As the weather turns colder, a young man’s thoughts turn toward…

November 20, 2003 at 1:46 pm


Holiday lights.

The first house that my wife and I bought was in a development with an active homeowner’s
association. The first year, we got a flier from the association that said:

Holiday decoration contest

$100 first prize
$50 second prize
$25 third prize

With hundreds of houses in the development, we didn’t figure we had any chance, but
we did put up a few more lives than usual, and somehow won second prize.

A monster was born.

After a trip to Point Defiance Zoo’s excellent Zoolights got
me thinking about animated light displays. I had wanted to do some microcontroller
programming, but didn’t have an application until now. I hooked up with one of the
robotics experts in my group, and bought the parts to build a BotBoard, and did the
hardware and software for an 8-channel light sequencer.

The sequencer was destined for a Santa animation. It starts with some flashing landing
lights, and then Santa and his reindeer appear. A few seconds later, Santa and the
presents move onto the roof, then up to the chimney, then disappearing down the chimney.
Pause, and the sequence repeats.

It was a lot of fun to write the software – the BotBoard runs
a Motorola 68HC11E2 processor
that is programmed over the serial port. A very cool processor with built-in timers
and other useful subsystems, but it’s a 8-bit architecture, and you get to program
it in assembly language (you can find compilers if you want). Debugging is interesting…

So, we got that project done, but only won third prize.

A few years passed, and I had some leftover BotBoards, so I built the second controller.
This one was a 16 channel controller, but uses the same basic architecture. It runs
a 10′ tree made up entirely of lights (well, lights, electrical conduit, and a whole
lot of wire).

For my most recent application, I wanted to do something different. One of the things
that I found annoying was that the lights that outlined the house were white, and
static. I wanted some thing different. I could have built another sequencer, but that
would have given me a quick switch between colors. I wanted something more subtle.

To do this, you have to get into dimming. That makes the project tougher, as you now
need to have tight control on the timing to get it to work. It’s also a bit harder
to fit everything into the 2K of EEPROM and 512 bytes (yes, bytes) of memory you have.
This one took me a while, but ultimately gave me a very good project.

In fact, I was able to write an article on
it for Nuts & Volts magazine.

So, as Thanksgiving approaches, I need to get ready to put up all three of the animated
displays and a few thousand over lights. The total number of lights is around 13,000.

I’ve been hoping to spend some time building some new sequencing – perhaps one that
can be driven over a serial port.

If you happen to live in the Bellevue area, you can stop by. I’m going to try to post
some pictures when it’s all up and running.

Oh, and if you think I’m out of control, take a look at this,
and of course, the granddaddy of them all, PlanetChristmas. 35,000 Lights.  Here’s
a video