Re: gEDA-user: Fun challenge: cat-5 cable tester

[DJ Delorie <dj@xxxxxxxxxxx>]

> It's much easier if you put the remote resistors in series (and
> needs one less, too):

Ok, that's a novel solution I hadn't thought of.

It doesn't solve the exact original challenge, but it's still the best
solution so far :-)

One of the ideas I had was to add weak pull-ups on the eight ADC
ports, so they could detect opens more reliably.  I think that solves
the floating input problem.

> 3. No static tester can detect the case where the pins are connected
> through properly, but the pairing of the wires in the cable is
> wrong.

Right, but even this simple one can tell if you swapped two wires on
one end, like if the wires crossed (or uncrossed) as you were
inserting them into the connector.

The system can even self-calibrate by pulling ALL the pins high (or
low) except one, and measuring Voh (or Vol) with that one pin.


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