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Broken/Fried Parallel port...
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lmcgill2@uiuc.edu
electronics forum beginner


Joined: 20 Apr 2006
Posts: 26

PostPosted: Tue Jun 27, 2006 3:27 pm    Post subject: Broken/Fried Parallel port... Reply with quote

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.
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hhc314@yahoo.com
electronics forum addict


Joined: 11 Sep 2005
Posts: 88

PostPosted: Wed Jun 28, 2006 8:23 pm    Post subject: Re: Broken/Fried Parallel port... Reply with quote

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, but using a laptop this is generally
impossible. 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.

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@uiuc.edu wrote:
Quote:
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.
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Tomi Holger Engdahl
electronics forum addict


Joined: 06 May 2005
Posts: 64

PostPosted: Thu Jun 29, 2006 9:05 am    Post subject: Re: Broken/Fried Parallel port... Reply with quote

hhc314@yahoo.com writes:

Quote:
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...

Quote:
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).

Quote:
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

Quote:
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@uiuc.edu 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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Dave
electronics forum addict


Joined: 30 Apr 2005
Posts: 73

PostPosted: Fri Jun 30, 2006 12:46 am    Post subject: Re: Broken/Fried Parallel port... Reply with quote

lmcgill2@uiuc.edu wrote:
Quote:
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.
Is this a data pin or a status pin on the port that you are attempting

to read?
Quote:
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 would not connect the 5V direct as this will cause problems is the

device is at a low level. It is better to use a 1K resistor tied to the
5V as a pull up.
Quote:
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).
A 1K resistor to 5V is 5MA and should be sufficient. I suspect the port

is not set to input mode if you are using a data bit.
Quote:
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?
Data pins are different from Status pins and some status pins have

inverted levels.
Quote:
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.
I don't have my chart handy, please indicate what Pin numbers you are

using.

Dave
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lmcgill2@uiuc.edu
electronics forum beginner


Joined: 20 Apr 2006
Posts: 26

PostPosted: Fri Jun 30, 2006 1:08 pm    Post subject: Re: Broken/Fried Parallel port... Reply with quote

CheapscateDave wrote:
Quote:
lmcgill2@uiuc.edu 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.
Is this a data pin or a status pin on the port that you are attempting
to read?
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 would not connect the 5V direct as this will cause problems is the
device is at a low level. It is better to use a 1K resistor tied to the
5V as a pull up.
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).
A 1K resistor to 5V is 5MA and should be sufficient. I suspect the port
is not set to input mode if you are using a data bit.
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?
Data pins are different from Status pins and some status pins have
inverted levels.
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.
I don't have my chart handy, please indicate what Pin numbers you are
using.



Thanks Dave for the help, I am trying to read from the data register.
To my knowledge, the 0-bit of the data register is pin 2 on the
parallel port, and the 7-bit is pin 9. The pin that is giving me wierd
results is pin 8. When i say wierd i mean it won't go "high" when
being told to do so by my ADC IC. In addition, my port is in
bi-direction mode, thanks, Lucas.
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Si Ballenger
electronics forum Guru Wannabe


Joined: 02 May 2005
Posts: 121

PostPosted: Fri Jun 30, 2006 3:33 pm    Post subject: Re: Broken/Fried Parallel port... Reply with quote

On 30 Jun 2006 06:08:22 -0700, lmcgill2@uiuc.edu wrote:


Quote:
Thanks Dave for the help, I am trying to read from the data register.
To my knowledge, the 0-bit of the data register is pin 2 on the
parallel port, and the 7-bit is pin 9. The pin that is giving me wierd
results is pin 8. When i say wierd i mean it won't go "high" when
being told to do so by my ADC IC. In addition, my port is in
bi-direction mode, thanks, Lucas.


You might want to consider using the parallel port status lines
to input your data. You would probably need two ADC chips to do
this, but it might be an easier setup. I've made the below setup
to input data into my parallel port.

http://www.geocities.com/zoomkat/status.htm
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Chris Jones
electronics forum Guru Wannabe


Joined: 06 May 2005
Posts: 278

PostPosted: Fri Jun 30, 2006 10:55 pm    Post subject: Re: Broken/Fried Parallel port... Reply with quote

lmcgill2@uiuc.edu wrote:

Quote:
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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petrus bitbyter
electronics forum Guru


Joined: 24 Mar 2005
Posts: 363

PostPosted: Sat Jul 01, 2006 1:50 pm    Post subject: Re: Broken/Fried Parallel port... Reply with quote

<lmcgill2@uiuc.edu> schreef in bericht
news:1151422060.776961.131260@x69g2000cwx.googlegroups.com...
Quote:
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.



Hmm... There are several tastes of parallel (printer) ports. In todays PCs,
you can usually choose the taste in the BIOS setup. Guess this is the first
thing you have to find out. Have a look at
http://www.beyondlogic.org/
part of parallel port interfacing for an overview. The same chapter also
describes a DOS tool for parallel port debugging.

petrus bitbyter
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Dave
electronics forum addict


Joined: 30 Apr 2005
Posts: 73

PostPosted: Sun Jul 02, 2006 2:23 am    Post subject: Re: Broken/Fried Parallel port... Reply with quote

Quote:
Thanks Dave for the help, I am trying to read from the data register.
To my knowledge, the 0-bit of the data register is pin 2 on the
parallel port, and the 7-bit is pin 9. The pin that is giving me wierd
results is pin 8. When i say wierd i mean it won't go "high" when
being told to do so by my ADC IC. In addition, my port is in
bi-direction mode, thanks, Lucas.

Lucas,
What I would do at this point is get 8 1K resistors and 8LEDs.
Connect -(minus)lead of each LED to pins 2 to 9, +lead of LED to each
1K resistor and all of the 1K resistors to your +5volt supply.
When the port is in output mode a 1 bit will turn the led off, a 0 bit
will turn the bit on.
When the port is in input mode it should read FF or 1 bit for each pin.
Starting with pin 2 start grounding the - LED lead and read the port,
remaining in input mode.
When the pin is grounded the LED should light and the port should read
a 0 for that bit.
Hope you can step your program to accomplish this.

Dave
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