Help with Converting SAADC ADC Value to Millivolts in nRF52810

RE: Help with Converting SAADC ADC Value to Millivolts in nRF52810

siltvm — Fri, 04 Oct 2024 10:18:02 GMT

Thank you Susheel Nuguru very much for your response.

RE: Help with Converting SAADC ADC Value to Millivolts in nRF52810

Susheel Nuguru — Fri, 04 Oct 2024 07:12:30 GMT

I overlooked to see that you are still using the old deprecated version of the SDK.

The implementation of adc_raw_to_millivolts() can be extracted from the header file from here ->https://github.com/nrfconnect/sdk-zephyr/blob/8005d4e87b9bcba25f441a51f4f5d29b541022b9/include/zephyr/drivers/adc.h#L883

If you can the vref, gain and resolution, then you can formulate it as shown in the code in the above link.

RE: Help with Converting SAADC ADC Value to Millivolts in nRF52810

siltvm — Thu, 03 Oct 2024 05:58:25 GMT

hi Susheel Nuguru ,Are there any other methods available for converting ADC values to millivolts?

RE: Help with Converting SAADC ADC Value to Millivolts in nRF52810

siltvm — Thu, 03 Oct 2024 05:52:07 GMT

hi Susheel Nuguru , There is no adc_raw_to_millivolts() function available in the nRF5 SDK version 17.0.2.

RE: Help with Converting SAADC ADC Value to Millivolts in nRF52810

Susheel Nuguru — Tue, 01 Oct 2024 18:03:52 GMT

To convert the ADC value into a voltage in millivolts, you can use the formula provided in the documentation here.:

RESULT = [V(P) – V(N)] * (GAIN/REFERENCE) * 2^(RESOLUTION - m)

Where:

V(P) is the voltage at input P
V(N) is the voltage at input N
GAIN is the selected gain
REFERENCE is the selected reference voltage
RESOLUTION is output resolution in bits
m is 0 for single-ended channels and 1 for differential channels

In your case, since you are using a single-ended input, m would be 0.

Here is a code snippet from the devzone thread that demonstrates how to convert the ADC value to millivolts:

int32_t mv_value = sample_buffer[0];
int32_t adc_vref = adc_ref_internal(dev);
adc_raw_to_millivolts(adc_vref, ADC_GAIN, ADC_RESOLUTION, &mv_value);

In this code, sample_buffer[0] is the ADC value, adc_vref is the reference voltage, ADC_GAIN is the gain, and ADC_RESOLUTION is the resolution. The function adc_raw_to_millivolts() converts the raw ADC value to millivolts.

Please note that the actual implementation might vary depending on the specifics of your project and the exact ADC configuration.