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TMS320F280045: Errata consult ADC: DMA Read of Stale Result

Jordan Cantillano
Intellectual 355 points
Part Number: TMS320F280045

The errata workaround: ADC: DMA Read of Stale Result say that a prior ADCRESULT value can be read by the DMA id the Interrupt is in Late mode. In the TRM table 13-8. ADC Timing Parameters,

say that Late mode (INTPULSEPOS =1), the expected value is the latest.

Question: The information seems to be contradicted, can you clarified ?

  • +1
    TI__Mastermind 27315 points

    Hi Jordan,

    To clarify, the timing diagram is correct in that if INTPULSEPOS=1,  at the end of tINT , current ADRESULT will be available for the corresponding SOC.  This is the case if you are reading the results by polling ADC interrupt for end of conversion and reading ADCRESULT immediately after that.  Due to internal signal latency, DMA reads on ADCRESULT can lead to reading of previous conversion values, as outlined in the errata and in order to flush the old data in DMA mode read, trigger two channels (first one will be dummy and second trigger will have the actual data).

    Let me know if this answers your query.

    Regards,

    Joseph