Re: [oc] ATA-3 or General ATA Questions

[Richard Herveille <richard@asics.ws>]

> I'm
> looking to program an FPGA to read a byte stream from a DVD-ROM drive
> (DVD-R Disc) and output the byte stream at 2MHz rate to a output
> bus.  All I want to do is to start the DVD reading and let it run
> until there is no more data.  Looking at the ATA-3 core it appears
> that I need to reset the system, use identify packet device to program
> timing registers, and then start reading data.  Is this correct? Any
> suggestions would be appreciated.  Do I need to worry about the DVD
> providing data faster than what I am using (is there some sort of timeout
> on the DVD end) ?

Hmm, interesting question.

Normally you should perform a "Identify Device" command towards
any connected ATA-devices. If you know on forehand what device will be
connected, you can skip this. Because the device will not report any
information you don't already have.

I think ATAPI supports play-and-forget, meaning tell the DVD to start
playing and it will stop when there is no more data. I am not sure about
this. But when looking at how DVD-ROMs, CD-ROMs and standard players
work, this should be possible.

The 2MHz output bus is way to slow. DVDs use UDMA for high-quality videos
(meaning 33MBytes per sec data). Read the ATA/ATAPI-5 manual. The cores
are all based on this.

Richard


> Scott Morris
> Research Engineer
> Battelle Pacific Northwest National
> Laboratory
> PO Box 999
> MS P8-20
> Richland, WA 99352
> Phone: 509-376-3860
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> Email:
> morris.scott@pnl.gov
>