So I got my new boarduino design in (with built-in USB!) and I have to test it so why not put it thru its paces with a BlinkM? Why not indeed!

Wiring it up to a boarduino is not as easy as simply plug&play as with an Arduino, so you’ll need a few wires. Still its very straightforward!

when you power it up it will immediately start doing its thing which is fading thru some nice colors

But the real fun is programming it…upload the Arduino Communicator sketch and then run the blink Sequencer on your computer. Connect and then select which colors to display

2 years ago when I worked on Duel Nature, I made a table of data that approximates a heartbeat. I couldnt quite duplicate it directly because the loop time is 3 seconds not 1 second, but I didn’t do too bad. Here it is in ‘autoplay’ mode with the heartbeat script. Sadly it doesnt seem like you can save the script to share it.

Click To Play

Add a coin cell, and you’ve got a ValenThrowieM (Valentine LED Throwie M)!

Click To Play

Next I wanted to experiment with talking to the BlinkM over i2c. I decided to make a little temperature display. When its cold, the LED turns blue, when its hot it turns red. For the sensor I simply used a LM34 which is super simple: just give it 5V and ground and the middle pin will be at +10mV/degF. So 68 degrees is 680mV.

I used a little heatshrink to protect the wires:

Then wrote a sketch to tell the LED to change color, here it is at room temperature (65deg, its cold in here)

Squeezing the sensor brings up the temp a bit, to maybe 85 degrees, a little pinker

Then some icey water (its in a plastic bag to protect both the sensor and my drink!)

and some hot tea

The final analysis?
The BlinkM worked well and is a nifty little thing, the Sequencer software could be improved (can’t save scripts, cant adjust loopspeed, clicking on a ‘frame’ doesnt display the RGB value…) but its impressive that theres any software at all. It seems like the real control comes from sending it direct i2c commands, so one would have to write a custom Arduino sketch to make it do what you want. (Or, probably better yet, a python script that talks to the Arduino communicator since at least then you’re not uploading sketches) While its not the right thing for people who want to make 100-LED blinky projects (since its ~$12 each), its probably a good accessory for someone with an Arduino who just needs a few lights for a standalone project. I could see them being popular as integrated into wearables/fashion technology. They’re hella bright too!

ps. I’d like to see someone show how to control them directly using a motherboard i2c port such as the ones that have temp (and sometimes IR) sensors.

For the Duel nature sculpure, I wanted to have a ‘breathing’ pattern where all the LEDs vary in brightness in a natural/organic way. A good example is the ’sleep indicator’ LED on recent Macs/Powerbooks. (There’s even a patent!) The problem is that, while the patent claims its a simple sinusoid (see the patent for the image), programming in a sinusoid doesn’t look nearly as good. So I decided to get the real waveform with a kludgy reverse engineering attempt:

I used a MIDIsense instead of a simple voltage divider because I want to extract the absolute LED brightness pattern and a photocell voltage divider acts ‘inversely’ (well, 1/R) instead of linearly (ie, just R). (The MIDIsense has an opamp to linearize the resistive sensor output)

There it is! There is a bit of ‘noise’ on the peaks because I’m picking up some of the PWM artifacts through the diffused white plastic.

OK so boards came in, and there’s 80-100 to be assembled. They’re pretty simple boards: 1 8-pin micro, 3 resistors, 1 capacitor and 2 4-pin header plugs. Since it takes a long time to solder, I designed the board for mass-manufacture: surface mount parts!

Eventually everyone needs to make a lot of PCBs (at home), the best way to do this is to use solder paste and a reflow oven. Since EYEBEAM has a laser cutter I can use it to make a screening stencil and a registration frame. (You can also buy stencils from your 4pcb.com and probably a bunch of other PCB manufacturers) Then it’s super fast to make tons of PCBs. Just silkscreen on solder paste (available at digikey), place the components, and bake!

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Last weekend I found an hour or two to relayout the PCBs to fit into the square tubing better. The boards are thinner and theres a tab below the microcontroller so you can grab it with a pair of pliers without damage.

There’s also a white silkscreen square to write an address to identify each PCB (since they’re addressable)

Then I checked the gerbers with GC Prevue and sent them off to 4PCB.com tuesday afternoon. With 2 day turn and overnight shipping that means they arrive Friday. Since it’s Kate’s first order with them, she gets $500 off the order… Basically we pay for shipping ($50).
Tomorrow I have to solder up 80 Duel Nature PCBs (maybe try out making silkscreens on the lasercutter)

(images (c) Kate Raudenbush)
I’ve been spending the last month on-and-off working on this exciting sculpture from ultra-talented Kate Raudenbush, who designed and is fabricating the main part of the 90′ sculpture. It is made of 240 ‘wings’ of 4′ x 8″ plasma-cut steel sheet and mirrored red acrylic. At the tip of each wing is a red LED.

(Starting the project…)
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