Does the Blackfin DMA perform fly-by transfers?
Yes, in the sense that data can be transferred between peripherals and off-chip memories without having to pass through on-chip (Level 1) memory. Additionally, a Bus Request/Bus Grant feature is available for sharing the External Memory Interface with another processor.
how to ensure/test this fly by transfer?
Sorry for the delay in the response to this question.
Fly-by transfers are between external devices. There is therefore no way for the Blackfin processor to be involved with the testing. Testing should be done at a system level.
The definition of fly-by DMA used here previously in this post may not be the best. A second definition of a fly-by DMA is that the data does not enter or exit the DMA controller (or the processor). The Blackfin requires one external cycle to read data from one external device and a second cycle to write a second external device. A fly-by would be done in one cycle directly from one external device to another. The data would therefore ‘fly-by’ the processor / DMA controller and require half the time.
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