A plurality of A / D conversion processing

[yokokawa]

How can I perform multiple A / D conversion?
I created a program with reference to the method of the old version of A / D conversion, but the function name and argument used are different and it does not work.
Please tell me how to do with "nRF5_SDK_15.0.0_a53641a" version.
Thanking you in advance.

[haakonsh]

Hey Yokokawa-san,

You need to use the SAADC driver API documentation. I also suggest that you compare the SAADC example of SDK15 with your old implementation. 

The programming flow when using multiple ADC channels is as follows: 

1. Initialize the SAADC driver with a call to nrfx_saadc_init.
2. Calibrate the offset with a call to nrfx_saadc_calibrate_offset. You need to wait for the SAADCs DONE event before you can proceed.
3. Initialize the SAADC channels you want to use with calls to nrfx_saadc_channel_init.
4. The SAADC will now sample all enabled channels sequentially when a SAMPLE task is triggered. 

Cheers,

Håkon.

[yokokawa]

I created the following program, but when I execute "nrfx_saadc_calibrate_offset ()", 
I get an error with "nrf_drv_saadc_channel_init ()".
Please tell me what processing is missing.

---------------------------------------------

void saadc_init(void)
{
    ret_code_t err_code;

/*-< SAADC Register initial parameter >-*/
    nrf_drv_saadc_config_t saadc_config = NRF_DRV_SAADC_DEFAULT_CONFIG; 

/*-< SAADC Channel Setting parameter >-*/
    nrf_saadc_channel_config_t channel0_config =
    NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);    /* Channel 0 data */
    nrf_saadc_channel_config_t channel1_config =
    NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);    /* Channel 1 data */

/*-< SAADC initial >-*/
    err_code = nrf_drv_saadc_init(&saadc_config, saadc_callback);
    APP_ERROR_CHECK(err_code);

/*-<ADC offset calibration >-*/
    err_code = nrfx_saadc_calibrate_offset();
    APP_ERROR_CHECK(err_code);

/*-< SAADC Channel Setting >-*/
    err_code = nrf_drv_saadc_channel_init(0, &channel0_config);    /* Channel 0 */
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_saadc_channel_init(1, &channel1_config);    /* Channel 1 */
    APP_ERROR_CHECK(err_code);

/*-<SAADC double baffer Setting >-*/
    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], SAADC_SAMPLES_IN_BUFFER);    /* 1st buffer  */
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], SAADC_SAMPLES_IN_BUFFER);    /* 2nd buffer */
    APP_ERROR_CHECK(err_code);

}

---------------------------------------------

Thanking you in advance.

[haakonsh]

/*-<ADC offset calibration >-*/
    err_code = nrfx_saadc_calibrate_offset();
    APP_ERROR_CHECK(err_code);
    
    while(nrfx_saadc_is_busy()) // Wait for calibration to complete
    {
        __WFE();    //
        __SEV();    //
        __WFE();    // This sequence puts the system to sleep (SystemON) while waiting
    }

/*-< SAADC Channel Setting >-*/ 
    err_code = nrf_drv_saadc_channel_init(0, &channel0_config);    /* Channel 0 */
    APP_ERROR_CHECK(err_code);

[yokokawa]

Errors no longer occur.
Thank you very much.

[haakonsh]

No problem :)