Today I received my copy of The Best of instructables, Volume 1. It’s a compilation of the best DIY projects found on the instructables site. Full of fantastic things, that you can do yourself. Flipping through the pages makes you want to go to your workbench and try them out.

And on page 111, tataaa, the Programmable LED.

I have to admit, I am a bit proud. Thanks instructables and Make for choosing my project.

After a while some users at Instructables began to rebuild, modify and improve the Programmable LED. Ok, that’s what Instructables is all about, to share and to distribute, but it was astonishing to me, how it worked.

This is a gallery of these derived and improved versions. Kudos to all the builders.

zzag

zzag did a great job with his version. Looks a bit steampunky to me. Very nice. Gary added a method to calibrate the LDR sensor, thanks for that.

Visit the comments for more images.

Tristan Roddis

Tristan made wearable computing for LEGO people. What a fantastic idea. He modified the source to record longer sequences. Thanks.

For more information visit his blog post about wearable computing or his Flickr set. He even did a video.

Sam

Sam (samirsky) did this mod to his Mini Robsapien. Great!

David Chatting

Dave was the first who built his version and posted pictures. And he found some bugs in the instructable, thanks for that.

The second version uses the button cell as a mirror. And here are his blog posts.

Dr. Skippy

Dr. Skippy ported the version from AVR to PIC microcontroller and used a SMT version. Really small. Really nifty.

Visit his blog for more details and source code. And don’t miss his complete doc as PDF.

Tod E. Kurt

Tod took the idea of a programmable LED to a new level. He sees them as Smart LED Prototypes, which means, you can add sensors and controllers and combine them into a single unit. This unit could then be programmed to e.g. light up in green when temperature is above 30°C. Wow.

Tod has also done two versions as PCBs. They look very promissing. Tod and ThingM are planning to have them in production and at Sparkfun within a month.

A good writeup of the smart LED idea is in his slides for the sketching07.

Alex

So this was my first version.

If you did a Programmable LED yourself, than let me know. I would be glad to add your pictures and links.

Links

• Programmable LED
• Programmable LED at Instructables, more detailed.

The rule behind this is very simple. All fireflies have nearly the same frequency for their flashing, but their phase is shifted. If a firefly receives a flash of a neighbour firefly, it flashes slightly earlier.

This circuit simulates fireflies with small microcontrollers.

A single Firefly

The board consists of 25 fireflies. Every single firefly is self contained, there is no over-all controller. A single firefly consists of:

• ATtiny13 microcontroller, 1k SRAM, 64 bytes RAM
• Light Dependant Resistor (LDR)
• LED
• 2 resistors

The circuit is the same as for the Programmable LED.

The complete Board

Assembling 25 fireflies on a prototype board is easy. Harder is to get the right distance between all fireflies. It has to be close enough to let one firefly influence another, but not the whole group.

The LEDs I used emit the light mostly straight up. So a kind of reflector is needed. I used a piece of paper which is located 5 mm above the LEDs. For the next version I would take LEDs with a wider light emitting angle and use a kind of diffuser, as proposed by Tod for his Smart LED Prototypes.

Here is a video. It is a bit dark as my camera is not very suitable for this.

• Synchronizing Fireflies on Instructables. That is a more detailed step-by-step instruction with more pictures, sourcecode, etc.
• More on the algorithm can be found here:
  Firefly Synchronization Ad Hoc Networks

The idea is to make the LED blinking sequence reprogrammable. This reprogramming can be done with light and shadow, e.g. you could use your flashlight.

How is it done?

It consists of an LDR, an LED and a tiny microcontroller. I used a ATtiny13v which is able to run with 1.8V. That makes it easy to power it with smallest batteries or even fruits.

Prototyping

All components can be easily used on a breadboard. Be aware, that you will need a separate programmer or an ISP adapter to program it.

The final version

The final version is powered by a CR2032 cell. It should have enough power for at least two weeks, depending on the light sequence it plays.

I have done a step-by-step instructable here.

Here are some responses to the instructable

• Reprogrammable LED Learns and Plays Back Light Sequences (MAKE)
• Smart LED Prototypes
• Dave Chatting’s version of the Programmable LED
• Dr.Skippy’s version, PIC based