i.MX RT Crossover MCUsのトピックRe: issue with repeated eDMA receive within interrupt

issue with repeated eDMA receive within interrupt

avbot — Sat, 30 Oct 2021 08:05:27 GMT

Can I safely use SPDIF_TransferSendEDMA within the eDMA callback interrupt?

Or is there a more basic way to trigger the same sized transfer over and over within the callback?

It seems that a lot of what SPDIF_TransferSendEDMA is redundant if essentially all the setup is the same each call.

Note: we cant use SPDIF_TransferSendEDMA within non-interrupt context for performance reasons.

Re: issue with repeated eDMA receive within interrupt

jeremyzhou — Mon, 01 Nov 2021 02:51:50 GMT

Hi,
Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
1) Can I safely use SPDIF_TransferSendEDMA within the eDMA callback interrupt?
Or is there a more basic way to trigger the same sized transfer over and over within the callback?
-- In my opinion, I'd highly recommend you to use the scatter-gather feature to configure the DMA to prepare the next transfer automatically, then you can activate the DMA easily in the callback function when completing the previous DMA transfer.
Have a great day,
TIC

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Re: issue with repeated eDMA receive within interrupt

avbot — Tue, 02 Nov 2021 23:51:56 GMT

Thanks Jeremy, can you please help advise how to make scattergather work?
I am first trying on the Rx side and tried to modify SPDIF_TransferReceiveEDMA and then calling it once to make a perpetual scatter gather. But it still only triggers the interrupt once. Here is what I have tried..

>make SPDIF_XFER_QUEUE_SIZE=1 so that next TCD is same as one just sent.
>set scattergather mode like this on each of left and right.
handle->dmaRightHandle->base->TCD[handle->dmaLeftHandle->channel].DLAST_SGA = handle->dmaRightHandle->base->TCD[handle->dmaLeftHandle->channel].DLAST_SGA; //self
handle->dmaRightHandle->base->TCD[handle->dmaRightHandle->channel].CSR = DMA_CSR_ESG_MASK | DMA_CSR_INTMAJOR_MASK;

Please help. Thanks!

Re: issue with repeated eDMA receive within interrupt

jeremyzhou — Thu, 04 Nov 2021 03:54:22 GMT

Hi,
Thanks for your reply.
1) Can you please help advise how to make scatter-gather work?
-- To provide the fastest possible support, I'd highly recommend you to refer to the scatter_gather demo (~\driver_examples\edma\scatter_gather) in the SDK library
Have a great day,
TIC

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Re: issue with repeated eDMA receive within interrupt

avbot — Thu, 04 Nov 2021 04:00:01 GMT

Hi Jeremy, I have reviewed that reference (and the other eDMA references) in great detail.
It does not directly apply because it is a one shot demo. What the confusion is for me as I have tried to get across in my post is how to make it continuous. Its not obvious from the comments in the code how to do this.
I would really appreciate if you can provide specific advice on this. Project is waiting for this solution so hoping you can assist soon. Thanks!