> I'm guessing that since you've mentioned negative voltages, your either
not
> familiar with the way the JDM design works, or you've connected it to the
> wrong pins on your serial port.
>
> Since most modern serial ports can't put out voltages as high as 14 volts
> the JDM "fakes" a ground reference to the lowest negative voltage the port
> can produce. Usually that puts the programmer "ground" at about 10 volts
> below the PC "ground" (this is often a problem when trying to do
in-circuit
> programming)
>
> If you use pic pin #31 (Vss) as the "ground", none of the programming
> connections should ever be below 0v (if they are, you're killing the pic)
>

There's a JDM derivative at http://www.qsl.net/dl4yhf/winpicpr.html

The software download includes a schematic that is based on the JDM design,
but shares the ground with the PC serial port. As a result, recommended to
be used only with flash devices.

I have built it, and it works great. Also, the software (winpic) is very
user friendly, works under XP, supports multiple programmers including
parallel port based ones, and is much faster than ICPROG.

And while you are there, Wolfgang has some other neat projects on the site
as well.

Regards,

Anand Dhuru




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