Re: FPGA for PCI based servo control board

[John Sheahan <jrsheahan-at-optushome.com.au>]

On Sun, Apr 06, 2003 at 11:36:07AM -0400, John Kasunich wrote:
> 
> BTW, I think gigabit ethernet is really unreasonable for an FPGA
> MAC on a homebrew board. ;-)

altera and xilinx both make fpga's with onboard CDR that 
can directly connect to a fiber transceiver. they do all the 
8b/10b and alignment and stuff. 16 bit internal data bus. 
The xilinx is from memory ~$80 in small quantity. 
Its also in a ~400 bin micro BGA So I don't want to assemble it.
Yes - its way overkill for my applications.
 
> 
> My experience with FPGAs (long ago) was that defining the
> design is the easy part.  Placing and routing are worst, and then
> you still have to lay out the PCB.  Still, I understand what you are
> saying, and I've gotta yield to your experience in this area.

fpga's have evolved too. 3000 series required interesting design
styles to get good utilization. Things have got steadily better. 

> 
> Yes.  The daughterboard approach works for ethernet and parallel port.
> It would be really cool if we could find a cable connector and a board
> stacking (daughterboard) connector with the same PC footprint.  Then
> the same I/O glass could be used to build a cable connected I/O board
> for ISA/PCI, and a motherboard for an ethernet or EPP daughterboard.
> I'll look into it.

this seems to be a reasonable suggestion. The footprint of the
daughter board can be pretty flexible, and will need some additional
resource, like power. but they can be extra pins, unused for the socket.
> 
> Great!  For you, the registers between the MAC and the control
> hardware are internal, but I'd still like to have them defined so
> the other designs will remain compatible.
> 
> I've got a few hours today.  I'm gonna start a web page with
> design documentation.  Doing this stuff in words only is very
> frustrating.
> 
> John, are you gonna be at NAMES or EMC Monday?  I'd love
> to sit down with you, Craig, and some paper for a couple of
> hours.  We could accomplish a lot.

Travelling to the US from Australia is too hard right now :(
And those full-body searches at the airport - yechhh.

Time I got my web page up and running too. 
BTW What schematic package do you use?  
I've got protel available. otherwise docs in ps / pdf / lyx works 
for me.

john