Re: DMA controller question...

[toddpw@ugcs.caltech.edu (Todd P. Whitesel)]

kpopple@imp.sim.es.com (Ken Poppleton) writes:

>I am working on a DMA controller for the AIIdsp board.  How
>important is it that the destination address counter be selectable
>as an up or down counter?  Is the ability to set the counter as
>a down counter usefull?  If you think the ability to make the destination
>address count down for DMA, please send me an example of where this
>could be used.

It is very unlikely that down counters will be useful for it. For them
to be useful, you have to have an application that needs to reverse arrays
of bytes and the only thing I can think of that might need this for a DSP
board is if you need to convert the endian-ness of the data and you want
to do it sneakily by having the DMA reverse the order of everything.

I think that you will be quite safe if you just ditch the down counters and
save yourself the trouble.

Todd Whitesel
toddpw @ ugcs.caltech.edu