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Last DMA Descriptor

Question asked by jitesh on Aug 10, 2009
Latest reply on Aug 11, 2009 by WassimB

Hi,

 

I have a DMA "chain" that I want to execute based on some signal coming from outside the system. I am getting the signal correctly into my system. The best method for such DMA transfers would be to chain the DMA together so that the required order fo transfers is done correctly. Hence, the best option would be to have the DMAs in descriptor mode. My question is what will be the next descriptor pointer for the last descriptor?

 

eg:

 

I have 2 DMAs to be done on PPI interrupt - DMA from memory block 1a to 1b followed by DMA from memory block 2a to 2b.

 

The descriptor structure which I use is -

{ Next descriptor, start_addr, end_addr }

 

I have 2 descriptors which detail as -

desc_1 = {desc_2, &1a, &1b};

desc_2 = { ### , &2a, &2b};

 

What should replace the ### ? Should it be NULL?

 

Just for information, I use the BF561 EZ kit.

 

Thanks,

Jitesh Butala

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