nRF52832 ADC

RE: nRF52832 ADC

Edvin — Thu, 31 Jan 2019 12:19:23 GMT

yes. But you should trigger this using a timer rather than in the callback event.

With your implementation below you risk that nrfx_saadc_sample() does not return NRF_SUCCESS for some reason. In this case, adc_complete is false, and you have not triggered a new sample, and you will not get a new callback, and never trigger the new sample.

Therefore you should at least not set adc_complete to false without checking that nrfx_saadc_sample() returned true.

RE: nRF52832 ADC

Fiske — Thu, 31 Jan 2019 09:27:20 GMT

I have tried the saadc example. It work. All my pcb boards are sent to customer, I have no boards to try now. I will try to set the SAMPLES_IN_BUFFER to 1 for next batch. The callback will be triggered every time I call nrfx_saadc_sample() if I set SAMPLES_IN_BUFFER to 1. Right?

[quote userid="26071" url="~/f/nordic-q-a/42749/nrf52832-adc/168798"]SAMPLES[/quote]

RE: nRF52832 ADC

Edvin — Thu, 31 Jan 2019 08:38:24 GMT

[quote user="Edvin Holmseth"]Each time a sample is trigged, one sample is taken (one sample per channel, if several saadc_channels are enabled, but it looks like you only have one). Note that you have to do n samples before the saadc callback is called, where n = SAMPLES_IN_BUFFER.[/quote]

You need to do several samples to trigger the event. As of now, you start with adc_complete=true, and you trigger one sample, and then you wait for the event before setting adc_complete to true again. But this will not happen before you do 4 more samples, because your SAMPLES_IN_BUFFER = 5, and you need to fill this buffer with samples before you get the saadc callback event.

Also, you don't process your logging, so even if you would get the ADC events, you wouldn't see it in your log, because NRF_LOG_FLUSH() is commented out.

Have you tried the saadc example from SDK\examples\peripheral\saadc ?

Try to copy all of the functions from this example. saadc_init(), saadc_sampling_event_init() and saadc_sampling_event_enable(), and for good measure, include NRF_LOG_FLUSH() and nrf_pwr_mgmt_run() as well.

RE: nRF52832 ADC

Fiske — Wed, 30 Jan 2019 06:36:37 GMT

I have followed your instruction. However, the saadc_callback still cannot be triggered. attached please find my main.c and sdk_config.h file

devzone.nordicsemi.com/.../4405.sdk_5F00_config.h devzone.nordicsemi.com/.../047883.main.c

RE: nRF52832 ADC

Edvin — Mon, 28 Jan 2019 10:04:20 GMT

Hello,

No. the buffer_convert will not trigger the sampling task for the saadc.

If you look in the saadc example there are two functions, saadc_sampling_event_init() and saadc_sampling_event_enable(). It is not trivial, but what these functions do is to connect the sampling function to a timeout callback of a timer using the PPI (which is done in saadc_sampling_event_enable()) and then enable this link (which is done in saadc_sampling_event_enable()).

You can either use this approach to trigger the samples. Each time a sample is trigged, one sample is taken (one sample per channel, if several saadc_channels are enabled, but it looks like you only have one). Note that you have to do n samples before the saadc callback is called, where n = SAMPLES_IN_BUFFER.

To play around with the sampling event, I made a project that triggers one sample by a button press. The main.c and sdk_config.h file for this project is included here. It should work if you replace main.c and sdk_config.h from the saadc example from SDK15.2.0 with these. Note that it does not use saadc_sampling_event_enable() and saadc_sampling_event_enable(), but the button_handler to trigger the saadc_sampling.

devzone.nordicsemi.com/.../main.c

devzone.nordicsemi.com/.../sdk_5F00_config.h

Best regards,

Edvin

RE: nRF52832 ADC

Fiske — Thu, 24 Jan 2019 02:13:40 GMT

Dear Edvin,
Below is my code. nrf_drv_saadc_buffer_convert() is called at saadc_init(). Therefore, I expect that saadc_callback will be called after the conversion is completed. Right?

void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{
    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {
        ret_code_t err_code;

err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAMPLES_IN_BUFFER);
APP_ERROR_CHECK(err_code);

//      int i;
   //     NRF_LOG_INFO("ADC event number: %d", (int)m_adc_evt_counter);
/*
        for (i = 0; i < SAMPLES_IN_BUFFER; i++)
        {
            NRF_LOG_INFO("%d", p_event->data.done.p_buffer[i]);
        }
        m_adc_evt_counter++;
*/
    }
}

void saadc_init(void)
{
    ret_code_t err_code;
    nrf_saadc_channel_config_t channel_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);

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

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

err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], SAMPLES_IN_BUFFER);
APP_ERROR_CHECK(err_code);

err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], SAMPLES_IN_BUFFER);
APP_ERROR_CHECK(err_code);

}

int main(void)
{
// signed int temperature;
bsp_board_init(BSP_INIT_LEDS);

APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
NRF_LOG_DEFAULT_BACKENDS_INIT();

saadc_init();

//……… followed by the SPI code
}

RE: nRF52832 ADC

Edvin — Wed, 23 Jan 2019 14:59:00 GMT

Hello,

Where do you trigger your saadc samples from? Where is nrf_drv_saadc_sample() called? Can I see your entire main.c file?

BR,

Edvin