Re: Broken/Fried Parallel port...

hhc314@xxxxxxxxx writes:

Lucas, given that you have one bit responding unlike the others, you
have likey somehow fried something.

Were you now using a laptop, I would have suggest that you simply plug
in another serial interface board,

In this case parallel interface card...

but using a laptop this is generally not possible.

Sand and true. Many laptops have USB interface, and there
are USB to parallel port adapters. Those adapters are
generaly OK for connecting norma printers as such,
but not usually suitable for many homebuilt electronics projects
(they can't be controlled with sofware like original PC
parallel port could).

This is one of the reasons why most of us interfacing out
PCs with something else use desktops with expansion slots. A $20
parallel interface card is a good deal cheaper than replacing a $2,000
laptop, and good luck if you have to try and repair it.

This is a good advice.
There are many different parallel port cards out there.
They generally work well with normal printer, but depending on
their type they work or might not work with the software
designed for normal parallel port.

On old PCs with ISA bus the expansion parallel ports were
simple and easy. Typically same handware as original port,
just different standardized I/O address. Direct I/O port
level accessing works when you just change I/O address.

PCI bus paralle port cards are different story.
Those PCI port parallel ports genrally use more or less different
hardware than ISA counterparts, and use entirely different
I/O addresses (there might be some that cna be configured).
With most PCI bus based parallel port the old fashioned I/O port
lever parallel port controlling fails. The software that is
written in this way fails. This means that generally the parallel
port contolling software and many paralle port gadgets fail
to work with parallel ports on PCI us expansion card.

USB parallel port interfaces are entirely different
in architecture than legacy PC parallel ports.
Parallel port contolling software and many paralle port gadgets
fail to work with parallel ports on PCI us expansion card.


I am still looking for the details how those coudl be used
for general purpose I/O like the parallel port on PC
motherboard or in ISA bus expansion cards. Details may be
one day added to this document on parallel port controlling:

Parallel port interfacing made easy
http://www.epanorama.net/circuits/parallel_output.html

Then too, there is alway the hope that you diagnosis of the problem is
incorrect. Personally I'd do some more tests before declaring the
interface on the laptop toast, since you really have to do something
really gross to destroy a parallel interface (which I assume you mean a
printer port). Did you try and test it with a printer to see if it
worked with that? That's what I would try first, just to distinquish a
problem with and a/d converter vs a problem with the laptop.

Good luck.

Harry C.








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.


--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/
.

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