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Timer triggered DMA transfer

Question asked by auer.andreas on Apr 26, 2013
Latest reply on Apr 26, 2013 by Clive One
Hello,

I'm working with a STM32F407 controller board. Right now, I want to trigger a DMA transfer with one of the internal timers (TIM1). The DMA transfer should read one gpio port and put it into the memory. The timer is configured in PWM mode and should trigger the DMA transfer on "update" (counter value is reset to 0) and on "compare" (output pin is toggled). 
I haven't tested this configuration right now, but as far as I read in the manual both events (update and compare) should be able to start the DMA transfer.

My question is, what's the delay between requesting the DMA transfer with the timer and reading the data from the port? This is important for me, because the PWM signal of the timer clocks an external ADC and the DMA transfer should copy the external ADC data into the internal memory. The ADC data is available 6ns after the rising edge of the clock. So, the DMA transfer must not start earlier than 6ns after getting triggered (6ns is one cpu clock).

Is there a good application note of how to setup a timer triggered DMA transfer?

Thanks a lot,
Andreas

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