It is based on the PIC18LF24K50 and consists of a circle of LEDs which randomly displays pre-defined patterns. Every badge has its own infrared transceiver (LED-receiver pair), so the fun begins when two or more badges spot each other: they go from Adagio to full on Rondo, losing their default, dull visual pattern for a more dynamic, attention grabbing one, but most importantly – they synchronize. This means that, in a group of people, all badges will play the same pattern in unison. Every badge can spread the pattern code, so the whole group, however large, soon becomes synchronized. But if one of them “gets lost” somehow, it will try to learn it back from a neighbor or it might even launch into its own, randomly generated one. Sometimes it manages to spread it further and you get to witness a battle for light show domination. The algorithm is quite simple: every badge plays its own pattern, while keeping its infrared eye open for someone else’s code. If it receives it and verifies the checksum, it stops the current pattern, transmits the special acknowledge code via infrared LED and starts playing the received pattern. If nothing was received, it randomly generates a new pattern code, transmits it, looks if someone acknowledged it and then runs the pattern. If there was an acknowledge, it switches to the “fast” mode. That’s it.
The beauty of microcontroller designs is that you can always add new features later, without affecting the cost. In this case, the infrared transmitter support was implemented in hardware, so the badge got upgraded with [Mitch Altman’s] TV-B-Gone function. I took Mitch’s database for switch-off codes for several hundred different models of TV sets, and wrote a PIC driver routine to transmit them.
The first badge was released about two months ago – it’s the red one in the photo. I decided to give it another feature which would require only the addition of a USB connector to the Bill Of Material. So, the Badge now functions as a Hardware Password Manager, at almost the same cost. It also improves on the visual interest of the badge. It looks like something purposeful, and not merely a fob for hanging around your neck.
There’s plenty of time to brainstorm some more features before next September is upon us. One of the things I will certainly be adding is contact information swapping — a steadfast of conference hardware badges like the Parallax’ badge. Of course this feature will not affect the cost, as both infrared transceiver and USB interface are already present. My son has also suggested adding some form of a Rock-Paper-Scissors game. It will play automatically when two players are connected.
Every badge will have its unique serial number, which will be transmitted by request. It has yet to be defined how this feature will be used, and which kind of external units will be built, as we don’t want to disturb anyone’s privacy.