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Calculating DMA ADC conversion time

Question asked by Lukasz Przenioslo on Oct 20, 2015
Latest reply on Oct 20, 2015 by Lukasz Przenioslo
Hello there,
I am having problem calculating the exact conversion time of ADC when using DMA ring buffering.

I was trying to find it in the STM32F4 datasheet but didnt find it.
I was trying to deduce it out using scope (toogle a pin each time interrupt is handled) but it doesnt seem right and it seem to be not linear.

My system clock is 168 Mhz. I believe it gives 48 Mhz peripheral clock. I am using 12 bit adc which is 15 cycles. Now when I start the DMA ADC cycle to measure only 1 time I get 5.7 us time. For 10 measures I get 11.4 us and 28.4 us for 20.

Is there an equasion to be able to calculate it?