Re: [PARPORT] unsuccessfull try of the example. of the doc

From: Tim Waugh (twaugh@redhat.com)
Date: Thu Jul 12 2001 - 09:09:17 EDT

  • Next message: Frederic Corne: "Re: [PARPORT] unsuccessfull try of the example. of the doc"

    On Thu, Jul 12, 2001 at 02:25:24PM +0200, Frederic Corne wrote:

    > the target machine is always into the select() and the the client get always
    > 0 for status from ioctl (fd, PPRSTATUS, &status) ;
    >
    > ??? what is wrong ??

    The problem is that the example is very bad. :-(

    This is wrong:

          int ready = Busy | nAck | nFault;
          ioctl (fd, PPWCONTROL, &ready);

    because Busy, nAck and nFault are status lines, not control lines.
    The fact is that a PC isn't a printer, and its port is wired
    differently. On top of that, I think that interrupt latency on PCs
    kills any chance of being able to actually masquerade as a printer.

    I'll add a note that says not to take the printer-side example too
    literally.

    Are you actually aiming to get two machines to communicate via
    parallel port, or is that just practice to write a driver for a
    peripheral?

    Tim.
    */


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