Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
21 years ago

DMA SPEED PROBLEM!

I have system with 3 SDRAM controllers 1'st is x16 SDRAM for storing code and data (MAIN_SDRAM) 2,3 is x8 for video memory (V1_SDARM,V2_SDRAM) All SDRAMs...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
21 years ago

The DMA transfer does go faster than the Nios2 when transferring into the 16-bit code/data memory, but because it has to compete with the Nios2 instruction and data masters, throughput isn't what you expect.

Some ideas to improve throughput:

1) Increase your Nios2 instruction cache size

2) Define an onchip memory, put the source array in it

3) Connect the DMA write master _only_ to the 8-bit destination memory or memories, if possible.

4) On the "Advanced" tab of the DMA GUI, check "byte transfers" only.

I don't think you'll be able to achieve a much higher transfer rate using the Nios2 alone (no DMA).

By the way, there's no need to set the DMA WEEN bit, at least for this example.