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Cannot get DMA Triggered with Timer Match

Question asked by James Massey on Oct 17, 2016

Hello,

 

I have a continuous clock coming into the SSP port (configured as a slave), but data is only valid immediately after a "DataReady" signal falls. I am generating a match on a timer (configured as a counter) when that occurs, but I cannot get the DMA to respond to that match. It is reading data continuously instead of reading only 32 bytes after the signal falls.

 

I set up the external match pin for MAT1[1] and confirmed the match is occurring as expected. I would expect the DMA interrupt to occur once and only once 256 clock cycles later, until the match condition occurs again. However, the DMA transfer is free running.

 

Can you see my mistakes?

 

I am very sorry but I could not get the code insertion to work properly, so I attached a text file with my code snippets - Again sorry.

 

Thank you in advance for any insight - James

Original Attachment has been moved to: snippet.txt.zip

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