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<!-- Text ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<!-- Overview ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<A NAME="overview"></A><HR>
<CENTER><H1>Driver Model</H1></CENTER>
<HR WIDTH="70%">
<PRE>
| +------------------------------------------------------+
S | | 'gpm -t msc -m /dev/lircm' or a well configured X |
O | | (see section 'Configuring lircmd') for details |
F | +--------------+---------------------------------------+
T | |
W | /dev/lircm (named pipe (FIFO) ==> one connection)
A | |
R | +-----------+-----------+ +-------------------------------+
E | | mouse daemon (lircmd) | | tools (irexec, irxevent, ...) |
| | configured with | | configured with ~/.lircrc |
| | lircmd.conf | | |
| +-----------+-----------+ +-----------+-------------------+
| | |
| +-------------+-------------+
| |
| /dev/lircd (socket ==> multiple connections)
| |
S | +----------------+--------------------------+
O | | decoder daemon (lircd), irrecord or mode2 | TCP/IP
F | | lircd is configured through lircd.conf +--- port
T | User space | | 8765
W | +------------------+------------------------+
A | |
R | |
E | |
| |
| |
| |
+---------------------------------+----------------------------------
| Kernel space | (character device
| | driver ==>
| +------------+----------+ one connection)
| | |
| /dev/lirc /dev/ttySx
| | |
| +------------+-------------+ +-----+---------------+
| | LIRC device driver | | Linux serial driver |
| | (with ioctl-interface) | | |
| +------------+-------------+ +----------+----------+
| | |
--+--------------------+----------------------------+------------------
| | |
| +----------+------------+ |
| | | |
| +-------+----------------+ +----+-----+ +-------+-----------------+
H | | serial / parallel port | | TV cards | | Irman/RemoteMaster/etc. |
W | +------------------------+ +----------+ +-------------------------+
|
</PRE>
<A NAME="formats"></A><HR>
<H1 ALIGN="CENTER">Formats</H1>
<HR WIDTH="70%">
<UL>
<LI><B>/dev/lirc:</B><BR>
<P>
highly depends on the mode selected with ioctls:
</P>
<DL>
<DT>LIRC_MODE_MODE2</DT>
<DD>
<P>
outputs packets containing an int value describing a IR
signal
</P>
<UL>
<LI>bits 0-23 contain the length of the pulse/space in
microseconds</LI>
<LI>bit 24 is either 0, meaning space, or 1, meaning
pulse</LI>
<LI>all other bits are unused</LI>
</UL>
<P>
Lengths greater than or equal to 16 seconds are clamped to
0xffffff.
</P>
<P>References:</P>
<UL>
<LI>drivers/lirc_serial/lirc_serial.c</LI>
<LI>drivers/lirc_parallel/lirc_parallel.c</LI>
<LI>tools/mode2.c (dumps the output from the driver to
stdout)</LI>
</UL>
<BR>
</DD>
<DT>LIRC_MODE_CODE</DT>
<DD>
<P>
outputs chars (8 bits)
</P>
</DD>
<DT>LIRC_MODE_LIRCCODE</DT>
<DD>
<P>
outputs codes of configurable length in big endian byte
order
</P>
</DD>
</DL>
</LI>
<LI><B>/dev/lircd:</B><BR>
<P>
outputs strings containing all information about the remote and the
pressed button.
</P>
<P>References:</P>
<UL>
<LI>daemons/lircd.c</LI>
<LI>tools/irw.c</LI>
</UL>
<BR>
</LI>
<LI><B>/dev/lircm:</B><BR>
<BR>
<UL>
<LI>MouseSystems<BR>
5 byte packets:
<UL>
<LI>byte 1: button information</LI>
<LI>byte 2: change on X axis</LI>
<LI>byte 3: change on Y axis</LI>
<LI>byte 4,5: 0</LI>
</UL>
</LI>
<LI>IMPS/2<BR>
4 byte packets: check the source code for details
</LI>
<LI>IntelliMouse<BR>
4 byte packets: check the source code for details
</LI>
</UL>
<P>References:</P>
<UL>
<LI>daemons/lircmd.c</LI>
</UL>
</LI>
</UL>
<A NAME="lirc_dev"></A><HR>
<H1 ALIGN="CENTER">Writing TV card drivers using lirc_dev</H1>
<HR WIDTH="70%">
<P>
The <em>lirc_dev</em> module is a helper and abstraction layer
for other modules. It registers <em>/dev/lirc</em> device in a
system (including support for devfs) and waits for plugin
registration. After that it serves device requests (open, read,
poll, ioctl, close) and if needed calls callback functions from
plugin(s) to communicate with the physical device.
</P>
<P>
Plugins can be registered and unregistered many times. The
current implementation allows two concurrent plugins, but can be
easily changed by increasing the MAX_IRCTL_DEVICES
definition. It also allows receiving of scan codes, which have
more than 8 bits. Current limit for a scan code is 16*8 bits and
also can be changed by increasing the BUFLEN definition.
</P>
<P>
For an API description see <em>lirc_dev.h</em>. The lirc_gpio
module can be treated as examples of using this API.<br> This
code contains many lines with debug messages (activated by
<em>debug</em> option) and they will sustain until more tests
will be performed.
</P>
<P>
<B>Warning:</B> Due to the used kernel API it requires kernel
2.2.4 or higher.<br> Any suggestions and questions are
welcome. <A href="mailto:alipowski@interia.pl">Artur
Lipowski</A>
</P>
<!-- Writing LIRC Applications +++++++++++++++++++++++++++++++++++++++ -->
<A NAME="applications"></A><HR>
<H1 ALIGN="CENTER">Writing Applications for LIRC</H1>
<HR WIDTH="70%">
<P>
As LIRC is able to both receive and send IR commands there are
two possible types of applications. Programs that send IR
commands like <em>xrc</em> and <em>irsend</em> or programs that
receive commands like <em>irexec</em>, <em>irxevent</em> and
<em>irpty</em>. Both types of applications will have to connect
to the lircd daemon using the socket interface usually located
in /dev/lircd. Communication on the socket uses human readable
format. The end of a line is indicated by a newline character.
</P>
<P>
Whenever lircd receives a IR signal it will broadcast the
following string to each client:</P>
<PRE>
<code> <repeat count> <button name> <remote control name></PRE>
<P>
<em>code</em> is a 64-bit encoding (in hexadecimal
representation) of the IR signal. It's usage in applications is
deprecated and should be ignored. The <em>repeat count</em>
shows how long the user has been holding down a button. The
counter will start at 0 and increment each time a new IR signal
has been received. The <em>button name</em> and <em>remote
control name</em> are defined in the lircd config file. Their
purpose should be quite self-explanatory. They must not contain
any whitespace.<BR>
The only other situation when lircd broadcasts to all clients is
when it receives the SIGHUP signal and successfully re-reads its
config file. Then it will send a SIGHUP packet to its clients
indicating that its configuration might have changed. This
feature is <NOBR>e.g.</NOBR> used in <em>xrc</em> to rebuild the
list of supported remote controls each time lircd's
configuration changes. The format of the packet will be
explained later.
</P>
<P>
Applications that want to send out IR commands can use the
following commands:
</P>
<PRE>
SEND_ONCE <remote control name> <button name> [<repeat count>]
SEND_START <remote control name> <button name>
SEND_STOP <remote control name> <button name></PRE>
<P>
The SEND_ONCE directive tells lircd to send the IR signal
associated with the given remote control and button name, and then
repeat it <var>repeat count</var> times. <var>repeat count</var> is
a decimal number between 0 and 600. If <var>repeat count</var> is
not specified or is less than the minimum number of repeats allowed
for that remote control, then this minimum value will be used
instead. SEND_START tells lircd to start repeating the
given button until it receives a SEND_STOP command. As repeating
of IR signals is very CPU intensive on most systems there should
be a limit on the time for repeating buttons in every
application. The number of repeats is internally limited to 600
which for most remotes is equal to one minute of
repeating. lircd won't accept any new send commands while it is
repeating.
</P>
<P>
lircd also understands the following commands:
</P>
<PRE>
VERSION
LIST [<remote control name>]</PRE>
<P>
The response to the VERSION command will be a packet containing
lircd's version.<BR>
The LIST command without further arguments can be used to get a
list of all remote controls known to lircd. If a name of a
supported remote control is given as argument all buttons of the
given remote control are listed in the reply packet. Have a look
at <em>xrc</em> for an example how this can be used.
</P>
<P>
There still remains to explain the format of lircd's reply
packets. Here is a formal description of the packets:
</P>
<PRE>
BEGIN
<command>
[SUCCESS|ERROR]
[DATA
n
n lines of data]
END</PRE>
<P>
The protocol guarantees that broadcasted messages won't
interfere with reply packets. But broadcasts may appear at any
point between packets. <em>command</em> is the command lircd is
currently processing. Its an exact copy of the command the
client application has sent. The only exception are SIGHUP
packages where <em>command</em> is substituted with SIGHUP. Note
that SIGHUP packages may appear just after you have sent a
command to lircd, so you have to make sure you don't confuse
them with replies. SIGHUP packages come without any further data
while each reply to a command contains either SUCCESS or ERROR
indicating the result of processing the command. In case of an
error the following data is a message explaining the
problem. This message can be used to create an error message for
the user.<BR>
If the command was successful, data is only sent for the
commands that return some information. Note that a packet
containing 0 lines of data can be a valid reply.
</P>
<!-- Writing LIRC Applications +++++++++++++++++++++++++++++++++++++++ -->
<A NAME="library"></A><HR>
<H2 ALIGN="CENTER">The lirc_client library</H2>
<HR WIDTH="70%">
<P>
If you only want to make your application receive IR commands
and if you don't want to mess with all the protocol stuff you
can use the <em>lirc_client</em> library that comes with LIRC
since version 0.6.0. With the help of this library your program
can look as simple as this:
</P>
<PRE>
/* $Id: technical.html,v 1.28 2007/07/22 07:30:25 lirc Exp $ */
/****************************************************************************
** irexec.c ****************************************************************
****************************************************************************
*
* irexec - execute programs according to the pressed remote control buttons
*
* Copyright (C) 1998 Trent Piepho <xyzzy@u.washington.edu>
* Copyright (C) 1998 Christoph Bartelmus <lirc@bartelmus.de>
*
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <errno.h>
#include <unistd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lirc_client.h"
char *progname;
int main(int argc, char *argv[])
{
struct lirc_config *config;
progname=argv[0];
if(argc>2)
{
fprintf(stderr,"Usage: %s <config file>\n",progname);
exit(EXIT_FAILURE);
}
if(lirc_init("irexec",1)==-1) exit(EXIT_FAILURE);
if(lirc_readconfig(argc==2 ? argv[1]:NULL,&config,NULL)==0)
{
char *code;
char *c;
int ret;
while(lirc_nextcode(&code)==0)
{
if(code==NULL) continue;
while((ret=lirc_code2char(config,code,&c))==0 &&
c!=NULL)
{
#ifdef DEBUG
printf("Execing command \"%s\"\n",c);
#endif
system(c);
}
free(code);
if(ret==-1) break;
}
lirc_freeconfig(config);
}
lirc_deinit();
exit(EXIT_SUCCESS);
}</PRE>
<P>
Before anything else you have to include the header file for the
lirc_client library. This is done with
</P>
<PRE>
#include <lirc/lirc_client.h></PRE>
<P>
Note that our example differs in this point because it was taken
directly from the lirc-0.6.0 source that comes with its own
<em>lirc_client.h</em> but we have to use the one that is
already installed on the system.
</P>
<P>
The next step is to initialize the library code with
<em>lirc_init()</em>. This function connects to lircd and does
some internal init stuff.
</P>
<PRE>
int lirc_init(char *prog,int verbose);</PRE>
<P>
The first argument to this function is the string users will
have to provide as <em>prog</em> token in their .lircrc config
files. If the second argument is non-zero error messages will be
printed to <em>stderr</em>. Otherwise no error messages will
ever be displayed. This function returns the file descriptor of
the socket that is connected to lircd or -1 if an error
occurred.
</P>
<P>
The example continues by reading a config file. This is done by
the <em>lirc_readconfig()</em> function:
</P>
<PRE>
int lirc_readconfig(char *file,struct lirc_config **config,
int (check)(char *s));</PRE>
<P>
If you want to load the default config file you should pass NULL
as first argument. If you want to load some other config file
the <em>file</em> argument should contain the complete path to
the file. Your program should give the user the possibility to
use an other than the default config file. You should also be
able to load multiple config files by calling this function
several times.<BR>
The <em>config</em> argument is used to pass the pointer to the
config file data structures back to your application. You will
need it for calls to the <em>lirc_code2char()</em> function. The
last argument is a call-back function that can be used to do
syntax checks with the config strings. The library code will
call the call-back function for all config strings where the
<em>prog</em> token in the config file matches the prog string
you provided with the <em>lirc_init()</em> function. If there is
an error in the config string the call-back function should
return -1, otherwise 0. If you don't need to do any syntax
checks you can pass NULL here. The function returns -1 if an
error occurred, 0 otherwise.
</P>
<P>
The <em>lirc_nextcode()</em> function blocks until there is
something available on the lircd socket. This way it can be used
in the main loop of your program like in our example.
</P>
<PRE>
int lirc_nextcode(char **code);</PRE>
<P>
If an error occurs (usually this means that the socket has been
closed by the daemon) this function returns -1. Otherwise it
returns 0 and <em>code</em> points to the next string available
in the data stream. This string has to be freed by your
application using the <em>free(3)</em> function. If no complete
string is available <em>code</em> will be NULL.<BR>
If you use some GUI-toolkit for your program then you probably
won't be able to use this function in your program's main loop
because this is already handled by the GUI-toolkit. In this
situation you should use the call-back abilities of the toolkit
that will notify you whenever there is some input available from
a file descriptor (you get the file descriptor from the
<em>lirc_init()</em> function). E.g. you can use the
<em>gdk_input_add()</em>/<em>gdk_input_remove</em>() functions
with gtk or the <em>QSocketNotifier</em> class with Qt. If you
don't have such functionality in your toolkit or can't use it
for some reason you can still use SIGIO signals for this
purpose. Check the documentation for your GUI-toolkit and
signal(2) for further information.<BR>
Please note that using call-backs you still have to use some
kind of while loop to read strings from the socket because
several strings may be available in the data stream and you will
only get a notification for the first one. This poses a problem
for us because <em>lirc_nextcode()</em> blocks until there is
something available from the socket which is not what we need
here. You can solve this problem by setting the
<b>O_NONBLOCK</b> flag for the socket using the
<em>fcntl(2)</em> function. Have a look at the current xirw code
that is available from the LIRC homepage for an implementation
example.
</P>
<P>
To get the config string that the user has provided in the
config file in response to a button press you use the following
function:
</P>
<PRE>
int lirc_code2char(struct lirc_config *config,char *code,char **string);</PRE>
<P>
<em>config</em> is a pointer to the config file data structure
that you can get with <em>lirc_readconfig()</em> and
<em>code</em> is the code transmitted to your application on the
lircd socket. If an action should be taken <em>string</em> will
point to the config string the user has provided in the config
file. The user might want to take several actions on a button
press so you have to execute this function until <em>string</em>
is NULL, which means that no more actions shall be taken, or an
error occurs. The function returns -1 if an error occurred, 0
otherwise.
</P>
<P>
In our example there are only two clean-up functions to be
explained.
</P>
<PRE>
void lirc_freeconfig(struct lirc_config *config);</PRE>
<P>
This functions frees the data structures associated with
<em>config</em>.
</P>
<PRE>
int lirc_deinit();</PRE>
<P>
<em>lirc_deinit()</em> closes the connection to lircd and does
some internal clean-up stuff.
</P>
<P>
I encourage you to use autoconf and automake for your
projects. To check for the lirc_client library all you have to
insert into your <em>configure.ac</em> (or <em>configure.in</em>)
file is the following:
</P>
<PRE>
dnl Check for LIRC client support
dnl This really is not worth making a separate file for it.
have_lirc=yes
AC_REQUIRE_CPP
AC_CHECK_LIB(lirc_client,lirc_init,
AC_CHECK_HEADER(lirc/lirc_client.h,true,have_lirc=no),have_lirc=no)
if test "$have_lirc" = "yes"; then
dnl AC_DEFINE(HAVE_LIRC);
true;
else
AC_MSG_ERROR([*** LIRC client support not available ***]);
fi</PRE>
<P>
There is also a more complex m4 macro in the contrib directory
of the current LIRC distribution if you plan to add LIRC support
to your application without using the lirc_client library.
</P>
<P>
While developing LIRC applications you might find a <A
HREF="http://www.fi.muni.cz/~xkutale1/en/lircemu/">emulator</A>
for lircd useful. With this emulator you don't need a remote
control to generate LIRC events. That way you can develop LIRC
applications even if you don't have a LIRC compatible device
yourself.
</P>
<A NAME="lircrcd"></A><HR>
<H1 ALIGN="CENTER">lircrcd protocol</H1>
<HR WIDTH="70%">
<P>
lircrcd syntactically uses the same protocol as lircd described
in the last section. It supports the following commands:
</P>
<DL>
<DT>IDENT <em>ident</em></DT>
<DD>
<P>
Each program connecting to lircrcd identifies itself using
this program. <em>ident</em> is the string that is used in
the prog token inside the .lircrc file.
</P>
</DD>
<DT>CODE <em>code</em></DT>
<DD>
<P>
When the client receives the <em>code</em> string from lircd
it will send it to lircrcd and will receive back the
applicable config string from the .lircrc config file. It
should resend the CODE command until nothing is returned
back which means that nothing (more) should happen in
response to <em>code</em>. This command is used each time
the lirc_code2char() function is called by a client.
</P>
</DD>
<DT>GETMODE</DT>
<DD>
<P>
lircrcd will return the current mode string.
</P>
</DD>
</DL>
<A NAME="packagers"></A><HR>
<H1 ALIGN="CENTER">Note for packagers</H1>
<HR WIDTH="70%">
<P>
If you want to make a binary package for lirc (.deb, .rpm, ...),
there are a couple of goodies you can take advantage of:
<dl>
<dt>--with-driver=all
<dd>
Builds support for as many devices as possible into a single
lircd binary.
</dd>
<dt>--with-driver=userspace
<dd>
The same as the all driver, but no kernel modules will be
built.
</dd>
<dt>--enable-sandboxed
<dd>
Prevents any changes out of the installation directory on "make
install":
<ul>
<li>will not create device nodes on /dev/</li>
<li>will not run depmod</li>
</ul>
</dd>
<dt>DESTDIR
<dd>
You should use <em>DESTDIR</em> and not <em>prefix</em> to install
into the sandbox, modules will be installed to <em>/lib/</em>
otherwise.
</dd>
<br>Finally, you should consider installing the doc/lirc.hwdb file.
This one is a parseable list of LIRC supported devices, which
is useful for LIRC configuration applications.<br>
For more information, refer to the next section.
</dl>
</P>
<A NAME="config"></A><HR>
<H1 ALIGN="CENTER">Note for configuration application developers</H1>
<HR WIDTH="70%">
<P>
If you want to make a configuration application, lirc provides
a parseable list of LIRC supported devices.<br>
<br>
This file is generated at compilation time, along with its <a href="table.html">HTML
equivalent</a> and is available as doc/lirc.hwdb in the source tree.
It should also be installed by the binary packages of your prefered
distribution (bug report otherwise!).
<br><br>
The format is:
<br>
[remote controls type]<br>
description;driver;lirc driver;HW_DEFAULT;lircd_conf;<br>
</P>
<A NAME="bugs"></A><HR>
<H1 ALIGN="CENTER">Known bugs</H1>
<HR WIDTH="70%">
<UL>
<LI>
<P>
If you use the <em>lirc_serial</em> or
<em>lirc_parallel</em> driver regularly to transmit
infra-red signals you might notice that your system clock
will slow down. During transmit the driver turns off
interrupts and hence some clock interrupts might get lost
causing system clock inaccuracy. Unfortunately in order to
ensure a good signal timing interrupts have to be
disabled. Currently no work-around is known for this problem
except using a program like <em>netdate</em> to synchronize
your system clock regularly.
</P>
</LI>
<LI>
<P>
The <em>lirc_serial</em> and <em>lirc_parallel</em> drivers
measure the time between interrupts on the serial resp.
parallel port to get a pulse and space representation of the
incoming infra-red signal. If interrupts are disabled by the
CPU for a rather long time (>100 µs, which happens
often e.g. during heavy IDE disk activity) some interrupts
might get lost and the incoming data stream becomes
disturbed. In this case decoding of the infra-red signal
will fail. This is the downside of the really simple
receiver circuits and can't be addressed in software except
keeping the time where interrupts are disabled to a minimum.
</P>
<P>
If you are using an IDE system you might want to try calling
<em>hdparm -u1 -d1</em> for all of your drives. This enables
DMA for the drive and allows the driver to unmask other
interrupts during handling of a disk interrupt. But be aware
that this can be dangerous for some (buggy) IDE
chipsets. Consult the hdparm man page for further
information.
</P>
</LI>
</UL>
<!-- +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<BR><BR>
<CENTER>[<A HREF="http://www.lirc.org/">LIRC homepage</A>]<BR>
<I>The LIRC Manual, last update: 17-Jan-2007</I></CENTER>
<BR><BR>
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distrib
>
Mandriva
>
2008.1
>
x86_64
>
media
>
main-testing
>
by-pkgid
>
69ad6d1b8ee1e33fb9804f7479b72e2f
>
files
>
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