bm2005: 16 10mm white LEDs, 9V battery wearable or serial
This web page documents a board with 16 LEDs, individually dimmable
running patterns or serially controllable
Board size: 3.00 x 3.00 two-layer, round with red soldermask
Project timeframe: July 2005; serial enhancements September 2006
Client: Leo Villareal
Webpage created: May 20 2007
(these pictures are of the serial prototype, hacked a bit.
units are round with red
soldermask for aesthetics.)
bm2005 (i.e. the blinky for
Burningman 2005) is the second generation of the wearable LED
blinkies for Leo Villareal / disorient.
(other years: bm2006, bm2004). bm2005 is a circle of
16 10mm white LEDs, and is
design variations on one board: standalone pattern synthesis, and
RS-485 controllable with a simple custom protocol.
I did the "architectural" design of both the hardware and software -
describing the hardware design and writing the core software that runs
everything. Todd Polenberg did the hardware layout, handled the
manufacturing, and wrote the pattern synthesis part of the software
with my occasional consultation. The hardware layout is a bit of
trick, while the board isn't particularly dense, the LEDs on one side
of the board in a perfect circle and the electronics are
as SMT as possible and are all on the backside.
The design is pretty simple: a TI TLC5940 16 channel PWM LED
driver, and a PIC18F252 to run the show.
The PIC software is in C using the CCS C compiler. The first
design for Burningman was built with a 9V holder for wearing
around. The later revision for serial control has two 4-pin
headers for daisy-chain for power/gnd/RS-485 and a standard 75176 8-pin
transceiver. Picutred above is the prototype for the serial
version, kludged to run off a 9V battery and with a pot to control
The TLC5940 is a very handly little chip, but not without some
hassles. See here for a
The RS-485 version hasn't been used much (at least not yet), but Leo
has used a few in experimenting for installations.
These also make excellent "headlights" for bicycle riding at night in
Oakland. Of course, being Oakland, you can't leave it on your
while you are at the bar...