[time-nuts] Form Factor and such, Big Picture

Hal Murray hmurray at megapathdsl.net
Thu Dec 23 00:40:29 UTC 2010


I think I'm missing the big picture.  What sort of things are people 
interested in building?  Will they all be a reasonable fit with a single Form 
Factor, Bus, and whatever?

I've been thinking of something like a mother board with FPGA that would fit 
in something like the Hammond boxes.  The idea is that the FPGA is the part 
that's hard for me because I can't handle soldering BGAs.  All the front-end 
analog stuff would go on a daughter card.

The hardware interface between the mother/daughter cards is just a row (or 3) 
of pins/sockets for 0.1 inch connectors.  (or anything similar)   Software 
interface is TBD.  It might make sense to publish a "standard" interface for 
some application so the same firmware on the motherboard would work for 
various front ends.

It might make sense to put an ARM next to the FPGA.  You can get a lot of CPU 
for $10-20.

I'm not sure what the back end sould look like.  I'd be happy with USB or 
Serial.  They are dumb/simple and don't require massive protocol stacks.  I 
could live with Ethernet, but it really raises the bar for getting off the 
ground.   (I'm not interested in running a web server on my toys.  All I want 
is simple command/response.  I'll put the web server on a PC that has access 
to all the archived data.)

It might make sense to have a back-end daughter card.


With that sort of setup, I think I could build a 5370 class box that I could 
use for long term data collection.  Does that seem reasonable?

I don't need the full flexibility of the 5370 front end.  I'm willing to use 
jumpers or a soldering iron for things like AC vs DC coupling and 50 ohm 
termination.


On the other hand, how much board space would a spectrum analyzer take?  
Should we be discussing 2 sizes of projects?




-- 
These are my opinions, not necessarily my employer's.  I hate spam.






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