Discussion in 'General Electronics Chat' started by Jer446, Nov 4, 2006.

  1. Jer446

    Thread Starter New Member

    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!
  2. beenthere

    Retired Moderator

    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.
  3. Jer446

    Thread Starter New Member

    Nov 4, 2006
    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.
  4. BladeSabre

    Senior Member

    Aug 11, 2005
  5. Jer446

    Thread Starter New Member

    Nov 4, 2006
    there is so much information on controlling stepper motors, but i cannot find any on normal dc motors..
  6. kubeek


    Sep 20, 2005
    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.