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eDMA from the bitband region on K20

Question asked by Jan Rychter on Dec 26, 2013
Latest reply on Dec 27, 2013 by Jan Rychter

I am trying to perform DMA transfers from the bitband region (0x22000000) on the K20, but eDMA reports a bus error on a source read (SBE set in the DMA_ES register). The same code works fine if I access my source data placed in the SRAM_U region at 0x20000000 (e.g. the same code does not report a bus error if I change DMA_TCD2_SADDR from 0x22000000 to 0x20000000 with no other changes).

 

At first I thought it was because of byte accesses, but the bitband region should support all kinds of reads, besides then I also tried with word reads, same result.

 

Is there an undocumented limitation of the eDMA engine? Is it unable to access the bitband region? (if so, that would be extremely disappointing)

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