Re: [PARPORT] port doesn't hold states

From: filip (
Date: Sun Apr 13 2003 - 06:29:46 EDT

  • Next message: Meles MELES: "Re: [PARPORT] continuous parport activity??"


    >> How I can not acknowledge?
    >The board you have connected to your parallel port connects the strobe and
    >acknowledge pins, which acknowledges data as soon as it is output. By
    >not having that connection, you wouldn\'t be acknowledging.

    I disconnected that pins, it didn't help.

    >> I checked, it works on some machines (generates square on pins - 0.5 Hz,
    >> 50%),
    >> but not on this one with main board:
    >What does it do on that one? Something or nothing?

    So, after Linux starts D7 is HIGH, D0 is LOW (I didn't check
    others pins), when I write 0x00 to port (using program I posted before),
    D7 changes to LOW for few ms (I can't measure exactly) and then
    returns to HIGH, D0 stay LOW.
    When I write 0xff D7 stay HIGH, D0 changes to HIGH for few ms,
    and then returns to LOW.
    If I write 0x00 then 0xff and repeat it with no delay pins are generating

    >Are you sure that there is no other program accessing the parallel port?
    >A printer spooler for example?

    I'm sure, I don't have a printer and I didn't install any printing software.

    I tried to use "short" - example driver form "Linux Device Drivers, 2nd Edition"
    By Alessandro Rubini & Jonathan Corbet. It initializes with no problems
    (first I removed ppdev and parport modules), and when I write to it (/dev/short0)
    the problem is the same.


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