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CCS/TMS320F28335: ADC Application note examples

Tahir Mahmood
Expert 1250 points
Part Number: TMS320F28335


Tool/software: Code Composer Studio

What is the difference between the two example Example 1-1 and Example 1-2 in the application note of ADC reference manuel for F28335? Are the both equivalent or is there any difference from the point of view of sampling the values? 

  • 0
    TI__Guru 61235 points

    Tahir,

    Example 1-1 uses dual-sequencer mode.  That is, there are two sequences of 4 double conversions each setup.  Each sequence has it's own trigger.  Example 1-2 uses cascaded sequencer mode.  That is, there is a single sequence of 8 double conversions setup with a single trigger.

    Regards,

    David

  • 0
    TI__Guru 62975 points
    Tahir,

    The end results are equivalent.

    -Tommy
  • 0 in reply to David M. Alter
    Expert 1250 points
    Why ADCCHSELSEQ3 is used in Example 1-1 and ADCCHSELSEQ2 is used in Example 1-2.Why we cannot use ADCCHSELSEQ2 in Example 1-1 for the values of 4 to 7 channels?
  • 0 in reply to Tahir Mahmood
    TI__Guru 62975 points
    Tahir,

    As David mentioned, Example 1-1 is in dual-sequencer mode so ADCCHSELSEQ1 and ADCCHSELSEQ2 are reserved for SEQ1, while ADCCHSELSEQ3 and ADCCHSELSEQ4 are reserved for SEQ2. Each SEQn can only handle 8 conversions.

    The programming looks strange in Example 1-1 because it appears that ADCCHSELSEQ2 is available. However, the simultaneous sampling mode is enabled so each CONVnn value represents two conversions. So ADCCHSELSEQ1 is enabling 8 conversions, which is the most that SEQ1 can handle. The next 8 conversions would need to be handled by SEQ2, which uses ADCCHSELSEQ3.

    -Tommy