Saturday, 1 September 2012

USB IR Receiver

This is a little USB infrared receiver based on an original design by Ben Ryves. It pretends to be a USB keyboard and works by mapping NEC IR codes to keystrokes --- controlling the chosen application through its keyboard shortcuts. (VLC is a good choice of application because it's possible to change its shortcuts to match the ones sent by the receiver.)

I slightly simplified the hardware removing a switch which the original used to send different sets of key-codes, for two applications without programmable shortcuts. The modified circuit diagram is below.
(Note that the circuit must run at 12 MHz. I think this was due to the timing of the IR reception routine.)

I also simplified the software, removing a detection routine for the SIRCS protocol. Ben's original software is here, while my modifications are here.  The USB stack is V-USB: this is a nice simple example of getting started with it.

The software detects codes sent by a Newsky DVB-T remote control, seen below.
An easy way to discover the type of your remote control and the codes it sends, is with Ken Shirriff's handy IR library for Arduino; use the IRrecvDump sketch.

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