topic Re: DMA request caused by a level triggered interrupt on the same port. in Kinetis Microcontrollers

DMA request caused by a level triggered interrupt on the same port.

ClausStovgaard — Tue, 17 Mar 2015 16:29:28 GMT

Hi All

I am working with a Kinetis K70, where I experience an issue not documented in the errata or reference manual.

On PORT A I use pin 4 to create DMA requests on rising edge. This in general works well.

I also use pin 24 as a level triggered interrupt from a SPI device. When the SPI device pulls the signal down, I disable the interrupt on the pin, and service the interrupt over SPI, before enabling it again.

Somehow either by the receiving, disabling or enabling the level triggered interrupt, I get a false DMA rising request.

If I change the level triggered interrupt to be edge triggered, I am not receiving any false DMA requests.

I am looking into further debugging this, but would like any input regarding the possibilities that mixing level triggered interrupts with DMA requests on the same port, generates false DMA requests.

Thanks Ahead.

Kind regards

Claus Stovgaard

Re: DMA request caused by a level triggered interrupt on the same port.

jeremyzhou — Wed, 18 Mar 2015 03:04:56 GMT

Hi Claus,

Thank you very much for your focus on Freescale Kinetis product. I'm glad to provide service for you.

Thanks for your sharing and I'd like to confirm with about you some points, as I'm not very clear with your issue now.

And I think the community is more befit to discuss with each other, if it is ok for you, I'll only reply to your question in the community later.

1. What's specific product number of the MCU you used?

2. What's the pin 24? Was the PTA24?

3. What was the function of the pin 24 during SPI communication? Did the pin 24 work as SPI_SIN pin?

I'm looking forward to your reply

Have a great day,
Ping

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