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Parallel port control register problem

Discussion in 'Electronic Design' started by zack, Mar 23, 2006.

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  1. zack

    zack Guest

    I need some advice and help. I have successfully done a parallel port
    interface circuit that consists of diodes and resistors. The LEDs
    represent the bits of CONTROL and DATA registers. everything else works
    fine except when i put values to the CONTROL registers. when i put `0'
    or `1' to any of the CONTROL register pins, all DATA LEDs will be on
    (but dimmer). checking back the DATA register value, it retains the
    previous value; didn't change to 255. I had to restart the program to
    reset the LEDs.
    i'm currently using Windows 2000, Visual C++ 6.0 on a Xeon platform. I
    don't think this is software issue, because I have tested the software
    and the circuit on a Pentium 3 platform. Does anyone have any opinion?
    Thank you very much.
  2. Si Ballenger

    Si Ballenger Guest

    Sounds like a software problem, as it fixes itself when you
    restart the program. Hardware usually "works the way it's wired"
    and doesn't change on its own.
  3. Donald

    Donald Guest

    That is correct, hardware will work the way its wired.

    Zack, check your wiring and post a schematic of the actual board.

  4. IF you are using win2000 i dont think you can write directly to the
    hardware. How are you doing this? Are you using DeviceIOControl() to
    write to the port?
  5. zack

    zack Guest

    finally i managed to get it done. it was not because of wiring or
    hardware issues. i went to -> right click `My Computer' -> click
    `Properties' -> `Hardware' tab -> click `Device Manager'. from there i
    clicked `Ports' -> double click `Printer Ports'
    there'll be a new window displaying the printer's properties. On `Ports
    Settings' tab i enabled `Enabled legacy Plug N Play detection' and the
    problem solved.
    I'm using Inpout32.dll library for Windows 2000
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