User:Cmsigler/lirc

Step-by-step setup guide for USB (MCE [Media Center Edition]) IR receiver with universal remote control

lirc quick-start guide

Author: Clemmitt M. Sigler, cmsigler--remove_this--dot-online@gmail-dot-com

Date: February 10, 2018

This is a quick-start guide only. Please refer to man pages of the commands and files used and online documentation for in-depth help.

Prerequisites

Get a USB IR receiver, preferably an MCE model which is almost always supported out-of-the-box
Re-purpose an old universal remote control you have lying around the house

Installation and verification

Install the lirc package
Plug in the USB IR receiver
Make sure there are fully charged batteries in your remote control
Get some kind of output/response from the remote using mode2:

   $ sudo mode2

Point the remote control at the IR receiver and press some buttons. This will attempt to autodetect the correct input device using the default "devinput" driver. However, this might not work without manual configuration of protocols.

If no button presses are detected for most keys, change IR protocols

If you get no response to the remote control buttons you want to use, you likely need to enable different protocols:

   $ sudo ir-keytable -p <protocol> -p <protocol> ...

Look at the output of ir-keytable (as well as cat /sys/class/rc/rc0/protocols). NOTE: When you have problems, sudo ir-keytable -p all is your friend!

If no button presses are detected for most keys, try different universal remote control device modes

You may also need to try different universal remote control device modes (TV, DVD, Audio, etc., buttons) in order to detect button presses when you're getting started. (You could possibly reprogram the universal remote's modes, but that would likely be a long trial-and-error process to find a setting that works.)

After reconfiguring IR protocols and remote control device mode, retest:

   $ sudo mode2

Point the remote control at the IR receiver and press some buttons. If button presses for most keys are not detected repeat the prior two steps until they are (or just use sudo ir-keytable -p all).

Setup and testing

If you have narrowed down what protocols you need to support for your remote control, set them:

   $ sudo ir-keytable -p sony -p rc-5

Otherwise, you can just use all protocols:

   $ sudo ir-keytable -p all

Determine the correct device for your IR receiver. Use either the default "devinput" driver or the older "default" driver:

   $ mode2 --driver devinput --list-devices
   $ mode2 --driver default --list-devices
   $ ir-keytable

Use the device found for your USB IR receiver, e.g., /dev/input/event11:

   $ sudo mode2 --driver devinput --device /dev/input/event11

or just try:

   $ sudo mode2 --driver devinput --device auto

See if button presses are detected.

If required, edit lirc_options.conf, e.g., if you're using the driver "default" instead of "devinput":

   $ sudo vi /etc/lirc/lirc_options.conf

Test your remote to see if scancodes are printed:

   $ sudo ir-keytable -t

See if button presses are detected.

Create a modified systemd lircd.service file which loads the correct protocols:

   $ sudo cp /usr/lib/systemd/system/lircd.service /etc/systemd/system/
   $ sudo vi /etc/systemd/system/lircd.service

At the end of the [Service] section add the following line:

/etc/systemd/system/lircd.service

[Service]
...
ExecStartPost=/usr/bin/ir-keytable -p <protocol> -p <protocol>

where each "<protocol>" string is replaced by the protocol(s) you need (or just use /usr/bin/ir-keytable -p all).

Start the lirc daemon so you can record keypresses in order to write an lircd configuration file for your remote control:

   $ sudo systemctl start lircd

Use irrecord to record keypress scancodes

Run:

   $ sudo irrecord

to save/record the keystrokes to be used for your application. Follow irrecord's instructions.

Install the recorded lircd configuration file:

   $ sudo mv device_name.lircd.conf /etc/lirc/lircd.conf.d/
   $ sudo chown root:root /etc/lirc/lircd.conf.d/device_name.lircd.conf

Move devinput.lircd.conf to devinput.lircd.dist to disable it, because you're not using an IR keyboard and/or mouse, just the IR receiver:

   $ sudo mv /etc/lirc/lircd.conf.d/devinput.lircd.conf /etc/lirc/lircd.conf.d/devinput.lircd.dist

Restart the lirc daemon so you use the newly created lircd.conf file:

   $ sudo systemctl restart lircd

Test to make sure the keys you recorded are correctly detected, that is, the correct key symbol is output for each button you press:

   $ irw

See if the correct key symbols are reported, and if repeated signals are properly rejected.

Troubleshooting

Keypresses aren't detected

Repeat sections #Installation and verification then #Setup and testing above.

Repeated keypress events

If you're having keypress repeating problems (each button press is echoed multiple times), examine the output of irw. The second column value is the repeat count. This will increment when repeated signals are detected. Each decoded button press with its count reset to "00" is reported as a separate button press event by lircd.

To fix this problem, generally the "gap" parameter sampled by irrecord in the device_name.lircd.conf file should be adjusted, often to a much larger value (e.g., from 44968 up to 113975).

After editing/adjusting any lircd configuration file, be sure to restart lircd (as shown above).

Final configuration

Write an lircrc file for your end user application

This file is used by all client programs built with lirc support that attach to lircd to read IR control events. Edit ~/.lircrc to issue commands to the program to be controlled. Test this configuration by running:

   $ ircat prog

to see if the correct "config" strings for program "prog" are being output when you press all the buttons you wish to use. If ~/.lircrc isn't read by your application or just doesn't work, an alternate default location is ~/.config/lircrc.

Final testing

Test!

Finally, run your end user application and test remote control button presses to control it. If it works, you're done! If not, review and repeat the above sections as necessary to get each configuration step working before proceeding to the next step or section.

– CMS