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TMS320F28335 ADC_Cal() Register Explanation

Rowan Doherty
Intellectual 380 points

Other Parts Discussed in Thread: TMS320F28335

I've noticed a few times people requesting to know the format and meaning of the two one-time programmable registers inside the TMS320F28335 that are used for ADC Calibration, but I've never any official information from TI.

The ADC Datasheet only mentions that they are reserved  but doesn't provide any further information on the meaning of the lower 14-bits of the ADCREFSEL register.

Is there a reason for this? I'm assuming it's something you don't share outside of the company, but it would really help us to know (basically we've performed some system-level calibrations on devices that were NOT running the ADC_Cal() function at start-up (don't ask why...) and now we would like to change the software to use the calibration routine, but we will have to perform the full system-level calibration again if we don't understand the values).

If you are unable to share this information outside of the company, could you please let me know.

  • 0
    TI__Genius 17181 points

    Rowan- correct the details of that register are not shared, but I can tell you that the 14 bits are for trimming the ADC for for both internal and external reference mode which in turn affects the gain error of the ADC.  The value which gets loaded during ADC_Cal() is derived from calibration done in the factory.  I hope that is enough information to make a proper decision about how to change the software.

    Regards, Joe