nrfx_saadc_sample_convert

[Juniorprogrammer]

Hi,

I was using the nrfx_saadc_buffer_convert to make everytime a single sample.

void saadc_init(void)
{
  ret_code_t  err_code;
   
  nrf_saadc_channel_config_t channel_config = NRFX_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN2);

  err_code = nrf_drv_saadc_init(NULL, saadc_callback_handler);
  APP_ERROR_CHECK(err_code);

  err_code = nrfx_saadc_channel_init(0, &channel_config);
  APP_ERROR_CHECK(err_code);

  err_code = nrfx_saadc_buffer_convert(m_buffer_pool[0], SAMPLE_BUFFER_LEN);
  APP_ERROR_CHECK(err_code);

  err_code = nrfx_saadc_buffer_convert(m_buffer_pool[1], SAMPLE_BUFFER_LEN);
  APP_ERROR_CHECK(err_code);
}

Now I did find out there is also nrfx_saadc_sample_convert. How do I initialize this?

And do I get my val then by val = p_event->data.done.p_value instead of val = p_event->data.done.p_buffer[i]

[Juniorprogrammer]

void saadc_callback_handler(nrf_drv_saadc_evt_t const * p_event)
{
  float val;

  if(p_event -> type == NRFX_SAADC_EVT_DONE)
  {
    ret_code_t err_code;
    uint8_t data[20];

    err_code = nrfx_saadc_sample_convert(0, &m_sample);
    APP_ERROR_CHECK(err_code);
  
    val = m_sample * 3.3 / 4096;
    
    sprintf((char*)data, "ADC: %.2f", val);
    uint16_t d_len   = strlen(data);
    err_code = ble_nus_data_send(&m_nus, data, &d_len, m_conn_handle); 
    APP_ERROR_CHECK(err_code);

  }
}

void saadc_init(void)
{
  ret_code_t  err_code;
   
  nrf_saadc_channel_config_t channel_config = NRFX_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN2);

  err_code = nrf_drv_saadc_init(NULL, saadc_callback_handler);
  APP_ERROR_CHECK(err_code);

  err_code = nrfx_saadc_channel_init(0, &channel_config);
  APP_ERROR_CHECK(err_code);

  err_code = nrfx_saadc_sample_convert(0, &m_sample);
  APP_ERROR_CHECK(err_code);

  //err_code = nrfx_saadc_buffer_convert(m_buffer_pool[0], SAMPLE_BUFFER_LEN);
  //APP_ERROR_CHECK(err_code);

  //err_code = nrfx_saadc_buffer_convert(m_buffer_pool[1], SAMPLE_BUFFER_LEN);
  //APP_ERROR_CHECK(err_code);
}

I tried this but don't get any value.

[Vidar Berg]

Have you verified that the calback is invoked with the NRFX_SAADC_EVT_DONE? Also, you should read the sample result from the event pointer as shown in the ble_app_proximity example.

[Juniorprogrammer]

Vidar Berg said:

Also, you should read the sample result from the event pointer as shown in the ble_app_proximity example

In the ble_app_proximity they are also using nrf_drv_saadc_buffer_convert().

That also worked for me, but I don't need a buffer. I tried to figure out how nrfx_saadc_sample_convert() works, but it works different.

void saadc_callback_handler(nrf_drv_saadc_evt_t const * p_event)
{
  float val;

  if(p_event -> type == NRFX_SAADC_EVT_DONE)
  {
    ret_code_t err_code;
    uint8_t data[20];

    err_code = nrfx_saadc_sample_convert(0, &m_sample);
    APP_ERROR_CHECK(err_code);
  
    val = m_sample * 3.3 / 4096;
    
    sprintf((char*)data, "ADC: %.2f", val);
    uint16_t d_len   = strlen(data);
    err_code = ble_nus_data_send(&m_nus, data, &d_len, m_conn_handle); 
    APP_ERROR_CHECK(err_code);

  }
}

void saadc_init(void)
{
  ret_code_t  err_code;
   
  nrf_saadc_channel_config_t channel_config = NRFX_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN2);

  err_code = nrf_drv_saadc_init(NULL, saadc_callback_handler);
  APP_ERROR_CHECK(err_code);

  err_code = nrfx_saadc_channel_init(0, &channel_config);
  APP_ERROR_CHECK(err_code);

  err_code = nrfx_saadc_sample_convert(0, &m_sample);
  APP_ERROR_CHECK(err_code);

  //err_code = nrfx_saadc_buffer_convert(m_buffer_pool[0], SAMPLE_BUFFER_LEN);
  //APP_ERROR_CHECK(err_code);

  //err_code = nrfx_saadc_buffer_convert(m_buffer_pool[1], SAMPLE_BUFFER_LEN);
  //APP_ERROR_CHECK(err_code);
}

I think I'm doing something wrong here:

val = m_sample * 3.3 / 4096;

Is there any example of using nrfx_saadc_sample_convert()?

[Vidar Berg]

Sorry, I read nrfx_saadc_sample_convert() as nrf_drv_saadc_buffer_convert(). But nrfx_saadc_sample_convert() is blocking and it does not make sense to call from the saadc handler. You can try to call nrfx_saadc_sample_convert() from main() after configuring the SAADC and see if that works.

[Juniorprogrammer]

Yes, I think that was the matter. I did make it an empty handler and call the function in my application timer. It works now. 

What is the difference between blocking and non-blocking mode? Does it have effect on the bluetooth functionality?