DMA transfer problem

Hi, i'm working on my design with NiosII , two sdram controller , 3 dma and some other peripheral.

Now all hardware and software seem working fine, except DMA. The program is working correctly from flash to Dram , where i can write and read on each dram controller without difficulty.

I have a lot of problem when i try to use the DMA, i'm using it directly with IOWR functions, i have cecked the contenents of DMA register in assembly and it's OK. (read and write are 32bit size)

When i use the dma i find on destination buffer for example only 24 bytes istead the 4096 requested........, the dram tsu and tco seem correct, in any case i try to reduce the system speed from 100 to 80 and after to 50 MHz, but with same result.

I cechk all topic about the dma in this forum, but i don't find any idea.

http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/dry.gif http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/dry.gif

any suggestion welcome........