Forum Discussion

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

SPI with DMA is not working?

Hi, everyone I am using SPI Master Core on FPGA to transmit data to SPI slave (offboard device). I want to use DMA to free my NIOS for other tasks during SPI data transfer. My Idea is NIOS...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

--- Quote Start ---

Avalon MM master : waitrequest

Avalon MM slave: dataavailable, endofpacket & readyfordata

How can it work? Thanks

--- Quote End ---

It doesn't. The MM interface hasn't got a waitrequest to hold the DMA off, effectively resulting in a TXOverrun at the second write.

The dataavailable and readyfordata are internally connected only and read as 'status' signals by a Nios II CPU.

Maybe you can try inverting the readyfordata and use that as a waitrequest.