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

Question asked by Claus Stovgaard on Mar 17, 2015
Latest reply on Mar 17, 2015 by jeremyzhou

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

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