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TMS320F280039C: ADC Zero Offset Calibration

Gesur ARIF
Prodigy 80 points
Part Number: TMS320F280039C


Hello Ti,

I am trying to read the offset of the AD module, but I am having issues with it.


VREFLO (internal connection). Do I have to enable anything else besides mapping the AD signal, in this case A or B or C 13 to the ADCSOC that I want to use?
I have my analog reference module configured to external reference and the reference mode of 1.65V.
I am currently reading a value of only 8IU (12bit value) and I am not sure if that would be accurate.
Also, do I have to perform the conversions for each module (Adca, Adcb, Adcc) and set the corresponding OFFTRIMS for each module?

The reference that I used is a 28006x which had a slightly different approach to this method:

I would like to use this offset in other computations, so I'd like to avoid last step from 39C.

Any info and help is much appreciated, thank you.

  • +1
    TI__Genius 11081 points

    Hello Gesur,

    Are you trying to add compensation for some board-level offset? By itself the F28003x device is already offset-calibrated from the factory; the offset trims are automatically loaded when you call the ADC_setVREF() function; you can also manually load using ADC_setOffsetTrim() or ADC_setOffsetTrimAll().

    To sample VREFLO on F28003x, you will need to use the INTERNALTEST mux. For details on this, please take a look at the TRM ADC chapter, under Additional Information > Internal Test Mode.

    Each ADC has a different offset trim, so yes you would need to repeat the procedure for each ADC module.

    Best regards,
    Ibukun