Re: Broken/Fried Parallel port...
- From: Chris Jones <lugnut808@xxxxxxxxxxxxxxxx>
- Date: Sat, 01 Jul 2006 00:45:27 +0100
lmcgill2@xxxxxxxx wrote:
Hello all, I have been working with an interfacing project lately and I
think I have "screwed up" my parallel port. When trying to read data
from the data register (set from an A/D converter) I wasn't getting
correct results. After some "experimenting" I realized one of the pins
isn't going "high" when being supplied voltage. Anyway, it seems if I
connect this pin directly to the +5 from the 7805 regulator it goes
high, but the A/D converter IC doesn't seem to se the pin high. I use a
multimeter and figured that this pin needs at leats 18mA to go high
while all the others need about 2 (maybe less). SO, my question is, is
this normal? Do specific pins on a parallel port act that differently
from eachother or have I fried something inside my laptop? Nonetheless,
my port still works, I just altered its functionality. So how could I
use my A/D converter to throw this malfunctioning parallel port pin
high? Could I use a transistor (2N3904?!?) somehow? Any help would be
excellent. THanks, Lucas.
Try connecting the laptop to a normal printer. If it works, the you are
lucky and you should probably stop experimenting with the laptop and get a
cheap second-hand computer with an ISA bus or PCI printer port card that
you can replace when you blow it up. I have damaged a parallel port card,
I think there was a static charge on a long cable when I plugged it in. I
was very pleased that it wasn't a laptop.
Some of the printer port pins can be programmed to be either inputs or
outputs, and it may be that the pin thinks it is an output. On some PCs I
never succeeded in making the main data lines of the printer port act as
inputs and I had to use a MUX chip on one of the status lines to read in
the bits one at a time instead of using the data lines.
Chris
.
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