Raspbery Pi. Getting Started with IR receiver using lirc-rpi overlay

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no coLIRC – Linux Infrared Remote Control

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  • Make sure you are connected to Internet: ‘ping google.com’ should produce answers from some IP address
  • After connected to Internet, install ‘lirc’: sudo apt-get install lirc
  • To enable lirc-rpi overlay (on that pin you connected) add the following line to config.txt (sudo nano /boot/config.txt):

dtoverlay=lirc-rpi,gpio_in_pin=18,gpio_out_pin=17

  • reboot with for this new configuration to have effect
  • After reboot, configure GPIO pin you just connected (assign gpio_out_pin to not connected one)

modprobe lirc-rpi gpio_in_pin-18 gpio_out_pin=17

  • check the connection succeeded:
    • ‘dmesg’ command should show the messages like below
    • and you should have lirc0 device: ‘ls /dev/lirc0’
[ 4.791065] lirc_dev: IR Remote Control driver registered, major 246
[ 4.928351] lirc_rpi: module is from the staging directory, the quality is unknown, you have been warned.
...
[ 5.968099] lirc_rpi: auto-detected active low receiver on GPIO pin 18
[ 6.028343] lirc_rpi lirc_rpi: lirc_dev: driver lirc_rpi registered at minor = 0
[ 6.032275] lirc_rpi: driver registered!
  • kill the loaded lirc-rpi

‘ps aux | grep lirc’ – to know if lirc process exists


pi@(none) ~ $ ps aux | grep lirc
root 393 0.0 0.4 3644 1548 ? Ss 14:18 0:00 /usr/sbin/lircd --driver=default --device=/dev/lirc0
pi 3149 0.0 0.4 3556 1776 pts/0 S+ 14:20 0:00 grep --color=auto lirc

In case ‘lirc’ process is there, use one of the following commands to kill it:


sudo /etc/init.d/lirc stop
sudo pkill lirc

Note: Just using ‘kill -QUIT <PID>’ will not help as the process lirc changes its PID constantly

    • start sensing key signals by

mode2 -d /dev/lirc0

Now if you press any button on your remote you is supposed to get a sequence on your screen that describes timing diagram of that specific signal

 

20151220_070023 20160102_092149

    • Teach LIRC about specific buttons of your remote control.

– First, save for yoursef LIRC’s default key-names


irrecord --list-namespace > ~/lirc_keys.txt

– Then, provide key-presses to the ‘irrecord‘ command: follow the instructions provided by the command and use your ~/lirc_keys.txt when asked to give names for specific buttons.

# 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

 

– After you are done lircd.conf will look like below


# Please make this file available to others
# by sending it to <lirc@bartelmus.de>
#
# this config file was automatically generated
# using lirc-0.9.0-pre1(default) on Sat Jan 9 11:49:38 2016
#
# contributed by
#
# brand: ./lirc.conf
# model no. of remote control:
# devices being controlled by this remote:
#

begin remote

name ./lirc.conf
bits 8
flags SPACE_ENC|CONST_LENGTH
eps 30
aeps 100

one 272 1843
zero 272 786
ptrail 272
pre_data_bits 8
pre_data 0xE2
gap 50265
toggle_bit_mask 0x0

begin codes
KEY_A 0xC4
KEY_B 0x44
KEY_C 0x84
KEY_D 0x04
end codes

end remote

 

  • Add lirc-pi to the configuration:

– change LIRC configuration (sudo nano /etc/lirc/hardware.conf) as following:


# /etc/lirc/hardware.conf
#
# Arguments which will be used when launching lircd
LIRCD_ARGS=""

#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=""
  • To have you lirc starting at RPi boot add the following line to your /etc/rc.local (sudo nano /etc/rc.local):
sudo /etc/init.d/lirc start
  • To see how LIRC decodes the keys you configured use ‘irw’ command and then press the buttons your LIRC learned.

Example:


pi@(none) ~ $ irw
000000000000e2c4 00 KEY_A ./lirc.conf
000000000000e2c4 01 KEY_A ./lirc.conf
000000000000e2c4 02 KEY_A ./lirc.conf
000000000000e284 00 KEY_C ./lirc.conf
000000000000e284 01 KEY_C ./lirc.conf
000000000000e284 02 KEY_C ./lirc.conf

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