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BF548: PPI-DMA Transfer with Descriptor List Mode

Question asked by PK.EMT on Jul 27, 2010

Hello,

 

my application reads nonstop video frames into the SDRAM (10 frame buffers).

For input I'm using a linked List of Descriptors. The video input process works

without any problems. The problem is the video output with a non cyclic order

of frames reading out from SDRAM. Controlled by image processing the order

of the output frames can be changed. For example 1, 2, 3, 4, 4, 6, 7, 8, 9, 9

that means frame buffer 5 and 10 will be displaced with 4 and 9.

 

So what's the best way to manage the descriptor list for output? If I change the

DMA_NEXT_DESC_PTR dynamically, the DMA output process stops.

 

Thanks for any help,

 

Peter

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