i.MX RT Crossover MCUsのトピックRe: Using ADC_ETC with EDMA, automatic transfer start?

Using ADC_ETC with EDMA, automatic transfer start?

jackking — Wed, 12 Feb 2025 21:27:52 GMT

I am looking at using ADC_ETC and DMA together on iMXRT1062. I see the SDK sample project (adc_etc_edma) which does transfer the ADC results using DMA successfully.

But, I also see that there is a call to EDMA_StartTransfer(&edmaHandle) after the EDMA callback sets a flag. According to the i.MX RT1060 Reference Manual Rev. 2 (page 3375), this should not be necessary, as the ADC_ETC completion should trigger a new DMA transfer directly. The ADC_ETC trigger chain is being triggered by the PIT, so this should allow the ADC_ETC->DMA transfer to run completely through DMA repeatedly.

I tried removing the StartTransfer call from the example, but the ADC_ETC does not seem to trigger a new DMA transfer. Is there some other setting that is required for the ADC_ETC to initiate a new DMA transfer?

thanks

Re: Using ADC_ETC with EDMA, automatic transfer start?

jackking — Thu, 13 Feb 2025 13:27:34 GMT

This is the line in the SDK example I am referring to:

Re: Using ADC_ETC with EDMA, automatic transfer start?

jackking — Thu, 13 Feb 2025 13:29:51 GMT

And the Reference Manual entry which suggests this should not be necessary:

Re: Using ADC_ETC with EDMA, automatic transfer start?

mayliu1 — Tue, 18 Feb 2025 04:15:21 GMT

Hi @jackking ,

Thank you so much for your interest in our products and for using our community.

I checked the i.MX RT1060 Reference Manual Rev. 3 page3451, it seems different from the version 2.

https://www.nxp.com/webapp/Download?colCode=IMXRT1060RM

I can not see all your code in the post. But I think you can check that whether the register DMA_CTRL[TIRGa_ENABLE]set to 1 when complete the the last trigger in chain in your project.

Wish it helps you.
If you still have question about it, please kindly let me know.

MayLiu

Re: Using ADC_ETC with EDMA, automatic transfer start?

jackking — Fri, 14 Feb 2025 03:17:38 GMT

I think you are looking at an old SDK version…

This version of the SDK does have an example for adc_etc_edma. The sample does enable DMA triggering for the ADC_ETC, using ADC_ETC_EnableDMA()

Re: Using ADC_ETC with EDMA, automatic transfer start?

mayliu1 — Fri, 14 Feb 2025 07:21:17 GMT

Hi @jackking ,

Thanks for your updated information.

Yes, I can import adc_etc_edma demo after update my SDK version 24.12.00.

Regarding your issue, I have consulted SDK expert in charge of the ADC module, he will explain that, Please keep patience.

Best Regards

MayLiu

Re: Using ADC_ETC with EDMA, automatic transfer start?

mayliu1 — Tue, 18 Feb 2025 03:24:45 GMT

Hi @jackking ,

Thanks for your patience.

I got the answer from the SDK expert in charge of the ADC module:

TCD0_CSR[DREQ] is set to 1 in the EDMA driver. The request is disabled after each major loop ends, so it needs to be re-enabled.

Wish it helps you.
If you still have question about it, please kindly let me know.

MayLiu