adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

Karl Ylvisaker — Tue, 05 Sep 2023 14:24:24 GMT

No problem at all! :)

Good luck with your development!

Best regards,
Karl

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

snowuyl — Tue, 05 Sep 2023 11:53:35 GMT

Thanks for your suggestion!

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

Karl Ylvisaker — Tue, 05 Sep 2023 11:05:39 GMT

[quote user="snowuyl"]Thanks for your reply! [/quote]

No problem at all, I am happy to help! :)

[quote user="snowuyl"]Do you suggest to use ADC_GAIN_1_6?[/quote]

This depends on the range of the signal you will be measuring. For instance, if your signal will be in the 0 - 3.6 V range then I would suggest using the 1/6 gain, yes.

Best regards,
Karl

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

snowuyl — Tue, 05 Sep 2023 09:03:38 GMT

Thanks for your reply! I am using internal reference. Do you suggest to use ADC_GAIN_1_6?

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

Karl Ylvisaker — Tue, 05 Sep 2023 08:59:57 GMT

Which Reference are you using? The input range is determined by the reference/gain, so you will get a larger range if you decrease the gain.

Best regards,
Karl

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

snowuyl — Tue, 05 Sep 2023 07:48:03 GMT

When I set gain to ADC_GAIN_4. ADC value of battery voltage is range from 364 to 387. How can I increase ADC value of battery voltage?

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

Karl Ylvisaker — Tue, 05 Sep 2023 07:39:16 GMT

Hello,

I am glad to read that you were able to resolve your initial issue! :)

[quote user="snowuyl"]Why adc_nrfx_channel_setup() limits maximum gain to ADC_GAIN_4?[/quote]

The possible gain configurations is limited by the SAADC's hardware capabilities.

Best regards,
Karl

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

snowuyl — Tue, 05 Sep 2023 06:10:50 GMT

I found the error is because I set gain of struct adc_channel_cfg to ADC_GAIN_128. Why adc_nrfx_channel_setup() limits maximum gain to ADC_GAIN_4?

static int adc_nrfx_channel_setup(const struct device *dev,
				  const struct adc_channel_cfg *channel_cfg)
{
	nrf_saadc_channel_config_t config = {
		.resistor_p = NRF_SAADC_RESISTOR_DISABLED,
		.resistor_n = NRF_SAADC_RESISTOR_DISABLED,
		.burst      = NRF_SAADC_BURST_DISABLED,
	};
	uint8_t channel_id = channel_cfg->channel_id;

	if (channel_id >= SAADC_CH_NUM) {
		return -EINVAL;
	}

	switch (channel_cfg->gain) {
	case ADC_GAIN_1_6:
		config.gain = NRF_SAADC_GAIN1_6;
		break;
	case ADC_GAIN_1_5:
		config.gain = NRF_SAADC_GAIN1_5;
		break;
	case ADC_GAIN_1_4:
		config.gain = NRF_SAADC_GAIN1_4;
		break;
	case ADC_GAIN_1_3:
		config.gain = NRF_SAADC_GAIN1_3;
		break;
	case ADC_GAIN_1_2:
		config.gain = NRF_SAADC_GAIN1_2;
		break;
	case ADC_GAIN_1:
		config.gain = NRF_SAADC_GAIN1;
		break;
	case ADC_GAIN_2:
		config.gain = NRF_SAADC_GAIN2;
		break;
	case ADC_GAIN_4:
		config.gain = NRF_SAADC_GAIN4;
		break;
	default:
		LOG_ERR("Selected ADC gain is not valid");
		return -EINVAL;
	}

	switch (channel_cfg->reference) {
	case ADC_REF_INTERNAL:
		config.reference = NRF_SAADC_REFERENCE_INTERNAL;
		break;
	case ADC_REF_VDD_1_4:
		config.reference = NRF_SAADC_REFERENCE_VDD4;
		break;
	default:
		LOG_ERR("Selected ADC reference is not valid");
		return -EINVAL;
	}

	switch (channel_cfg->acquisition_time) {
	case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 3):
		config.acq_time = NRF_SAADC_ACQTIME_3US;
		break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 5):
		config.acq_time = NRF_SAADC_ACQTIME_5US;
		break;
	case ADC_ACQ_TIME_DEFAULT:
	case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10):
		config.acq_time = NRF_SAADC_ACQTIME_10US;
		break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 15):
		config.acq_time = NRF_SAADC_ACQTIME_15US;
		break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 20):
		config.acq_time = NRF_SAADC_ACQTIME_20US;
		break;
	case ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 40):
		config.acq_time = NRF_SAADC_ACQTIME_40US;
		break;
	default:
		LOG_ERR("Selected ADC acquisition time is not valid");
		return -EINVAL;
	}

	config.mode = (channel_cfg->differential ?
		NRF_SAADC_MODE_DIFFERENTIAL : NRF_SAADC_MODE_SINGLE_ENDED);

	/* Keep the channel disabled in hardware (set positive input to
	 * NRF_SAADC_INPUT_DISABLED) until it is selected to be included
	 * in a sampling sequence.
	 */

	nrf_saadc_channel_init(NRF_SAADC, channel_id, &config);
	nrf_saadc_channel_input_set(NRF_SAADC,
				    channel_id,
				    NRF_SAADC_INPUT_DISABLED,
				    channel_cfg->input_negative);

	/* Store the positive input selection in a dedicated array,
	 * to get it later when the channel is selected for a sampling
	 * and to mark the channel as configured (ready to be selected).
	 */
	m_data.positive_inputs[channel_id] = channel_cfg->input_positive;

	return 0;
}

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

snowuyl — Tue, 05 Sep 2023 05:30:31 GMT

devzone.nordicsemi.com/.../0537.minimal_5F00_log_5F00_battery.zip

RE: adc_nrfx_saadc: Channel 0 not configured, adc_read() failed with error code -22

snowuyl — Tue, 05 Sep 2023 05:29:11 GMT

devzone.nordicsemi.com/.../4857.custom_5F00_nrf52832.zip