Computing stuff tied to the physical world

Meet the Infrared Plug

In Hardware, Software on Nov 12, 2010 at 00:01

The new Infrared Plug needed a small adjustment to work, but now it’s working properly. Here’s my hand-soldered prototype:

Dsc 2243

Fits on any of the JeeNode ports, of course. The DIO pin controls the IR output, which is pulsed at 38 KHz (38.28 KHz on my unit, more than close enough). The light is generated with one or two IR LEDs. With one LED, the peak current is ≈ 50 mA (a bit high for the AA Power board) – with two LEDs, the current is ≈ 10 mA. That will no doubt have a lower range, but you could tape one of the LEDs onto a specific appliance, while still letting the other one shine into the room (or a second device).

The input is a 38 KHz detector, with its signal available on the AIO pin.

The “InfraredPlug class” in the Ports library makes it easy to interface to this plug, as described in recent posts.

I’ve also added an “ir_repeater.pde” demo sketch, which repeats any NEC command it receives three times, at 1-second intervals. When I press “Forward” on my Apple Remote, it’ll end up skipping 3 extra songs forward. Can’t quite think of a use for that, but it helped me flesh out the bugs:

Screen Shot 2010 11 11 at 18.16.58

There is a bit of logic in there to convert the incoming slot count to a bit pattern.

Sample output:

Screen Shot 2010 11 11 at 18.16.51

The Infrared Plug is now in the café and the shop.

  1. couple of typos JC, one right above this comment box “infared” and then on the first line of the product page and wiki description.

    Cool plug though, might have to have a play with one of them, maybe with extra bright leds so I can turn the neighbours hifi down!

  2. Good work! I’m going to use this IR Plug with a JeeNode, as part of my speed gate project (speed measuring device). Thinking of mounting a IR reflector mirror ( 3 – 5m in opposite direction of the IR Plug on tripods.

    As soon as an object (or lets call it an athlete :) crosses the beam, the JeeNode will signal the JeeLink attached to my laptop. With the 2nd or third interceptions being signalled, velocity can be determined.

    I will keep you posted and add the project to your list.

    • Thanks for the mirror link – if these work as “cats eyes” then you don’t even need to align things very accurately. It could be a really convenient way to use the IR plug as line-of-sight interruption beam.

      Sounds like a fun project, btw :)

  3. What is a typical range you might expect between two IR plugs? (I suppose it could always be increased with external optics, if they are always looking in a fixed direction)

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