Re: [PARPORT] reading/writing to the parallel port

From: Charles Lepple (
Date: Mon Nov 04 2002 - 08:12:36 EST

  • Next message: Stuart Powell: "[PARPORT] PCMCIA Adapter + Backpack CD-ROM"

    On Monday, November 4, 2002, at 02:15 AM, Tou Nou Thao wrote:

    > This is my first time using Linux as I am trying to get my program to
    > run on the parallel port. I'm writing to the parallel port using outb
    > but I get a seg fault.

    try libieee1284:

    > I have read/write access but I'm not the root user

    If you're using outb, device file permissions don't matter. In order to
    use port I/O with inb/outb and friends, you need to be root. You also
    need to enable access to those particular ports with ioperm(), or you
    can just raise the I/O privilege level with iopl() (which is less
    desirable, since it doesn't catch accesses to ports other than the
    requested port range like ioperm).

    if you use /dev/parport*, then you can set up permissions so that a
    non-root user can access the parallel port.

    > . Can someone direct me to an archive (I'm sure this has been
    > discussed) or a website? Thanks a lot.

    you probably want to use libieee1284 or a similar abstraction library,
    as many of these problems have been addressed already.

    Charles Lepple <>

    -- To unsubscribe, send mail to: -- -- with the single word "unsubscribe" in the body of the message. --

    This archive was generated by hypermail 2b29 : Mon Nov 04 2002 - 08:17:18 EST