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JulienD
JulienD
Associate III
September 13, 2016
Question

Which interrupt for complete uart transfer with DMA

  • September 13, 2016
  • 4 replies
  • 747 views
Posted on September 13, 2016 at 15:07

Hi,

With STM32L1, I need to know when a frame transmition is complete when sent

on uart using DMA.

By complete, I mean, the last bit has been sent on the line because I need to activate

a buffer when data is transmitted, and deactivate it when nothing more has to be send.

I tried with the dma TC, but it fires 2 bytes before the end. I supposed that's because

the uart has a 2 bytes buffer.

I was neither successfull with the uart TC.

Now, I suspect a bug, but if you can tell me which interrupt I should look for, the debug

would be more straight forward.

Thanks

Julien
    This topic has been closed for replies.

    4 replies

    waclawek.jan
    waclawek.jan
    Super User
    September 13, 2016
    Posted on September 13, 2016 at 22:22

    > I was neither successfull with the uart TC.

    That's bad luck because that's supposed to indicate the end of transfer.

    JW

    jpeacock23
    jpeacock23
    Associate
    September 14, 2016
    Posted on September 14, 2016 at 14:05

    You might want to check your code again.  The TXE interrupt occurs before buffer is empty, as you describe.  The TC occurs after the last bit is shifted out.  From your description you are looking at the wrong event. 

    Are you enabling TC only after the last byte has been sent?  If you have long inter-character gaps you can see TCs interleaved with TXEs.

      Jack Peacock

    mark239955_stm1
    mark239955_stm1
    Visitor II
    September 16, 2016
    Posted on September 17, 2016 at 00:35

    Try waiting for a UART TC interrupt, instead of a DMA TC interrupt.

    JulienD
    JulienDAuthor
    Associate III
    October 4, 2016
    Posted on October 04, 2016 at 12:26

    OK, thanks to all. I will do some tries with TC interrupts.

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