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Using a parallel port to control a remote control...

Hi!

I am wondering if this will work, and dont want to destroy anything
trying,,,

i know theres products out there that do this, but I want to make my
own...

Through software I can control turning on individual pins out my
parallel port.. The switch on my remote basically just closes the
circuit for that particular button.. I want to know if the voltage
going through the remotes button when closed (5v) matches the voltage
comming out of my parallel port (which it does), is there a way I can
wire in my parallel port to activate the button through software?

So one end of the switch has 5v, and the other has nothing until the
switch is pressed.. Can I just wire in the data line of my parallel
port to the end of the switch that is doing nothing. Then when I turn
on that data line +5 will go and the remote will think the button was
pressed and act accordingly?>

Do I need to tie the ground out the parallel port to the ground on the
controller?

thanks for your help
 
R

Rick

Jan 1, 1970
0
Hi!

I am wondering if this will work, and dont want to destroy anything
trying,,,

i know theres products out there that do this, but I want to make my
own...

Through software I can control turning on individual pins out my
parallel port.. The switch on my remote basically just closes the
circuit for that particular button.. I want to know if the voltage
going through the remotes button when closed (5v) matches the voltage
comming out of my parallel port (which it does), is there a way I can
wire in my parallel port to activate the button through software?

So one end of the switch has 5v, and the other has nothing until the
switch is pressed.. Can I just wire in the data line of my parallel
port to the end of the switch that is doing nothing. Then when I turn
on that data line +5 will go and the remote will think the button was
pressed and act accordingly?>

Do I need to tie the ground out the parallel port to the ground on the
controller?

thanks for your help

One of my first projects in the old days was to use a couple of
CD4051s tied to the keyboard matrix of a shortwave radio. A Commodore
64 drove them. I suppose you could use a similar scheme if your remote
keys are scanned....
 
Thanks for your reply.. the C64 is awesome.. still have one..
anyways...

I am still a bit confused.. I write software and havent dabbled into
the hardware aspect very much..

Can I just take say, d0 (the first data pin on the parallel port) and
run it directly to the controller? Just 1 wire? or do I have to run the
ground wire as well?

Thanks for your help.. Like I said I am just getting started in this
hardware stuff,,,

I also am not really that concerned if I blow up my xbox
controller/computer/house.. but i would like to know if I am doing
something completely wrong...,
 
P

Pooh Bear

Jan 1, 1970
0
Hi!

I am wondering if this will work, and dont want to destroy anything
trying,,,

i know theres products out there that do this, but I want to make my
own...

Through software I can control turning on individual pins out my
parallel port.. The switch on my remote basically just closes the
circuit for that particular button.. I want to know if the voltage
going through the remotes button when closed (5v) matches the voltage
comming out of my parallel port (which it does), is there a way I can
wire in my parallel port to activate the button through software?

So one end of the switch has 5v, and the other has nothing until the
switch is pressed.. Can I just wire in the data line of my parallel
port to the end of the switch that is doing nothing. Then when I turn
on that data line +5 will go and the remote will think the button was
pressed and act accordingly?>

Do I need to tie the ground out the parallel port to the ground on the
controller?

No, it's not that simple.

The keypad on your remote consists of a 'crosspoint' switch arrangement
where there are X by Y lines to minimise the number of connections needed
to provide a total of up to X times Y buttons.

Each switch button is an isolated switch ( normally a conductive rubber
'pill' ).

Also, remotes don't work on 5V, typically around 3V from a couple of AA or
AAA cells ( more like 2.5V and less as the batteries reach end of life ).

Whilst it would be possible to provide an interface from a parallel port,
I wonder if you really fancy going to all the trouble.

What's the application ?

Graham
 
it actually is 5v.. i am using it to control my xbox via wireless xbox
controller.. I tore it apart and verified it is 5v... Just trying to
simulate digital button presses on it.. Dont need to bother with the
analog buttons on the controller...You are correct the switch is using
one of those conductive rubber pills...

thanks for all the help
 
R

Rick

Jan 1, 1970
0
it actually is 5v.. i am using it to control my xbox via wireless xbox
controller.. I tore it apart and verified it is 5v... Just trying to
simulate digital button presses on it.. Dont need to bother with the
analog buttons on the controller...You are correct the switch is using
one of those conductive rubber pills...

thanks for all the help

As others have pointed out, the keyboard is a switch matrix. The
matrix is scanned by a processor to detect a switch closure. Review
anything you can find on "how a keyboard works" and you will see why
just putting a voltage on one line won't work.

The hardware requirements were quite minimal in my little project-you
should be able to figure something out. If I still have any drawings
around I'll email them to you....
 
M

Meindert Sprang

Jan 1, 1970
0
Rick said:
As others have pointed out, the keyboard is a switch matrix. The
matrix is scanned by a processor to detect a switch closure.

And how do you *know* it's a matrix?
What I mean is: I have designed a remote control for Garmin GPS's which only
required 8 keys. Since I used a micro that had 16 I/O pins, it was quite
pointless to make a matrix. It was much easier to give each switch it's own
input.

If it is not a matrix, a simple NPN transistor between the switch and ground
(that is, *if* they switch to ground) will do. Drive the base through a 10k
resistor from the LPT port. And connect the ground of the LPT port to the
ground of the remote. If it is a matrix, use bilateral switches like the
4066. Powered from the remote's supply, such a switch can be operated
'floating' on a matrix point.

Meindert
 
R

Rick

Jan 1, 1970
0
Meindert Sprang said:
And how do you *know* it's a matrix?
What I mean is: I have designed a remote control for Garmin GPS's which only
required 8 keys. Since I used a micro that had 16 I/O pins, it was quite
pointless to make a matrix. It was much easier to give each switch it's own
input.

If it is not a matrix, a simple NPN transistor between the switch and ground
(that is, *if* they switch to ground) will do. Drive the base through a 10k
resistor from the LPT port. And connect the ground of the LPT port to the
ground of the remote. If it is a matrix, use bilateral switches like the
4066. Powered from the remote's supply, such a switch can be operated
'floating' on a matrix point.

Meindert

Well, to be honest, I don't even know what an xbox is, lol...

And I did use bilaterals, by the way...
 
M

Meindert Sprang

Jan 1, 1970
0
Rick said:
Well, to be honest, I don't even know what an xbox is, lol...

:). It's MicroShafts counterpart of the Playstation 2...
And I did use bilaterals, by the way...

I used them decades ago to drive the keys of my TI programmable calculator,
to load programs and to convert cheap $10 calculators into counters by
driving the '=' key. You had to type '1+' first to get it going :)

Meindert
 
R

Rick

Jan 1, 1970
0
Meindert Sprang said:
:). It's MicroShafts counterpart of the Playstation 2...


I used them decades ago to drive the keys of my TI programmable calculator,
to load programs and to convert cheap $10 calculators into counters by
driving the '=' key. You had to type '1+' first to get it going :)

Meindert


Gosh, that reminded me of a thing I made way back when to display the
finishing order of 4 Pinewood derby cars. It used a calculator with
about a billion ICs for timing, latching, sensing, etc. Boards stacked
on top of each other, crammed into a box with the calculator mounted
on top..

Almost laughable looking back at it !.
 
I

Iwo Mergler

Jan 1, 1970
0
Hi!

I am wondering if this will work, and dont want to destroy anything
trying,,,

i know theres products out there that do this, but I want to make my
own...

Through software I can control turning on individual pins out my
parallel port.. The switch on my remote basically just closes the
circuit for that particular button.. I want to know if the voltage
going through the remotes button when closed (5v) matches the voltage
comming out of my parallel port (which it does), is there a way I can
wire in my parallel port to activate the button through software?

So one end of the switch has 5v, and the other has nothing until the
switch is pressed.. Can I just wire in the data line of my parallel
port to the end of the switch that is doing nothing. Then when I turn
on that data line +5 will go and the remote will think the button was
pressed and act accordingly?>

Do I need to tie the ground out the parallel port to the ground on the
controller?

thanks for your help

Consider using optocouplers. Drive the LED part from the
parallel port (use a resistor) and have the transistor
'press' the button.

If you can't be bothered to measure the polarity, just try
it both ways.

Regards,

Iwo
 
S

Si Ballenger

Jan 1, 1970
0
I did some tinkering some time back with an IR remote control to
control it via my computer. You can do what you want to do via
the parallel port with out too much trouble. The remote I
tinkered on (below) had the buttons in a 5x7 matrix. I did some
testing, and this remote can be controlled via the parallel port
using two 74HCT259 chips (in multiplex mode) connected to the
parallel port, 12 5k resistors on the chip output lines (5 on one
chip and 7 on the other), connected to 12 NPN transistors (7 in
one bank and 5 in the other), 5 diodes on the 5 transistor bank
(to prevent back feed), and 12 wires connected to the remote chip
and to the 12 transistors, You will need to sort out the pins on
the IR chip with a "beep" continuity multimeter to figure out the
wire/button maxtrix. The transistors, resistors, and diodes could
probably be replaced with two 4066 switch chips (I haven't tried
those yet). Down the road if I get the time I'll wire one up and
put the schematic on my web page. Somewhere on the net there is a
schematic of a Radio Shack IR remote control that shows the
typical button matirix. My remote has 33 buttons (out of 7x5=35)
on it. All can be controlled using this type of setup.

http://www.geocities.com/zoomkat/irmods.htm

Just as a followup, below is a pdf of the schematic for an IR
remote showing the button matrix and how they connect to the chip
in the remote. .

http://www.hifi-remote.com/files/schematics/15-1925.pdf
 
circuit for that particular button.. I want to know if the voltage
going through the remotes button when closed (5v) matches the voltage
comming out of my parallel port (which it does), is there a way I can

You've almost certainly got this the wrong way around; closing the
switch either closes one loop in a matrix or grounds one pin on a
micro, but either way the "open" state is high, not low.

Doing it this way is irksome. Go to www.lirc.org and you will find a
ready-made solution to transmit and receive IR codes from your
computer.
 
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