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
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Based on a mono audio amp - LM386
Powered by a battery 4LR44 – 6V
3.5mm audio jack
Operating range 10m
How IR works
Space Coded Signal
Pulse Coded Signal
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0
1
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1
Figure 1 – REC-80 coding scheme
Transition Coded Signal
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1
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0
Figure 2 – RC-5 coding scheme
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1
Figure 3 – 38kHz modulation
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.
Infrared via Audio? How it works?
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We use the Android’s audio card driver to generate
and transmit the modulated data on a sine wave
@38Khz 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
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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 – http://www.github.com/irdroid
• Schematic and PCB files http://www.irdroid.com/irdroid/irdroid.zip
• Irdroid app(apk) – Android Market