LIRC

Related articles
LIRC/Quick start guide
From the
official website
:
LIRC
(Linux Infrared Remote Control) is a package that decodes and sends infra-red signals of many (but not all) commonly used remote controls.
Note
Since 4.18 the kernel can decode the signals of some IR remote controls using BPF, making LIRC sometimes redundant.
[1]
This article covers setup and usage of LIRC with serial or USB infrared devices.
LIRC is a daemon that can translate key presses on a supported remote into program specific commands. In this context, the term, "program specific" means that a key press can do different things depending on which program is running and taking commands from LIRC.
A button on the remote is pressed causing it to transmit an IR or RF signal.
The signal is received by the receiver connected to the Linux computer.
The kernel (via the correct module) use presents pulse data from the remote on a device like
/dev/lirc0
,
/dev/input/eventX
,
/dev/ttyUSBX
or
/dev/ttyS0
.
/usr/bin/lircd
uses the information from
/etc/lirc/lircd.conf.d/foo.conf
to convert the pulse data into button press information.
Programs that use LIRC translate the button press info from
/usr/bin/lircd
into user-defined actions according to
~/.config/lircrc
or to program-specific mappings.
Installation
Install
the
lirc
package.
Configuration
Receiver and transmitter configuration
Note
This section is a quick summary. Complete documentation is available
upstream
.
The
driver
and/or the
device
for the LIRC service may need to be specified in order to run properly. Look for messages like these in the
journalctl
output if the service abruptly stops while running LIRC-dependent programs such as
irrecord
:
Driver `devinput' not found or not loadable (wrong or missing -U/--plugindir?).
readlink() failed for "auto": No such file or directory
Set these in the configuration file and then restart the service.
/etc/lirc/lirc_options.conf
[lircd]
driver =
driver-name
device = /dev/
path-to-dev
Serial port
Tip
For DIY schematic refer to serial port
receivers
and
transmitters
documentation. Note that serial port device much more reliable than
audio_alsa
or
audio
.
Modern kernel has
serial_ir
module, which supersedes older
lirc_serial
driver. It supports even DIY receivers and transmitters, connected to the motherboard's serial port. Install
setserial
AUR
and run:
# setserial /dev/ttyS0 uart none
# modprobe serial_ir
After loading
serial_ir
module, device
/dev/lirc0
will be
created
by kernel. If not, check the
journal
for any relevant errors. An LIRC configuration example for serial device:
/etc/lirc/lirc_options.conf
[lircd]
driver          = default
device          = auto

[modinit]
code = /usr/bin/setserial /dev/ttyS0 uart none
code1 = /usr/sbin/modprobe serial_ir
Sound card
Note
Using sound card as infrared device has plenty pitfalls and does not gives advantage over other hardware setup.
Sound card with connected external DIY circuits can be used to
receive
and
transmit
IR codes.
audio_alsa
driver
included in
lirc
, but supports only reception.
Unmute microphone input with
alsamixer
and set enough gain. You can check waveform and gain with
audacity
. There should be distinguishable square pulses: not flatlined, nor overloaded. Also good demodulated pulses easily perceptible by ear. Note that LIRC and
irrecord
reads
positive pulses in right audio channel
. Negative pulses will not work.
/etc/lirc/lirc_options.conf
driver          = audio_alsa
device          = default
audio
driver
included in
lirc-git
AUR
and supports both reception and transmission. Note, that default latency around 0.02 can cause "Warning: Output underflow" and corrupted transmission - receiver will not respond to it. Try a higher value like 0.05.
Increase sound card output loudness, otherwise LED signal will be weak and range is low. LED flash can be detected with smartphone camera, as it sensitive to infrared wavelengths.
/etc/lirc/lirc_options.conf
driver          = audio
device          = ALSA:default@48000:0.05
Remote configuration
Directory
/etc/lirc/lircd.conf.d/
contains system-wide configuration files for remotes. Each
*.conf
file corresponds to one device and describes its protocol, scancodes and keycodes. It allows LIRC receive and send signals for specific hardware. These files are not included in
lirc
package and should be found somewhere or created by user.
Searching for remote configuration
Plenty of configuration files can be found in the
LIRC remotes database
. Follow the url or use
irdb-get(1)
to search the database.
An example using
irdb-get
to find a configuration file for a "Streamzap" remote:
$ irdb-get find stream
atiusb/atiusb.lircd.conf
digital_stream/DTX9900.lircd.conf
snapstream/Firefly-Mini.lircd.conf
streamzap/PC_Remote.lircd.conf
streamzap/streamzap.lircd.conf
x10/atiusb.lircd.conf
$ irdb-get download streamzap/streamzap.lircd.conf
Downloaded sourceforge.net/p/lirc-remotes/code/ci/master/tree/remotes/streamzap/streamzap.lircd.conf as streamzap.lircd.conf
Once identified, copy the needed
.conf
to
/etc/lirc/lircd.conf.d/
to allow the daemon to initialize support for it.
# cp streamzap.lircd.conf /etc/lirc/lircd.conf.d/
Creating remote configuration
Remote control configurations can be created using
irrecord(1)
, which guides users trough the process. If using a detected remote, invoke it like so:
# irrecord --device=/dev/lirc0 MyRemote
The program will instruct user to begin hitting keys on the remote in an attempt to learn it, ultimately mapping out every button and its corresponding scancode. When finished, save the resulting file to
/etc/lirc/lircd.conf.d/foo.conf
and proceed. Consider sharing configuration file with others.
Application-specific actions
Tip
Many application-specific lircrc files are available on the internet.
Bind keycodes to application-specific actions by placing their respective configuration files in
~/.config/lircrc/
which should be created manually if desired, see
lircrc(5)
.  This only works for LIRC-aware applications, like
MPlayer
,
VLC
,
MythTV
and
totem
(
Kodi
also supports LIRC but does so in a non-standard way, see
Kodi#Using a remote control
).
Define these application-specific configurations in separate files and include them in
lircrc
, like:
include "~/.config/lircrc/mplayer"
include "~/.config/lircrc/mythtv"
include "~/.config/lircrc/vlc"
Running as a regular user
By default,
lircd
runs as root.  For increased stability and security, upstream recommends running it as a regular user.  See Appendix 14 at
this
link.
User the AUR package for lirc-user-service
lirc-user-service
AUR
is offered which does everything automatically.
Testing
Start/enable
lircd.service
.
Receiving commands
Run
irw(1)
, point remote to the receiver and press some buttons. Received codes will be printed to stdout.
$ irw
000000037ff07bfe 00 One mceusb
000000037ff07bfd 00 Two mceusb
000000037ff07bfd 01 Two mceusb
000000037ff07bf2 00 Home mceusb
000000037ff07bf2 01 Home mceusb
If
irw
gives no output:
Run
mode2
or
xmode2
to see if LIRC actually read something from IR sensor, if no - check the hardware
If
mode2
receives pulse data, check the configuration files in
/etc/lirc/lircd.conf.d/
for errors
Transmitting commands
List registered remotes (configuration files):
$ irsend LIST "" ""
LG_6710CMAP01A
List available codes for the specific device:
$ irsend LIST LG_6710CMAP01A ""
0000000000007887 KEY_POWER
000000000000f807 KEY_MUTE
000000000000e817 KEY_VOLUMEUP
...
Choose discovered device
LG_6710CMAP01A
and send command
KEY_POWER
:
$ irsend SEND_ONCE LG_6710CMAP01A KEY_POWER
Troubleshooting
Remote functions as a keyboard
When using Xorg
Xorg
detects some remotes, such as the Streamzap USB PC Remote, as a Human Interface Device (HID) which means some or all of the keys will show up as key strokes as if entered from the physical keyboard. This behavior will present problems if LIRC is to be used to manage the device.
To disable, create the following file and restart X:
/etc/X11/xorg.conf.d/90-streamzap.conf
Section "InputClass"
  Identifier "Ignore Streamzap IR"
  MatchProduct "Streamzap"
  MatchIsKeyboard "true"
  Option "Ignore" "true"
EndSection
Do not forget to alter the
MatchProduct
property according to one shown in
Name
from output of
$ grep -e IR /proc/bus/input/devices
For example
WinFast
for
N: Name="cx88 IR (WinFast DTV2000 H rev."
Not using Xorg
Blacklist the offending modules by creating
/etc/modprobed.d/streamzap.conf
to suppress this behavior. An example is provided for the Streamzap remote.
install ir_sharp_decoder /bin/false
install ir_xmp_decoder /bin/false
install ir_rc5_decoder /bin/false
install ir_nec_decoder /bin/false
install ir_sony_decoder /bin/false
install ir_mce_kbd_decoder /bin/false
install ir_jvc_decoder /bin/false
install ir_rc6_decoder /bin/false
install ir_sanyo_decoder /bin/false
Changing default configuration
Users not getting any output from
irw
may have the default configuration in
/etc/lirc/lirc_options.conf
incorrectly setup (or might have been overwritten by an update).
First, check if
/dev/lirc0
is present:
$ mode2 --driver default --device /dev/lirc0
Watch the output while pressing buttons on the remote. If output is present, edit
/etc/lirc/lirc_options.conf
changing the
driver
and
device
appropriately.
If no output is presented, the task becomes locating the correct driver/device combination. First check what combination lirc detected by default. Run
ir-keytable
from the
v4l-utils
package. and check the output. It will look similar to this:
Found /sys/class/rc/rc0/ (/dev/input/event5) with:
       Driver ite-cir, table rc-rc6-mce
       Supported protocols: unknown other lirc rc-5 jvc sony nec sanyo mce-kbd rc-6 sharp xmp
       Enabled protocols: lirc
       Extra capabilities: <access denied>
In this case, LIRC automatically detected
/dev/input/event5
as the IR device, which uses the
devinput
driver. Check if this combination is working by running:
$ mode2 --driver devinput --device /dev/input/event5
Now try pressing buttons on the remote. If there is no output, try different driver and device combinations.  Once a working combination has been identified, change
driver
and
device
in
/etc/lirc/lirc_options.conf
appropriately.
Example
An example configuration for a MCE RC6 compatible receiver:
/etc/lirc/lirc_options.conf
[lircd]
nodaemon        = False
driver          = default
device          = /dev/lirc0
output          = /var/run/lirc/lircd
pidfile         = /var/run/lirc/lircd.pid
plugindir       = /usr/lib/lirc/plugins
permission      = 666
allow-simulate  = No
repeat-max      = 600

[lircmd]
uinput          = False
nodaemon        = False
See also
Project site
Upstream documentation
Upstream Configuration Guide
Remotes database
MythTV Wiki:Remotes article
Linux Streamzap configuration files