ADC calibration setup. What does it do

[Dat3108]

I am using nRF54L15 with Zephyr to measure voltage with ADC. In the struct adc_sequence there is a calibrate bool, but I am not sure what it does. What is the reference that the MCU do this calibration on?

I believe that the MCU has already a ADC calibrate value (or several values, due to temperature offset, ADC gain & offset error, ...) when it is tested at factory, and this value can be stored in the memory. Does the nRF54L15 have this value and can I get/read it from memory?

[Hieu]

Hello Dat3108,

I believe that the MCU has already a ADC calibrate value (or several values, due to temperature offset, ADC gain & offset error, ...) when it is tested at factory, and this value can be stored in the memory. Does the nRF54L15 have this value and can I get/read it from memory?

The SAADC in the nRF54L15 doesn't have such calibration data stored in memory. Instead, it can calibrate itself, and the calibration can be triggered by the application/firmware.

Considering that fact and the comment above the calibrate flag, I would understand that the flag controls whether a calibrate is automatically done before each sampling.

For more information about the SAADC, please refer to the nRF54L15 Datasheet: https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/saadc.html.

Hieu

[Dat3108]

Hi Hieu,

Thank you for your reply. 

I have another question. In the datasheet it said the calibration is for temperature offset calibrate, so what exactly does this calibration do? Does it take a reference to a specific temperature (room temperature or absolute temperature, etc...) to make its calibration?

I just want to know to what extent can I improve the ADC in order to use the chip's ADC as good as possible for my application.

Thanks!