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Altera_Forum's avatar
Altera_Forum
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14 years ago

SGDMA debug

Hello, I am trying to learn how to use SGDMA to transfer data to memory. First of all, I am trying to connect SGDMA TX directly to SGDMA RX and check results. You can find the source code ->here<-...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

So do you have 1MB of data split into 10 individual buffers (so ~100KB each)? If so then you'll need to use smaller buffers since the SGDMA can't transfer any more than 65535 bytes because the transfer field of the descriptor is only 16 bits wide. I might be misinterpreting what number_of_buffer and length_of_buffer represent.

Do you have to continuosly sample? I ask because it sounds like you have enough SGDMA and memory bandwidth to handle 200MS/s but you might need some long descriptor chains in order for Nios II to be able to keep up with the maintence (asumming you use ping-pong buffering). Also if you continously sample and need to ship the data offchip over Ethernet Nios II will not be able to keep up with that over TCP (it'll struggle to do that with UDP).