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EDMA3 on DM6446 queries

Amit Kale
Prodigy 170 points


Hello All,

I am currently working on DM6446 (CCS). Actually, I am writing my own API's for EDMA3 using the TI documents.

I have got the DMA working for A sync and AB Sync mode. Currently I am passing the channel Id along with transfer parameters, to the API.

I would like to change it to polling where, I poll for free channel and pass it to my DMA transfer API.

There are few more queries which I have

1. Is a particular DMA Channel is always mapped to a corresponding PaRAM set i.e. PaRAM set number and DMA channel number are same?

   I just needed a confirmation for this, as in QDMA is it possible to map one channel to any PaRAM Set?

2. Do we have to explicitly keep a track which channel is busy or there are some status register looking at which we can obtain the free and busy

   channel Ids.

 

Thanks and Regards

amit.

  • TI__Expert 3990 points

    Amit,

    Mapping from a DMA channel to a PaRAM Set is SoC specific. In DM6446, it doesn't exist. Moreover, we have to explicitly track the channel usage as there is no direct status register which could tell about the DMA channel state.

    Let me know if it helps.

    Regards,

    Anuj

     

  • in reply to Anuj Aggarwal
    Prodigy 170 points

    Anuj,

    "Mapping from a DMA channel to a PaRAM Set is SoC specific.", I have another query on this. 

    Assuming that we are using channel 1, and if we set some random PaRAM entry's (say PaRAM set 20)  OPT field with TCC as 1.

    we fill valid data for the A_CNT, B_CNT,.. SRCIDX etc. and we trigger the transfer for channel 1 using the ESR, so which PaRAM set will channel 1 use.

    Or in other words,  will it search for the transfer parameters in PaRAM set 1? I m bit confused on this, because I didn't come across anything which explicitly

    mentions this case.

    Thank you for the reply

     

    Regards

    amit.

  • in reply to Amit Kale
    TI__Expert 3990 points

    Amit,

    In the scenario mentioned above, channel 1 will ALWAYS use PaRAM Set 1 as the mapping between DMA channel and PaRAM Set doesnot exist. For SoCs like DM648, you can use any PaRAM Set with any DMA channel as the mapping feature exists there.

  • in reply to Anuj Aggarwal
    Prodigy 170 points

    Anuj,

     

    Yes, in DM648 there will be DCHMAP register to do the mapping. Thank you, this helps a lot!

     

    regards

    amit.