Processing DMA messages while they are being sent.

Westin Sykes

I am trying to make a CAN buffer that I can periodically (at a controlled rate) scan through moving messages around. I am doing this with DMA to create virtual mailboxes. The DMA works, but in order to scan through, I need to know where DMA most recently written to or something to get the address of the most recent valid and complete frame. It seems there is a register for telling the current destination address of a DMA channel, but it only is updated if the DMA is preempted. Is there a good way for me to find the most recent fully written frame?

over 10 years ago

0 Zhaohong Zhang over 10 years ago

TI__Mastermind 22715 points

One option is to enable DMA frame transfer completion interrupt. You can maintain a counter in the ISR so that you know which frame has completed.

Thanks and regards,

Zhaohong

0 Westin Sykes over 10 years ago in reply to Zhaohong Zhang

Expert 1315 points

I considered that, but have a couple issues with doing that. We are trying to avoid extra interrupts, and at times, interrupts are disabled for some period of time, and I think that could cause issues if CAN messages came in while the interrupts were disabled.

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Processing DMA messages while they are being sent.