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PSoC™ 5, 3 & 1 Forum Discussions

euggersh
Level 4
Level 4
5 sign-ins First solution authored 50 replies posted

In the following setup:

pastedImage_0.png

I'm sending two bytes and then read 10 back, as seen here:

pastedImage_1.png

After the two bytes are sent, I clear the SPI Rx FIFO, which clears the DRQ to the Rx DMA channel.  I then transmit 10 dummy bytes to read 10 bytes back.  As you can see in the trace above, the Rx interrupt (driven by the DMA NRQ signal) occurs at the beginning of the last byte being clocked in, rather than at the actual completion of the transfer.

I've tried this with different transfer sizes and this always happens one byte early.  The transfer does complete before I get around to handling it, so it effectively works, but I'd like to understand what's going on here and avoid future problems.

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himam_31
Employee
Employee
50 likes received 25 likes received 10 likes received

Hello,

Can you please share the project with us. We wold like to review the SPI component configuration, especially the interrupts. Also can you please let us know the details about the signals in the Scopeshot and the TopDesign. This would help us to correlate the signals correctly.

Thanks,

Hima

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