NAME

       libieee1284 - IEEE1284 communications library

SYNOPSIS

               #include <ieee1284.h>
               cc files... -lieee1284

OVERVIEW

       The libieee1284 library is a library for accessing parallel port devices.

       The model presented to the user is fairly abstract: a list of parallel ports with arbitrary names, with
       functions to access them in various ways ranging from bit operations to block data transfer in one of the
       IEEE 1284 sanctioned protocols.

       Although the library resides in user space the speed penalty may not be as bad as you initially think,
       since the operating system may well provide assistance with block data transfer operations; in fact, the
       operating system may even use hardware assistance to get the job done. So, using libieee1284, ECP
       transfers using DMA are possible.

       The normal sequence of events will be that the application
        1.  calls ieee1284_find_ports to get a list of available ports
        2.  then ieee1284_get_deviceid to look for a device on each port that it is interested in
        3.  and then ieee1284_open to open each port it finds a device it can control on.
        4.  The list of ports returned from ieee1284_find_ports can now be disposed of using
           ieee1284_free_ports.
        5.  Then when it wants to control the device, it will call ieee1284_claim to prevent other drivers from
           using the port
        6.  then perhaps do some data transfers
        7.  and then ieee1284_release when it is finished that that particular command. This
           claim-control-release sequence will be repeated each time it wants to tell the device to do
           something.
        8.  Finally when the application is finished with the device it will call ieee1284_close.

       Usually a port needs to be claimed before it can be used. This is to prevent multiple drivers from
       trampling on each other if they both want to use the same port. The exception to this rule is the
       collection of IEEE 1284 Device IDs, which has an implicit open-claim-release-close sequence. The reason
       for this is that it may be possible to collect a Device ID from the operating system, without bothering
       the device with it.

CONFIGURATION

       When ieee1284_find_ports is first called, the library will look for a configuration file,
       /etc/ieee1284.conf.

       Comments begin with a '#' character and extend to the end of the line. Everything else is
       freely-formatted tokens. A non-quoted (or double-quoted) backslash character '\' preserves the literal
       value of the next character, and single and double quotes may be used for preserving white-space. Braces
       and equals signs are recognised as tokens, unless quoted or escaped.

       The only configuration instruction that is currently recognised is “disallow method ppdev”, for
       preventing the use of the Linux ppdev driver.

ENVIRONMENT

       You can enable debugging output from the library by setting the environment variable LIBIEEE1284_DEBUG to
       any value.

FILES

       /etc/ieee1284.conf
           Configuration file.

SEE ALSO

       parport(3), parport_list(3), ieee1284_find_ports(3), ieee1284_free_ports(3), ieee1284_get_deviceid(3),
       ieee1284_open(3), ieee1284_close(3), ieee1284_claim(3), ieee1284_release(3), ieee1284_data(3),
       ieee1284_status(3), ieee1284_control(3), ieee1284_negotiation(3), ieee1284_ecp_fwd_to_rev(3),
       ieee1284_transfer(3), ieee1284_get_irq_fd(3), ieee1284_set_timeout(3)

AUTHOR

       Tim Waugh <twaugh@redhat.com>
           Author.

COPYRIGHT

       Copyright © 2001-2003 Tim Waugh

                                                   09/18/2007                                     LIBIEEE1284(3)