Consumer IR

This article describes how to receive and transmit signals from home appliances that operate in the infrared (that is, most of the remotes from TVs, air conditioners, etc).

Hardware

IR receiver

IR transmitter

Warning! In revisions 5.8 and older IR-port (to connect the transceiver) is missing!

On Wiren Board 5 (before revision 5.6.1) the required signals are output to the 3.5 mm mini-jack connector with the following Pinout:

• Tip (left audio channel) - 5V power/IR transmission.
• Ring (right audio channel) - IR reception
• Sleeve (ground) - ground

Pinout connector allows you to connect common IR receivers and transmitters from home appliances.

To receive IR signals, you need to connect the receiver (combined WB-CIR-TR transceiver). The nominal carrier frequency of the receiver must be approximately the same as the carrier frequency of the used remote control, otherwise the signal from the remote control may deteriorate or be completely impossible to receive.

To transmit IR signals it is recommended to use a ready combined IR transceiver WB-CIR-TR, Samsung IR Blaster bn96/26652a or similar.

Technical details

Mini-jack 3.5 mm Pinout on Wiren Board 5 :

• Tip (left audio channel) - 5V power/IR transmission.
• Ring (right audio channel) - IR reception
• Sleeve (ground) - ground

To receive IR signals, receivers of the type TSOP1738, AX-1838HS or similar are used. The IR led is used to transmit IR signals, the current limiting resistor is not required (built into the controller) When transmitting, the supply voltage will be modulated by the transmitted signal and the carrier. The WB-CIR-TR transceiver contains a TSOP type receiver and an IR led. Parasite power is used to power the receiver.

Hardware

At the kernel level for the work with IR to Wiren Board 5 the driver meets the lirc-pwm. It provides the / dev/lirc1 device.

This device interacts with daemon lircd from package LIRC that provides decoding of the pulse sequence in the event pressed on the remote control buttons according to the configuration files, remotes. This daemon is also capable of performing a reverse conversion to transmit button push signals to controlled devices.

Finally, the stream of events from lircd in message MQTT and back runs the demon wb-mqtt-lirc

Installation and configuration

Required packages (wb-mqtt-lirc, lirc-scripts, wb-mqtt-lirc), as well as the correct config file /etc/lirc/hardware.conf is installed in a standard image starting from version 201512070633.

• Download or generate the remote configuration file and put it in /etc/lirc/lircd.conf.d/.

Download ready remote config

root@wirenboard:~# irdb-get update
root@wirenboard:~# irdb-get find 687C
sony/RM-687C.lircd.conf
root@wirenboard:~# irdb-get download sony/RM-687C.lircd.conf
Downloaded https://sourceforge.net/p/lirc-remotes/code/ci/master/tree/remotes/sony/RM-687C.lircd.conf as RM-687C.lircd.conf
root@wirenboard:~# mv RM-687C.lircd.conf /etc/lirc/lircd.conf.d/

Creating a new remote config

After completing configuration, restart the service lirc and wb-mqtt-lirc

root@wirenboard:~# service lirc restart && service wb-mqtt-lirc restart

MQTT interface

wb-mqtt-lirc creates a device "/devices/wb-lirc/", accepted clicks are published in the topic "/devices/wb-lirc/controls/Key" in the format <switch_name>:<button_name>:<repeat>. After releasing the button, a message with an empty body is published in this topic.

Example:

root@wirenboard:~# mosquitto_sub -v -t '/devices/wb-lirc/#'
/devices/wb-lirc/meta/name IR Remote Control
/devices/wb-lirc/controls/Key/meta/order 1
/devices/wb-lirc/controls/Key/meta/type text
/devices/wb-lirc/controls/Key Sony_RM-687C:KEY_7:0
/devices/wb-lirc/controls/Key Sony_RM-687C:KEY_7:1
/devices/wb-lirc/controls/Key Sony_RM-687C:KEY_7:2
/devices/wb-lirc/controls/Key Sony_RM-687C:KEY_7:3
/devices/wb-lirc/controls/Key (null)

To send a button press, you should publish the message in the format <button name>:<button name> in the topic "/devices/wb-lirc/controls/Key/on"

= = = Not working reception ==

• Make sure the driver "sees" pulses from the receiver.
  • Stop service lirc (command "service lirc stop")

  • root@wirenboard:~# mode2 -d /dev/lirc1

    The numbers should run when you press the buttons on the remote, if not - the problem is in the "hardware" or in the mismatch of the carrier of the remote and the receiver. You should try using a different receiver.

• Make sure that lirc can decode pulse sequences according to the configuration of the remote control:
  • Run back lirc ('service lirc start')

  • root@wirenboard:~# irw

    Due to run lines when you press the buttons on the remote. If mode2 works and irw doesn't, there is a problem with the remote config. It is worth trying to use another config, or create a new one.

Transmission is not working

• Try to transmit referring to LIRC directly:

root@wirenboard:~# irsend SEND_START Sony_RM-687C KEY_3
...
root@wirenboard:~# irsend SEND_STOP Sony_RM-687C KEY_3

(the name of the remote and buttons should correspond to the configuration used).

• Make sure that the hardware is working - for example, you can look at the IR led through the smartphone camera (the led should blink when transmitting)