ADC converting data to the buffer doesn't work in button handler

[sosse]

I am using S130, and I try to write an very simple program, when I push button_1 then it read ADC and print it our by UART. So, write a "nrf_drv_adc_buffer_convert" code inside the bsp_event_handler to detect BSP_EVENT_KEY_1 is pushed. But I got an error (fatal).

But when I changed the "nrf_drv_adc_buffer_convert" to "nrf_drv_adc_sample_convert" (single ADC conversion). It works fine.

Why I got fatal error when I put "nrf_drv_adc_buffer_convert" inside bsp_event_handler? What is different to "nrf_drv_adc_buffer_convert" and "nrf_drv_adc_sample_convert" ?? Please somebody explain it.

[Stefan Birnir Sverrisson]

Hi sosse

Thank you for your question.

The nrf_drv_adc_buffer_convert function does not sample on its own, it just sets up buffers and makes things ready for sampling, but it does not sample. The nrf_drv_adc_sample_convert however converts a single ADC sample and returns when sampling is finished. I think this is somewhat explained in the ADC driver documentation.

Edit 23.8.2016 There is an example on Nordic's github that triggers ADC sampling when Button 4 is pressed on the nRF51-DK board. It uses the scheduler to execute the adc commands. I have tested it with nRF5 SDK 11.0.0 and S130 2.0.1.

[sosse]

Thank you for your answer. I understand "nrf_drv_adc_buffer_convert" function does not sample. But how can I sample when button event is occurred?
Here is my code related to the button event handler, but I got an error from "nrf_drv_adc_buffer_convert".

 void bsp_event_handler(bsp_event_t event)
{
    uint32_t err_code;
    switch (event)
    {
	case BSP_EVENT_KEY_1:
		printf("BSP_KEY_1 is pressed...\r\n");	
        app_sched_event_put(0,0,(app_sched_event_handler_t)my_adc_value_update);		
		break;
    }
}


void my_adc_value_update(void){
    APP_ERROR_CHECK(nrf_drv_adc_buffer_convert(adc_buffer,ADC_BUFFER_SIZE));
    nrf_drv_adc_sample();
}	

Am I doing something wrong??

But when I changed in the "my_adc_value_update" function as follows..

  APP_ERROR_CHECK(nrf_drv_adc_sample_convert(&m_channel_config, &adc_single_buffer));
  printf(".........................%d\n",adc_single_buffer);

It works fine.

[Stefan Birnir Sverrisson]

Hi Sosse I have updated my answer with an example that hopefully addresses what you are trying to do. Otherwise let me know.

[sosse]

Thanks, I will try it!

[sosse]

I tried. I used an example code from link text.

In the example, it doesn't have power_manage(); after nrf_drv_adc_sample(); But when I input power_manage(); It works fine. I don't know why. I hope you can explain this. Thank you.