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Parallel port control register problem

Hi, 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.

Reply to
zack
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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.

Reply to
Si Ballenger

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

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

donald

Reply to
Donald

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?

Reply to
The Real Andy

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

Reply to
zack

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