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F28066 ADC issue

Young Hu
Expert 4185 points

Hi C2000 Champs,

My customer is designing their motor control inverter using F28066PZT. Now this project is mass production. However, recently they found some inverters reported error. And they found the problem came from the ADC sampling. ADC is triggered by PWM.

In their code, if two ADC channels were added, ADC result1 and result2 registers would be affected. For example, the accepted results were 2030, if the init code was commented. And if two ADC channels were utilized, the ADC result would be 2050, then an error was report. Sometime, if the PWM frequency was changed manually or ACQPS was set to larger value(09h, or 0Ah for example), ADC result can be correct again occasionally. 


 

Would you kindly help me analyze where the problem came from?

Thanks.

BR,

Young

  • 0
    TI__Guru 60865 points
    Hi Young,

    Is the error on SOC8? Is it possible that the RRPOINTER is causing SOC8 to be the first conversion each time the ePWM trigger is received? Please check the status of the RRPOINTER in the time after all conversions have completed, but before the next ePWM trigger occurs.