LIRC
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.
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
Configuration
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 config file and then restart the service.
/etc/lirc/lirc_options.conf
[lircd] driver = driver-name device = /dev/path-to-dev
Scancode mapping
/etc/lirc/lircd.conf.d/foo.conf
is the system-wide configuration translating scancodes to keycodes. This directory may contain multiple conf files and each one is specific to each remote control/receiver on the system. These files are user-created config files and not directly supplied by lirc.
The definition of scancodes to keycodes is required to allow LIRC to manage a remote.
Remotes database
LIRC provides configuration files for many remote controls in the remotes database. Use irdb-get(1) to search the database or simply browse to the URL and do the same.
Refer to creating remote configurations if configs for your specific hardware are not in either location.
An example using irdb-get
to find a config 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 configurations
Remote control configurations can easily be created using irrecord(1), which guides users along the needed process. If using a detected remote, invoke it like so:
# irrecord --device=/dev/lirc0 MyRemote
The program will instruct users 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.
Application-specific actions
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"
Usage
Start/enable lircd.service
.
Test the remote using irw(1), which simply echos anything received by LIRC when users push buttons on the remote to stdout.
Example:
$ 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, double check the config files in /etc/lirc/lircd.conf.d/
for errors.
Running as a regular user rather than as root
By default, lircd runs as user root. However, for increased stability and security, upstream recommends running it as a regular user. See Appendix 14 at this link.
To do this, create and provision a lirc user:
# groupadd -r lirc # useradd -r -g lirc -d /var/lib/lirc -s /usr/bin/nologin -c "LIRC daemon user" lirc # usermod -a -G lock,input lirc
Augment the package-providing service unit by creating a lircd Systemd#Drop-in files:
# systemctl edit lircd
[Service] User=lirc Group=lirc CapabilityBoundingSet=CAP_SETEUID MemoryDenyWriteExecute=true NoNewPrivileges=true PrivateTmp=true ProtectHome=true ProtectSystem=full
To allow /dev/lirc*
devices to be accessible for the lirc group and to grant r/w access for the lirc group to USB devices using ACLs, copy the following udev rule into place:
# cp /usr/share/lirc/contrib/60-lirc.rules /etc/udev/rules.d/
To allow access to the lirc group to be able to create a PID file, create the following lircd tmpfile which will supersede the package provided one (which makes ownership only to root):
/etc/tmpfiles.d/lirc.conf
d /run/lirc 0755 lirc lirc -
Reboot the system to verify expected function.
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
$ cat /proc/bus/input/devices | grep -e IR
For example WinFast
for N: Name="cx88 IR (WinFast DTV2000 H rev."
On an ARM device 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