Re: gEDA-user: terminators

[Ben Jackson <ben@xxxxxxx>]

On Sun, Apr 05, 2009 at 01:19:32AM -0400, DJ Delorie wrote:
> 
> Hmmm... maybe I'm going about this the wrong way.  Would it make more
> sense to get rid of the LA on that side, move the sdram chip as close
> as I can to the FPGA, and use something like chipscope

That's what I'd do.  At the sort of volumes you and I work with it's
a lot cheaper to use a FPGA big enough to include chipscope/signaltap
even in the full design than to allow for an LA hookup.

If things are going wrong due to external timing or signal issues the
LA won't help anyway -- you'll need a good scope.

> signals?  I've got both SPI and addr/data connections to the MCU on
> the other side to get the data out.

Why not just use chipscope?  I thought you could get that for free
these days (although admittedly I use Altera mainly for free Signaltap
myself).

> > Here's another idea.  Instead of the LA, use a scope
> 
> My scope is nowhere near fast enough for that.  The LA is 500 ms/s or
> can be externally clocked up to 200 mhz.  The scope is only 32 ms/s.

Hard to believe the LA expects signals that fast without active probes.
The probes I've seen have the .1" type headers on the LA end, but the
far end have active probes and other connectors (typically mictor) and
cost $1500/set.

-- 
Ben Jackson AD7GD
<ben@xxxxxxx>
http://www.ben.com/


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