[PARPORT] Reading individual data pins from user-space application?

From: Jan Prikryl (prikryl@vrvis.at)
Date: Wed Jul 26 2000 - 13:16:05 EDT

  • Next message: Jeremy Elson: "Re: [PARPORT] Reading individual data pins from user-space application?"


    after getting the userland parport driver to work (thanks Tim) I have
    another problem:

    I have a very simple pen-like device with three microswitches
    grounding pins D0 - D2 to the ground data od the port. Allowing access
    to "/dev/port" for normal users I am able to switch the port to
    data-input mode and read whether pins D0 - D2 are grounded or not. I
    thought the safer way of reading the parallel port would be possible
    using the userland driver ioctl() calls, but I do not get any
    meaninful input from the port either using read() on port that has
    been set to input mode, or using ioctl(PPRDATA).

    The sequence is ioctls after opening the port for reading/writing that
    I have tried was

            PPSETMODE to IEEE1284_MODE_ECP
            PPDATADIR to 1
            PPRDATA (or read() one byte)

    Am I doing something wrong or is this task something that ppdev has
    not been designed for?

    -- jan

     Jan Prikryl | vr|vis center for virtual reality and visualisation
     <prikryl@vrvis.at> | http://www.vrvis.at

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