PoE Powers Christmas Lights, But Opens Up So Much More

Addressable LEDs are a staple of homemade Christmas decorations in our community, as is microprocessor control of those LEDs. So at first sight [Glen Akins]’ LED decorated Christmas tree looks pretty enough, but isn’t particularly unusual. But after reading his write-up you’ll discover there’s far more to the project than meets the eye, and learn a lot about the technologies behind it that has relevance far beyond a festive light show.

The decoration is powered exclusively from power-over-Ethernet, with a PIC microcontroller translating Art-Net DMX-over-Ethernet packets into commands for the LED string. The control board is designed from the ground up and includes all the PoE circuitry, and the write-up  gives a very thorough introduction to this power source that takes the reader way beyond regarding PoE as simply another off-the-shelf black box. Along the way we see all his code, as well as learn a few interesting tidbits such as the use of a pre-programmed EEPROM containing a unique MAC address.

So if your house has CAT5 wiring and you want an extra dimension to your festive splendour, you’ve officially got a whole year to build your own version. He’s featured here before, with his buzzer to break the Caps Lock habit.

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An Even Larger Array Of Many LEDs And No Ping-Pong balls

Color Led Matrix

[George] has gone pro with his latest RGB LED panel. We’ve chronicled [George’s] journey toward the elusive land of LED nirvana for a couple of years now. He started with an 8×8 rainbow board of many ping-pong balls. When that wasn’t enough, he upped the ante to a 32×16 array of ping-pong balls. Still not satisfied, [George] has now increased the size to two 20×15 panels, for a total of 600 LEDs. While this is only a modest size increase from the previous incarnation, the major changes here have been in the design and construction of the array.

[George] found himself using his LED panels in some professional settings. The stresses of moving and rigging the panels revealed several design weaknesses. The point to point discrete LED design tended to short, leading to troubleshooting by poking at wires in a dark club. The control code was also a mixed bag of solderlab’s code, [George’s] code, and various scripts. Even the trademark ping-pong ball light diffusers were a problem, as they created a fire hazard. [George] took all the lessons from the first and second LED arrays and started a new design – the MX3. The panel frames were constructed by a professional metal shop. Starting with a square steel tube backbone, and aluminum panel shell was welded into place. The steel tube provides a hardpoint mount for any number of rigging options. The front panels are medium-density fibreboard, treated with a fire-retardant paint.

The electronics have also changed. Gone are the individual RGB LEDs. [George] has switched over to the common WS2812 LED strings. Panel mounted Raspberry Pis control the LED strings. Communication is via Art-Net, an Ethernet implementation of the common DMX512 protocol commonly used in stage lighting. The final result looks great.  We’re impressed with how much [George] has accomplished at such a young age (He was 16 last June).

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