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TMS320F28035: How to improve the conversion time for ADC

Kengo Furuya
Expert 7650 points

Part Number: TMS320F28035

Hello,

I want to improve the conversion time even if I have a lot of SOC for ADC. So, I want to set Low/High prioritize for each SOC. For example, high priority SOC is triggered by every PWM, and low priority SOC is triggered alternately. So, please answer to the followings.

 If TRIGSEL is changed on the every PWM interrupt cycle, is it no problem?

Could you let me know the response time from TRIGSEL is set?

While ADC is in conversion, TRIGSEL is changed. Is it acceptable for ADC? Any problem for the conversion data from ADC?

For example, I'm considering following case. The TRIGSEL of SOC2-3 and 4-5 will be changed on the PWM interrupt cycle.

<Sequence1>

SOC0-1 PWM trigger (High priority and trigger is fixed)

SOC2-3 PWM trigger (Low priority)

SOC4-5 Software trigger and don't get ADC data (Low priority)

↓

<Sequence2>

SOC0-1 PWM trigger (High priority and trigger is fixed)

SOC2-3 Software trigger and don't get ADC data (Low priority)

SOC4-5 PWM trigger (Low priority)

↓

<Sequence1>

↓

<Sequence2>

Please let me know if any recommendation.  

Regards,

Furuya

  • 0
    TI__Guru 60865 points
    Hi Kengo,

    Writes to the trigger select should be effective immediately. There should also be no issue with samples being corrupted if you change the trigger select in the middle of a conversion. I would try to avoid changing the trigger select close to the trigger instant so that you don't miss samples.

    An easier method to get some SOCs to convert every-other ePWM period would probably be to use another ePWM module synchronized to the main ePWM that is either running with twice the period or has the event prescaler set such that only every other compare/zero/period match triggers the ADC.

    This may also be easier to accomplish on F2807x Piccolo devices using the "burst mode" method of sequencing.