EQADC TUE Value on MPC5777C

[berat24]

Hello everyone,

I would like to ask 2 different questions about TUE value.

1) I am taking TUE value as 8 looking at the datasheet but my calibration function sometimes returns unsuccesful value (it is non-zero value) as the calculated result is higher than TUE. Therefore, my code cannot leave the calibration function for a while. Is this problem usual? What can I do for handle it?

Note: I am working on development board of NXP.

2) Is there any opportunity to decrease TUE value using moving average method? It could be possible?

[davidtosenovjan · Accepted solution]

Considering A/D conversion as a whole system, mainly ADC supply and ADC reference (their level and noise) may be affected by temperature drifts (it is application dependent).

For reducing temperature drift influence, runtime ADC calibration sequence is recommended. Pay attention to AN2989, section 3.2:
https://www.nxp.com/docs/en/application-note/AN2989.pdf

It would be appropriate to mention this device is affected by 2 errata related to ADC accuracy (ERR008313 and ERR010453):
https://www.nxp.com/docs/en/errata/MPC5777C_3N45H.pdf

Just to note that AN2989 recommends in section 3.4 to choose median value to minimize inluence noise effect of conversion of reference channels.

Regarding ADC conversion itself, eQADC module does not offer average conversions, but you may perform something like that SW way, it is up to you.