If you have been following the blog then you will already know that I have decided to make my own home-brew receiver to use with the MediaBox. There are various types of receivers that LIRC supports, but the one I have decided to make is a simple IR receiver module (TSOP1736) connected to the CD-In port on the motherboard. The reason I have decided to go with this is due to its simplicity.
Follow up:
The TSOP1736 will receive a signal from any IR transmitter which is modulating at 36 KHz (The 36 in ‘TSOP1736’ is the frequency). You could equally use a 38 KHz, 56 KHz or any other frequency, but I have gone for 36 KHz due to the fact that the remote controllers I intend on using transmit at that frequency.
LIRC has many drivers to support the various devices that connect to the PC, but the driver we will be using is called audio_alsa. This driver basically uses the alsa library (common to most Linux distributions) to capture audio samples from a preconfigured input of your choice on the PC’s sound card. You can find more information on this particular circuit on the LIRC website.
I managed to find a TSOP1736 from an old IR receiver that came with a TV capture card, I constructed a prototype by butchering a Y splitter Molex cable for the power source pin (pin 2). Since the TSOP1736 requires a +5v supply I used the red cable from the Molex plug, then connected the ground (pin 1) to the Molex plug’s ground pin, I then connected the signal pin of the IR receiver (pin 3) to the left channel of a butchered CD-in/AUX cable. You can usually find these going from the back of your CD-ROM drive and look like this.
They are seldom used as most software will digitally extract the audio when playing an audio disc. The ground pin of the CD-in cable was then also connected to the ground pin on the Molex plug. So that was it, time to test it works.
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