libieee1284 - IEEE1284 communications library
cc files... -lieee1284
The libieee1284 library is a library for accessing parallel port
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
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
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
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
You can enable debugging output from the library by setting the
environment variable LIBIEEE1284_DEBUG to any value.
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_transfer(3), ieee1284_get_irq_fd(3), ieee1284_set_timeout(3)
Tim Waugh <firstname.lastname@example.org>
Copyright © 2001-2003 Tim Waugh