To help me in my home projects, I just made two at89c2051 with a 20x4
LCD to do the nasty job of capture 2x RS232 and display it, just
eliminated the "sometimes guessing games".  A 32k RAM saves the captured
data.

Interface this solution to a PC parallel port and using any VB software
to show it at the PC would be nice, of course using two PC serial ports
can also be done, but it is not so exciting, and sometimes you just
can't have IRQ's enough to deal with the interruptions at those serial
ports.

As this chip is running at high clock it was possible to implement a
digital logic analyzer with 8 or more port bits, but, I belive it would
lead me to more problems than solutions because it would never be fast
enough, so I never did it.

A nice HP1630G is not that expensive if you really need one (used is
around $700).

Wagner Lipnhasrki - Orlando, FL
http://www.ustr.net


"Richard A. Smith" wrote:
>
> On Fri, 9 Apr 1999 14:18:55 -0700, Scott Dattalo wrote:
>
> >windows (running mplab). He was able to use Linux as a comm-analyzer. The
> >only thing though was that he was limited to half-duplex. This means he
> >could only see what the pc was sending to the picstart OR what the
> >picstart was sending to the pc. He couldn't see both at the same time. We
> >suspect if he had two serial ports that he could capture all of the
> >communication at once. This beats the hell out of using a DSO or logic
> >analyzer.
>
> Was it only half-duplex because of Hardware limitations?
> If so then I have a book that has a schematic allowing you
> to hook both TX lines up to the RX line of another PC. That
> way you can see what both devices are sending as long as
> they don't both send at the same time.
>
> I seem to remember that it just isolates each TX line with
> a diode so that they can't drive each other.