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How to activate DMA Request with DCAN2 IF2 Channel?

Pashan None
Genius 5660 points

Hello Support,

I can understand that DCAN2 IF3 can generate DMA Receive Request which will transfer DCAN2 Receive Message RAM contents to CPU RAM.

Because IF3 is supposed to be used with DMA, so there is no BUSY Bit in the IF3.

It is to be used always in Auto-Receive Mode. It makes sense to use with DMA.

For TMS570LS31x device, I see that DCAN2 IF2 is connected to DMAREQ[5].

Question is how DMA Receive Request can happen with DCAN2 IF2 interface similar to DCAN2 IF3?

There is a BUSY Bit in IF2 CMD Register. That has to be checked before Reading from CAN Message Object using IF2 Interface.

Any better explanation of using IF2 with DMA in both Receive as well as Transmit mode will help me.

Thank you.

Regards

Pashan

  • 0
    TI__Intellectual 1350 points

    Hello Pashan,

    the DCAN2 IF2 DMA request is triggered if it is enabled by the DE2 bit in the DCAN CTL register, additionally in the DCAN IF2CMD register the DMA Active bit needs to be set. Then the transfer from/to IF2  and message RAM needs to be triggered. Once the transfer completes the DMA request will be triggered. Compared to the the IF3 which is specifically optimized for usage with DMA , you have a less automated process when using IF1/2 with DMA.

    Best regards

    Andreas

     

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