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ADC sequence conversion time

Question asked by theoeffect on Oct 9, 2017
Latest reply on Oct 10, 2017 by BruceLuo

Hi,

I am using the ADC converter in the ADuCM320 with the sequencer and DMA. I get correct results from the conversion and the system is functionally working fine.

However, when checking the time it takes to convert a sequence of ADC channels I get a different result to what I would expect.

When running at 80ksps (12.5us per channel) and having a sequence of N channels the conversion time is (12,5 x N)+25 us.

When running at 40ksps (25us per channel) and having a sequence of N channels the conversion time is (25 x N)+50 us.

What I would expect is (12.5xN) us and (25xN) us. So, it looks like it takes an additional 2 conversion cycles to every sequence. I tried this for a number of values for N between 5 and 23, and the result seems very reproducible.

 

Question: Does the hardware indeed add 2 additional cycles to the conversion timing by design, or is it more likely an error in one of the settings I am making ? 

 

 

THX,

Theo

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