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Trigger multiple DMA's off same event?

Started by Brian C. Lane November 23, 2005
Is it possible to trigger 2 DMA's off the same McBSP event?

Eg. McBSP codec receive event triggers a receive DMA which reads data
from that McBSP.

Same receive event triggers a different DMA that writes to a different
McBSP's transmit register.

Can this be done?

Thanks,

Brian

--
-----------------
Brian C. Lane (W7BCL) Programmer
www.shinemicro.com RF, DSP & Microcontroller Design


hi Brian,

TI docs doesnt mention anywhere that you cannot do
this. But, the RRDY is the bit that directly drives
the REVT, for DMA triggering.This bit is cleared when
the DRR is read by the DMA which is synchronised to
it. In our case, there can be a contention for
clearing this RRDY bit.

In any case, how will you ensure that dma write to the
other mcbsp for transmit is synchronised? i mean, if
the dma writes to the transmit register before the
data has been driven out on DX, the transmission is in
error.

may be you can synchronise the mcbsp recive event to
one dma and transmit event of other mcbsp to second
dma. Data transfer between the dma can be done by
managing a buffer. you can even make use of the half
full interrupt of the receive dma to inform the cpu to
initialise second dma which works on the transmit sync
event.

regards,
Dileepan.

--- "Brian C. Lane" <brian@bria...> wrote:

> Is it possible to trigger 2 DMA's off the same McBSP
> event?
>
> Eg. McBSP codec receive event triggers a receive DMA
> which reads data
> from that McBSP.
>
> Same receive event triggers a different DMA that
> writes to a different
> McBSP's transmit register.
>
> Can this be done?
>
> Thanks,
>
> Brian
>
> --
>
-----------------
> Brian C. Lane (W7BCL)
> Programmer
> www.shinemicro.com RF, DSP & Microcontroller
> Design >
>
> c54x-unsubscribe@c54x...

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