Chapter 15. Infrared

What is missing on most android devices is an infrared interface. The solution is to use the 3.5mm audio socket to connect an IR transmitter. Having this, many things can be done with the android device:

  1. Remote controller for TV and other multimedia devices

  2. Door opener

  3. Camera remote controller

LIRC the Linux Infra Red Controller package has been taken over to Android. Since most android devices lack on IR receiver capabilities the required config files can not be made. To made them a Linux computer with Lirc is the option.

The simplest hardware driver is it is limited to send out about 3m. More advanced designs use extra power as from a battery to improve this as or use a bluetooth to audio converter where the android device communicates with the bluetooth devices via bluetooth and the IR transmitter is plugged to the bluetooth device. Since the bluetooth device has some power and it is stationary, any kind of IR transmitters and distances can be handled.

Irdroid sells transmitter (IR and bluetooth) and has it remote controller SW

Conversal is a remote controller using LIRC (or/and for Linux multimedia centers SSH)

Androlirc is the straight forward porting of LIRC and is considered a legacy application replaced by Conversal.

Androlirc will probably no more further developed and Conversal seems to go into a different direction than just be a remote controller. Therefore it looks that I will write my own app.

PhotoIRmote (not free) is controlling a camera . It is actually very easy to control a camera. Since a remote controller has maybe just two buttons, two audio files can be created that can be sent out using a IR transmitter. It is so simple that I will probably write my first app for that. Unfortunately my camera collection is not so big therefore I can not test and support many cameras. The problem is to know the ir wave forms and that are not well or not at all documented in public. I plan to do it sound file based, so new cameras can be added without any necessary programming.

Unfortunately Androlirc and Conversal are not stable and have a lot of issues on my Samsung Galaxy S3 sending audio to a Belkin bluetooth device. I guess that something (probably Belkin bluetooth device or bluethooth sw ) handles the lirc ir audio as sound and disturbs it using maybe something as a sound compression algorithms. Indication for that came from observation recording ir signals with a native Linux PC using the soundcard with alsa and observing them using audacity or using an real oscilloscope. The signals look disturbed. Everything from a native Linux PC works but almost every thing from Samsung Galaxy S3 towards the Belkin bluethooth device does not. I did not do a lot of tests with directly connection the ir transceiver to my Galaxy S3, since it is too new. An other obstacle is that the voltage amplitude is too small to make the simple ir transmitter working.

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