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ADC sample rate

Question asked by Ngai yuk kong on May 4, 2018
Latest reply on May 7, 2018 by AvaTar

Hi all,

 

I have seven adc channels to convert using STM32F051. I set the ADC to be triggered by timer 15. I also setup DMA to put all the converted results to a memory buffer and have a Transfer complete interrupt set. 

 

Here is the setting: 

Timer 15 using 100KHz

ADC set to complete whole sequence 

DMA in circular mode

 

Everything work except that when I toggle a I/O inside the DMA interrupt, I got the frequency around 5KHz.

 

Any direct correlation between this 5KHz with my timer 100KHz? The MCU specification has a diagram showing that during the conversion the timer trigger will be ignored until all the conversion is complete. Does it mean that there is no way to control the sampling rate????

 

Many thanks..

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