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

[Chris Albertson]

Comms onthe text below:  I would eliminate the "moterboard" completely
and incorporate it's function inside module that is built to the same form
factor as the modules that you have have plugged into the motherboard.

Big advantage is (1) mechanically much simpler and (2) yu can actually
change out the "motherboard".  (3) Every part of the system looks like
every other part of the system(4) you do noot need to guess the maximum
number of daughter cards, the bus is now a cable and not a PCB.

At this point in time, I think we should stick to system level issues and not
get into internals of a "module".  But we do need a working list of possable
modules.   People have proposed at least these

1) A "core" timer modula like PICTIC but with better specs
2) signal conditioning like trigger, attenuator...
3) An interface module.  There might be several different kinds of these.
one might have USB to a computer one might allow use of the counter
stand-alone with no computer, we'd say this module interfaces to a human.)

I can think of 50 kinds of modules some one might want but right now
the goal is to define what a module should look like on the outside
mechanically and electrically.

The mechanical part turned out to be hard.  It has to be something someone
can either buy cheap off the shelf or build using common tools at home.

Then when you think that a basic system might have one two modules the
"backplane" could easy be a jumper cable.

I don't know if a spectrum analyzer is out of scope.   I'm sure once someone
sees an "Open Counter" that has a good signal conditioner module and a good
interface module and a basic "pictic like" core counter they will think.  "Gosh
I can build a module with a A/D chip and a computer and I'd have an SA for
under $200.

I hope to be surprised at the modules people build in the future

About an FPGA or a CPU.  First off if you have an FPGA you can put a CPU
inside of it.  Some "soft CPUs" don't take more than a fraction of the gates.
There are some free "Soft ARM" designs and even soft SPARC and
and 8051.  If you REALLY need power Intel has an Atom CPU and an
FPGA on the same chip.

That said, I hope we do not need this.  The software is not
something you finish in a few months.


> Again, my thinking. Main board has 2, possibly 4 input daughtercard
> connectors. Internal interconnect pinout is well defined, though, as I
> said earlier, some pins may be 'designated for future use' and simply
> run to spare pins on a microcontroller or FPGA.
>
>> It might make sense to put an ARM next to the FPGA.  You can get a lot of CPU
>> for $10-20.
>
> ARM or other general purpose CPU is interesting, but at what cost for
> complexity and/or software development? It would require RAM, IO
> support, and boot rom at the very least. Not insurmountable, but at a
> cost to complexity.
-- 
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Chris Albertson
Redondo Beach, California