From: Spiro Trikaliotis (trik-news_at_gmx.de)
Date: 2002-04-16 18:26:27
Hello MV,
MagerValp wrote:
> Speaking of which, does anyone have any schematics for a simple logic
> analyzer?
if it has to be low-cost: For this purpose, I once wrote a program for the
PC which listens on the parallel port (polling) and recognizes every single
change of the line states. With a bidirectional parallel port, you have
13 inputs with this approach with a resolution of approx. 4 us on a plain
DOS machine - this is limited by the I/O, it would be possible to be faster
with a special I/O card which uses memory mapped I/O (possibly, even a PCI
card might help, but I'm not sure). Thus, you would have a very simple digital
analyzer with a resolution of about 250 kHz. Is this enough?
The schematic is very easy: Just connect the inputs with the parallel port's
pins (details can be given if wanted) in case you have "compatible" voltages,
or use fast diodes to pull the parallel port's pins down.
Spiro.
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