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Looking for a lost bit in SIC_ISR

Question asked by nblatsos on Jan 27, 2014
Latest reply on Feb 19, 2014 by demonb

I am working with a BF518x and ran into a situation i didn't fully understand.  I have an mdma transfer that occurs a dozen or so times a second.  I expect an interrupt to occur once the transfer completes.  Inside the interrupt handler, I read the corresponding SIC_ISR register one time when i enter the handler and check which SIC_ISR bit got me there. Then I check each peripheral under that sic bit to determine the source.    Most transfers, lets say 99/100 transfer all data, hop into the appropriate interrupt handler and get processed exactly as I intend.  The other times, the very first read of the SIC_ISR has no bits set, that correspond to the active interrupt vector.  I did get the interrupt, to the correct handler, and if I check each peripheral and skip checking the SIC_ISR register everything works every time.  I just want to understand why the SIC_ISR bit is getting cleared before i clear the status causing it.

 

Thanks,

-Nick B.

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