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TMS320F28069: Silicon errata: ADC: initial conversion

Joost de Bruin
Prodigy 200 points
Part Number: TMS320F28069
Other Parts Discussed in Thread: C2000WARE

To avoid the 'initial conversion' error:

'When the ADC conversions are initiated by any source of trigger in either sequential or simultaneous sampling mode, the first sample may not be the correct conversion result.'

While using software force as trigger, I tried to avoid this error by starting conversion 'sequentially' as follows:

    AdcRegs.ADCSOCFRC1.bit.SOC12 = 1;   // Start of conversion dummy motor temperature
    AdcRegs.ADCSOCFRC1.bit.SOC13 = 1;   // Start of conversion motor temperature
    AdcRegs.ADCSOCFRC1.bit.SOC14 = 1;   // Start of conversion coolant temperature
    AdcRegs.ADCSOCFRC1.bit.SOC15 = 1;   // Start of conversion fuse temperature

However I am starting to doubt whether this will give me reliable results (mainly because I get unexpected results, which could be due to an different bug). Does anybody know if this will work, and if not, how else you are supposed to get reliable results from S/W force started conversions?

  • 0
    TI__Mastermind 25850 points

    Hi Joost de Bruin,

    What the Errata is describing is that the first conversion result may not be correct. In your case you would have to discard/not use ADCRESULT12. 

    The ADC software examples within C2000Ware implement this errata. I would suggest taking a look at the examples and see if you can get the right results that way.

    C:\ti\c2000\C2000Ware_version\device_support\f2806x\examples\c28

    Best Regards,

    Marlyn

  • 0 in reply to Marlyn Rosales Castaneda20
    Prodigy 200 points

    Yes that is what I thought. However I started doubting if S/W forcing them like this qualifies as a 'sequence'', or am I just starting 4 'sequences' of 1 and are they thus all four unreliable. I realised now I should try to start the S/W force by writing a single value to AdcRegs.ADCSOCFRC1, however I do not have access now, will report results next week.