AnsweredAssumed Answered

eDMA trigger from GPIO

Question asked by Terry Biberdorf on Feb 5, 2018
Latest reply on Apr 5, 2018 by Jorge Antonio Alcala Vazquez

I'm using MCUXpresso IDE v10.1.0 and a FRDM-K64 development board.


I would like to have a DMA memory to memory operation trigger from SW3 event.


I have a github project created that seems to partial work:

GitHub - tsbiberdorf/SPI_ScatterGather: FRDM-K64F sample code for SPI DMAMUX Scatter Gather  

SHA Id: fbedd903fd191013ef8aba7d4587874ac92f5f5b


The project has a DMA event happening on the first press of SW3, then it required 4 SW3 presses, followed by 4 more SW3 presses.  This all matches the TCD operations I have programmed in the method: circularBufferScatterGather()


The part that has me frustrated is that I cannot get the loop to repeat again.  What setting or API call do I have to make to have another loop of SW3 presses of 1/4/4 again?


I believe I need to request a EDMA_TcdSetChannelLink() to link the major scatter/gather operation back to the start, but the call does not work and I'm not sure why.


I will eventually want this operation to work on SPI communication, but to test all available SDK API calls I'm starting with memory to memory operations.