nrf52 SAADC - NRFX_SAADC_EVT_DONE never called

[BardenDK]

using nRF5SDK 160098a08e2

I have the following code:

#define ADC_NOF_SAMPLES 16u
static int16_t s_sample_buffer[ ADC_NOF_SAMPLES ];
static nrf_saadc_channel_config_t const s_adc_channel0 = NRFX_SAADC_DEFAULT_CHANNEL_CONFIG_SE( NRF_SAADC_INPUT_AIN5 );
static void saadc_event_isr( nrfx_saadc_evt_t const *p_event )
{
    volatile uint32_t numOfSamples = 0;
    switch ( p_event->type )
    {
    case NRFX_SAADC_EVT_DONE:  // Event generated when the buffer is filled with samples.
        numOfSamples = p_event->data.done.size;
        break;
    case NRFX_SAADC_EVT_LIMIT: // Event generated after one of the limits is reached.
        break;
    case NRFX_SAADC_EVT_CALIBRATEDONE: // Event generated when the calibration is complete.
        {
            nrfx_err_t err;
            err = nrfx_saadc_buffer_convert( &s_sample_buffer[0], ADC_NOF_SAMPLES );
            APP_ERROR_CHECK(err);
            /*err = nrfx_saadc_sample();
            APP_ERROR_CHECK(err);*/
        }
        break;
    default:
        break;
    }
}

    nrfx_err_t err;
    static nrfx_saadc_config_t const s_saadc_config = {
            .resolution = NRF_SAADC_RESOLUTION_12BIT,
            .oversample = NRF_SAADC_OVERSAMPLE_256X,
            .interrupt_priority = NRFX_SAADC_CONFIG_IRQ_PRIORITY,
            .low_power_mode = false
    };

    // ADC driver is initialized in non-blocking mode, since an event handler is given
    err = nrfx_saadc_init( &s_saadc_config, saadc_event_isr );

    if ( err == NRFX_SUCCESS )
    {
        // Initialize the ADC channel 0
        err = nrfx_saadc_channel_init( 0, &s_adc_channel0 );

        if ( err == NRFX_SUCCESS )
        {
            /*
            * Calibrate the offset with a call to nrfx_saadc_calibrate_offset.
            * You need to wait for the SAADCs DONE event before you can proceed.
            * */
            do
            {
                err = nrfx_saadc_calibrate_offset();
            } while ( err == NRFX_ERROR_BUSY );

            rc = 1u;
        }
    }

I never receive NRFX_SAADC_EVT_DONE. Please advise

[Karl Ylvisaker]

Hello,

Could you tell me, are you working out of the provided SAADC example from the SDK?
Please provide the entire source code, as the root cause for your error might be located elsewhere.

For future reference, when inserting code as part of a question, I ask that you format it with the code option to significantly increase readability.

Best regards,
Karl

[BardenDK]

Karl Ylvisaker said:

You are in fact enabling the legacy layer, in your app_config.h(SAADC_* applies to the legacy layer). So this might be unintentional?
Have you taken a look at the provided SAADC example that is provided in the SDK, for reference on how to setup and use the SAADC?

If i remove the defines from app_config, my application wont compile because of undefined references:

undefined reference to `nrfx_saadc_buffer_convert'

So, SAADC_ENABLED must be defined to use the nrfx_saadc_* API.

Karl Ylvisaker said:

Furthermore, it seems like you do not set your SAADC IRQ priority. Is this intentional?

I do, here:

    nrfx_err_t err;
    static nrfx_saadc_config_t const s_saadc_config = {
    		.resolution = NRF_SAADC_RESOLUTION_12BIT,
    		.oversample = NRF_SAADC_OVERSAMPLE_DISABLED,//NRF_SAADC_OVERSAMPLE_128X,//NRF_SAADC_OVERSAMPLE_256X,
    		.interrupt_priority = NRFX_SAADC_CONFIG_IRQ_PRIORITY,
    		.low_power_mode = false
    };

    // ADC driver is initialized in non-blocking mode, since an event handler is given
    err = nrfx_saadc_init( &s_saadc_config, saadc_event_isr );

Karl Ylvisaker said:

How are you attempting to access these conversions? Does the call return without error, and if so; what is placed in the buffer after the call?

I do not attemt to access the conversions, because I wait for the done event that never happens.

The calls to the following function report success:

	case NRFX_SAADC_EVT_CALIBRATEDONE: // Event generated when the calibration is complete.
		{
			nrfx_err_t err;
			err = nrfx_saadc_buffer_convert( &s_sample_buffer[0], ADC_NOF_SAMPLES );
			APP_ERROR_CHECK(err);
			err = nrfx_saadc_sample();
			APP_ERROR_CHECK(err);
		}
		break;

after call to nrfx_saadc_sample(), one measurement is put into the buffer.

No further measurements are performed it seems.....