AnsweredAssumed Answered

STM32F407 DMA stops working

Question asked by ken on Dec 23, 2012
Latest reply on Dec 24, 2012 by ken
This problem has me stumped for the past three days. Before I get into the problem I have a few questions. When I look at the memory maps, are addresses, eg. 0x0800 0000,  in byte format or word format?

I am using STM32F407 and running IAR EWARM.

As far as I can tell, I believe the 64KB CCM is at 0x1000 0000 and the 112KB SRAM begins at 0x2000 0000. Where does the 16KB SRAM begin? (again are these byte addresses?)

My problem is I am running two DMA2 operations.
SPI1_TX on DMA2 Stream5 Channel3, memory to peripheral,
and DCMI on DMA2 Stream1 Channel1, peripheral to memory

I can get the SPI1_TX running fine. The strange thing is I have gotten both DMA requests to work on a number of occasions in the past but sometimes it fails. Now the failure is permanent.
The symptom is whenever I enable the DCMI DMA, the SPI DMA fails, DMA_S5CR EN = 0 , the error is usually transfer error and FIFO error, or AHB bus error, as if there is contention somewhere.

The DCMI requests are running at 42MHz.

I tried separating the two memory requests into the separate 112KB and 16KB blocks with no luck. I tried changing priorities by moving to different streams.

The puzzling thing is why it would work sometimes.