false Steps in ADC measurements

[Clanc1]

Hi, 
I am trying to measure a sensor once a second. 
I require to use oversampling to get 14bits of resolution to meet our target. 

We are observing a large step in values that are not consistent with the actual data. 
No change in temperature. 

Is this a common problem with the NRF internal ADC? If not what can we do to find the problem. 




Cheers, 
Clancy. 

[Kenneth]

Hi, 

Are you possibly executing an offset calibration (TASKS_CALIBRATEOFFSET) at this time? The offset calibration can switch between two codes if it's close to the limit between two calibration steps in the DAC. The accuracy of the calibration DAC is approximately 4 LSB12b, which means that in 14-bit mode the calibration step is approximately 16 LSB14b (differential mode, in In single ended it will be 2 x 16 LSB14b). I would consider this the most likely cause, but let me know otherwize.

Best regards,
Kenneth