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TMS570LS3137: DMA function application

Part Number: TMS570LS3137

Hello 

Team

 I have some question about dma function

1.The dma function of can or sci ,What is the maximum capacity ,means How many bytes at most?

2.If the data in DMA is not read,dose the new data will overwrite the original data?

3.If the DMA data is full, will the new data overwrite the old data

 Thankyou

  • 1.The dma function of can or sci ,What is the maximum capacity ,means How many bytes at most?

    The block transfer size is IETCOUNT x IFTCOUNT. IETCOUNT and IFTCOUNT are defined in ITCOUNT register

    The read element size and write element size for SCI should be 8 bits if multi-buffered mode is not used. In multi-buffered mode, the element size can be 64-bit. The element size for CAN TX and RX can be 64-bit either.

    2.If the data in DMA is not read,dose the new data will overwrite the original data?

    Data in DMA: do you mean data in CAN data registers (DCAN IFxDATA and DCAN IFxDATB) and SCI data registers (SCIRD, or LINRX0/LINRD1 for multi-buffered mode)?

    In multi-buffered mode, the SCI RX DMA request is triggered once the last character of the programmed number of characters (LENGTH) are received and copied to the corresponding RDy buffer successfully. The DMA should transfer the data from RDy to the destination address automatically. If the DMA transfer is arbitrated out, the data in RDy is not transferred on time, the next coming data will overwrite the RDy. Same for CAN.

    3.If the DMA data is full, will the new data overwrite the old data

      DMA data: do you mean RX data in destination memory? Yes, it will be overwritten.

  • Thank you