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Even PCs understand infrared-signals by now. Many newer laptops/notebooks have their own IR-Port which enables them to transfer data to another device (cellular phone, printers, etc.) or even to another laptop.
Some TV-Tuner-Cards are sold with an IR-remote, too. Mostly you have to pay more (sometimes a LOT more) for this comfy add-on.

As the typical Linux-User is thrifty and likes some manual work it is not suprising that you find software and hardware solutions for DIY on the internet.
After all you probably own too many remote controls lying at home. Connected to a computer you could define the function keys, too.

Change to the next MP3-song, adjust the volume or even change the station in kwintv just with your fingertip? No problem! The usability is - as usual - infinite. But you can't just start programs, you can also simulate mouse-events with your remote control for using it with your browser. ("Browse at your fingertips" ;) )
More useful would a remote control be for presentations: Change the slide beamed on the wall by a beamer connected to a laptop with your remote control. The audience would be amazed...

Drivers for using a remote control with a linux-computer have existed for a longer time now, so it is not suprising that many multimedia programs support remote controls. Those programs provide special commands which can be interpreted and be done while the user mustn't care about details.

compiling some hardware

Before you can use the remote control you'll need an infrared-receiver.
You can buy one, which is connected to the serial port, but you will have to pay a fortune (mostly 35 EUR and more) and they won't work better than the DIY-version which costs about 8 EUR.

Furthermore those products are sold with windows-software (if ever) and why should you pay for that?

The used parts are neither exotic nor expensive so you should find them at the most-chaotic supplier. In case of emergency: You can order these devices at "Conrad Electronic". You find the article-IDs in the table below.

If you're a bit skilled it should be peanuts putting those parts together as shown on the circuit-plan, even for unexperienced Amateurs. Although only 3 pins of the serial port connector are used it is suggested to buy a serial cable (with 9 pins) and cut it in the middle. But remember: Use a cable-tester to find out which cable belongs to which pin. Don't use them randomly ;) .
The pins are usually numbered on the connector-side. As a matter of fact, not everybody (mostly the vendors) knows about that... :( .

The used pins of the jack are

The receiver circuit looks like this:

( download EPS-File )

and should look like this when assembled:

The assembled circuit can be very compact, depending on your technical knowledge. It is recommend to put the plate in a small case, but don't forget a hole for the receiver-module. You can also make it an "integrated" device by putting it inside your computer.

The receiver shown on the LIRC-Homepage is very compact. The receiver itself takes place in a serial plug.

Software installation

As soon as the receiver is completed you surely want to know whether it works. At first you need to install the needed software which can be found on the Homepage of the LIRC Project (Linux Infrared Remote Control) on http://www.lirc.org. The current version is 0.6.3. In case of problems it could be useful to use the newest CVS-version or (in case you don't know how to use CVS) the latest snapshot (can be found at http://www.lirc.org/software/snapshots/).

After unpacking into the /tmp-directory

  >> tar zxvf lirc-0.6.3.tar.gz -C /tmp
  

  >> cd /tmp/lirc-0.6.3
  >> ./configure
  

With the first menu-item - called "driver configuration" - you can configure (who thought THAT?) what kind of IR-receiver you are using. As for our DIY-type the type "Home-brew..." should do ;) Following this hard decision you have to choose the serial port and the interrupt the receiver can be found at. Now LIRC wants to know whether we want to send IR-signals. As we have no IR transmitter diode in our circuit the point "With transmitter diode" remains blank. The 2nd item "Software generated carrier" can be left activated.

After that we will (hopefully) be back in the main menu for taking care of point 2 called "Software configuration". Because we want to control X-Applications with our remote control the option "Compile tools for X-Windows" has to be activated. All other options should be blank.

And here we are again: back in the main menu. This time we choose "Save configuration & run configure" which is the 3rd item in the menu.

When the configure-script finished without error mesages (you maybe get a warning saying the serial ports are not implemented as module but directly compiled into the kernel) you can start compiling the software:

  >> make
  

  >> su 
  [password]
  >> make install
  

Lirc uses its own device to communicate with the hardware. Depending on the distribution this file (/dev/lirc) may already exist, otherwise you have to create it (as root) yourself:

  >> mknod /dev/lirc c 60 0
  

After all this work you can test your receiver. The easiest way to do this is using xmode2 under X which should be found in lirc's tools-direcory.

  >> xmode2
  

If there are some peaks which do not come from your remote control these are mostly peaks caused by the normal light in your room.

Hint: Try all remote controls you can find in your house and you will see how many different kinds of signals (correct: protocols) exist.

learning sessions

Though there are many different remote controls, no software knows them all. Some configuration files for different kinds of remote controls can be found on the LIRC Website http://www.lirc.org/remotes/, But it's a lottery as to whether your one is listed there or not.
Because of this LIRC comes with its own program to create configuration files for your remote control(s). The program you need is irrecord and is located in lirc's daemons subdirectory. You have to create a configuration file for every remote control you want to use with lirc. According to the programs license you have to mail your configuration file to the program author to enable him to increase the number of supported remote controls.

To avoid errors by other light than the IR signals the author of irrecord supposes to do the learning process in a dark room.

The program is started using:

  >> irrecord /tmp/remote1.config
  

The next step is to give every key a name (without blanks). This name is used for referencing in the configuration file we're going to create later. After naming the key has to be pressed several times.

After all keys have been named you can quit the program simply by pressing the "Enter"-key without entering a name first.
Our created configuration file can be found at /tmp/remote1.config and should be copied to /usr/local/etc/lircd.conf.

  >> cat config1 config2 >config
  

  [...]
        begin codes
            Volume_down              0x000000000000601F
            Volume_up                0x000000000000205F
            Audio_Mute               0x000000000000502F
            Class                    0x0000000000002956
            Tuner_Next               0x000000000000007F
            Tuner_Prev               0x000000000000403F
            CD_Next                  0x0000000000005C23
            CD_Prev                  0x0000000000003C43
            CD_Stop                  0x0000000000001C63
            CD_Disc                  0x0000000000001D62
            CD_Pause                 0x0000000000007C03
            CD_Play                  0x0000000000006C13
            DeckA_Rew                0x000000000000255A
            DeckA_Forw               0x000000000000453A
            DeckA_Stop               0x0000000000005926
            DeckA_Rec                0x000000000000057A
            DeckA_Play               0x0000000000003946
            DeckA_PlayRev            0x0000000000007906
            DeckB_Play               0x000000000000542B
            DeckB_PlayRev            0x000000000000344B
            DeckB_Stop               0x000000000000641B
            DeckB_Rec                0x0000000000000C73
            DeckB_Forw               0x0000000000004C33
            DeckB_Rev                0x0000000000002C53
            Phono                    0x0000000000002857
            CD                       0x0000000000004837
            Tuner                    0x0000000000006817
            Tape1                    0x0000000000000877
            Tape2                    0x000000000000700F
            Sleep                    0x0000000000005D22
            Power                    0x000000000000106F
        end codes
  
  end remote
  

Configuration

Naming and announcing of one (or more) remote control(s) is being done system-wide by our just created, brand new configuration file /usr/local/etc/lircd.conf. The configuration which key should do which command can be done for each user seperately (or easier: they can do it by themselfes). To do so, a file named .lircrc has to be created in the user's home directory. Here is an example what a ~/.lircrc-file could look like (The key names can be different with you):

  begin
    	prog   = irexec	
    	button = CD
    	config = xmms & 
          mode   = xmms	
  end
  
  begin
    	prog   = irexec	
    	button = Sleep
    	config = xterm & 
  end
  
  

Finally some more programs must be run:
At first the lircd daemon has to be started (located in the lirc-0.6.3/daemons/lircd subdirectory). This has to be done as root user.

  >> ./lircs -c
  

Fine Tuning

The most important programs to be controlled by a remote control would be MP3-player and tv-applications.
As for xmms a plugin for using remote controls is available at http://sourceforge.net/project/showfiles.php?group_id=5444"

After compiling the created libraries have to be copied from the .libs directoy either to xmms's global plugin-directory or to the local plugin-directory (~/.xmms/Plugins). After restarting xmms the new plugin can be activated in the preferences-menu:

XMMS now understands the following commands which can be used directly in the LIRC-configuration file

      PLAY                            ONE
      STOP                            TWO
      PAUSE                           THREE
      PLAYPAUSE                       FOUR
      NEXT [<tracks>]                 FIVE
      PREV [<tracks>]                 SIX
      SHUFFLE                         SEVEN
      REPEAT                          EIGHT
      FWD [<sec>]                     NINE
      BWD [<sec>]                     ZERO
      VOL_UP [<percent>]              SETPOS
      VOL_DOWN [<percent>]            QUIT
      BAL_LEFT [<percent>]            LIST
      BAL_RIGHT [<percent>]           SELECT <chars>
      BAL_CENTER         		    PLAYLIST_CLEAR             
      PLAYLIST_ADD <file>
  

Xawtv supports IR-remotes (as of newer versions) by itself and does not need any plugins. The newest xawtv version can be found at http://bytesex.org/xawtv/.
The commands to be used with xawtv are the same which the program xawtv-remote (comes with xawtv) can send to a running xawtv. The command which are interesting regardig the use of a remote control are:

  setstation [ <name> | <nr> | next | prev | back ]
  setchannel [ <name> | next | prev ]
  setinput [ <input> | next ]
  capture [ on | off | overlay | grabdisplay ]
  volume [ inc | dec | mute | <n> ]
  snap [ jpeg | ppm ] [ full | win | widthxheight ] <filename> ]
  movie file <filename> | start | stop
  fullscreen
  msg text
  quit   
  keypad n
  

Further informations can be found on the xawtv-remote manpage.

A ~/.lircrc-file could e.g. look ike this (partly published):

  begin
    	prog   = irexec	
    	button = CD
    	config = xmms & 
          mode   = xmms	
          flags = once
  
  end
  
  begin
    	prog   = irexec	
    	button = Tuner
    	config = xawtv  & 
          mode   = xawtv	
          flags = once
  end
  
  begin
    	prog   = irexec	
    	button = Sleep
    	config = xlock & 
  end
  
  
  begin xmms
    begin
      prog = xmms
      button = CD_Play
      config = PLAY
    end
    begin
      prog = xmms
      button = CD_Pause
      config = PAUSE
    end
    begin
      prog = xmms
      button = CD_Stop
      config = STOP
    end
  [...]
  end xmms
  
  begin xawtv
    begin
            prog   = xawtv
            button = DeckA_Play
            config = setstation next
    end
    begin
  	prog   = xawtv
  	button = DeckA_PlayRev
  	config = setstation prev
    end
    begin
  	prog   = xawtv
  	button = DeckA_Rec
  	config = fullscreen toggle
    end
  [..]
  end xawtv
  

Every remote control has at least one key less than needed. LIRC gives you the possibility to use more than one key at a time. The entry

          mode   = xmms	
  

  begin xmms
   [... define keys here ...]
  end xmms
  

start automatically

For starting the daemon automatically the use of an init-script is - as usual - suggested. Some samples for init-scripts are provided in the contrib subdirectory but though these files are not only depending on the distribution as also depending on versions we suggest to copy a existing init-file of your distribution and modify it.

This init-script effects that the lirc-daemon is beeing started during every booting. Aditionally the users have to start the irxevent and irexec --daemon which execute the commands assigned to the remote control keys. This is usually be done by th lircs script located in the contrib subdirectory.

This script should not be executed as root but as user who owns a .lircrc file in his homedirectory.
whether the command

  lircs -c
  

Placing the command in the init-file you have to execute it without root-rights using the

  su nonrootuser -c "umask 022; /path/to/lircs -c"
  

Otherwise the command lircs -c has simply to be added to the user's ~/.xinitrc file to start it when the GUI starts.

The creation of X-events like mouselicks using LIRC is more difficult and will be theme of a LIRC-report in the 7th issue of the Linux NetMag

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