Thread Starter


Joined Nov 4, 2006
Hello. I am in the process of making a new robot to play with. I want to be able to control my dc motors (windshield wipers) through the parallel port. I need to have some sort of graphical interface so i can control them easily, without editing code.
I am finishing up my h-bridges, which i assume i will need to source the motors. What other hardware do i need?
How could i do this? Can anyone give me an example to someone who has done something the same?
I am not good at all at programming, but am somehwhat sufficient with the electronics. Thanks!


Joined Apr 20, 2004

You may have a hard time. GUI's, like Windows, don't have low-level hardware level bit-twiddling enabled. You can't POKE or PEEK I/O addresses. Even with something like Visual Basic, you still have to write code to perform functions. VB with some in-line assembler to work with the parallel port might do the trick.

Your parallel port has basically the ability to output TTL-level voltages, but won't source/sink significant current. You will need at least one level of hardware to buffer the port outputs to the h-bridge.


Joined Sep 20, 2005
oh i know i will absolutely need some sort of hardware to drive my motors.. I have h-bridges made, and have been looking at this...
The only thing with that is i dont think i can control speed as well, and then i have no idea how to program it.
You can control the speed of a motor by pulse modulation, but probably not in both directions just with H-bridge.

With H-bridge you can only reverse the motor but you cannot disconnect the motor entirely, which you need to achieve pulse modulation - pulse reversing of the motor doesn´t seem to be the right solution.
You would need to make some kind of tri-state H-bridge which would be able to close one pair, leave all open, and close the second pair of transistors.

I was trying to accomplish something similar with delta connected stepper motor (three windings in triangle), but I never achieved the tri-state coding. I just made 8 half-bridges with LED state signalization controlled by the parallel port.