RE: Dev Academy Lesson 6 Exercise 2 – nrfx ADC is non-blocking but does not wait for conversion to complete

Vidar Berg — Mon, 17 Feb 2025 13:30:59 GMT

The team has added a note about SAADC calibration in the course now:

Thanks again for your feedback.

RE: Dev Academy Lesson 6 Exercise 2 – nrfx ADC is non-blocking but does not wait for conversion to complete

Vidar Berg — Fri, 14 Feb 2025 15:13:15 GMT

Hello,

Thank you for the feedback. I will relay this to the team responsible for this course. I also think it is worth mentioning about the calibration. The blocking part appears to be covered already in the updated course:

Best regards,

Vidar

RE: Dev Academy Lesson 6 Exercise 2 – nrfx ADC is non-blocking but does not wait for conversion to complete

chris22222 — Thu, 13 Feb 2025 22:29:33 GMT

I figured this out. I found NULL was passed as the event handler to this:

/**
 * @brief Function for setting the SAADC driver in the simple mode.
 *
 * The simple mode allows obtaining a single sample from each requested channel.
 * The conversion can be done in a blocking or non-blocking manner.
 * Sampling is initiated by calling @ref nrfx_saadc_mode_trigger() once.
 *
 * @param[in] channel_mask  Bitmask of channels to be used in the simple mode.
 * @param[in] resolution    Resolution configuration.
 * @param[in] oversampling  Oversampling configuration.
 * @param[in] event_handler Event handler provided by the user. In case of providing NULL,
 *                          the conversion will be performed in the blocking manner.
 *
 * @retval NRFX_SUCCESS             Initialization was successful.
 * @retval NRFX_ERROR_BUSY          There is a conversion or calibration ongoing.
 * @retval NRFX_ERROR_INVALID_PARAM Attempt to activate channel that is not configured.
 */
nrfx_err_t nrfx_saadc_simple_mode_set(uint32_t                   channel_mask,
                                      nrf_saadc_resolution_t     resolution,
                                      nrf_saadc_oversample_t     oversampling,
                                      nrfx_saadc_event_handler_t event_handler);

I wish this was more clearly written out.

Also the offset discrepancy was caused by not calling

nrfx_saadc_offset_calibrate() prior to starting the conversion in the sample.