how to control a robot conected to paralel port?

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Two 74154's would be the maximum you can drive directly from 8 data outputs, to drive more you would need to include some type of addressing scheme as part of your circuit with accompanying programing, this will make it abit more complex to build.

Most, if not all, mux's have an enable pin that you have to make either high or low to "choose" the chip, using this scheme you can control upto 16 74154's for a grand total of 256 addressable multiplexed outputs.

Obviously trying to fit 17+ 74154's ( 24 pins each ) on a PC board would consume an enormous amount of board realestate. why do you want so many outputs or what is the application ?
 
I was thinking about making an LED "screen" that could display text and stuff. A 10x10 LED screen would be 100 LEDs. It was just an idea I had.

I do a lot of stuff with the parallel port and more than 8 outputs would be useful sometimes - so when I found this forum I thought I'd check to see if anyone knew how to do it.

www.JBProjects.net if you want to see some of the stuff I've done.

Thx for your help.
 
I was thinking about making an LED "screen" that could display text and stuff. A 10x10 LED screen would be 100 LEDs.
Click to expand...

Wish you had mentioned that earlier, in that case you only need two mux's( or decoders) connected in a row-column arrangment to make an LED matrix.
 
It seems like you've got plenty of software solutions, but I have my solution posted on **broken link removed** if you're interested. It's in C++, currently all it does is make various patterns flash on 8 leds hooked up to the port.
 
I'm sort of at the stage of considering to build it now.

I was thinking ... If I had 255 possible outputs (and 255 LEDs), I'd be able to turn on any LED I wanted, but not any combination of LEDs, so display a number or something if they were in a square formation.

Is there any way to be able to control say 100 LEDs and be able to output any combination of those 100 to display text and numbers? If it can't be done with the parallel port, is it possible to do it with the serial port and a decoder or a solution like that?

Thanks.

Jon
 
http://www.lvr.com/

Here is the link which help using almost port types. And if you wanna to control LTP in win XP, you have to boot PC in DOS, then rename DLLCACHE folder to backup_dllcache (for example). Finally, you copy .dll to SYSTEM32.

In win XP, this folder contents many .dll files which are used to back up dll files in system32. If you rename this folder, win XP cannot backup dll files. If you wanna make win XP normal, rename again it to dllcache, your windows will be clear as it used to be. Now, you can use almost languages to control LTP.

In this link they give a clear detail.

The problems usually come as we need to drive a robot with the simulator running. Then we should use visual languages. This link help muchie.

By the way, this link have many tutorials on port types.

Good luck
 
Sorry for the confusion there,

I'm wondering about the matrix LEDs, not programming the parallel port.

My question just kinda got mixed up in this topic =)
 
U may use the LTP with upto 12 outputs, a 74LS138 is a 8bit output decoder (3 inputs). As you have 3 74LS138, you need 3 * 3 bit to get 3*8 bits outputs. 3 bits output from LTP is used to select chip. With 24 bit outputs, you may control 12 x 12 matrix of leds.

Goodluck
 
If I have 24 outputs, then I would arrange it 12 outputs on one side and 12 on the bottom, similar to this:

X
X
X
X
X
XXXXXXX

X represents 2 outputs.

Then an LED would have one leg on the side set of outputs and one leg in the bottom set.

I'm assuming that's how you meant I should set it up. Did I understand that correctly? If not, how should I wire it up?

Also, with that setup - would I be able to display any combinations of lights in the 12x12 matrix?

Thanks.
 
No, this is the schematics of a 16x16 led. You may try to build it. You must use some transitors like this. Because, if you connect them directly, you cannot control all the matrix

1
2
3
_ A B C

If I connect the led like this picture matrix.jpg, and I want to set A1 off, so A: LOW and 1 LOW or A: HIGH, 1:HIGH

Then, if A: HIGH, I cannot set A2 LOW
if 1: LOW, I cannot set B1 HIGH

So, try it with the first picture.
 

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Hi all,

U will got probelm to access parallel port on Windows XP, WIN 2K, NT.

U can use the porttalk driver from www.beyondlogic.org or IOdll from www.geocities.com/bagtool/parallel_access.html to get access to parallel port.

free 8)
 
Great site free1 that beyond logic one had just what i was looking for a usb pdf.. thanks..
 
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