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LIRC Notes

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I installed the lirc library and I tried to use it, I need this for a project

sudo mode2 -d/dev/lirc0
Using driver default on device /dev/lirc0
Trying device: /dev/lirc0
Please use the --raw option to access the device directly instead through the abstraction layer

If I use with –raw

Using raw access on device /dev/lirc0
Problems: this device is not a LIRC kernel device (it does not
support LIRC_GET_REC_MODE ioctl). This is not necessarily a
problem, but mode2 will not work.  If you are using the --raw
option you might try using without it and select a driver
instead. Otherwise, try using lircd + irw to view the decoded
data - this might very well work even if mode2 doesn't.

I am new to the PI world, I don’t know where the problem is. The receiver? The circuit? Pins? Please help !

CONTEXT: I just want to record some IR signals so I can use them after. This is the circuit I used : https://www.hackster.io/austin-stanton/creating-a-raspberry-pi-universal-remote-with-lirc-2fd581

 New contributor
  • Given that we have no information about the receiver, the circuit, or the pins how are we meant to help? Some context about what you are doing and how is needed. – joan 2 hours ago
  • I’ll edit in the question – Teofil Sandu 2 hours ago
  • @Teofil Sandu, I skimmed through the tutorial hackster.io/austin-stanton/… to see if you missed anything in your installation procedure. Now I am scribbling something and hopefully can make an answer. I am going very slow because I am also a lirc newbie and have not tried this lirc thing before. – tlfong01 44 mins ago    
  • @Teofil Sandu, Now I have summarized the installation and testing procedure in Appendix A of my answer. The tutorial is a bit out of date. I worried that the driver or kernel is not compatible with your Rpi3B+ raspbian 9 stretch (let me know if my guess of your config is correct). The tutorial also suggests to read the LIRC user guide. I have never read this guide. So I need to first skim through it, to understand what the hell is “Mode 2”, and should I indeed to use Mode2. – tlfong01 26 mins ago   
  • @Teofil Sandu, Now I have googled the LIRC wikipedia but found it too brief. But at least now know what does “LIRC” stands for (See Appendix B). I need to google further to learn more. – tlfong01 18 mins ago   Edit   
 Teofil Sandu is a new contributor. Be nice, and check out our Code of Conduct.

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    Question

    I am installing LIRC and found a problem. Can you help?

    Answer

    / to continue, …

    References

    (1) Creating A Raspberry Pi Universal Remote With LIRC – Austin Stanton 2017mar24, 68,705 views

    (2) LIRC – Wikipedia

    (3) LIRC Introduction from official LIRC web site

    Appendices

    (A) Installing and testing LIRC

    ***Materials*** 
    (1) Raspberry Pi 2
    (2) 940nm IR LED 40deg - 40 degree viewing angle. Bright and tuned to 940nm wavelength.
    (3) 38khz IR Receiver - Receives IR signals at remote control frequencies
    (4) PN2222 Transistor - Transistor to help drive IR LED
    (5) 10k Ohm resistor - Resistor that goes between RPI GPIO and the PN2222 transistor
    
    ***Installation***
    sudo apt-get install lirc
    Add to your /etc/modules file by entering the command below:
    sudo cat >> /etc/modules <<EOF
    lirc_dev
    lirc_rpi gpio_in_pin=23 gpio_out_pin=22
    sudo cat > /etc/lirc/hardware.conf <<EOF 
    
    # /etc/lirc/hardware.conf
    # Arguments which will be used when launching lircd
    LIRCD_ARGS="--uinput"
    # Don't start lircmd even if there seems to be a good config file
    # START_LIRCMD=false
    # Don't start irexec, even if a good config file seems to exist.
    # START_IREXEC=false  
    # Try to load appropriate kernel modules
    LOAD_MODULES=true
    # Run "lircd --driver=help" for a list of supported drivers.
    DRIVER="default"
    # usually /dev/lirc0 is the correct setting for systems using udev
    DEVICE="/dev/lirc0"
    MODULES="lirc_rpi"
    # Default configuration files for your hardware if any
    LIRCD_CONF=""
    LIRCMD_CONF=""
    ######################################################## 
    EOF
    Edit your /boot/config.txt by entering the command below:
    cat >> /boot/config.txt <<EOF
    dtoverlay=lirc-rpi,gpio_in_pin=23,gpio_out_pin=22
    EOF 
    Now restart lircd so it picks up these changes:
    sudo /etc/init.d/lirc stop
    sudo /etc/init.d/lirc start
    ***Testing the IR Receiver***
    Testing the IR receiver is relatively straightforward. Run these two commands to stop lircd and start outputting raw data from the IR receiver:
    sudo /etc/init.d/lirc stop
    mode2 -d /dev/lirc0
    Point a remote control at your IR receiver and press some buttons. You should see something like this:
    space 16300
    pulse 95
    space 28794
    pulse 80
    space 19395
    pulse 83
    space 402351
    pulse 135
    space 7085
    pulse 85
    space 2903
    If you don’t, something is probably incorrectly configured. Triple check that you’ve connected everything properly and haven’t crossed any wires. I highly recommend referring to the schematics I linked to above. There is also some trouble shooting advice in the RaspberryPi Forum thread I linked to above. Finally - you may want to do this in a dark room. I found that my desk lamp and overhead light would cause the IR receiver to think it was receiving valid signals.
    ***Testing the IR LED***   
    You’re going to need to either find an existing LIRC config file for your remote control or use your IR receiver to generate a new LIRC config file(find existing remote profiles here). In my case, I created a new LIRC config file. To do this, read the documentation on the irrecord application that comes with LIRC.
    When using irrecord it will ask you to name the buttons you’re programming as you program them. Be sure to run irrecord --list-namespace to see the valid names before you begin.
    Here were the commands that I ran to generate a remote configuration file:
    # Stop lirc to free up /dev/lirc0
    sudo /etc/init.d/lirc stop
    # Create a new remote control configuration file (using /dev/lirc0) and save the output to ~/lircd.conf
    irrecord -d /dev/lirc0 ~/lircd.conf  
    # Make a backup of the original lircd.conf file
    sudo mv /etc/lirc/lircd.conf /etc/lirc/lircd_original.conf    
    # Copy over your new configuration file
    sudo cp ~/lircd.conf /etc/lirc/lircd.conf    
    # Start up lirc again
    sudo /etc/init.d/lirc start    
    Once you’ve completed a remote configuration file and saved/added it to /etc/lirc/lircd.conf you can try testing the IR LED. We’ll be using the irsend application that comes with LIRC to facilitate sending commands. You’ll definitely want to check out the documentation to learn more about the options irsend has.    
    Here are the commands I ran to test my IR LED (using the “Roku” remote configuration file I created):    
    # List all of the commands that LIRC knows for 'Roku'
    irsend LIST Roku ""    
    # Send the KEY_POWER command once
    irsend SEND_ONCE Roku KEY_POWER    
    # Send the KEY_VOLUMEDOWN command once
    irsend SEND_ONCE Roku KEY_VOLUMEDOWN
    I tested that this was working by pointing the IR led at my Roku receiver and testing whether I could turn it on and press enter.    
    sudo cat > /etc/lirc/hardware.conf <<EOF     
    # /etc/lirc/hardware.conf
    # Arguments which will be used when launching lircd
    LIRCD_ARGS="--uinput"  
    # Don't start lircmd even if there seems to be a good config file
    # START_LIRCMD=false    
    # Don't start irexec, even if a good config file seems to exist.
    # START_IREXEC=false    
    # Try to load appropriate kernel modules
    LOAD_MODULES=true    
    # Run "lircd --driver=help" for a list of supported drivers.
    DRIVER="default"    
    # usually /dev/lirc0 is the correct setting for systems using udev    
    DEVICE="/dev/lirc0"
    MODULES="lirc_rpi"    
    # Default configuration files for your hardware if any    
    LIRCD_CONF=""
    LIRCMD_CONF=""
    EOF
    

    (B) LIRC – Wikipedia

    LIRC (Linux Infrared Remote Control) is an open source package that allows users to receive and send infrared signals with a Linux-based computer system. With LIRC and an IR receiver the user can control their computer with almost any infrared remote control (e.g. a TV remote control). The user may for instance control DVD or music playback with their remote control.

    (C) LIRC Introduction from official LIRC web site

    What is LIRC?

    LIRC is a package that allows you to decode and send infra-red signals of many (but not all) commonly used remote controls.

    Recent linux kernels makes it possible to use some IR remote controls as regular input devices. Sometimes this makes LIRC redundant.

    However, LIRC offers more flexibility and functionality and is still the right tool in a lot of scenarios. The most important part of LIRC is the lircd daemon which decodes IR signals received by the device drivers and provides the information on a socket. It also accepts commands for IR signals to be sent if the hardware supports this.

    The user space applications allows you to control your computer with your remote control. You can send X11 events to applications, start programs and much more on just one button press.

    The possible applications are obvious: Infra-red mouse, remote control for your TV tuner card or CD-ROM, shutdown by remote, program your VCR and/or satellite tuner with your computer, etc.

    Using lirc on Raspberry Pie is quite popular these days.

    Supported remote controls

    There are some config files for remote controls at the remotes database. This is about 2500 devices and counting. These devices should work with the general drivers or (if it lacks timing info) the driver used to create them.

    If you can’t find your remote control here it does not mean that your remote control is not supported. It’s just that there is no config file for it yet.

    All remote controls that are supported by learning remote controls i.e., almost any, should also work with LIRC.

    Supported capture devices

    Besides a remote control you also need a capture device to read the data from the remote.

    Former versions focused on home-brew capture hardware connected to the serial or parallel port. Descriptions how to build such hardware can be found here. Current versions of LIRC also support a broad range of other hardware.

    As a starter, you can use the kernel built-in support for many USB dongles and similar. Besides this LIRC supports basically any conceivable way to capture your data including serial devices, parallel ports, sound input etc. You can see the complete list in the left pane.

    .END

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