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Triggers for ADC converters

John Coppens
Intellectual 360 points

This seems a rather basic question. Yet, I haven't seen any reference to this.

On initializing ADC converters, a sample rate is specified (125k/250k/500k/1M). How does this collaborate with the triggers, which can be set to come from a number of sources?

Eg. I could initialize the ADC with 250ksps, and connect it to a timer trigger source of, say, 200ksps. How do these two work together? (Or how do I make them work together? I need 100ksps, which is easily generated by timers, but not by the ADC sample rates).

Would it be correct to assume the 125/250/etc are the clocks of the sequencers, while the triggers trigger the start of the sequencer?

Cheers,

John

  • 0
    TI__Guru**** 244450 points
    Hello John,

    The ADC Sample rate is for minimum conversion interval. So if you use a timer to generate a trigger at 1 per second, and the ADC for 1 MSPS, then the conversion time taken by ADC will still remain w.r.t. 1MSPS, i.e. 1uS. Hence after 1us from the trigger the ADC would have converted the digital equivalent of the analog.

    As another example if the Sample Sequence is programmed for 4 channels at 1MSPS, then the ADC interrupt will get asserted ~4us from the trigger. The same logic applies to other sampling rates.

    Regards
    Amit