STM32H743 ADC DMA performance calculations

Baker Ngan · ‎2018-03-08

Posted on March 09, 2018 at 06:42

So I am working with an STM32H743 MCU. I have it setup so I am using ADC1 to do a continuous sample of channel 3 and 10 over DMA. All works fine and I get a dma interrupt for conversion complete every ~10 usec. However when I use ADC3 now and sample channel 5 and 18 over DMA as well, my conversion time for ADC1 has increased to almost twice the amount, up to ~20 usec. I have tried using ADC2 as well and ADC1 and ADC2 in simultaneous mode, however I get a similar result. If I use 2 ADCs, shouldn't those 2 conversions happen in parallel? I have seperated out ADC1 and ADC3 to different DMA controllers as well ( one using DMA1 channel 0 and one using DMA2 channel3). Results of the conversion look fine so, I am sure it is configured correctly, however I don't understand why adding a separate ADC would increase the time of the other ADC.

Thanks,

#hal-adc #dma-adc

Darius B · ‎2018-03-09

Posted on March 09, 2018 at 12:03

>>however I don't understand why adding a separate ADC would increase the time of the other ADC.

If we have one ADC converter and 10 ADC channels. Then only one channel is connected to converter. After conversion first channel, next ADC channel is connected .... while all ADC channel inputs converted. So conversions time are multiplay by channel number.

BR.

Darius Babrauskas