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Altera_Forum
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17 years ago

Avalon-ST backpressure with SGDMA

Hi, I have a custom SOPC component with multiple Avalon streaming ports supporting backpressure, using a ready latency of 0. For testing, I've connected a sink port up to an Altera SGDMA compo...
Altera_Forum's avatar
Altera_Forum
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17 years ago

I think what you are experiencing is due to the fact that the SGDMA is using a readyLatency of 1 instead of 0. The behavior you are describing matches that condition. See section 6.6 of the Avalon Interface Specifications document.

SOPC builder is supposed to give you an error indicating that the source and sink interfaces have incompatible readyLatency values. I take it that's not the case. It doesn't surprise me. The SGDMA core in 7.2 had some issues. To my knowledge the SGDMA core has only been used by Altera for the TSE MAC. I'd be surprised if it's been tested with anything else.

Jake