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STM32F4 DMA streams init sequence

Question asked by Gregorsanec.Toni on Jan 23, 2014
Latest reply on Feb 18, 2014 by Amel N
Hello all,

while implementing two different tasks for DMA2 transfer, which of course
uses different streams and channels I have noticed, that stream initialization sequence
plays some role. For example I am using stream 3 and stream 1 and if I initialize
first stream 3 followed stream 1, then sometimes happens, that data is not transferred
in the right way. If start-up sequence initializes first stream 1 followed stream 3 I am
not experiences any troubles. In my case interaction is between DCMI-SDRAM-SD
which all uses DMA to transfer data.
Could someone give me some explanation of this curious case? 
Since I do not know the reason why is this like explained I am worried, that this is not
just some coincidence and later my fails!

Second question is, in what relationship are DMA streams and DMA channels. Like I see
number of streams are the same as numbers of channels, but in some examples stream
number does not match channel number! Why this reason? I also tried to change channel
number and DMA fails. 

regards

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