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STM32L4 - ADC synchronuous clock mode wrong

Question asked by Vinci on Nov 4, 2015
Latest reply on Nov 7, 2015 by Vinci
Hello there

I've a question regarding the ADC conversion time on the STM32L476. According to the datasheet the fastest possible conversion time running at 80MHz is 187ns. Does this also count for the continuous conversion mode + DMA?

From my observations I'd say there is some kind of overhead involved in this particular conversion mode. Currently I've a motor PWM running at 50µs and start a current measurement of 128x samples each timer trigger. At 80MHz 128x samples should be around ~24µs or "half a PWM period". Well... thats not the case...

The actual motor current looks like that: Oscilloscope
Whereas the measured 128x samples look like that: MATLAB plot

As you can see those 128x samples represent almost a whole PWM period although they should only be ~24µs in length... How is that possible?