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TMS570 sci dma receive is not working

Constantin Wiesener
Intellectual 540 points

Other Parts Discussed in Thread: HALCOGEN, TMS570LS3137

I've followed the instructions from the forum and from the halcogen example for SPI. I used the TRM too.

But still the packages are not received in the destination array.

The test project is attached.


kind regards,

C.W.1261.rs485_test_dma.zip

  • 0
    TI__Guru**** 191886 points

    Hello C.W.

      I think the problem is with the DMA request assignment. You assign DMA request 29 to channel 0 instead of request 28. You should change to below. Request 29 is for TX. Request 28 is for RX. Since you want to use the DMA to transfer from the RD to the RAM you need to use the RX DMA request to trigger the DMA. Once changed, I was able to see the "Reached" statement printed out on the console after I entered 12 characters on the CCS terminal.

    // assign dma

    dmaReqAssign(DMA_CH0, 28);

    regards,

    Charles

  • 0 in reply to Charles Tsai
    Intellectual 540 points

    Hi Charles,


    good to know since there is no information in the manual (TRM) there is only a mentioned that there is bitfield for each channel with 32 request lines. But it is not mentioned how this request lines are explained in detail.

    I think it would be nice to have it in the manual.

    Kind regards,

    C.W.

  • 0 in reply to Constantin Wiesener
    TI__Guru**** 191886 points

    Hello C.W,

      The DMA request map information can be found in the datasheet. For example, if you are using TMS570LS3137 part (sprs162b.pdf), the DMA request map can be found in the section 4.16.2. The reason we did not include the request mapping in the DMA chapter of the TRM is that we want to keep the module in a more generic way across different part numbers. Please let me know if you have further question. Hope the datasheet will clarify your questions.

    Regards,

    Charles

  • 0 in reply to Constantin Wiesener
    TI__Guru 69070 points

    C.W.  Thanks for pointing out this shortcoming in the TRM.   

    There is a link like this:

    Submit Documentation Feedback

    On the bottom of each TRM page.  If you see something like this in the future you can submit your feedback this way even if you don't need to make a forum post.  These feedbacks go into the queue for the next document revision.

    You have something very valuable which is a fresh set of eyes and the mindset of someone trying to use the product, and we sometimes can stare at something like this in the doc and knowing the answer don't even recognize the problem.  So thanks very much ahead of time for everything you point out.

    I submitted the doc feedback on this item though - for the register descriptions starting with HWCHENA, where they just say 'the corresponding hardware enable bit' but as you pointed out doesn't state that bit 0 corresponds to channel 0, etc..

     

  • 0 in reply to Charles Tsai
    Prodigy 80 points

    HI Charles,

    My name is Thomas, and I've been trying to find this (sprs162b.pdf) file everywhere with no success. Can you direct me to this file or give me a link to it?

    Thank you,

    Thomas Renick

  • 0 in reply to Thomas Renick
    TI__Guru**** 191886 points

    Hi Thomas,

      There is a newer version at the link below. Please go to section 6.16.2 on page 95 for the DMA Request mapping.

      http://www.ti.com/lit/ds/spns162c/spns162c.pdf

  • 0 in reply to Charles Tsai
    Prodigy 80 points
    Hey Charles,

    Thank you, just what I need.

    regards,

    Thomas