to the characteristic.

Right now, I have it implemented like this:

 //..
  while(1){
    NRF_LOG_INFO("Buzzing! within pwm_play");
    (void)nrfx_pwm_simple_playback(&m_pwm0, &seq0, 3, NRFX_PWM_FLAG_STOP);
    nrf_delay_ms(500);
  }
  //..

From debugging, all I see is that, after writing 0x01, the server starts buzzing, but and it goes to the breakpoint I set at the NRF_LOG_INFO() call. However, it never goes to the pwm_stop() function I implemented when I write 0x00.

What I also find interesting is that the NRF_LOG_INFO doesn't print when running the debugging mode. Could it be because it needs a delay after the NRF_LOG_INFO() call so that it's able to print the text? I've tried 100ms and it still woudn't print.

Best regards,

Ernesto

RE: How to have a beep after another in a loop with PWM?

Kenneth — Fri, 08 Jul 2022 07:47:01 GMT

Hi Ernesto,

It's not clear to me where the code is hanging when you write "Somehow, the sever application gets stuck in the for or while loop. I write 0x00 to the characteristic", it should be possible to find where the code is hanging by debugging.

If you just want to forcefully stop the PWM you can always disable it? E.g. by nrfx_pwm_uninit(). When disabled the pin used by PWM will fall back to the PIN_CNF[] for the pin in question.

Alterntively you may look into disabling and enabling the PWM directly without using the nrfx_pwm driver. E.g. if you want to disable PWM, but still allow calling nrfx_pwm_simple_playback(), but calling it should have no effect, then you may simply consider calling:

NRF_PWM0->ENABLE = 0; // stop PWM (calling nrfx_pwm_simple_playback() will have no effect)
NRF_PWM1->ENABLE = 1; // start PWM (calling nrfx_pwm_simple_playback() will have an effect)

Best regards,
Kenneth

RE: How to have a beep after another in a loop with PWM?

builder01 — Fri, 08 Jul 2022 06:25:02 GMT

Hi, I'm sorry I wasn't clear.

I also don't understand how the forwarded ticket relates to my problem. I'm not using .values.p_individual = &m_demo1_seq_values but .p_common, so my sequence has a length > 1.

Let me try to simplify the explanation of my problem:

My aim is to implement the the pwm_play() function like this:

static void pwm_play(void){

//..

    for(int i=0;i<100;i++){
      (void)nrfx_pwm_simple_playback(&m_pwm0, &seq0, 3, NRFX_PWM_FLAG_STOP);
      nrf_delay_ms(500);
      }

}

Or, even better:

static void pwm_play(void)
{
    nrf_pwm_sequence_t const seq0 =
    {
        .values.p_common = sequence_values,
        .length          = NRF_PWM_VALUES_LENGTH(sequence_values),
        .repeats         = 0x00,
        .end_delay       = 0,
     };

    while(1){
        (void)nrfx_pwm_simple_playback(&m_pwm0, &seq0, 3, NRFX_PWM_FLAG_STOP);
        nrf_delay_ms(500);
    }
}

When I write to my buzzer characteristic, the buzzer_write_handler() function works properly by beeping and having pauses in between beeps due to the nrf_delay_ms() function. However, when I write 0x00 to the characteristic, the buzzer_write_handler() function doesn't work as it doesn't stop the beeping.

In other words, this part of the handler function code:

//..
    else if (new_status.p_data[0] == 0x00)
    {
        pwm_stop();
        NRF_LOG_INFO("Buzzer is quiet.");
    }

is not executed, or is executed but doesn't stop the beeping. Somehow, the sever application gets stuck in the for or while loop. I write 0x00 to the characteristic, and even read it back as well, and it says is 0x00. So, I, at least, know that the characteristic is being properly written to.

Is there a proper way to implement the pwm_play() function such that it can be properly shut off by the buzzer_write_handler() when I write 0x00 to it.

As I said earlier, the only way I could make it work (i.e. beeping stops when writing 0x00 to the char.) is by taking out the ..._simple_playback() function out of any loop, and using the NRFX_PWM_FLAG_LOOP flag. Unfortunately, this is not desired because the LOOP flag will keep playing the tone without any pauses, as I do them using the nrf_delay_ms() function.

Let me know if anything is still not clear.

Best,

Ernesto

RE: How to have a beep after another in a loop with PWM?

Kenneth — Thu, 07 Jul 2022 12:14:56 GMT

I don't quite understand your problem, but I could find someone else reporting something similiar, so I am pointing you to this case and hopefully that will also help you: Pwm Stays on even when proper stop functions are called

Kenneth