Re: LPC bus in a geode sc1200

[Carlos Ojea Castro]

On 5/10/06, Lennart Sorensen <lsorense@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, May 10, 2006 at 09:55:47AM +0200, Carlos Ojea Castro wrote:
> > Thank you very much for your reply, Len.
> > I will also have an FPGA (I think it will be on port 0x1400 or so). I
> > am writing to LPC using 'outb' like this: outb (data, port);
> > So I see an I/O write on the LPC bus, that is: 2 bytes for address and
> > 1 byte for data (it tooks one microsecond per transfer).
> >
> > To speed up things, I wish to transmit more than 1 byte for data in
> > each transfer (if possible).
> > Accordingly with page 194 of the sc1200 processor data book, it is
> > also possible to do a "Bus Master Memory Write" to transmit 1,2 or 4
> > bytes.
> > Do you know how can I make a "Bus Master Memory Write" to the LPC?
>
> Well I know we don't do that.  We have very little data, just board
> status information from various places on the board.  LPC does support
> doing DMA, which I believe is done in the same way it was done on ISA at
> least as far as the software is concerned.  How to implement DMA for LPC
> in the FPGA I have no idea.  The LPC specifications would probably tell
> you.  I imagine it involves setting up a DMA buffer in RAM (in the first
> 16MB probably) and then sending a command to the FPGA telling it to do a
> DMA transfer from that memory location using the LPC DMA commands.
>
> Len Sorensen

Well at this moment, using the low address byte to transmit data, I
can transmit 100.000 bytes in about 63 milliseconds, maybe it is
enough. Will try DMA anyway...
Thank you very much!

Regards,
Carlos
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