Infrared Remote for Android Georgi Bakalski & Boris Ribov

Irdroid – IR remote for Android Universal remote control IR TV, STB, DVD, DVB Open source application and open hardware modules Control other devices that use IR Port of LIRC for Android (Linux Infrared Remote control) Supports LIRC configuration files (the database contains more than 2000 supported devices.

Irdroid v2.0 : Operation connections diagram

The Irdroid v1.0 amplification module Based on a mono audio amp - LM386 Powered by a battery 4LR44 – 6V 3.5mm audio jack Operating range 10m

How IR works There are two IR standards: REC-80 and RC-5; REC-80 code the pulse or pause length; RC-5 code the signal transition; Both the standards uses 38kHz carrier and can be determined by duration of T1 and T2; ? The only question is how to produce 38kHz from the output DACs of the Android device. Figure 1 – REC-80 coding scheme Figure 2 – RC-5 coding schemeFigure 3 – 38kHz modulation

Infrared via Audio? How it works? We use the Android’s audio card driver to generate and transmit the modulated data on a sine using standard sampling rate at 44.1kHz; The IR timing DATA is modulated on a sine wave, half of the carrier frequency (19KHz) After a dual optical rectification of the sine wave via the two IR LEDS in the hardware module, the full frequency of 38KHz is emitted via the LEDs as IR Light. The Sine wave is inverted on the right channel, so that to double the voltage and to achieve greater remote control range The Simplest schematic that work with Irdroid is shown on the left. It consist of just two IR LEDs one resistor and audio jack. The IR range using the schematic on the left is limited to 50cm to 1m which depend on the particular android device. We have decided to increase this range by amplifying the signal via a active module and by using a battery.

V1.0 module schematic

V2.0 module schematic

Tools and Software used Android NDK and SDK development kits Eclipse IDE and ADT plugin for Eclipse Orcad for schematics and PCB Design Corel draw for v2.0 panel designs

Thank you for your attention. Questions ? Irdroid source – Schematic and PCB files Irdroid app(apk) – Android Market