Tinkerlog

Last week I invested some time to solder 64 Firefly boards. Only 2.432 solder joints later I was ready for some videos.

Every firefly acts completely autonomously, it has its own tiny controller, eye and luminary. They are all connected for power supply only.

Here are some different configurations.

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Often, when I am tinkering with a controller on a breadboard, I have to open up the according datasheet, only to look up the pinout. So I designed a simple page with all of of the pinouts that I use most. It has:

• 8-pin AVRs, ATtiny25/ATtiny45/ATtiny85
• 20-pin AVR, ATtiny2313
• 28-pin AVRs, ATmega48/ATmega88/ATmega168/ATmega328
• Arduino to ATmega mapping
• ISP header, 6-pin and 10-pin
• FTDI-cable

Maybe it’s helpful for others as well. You can download it as:

• micro-cheat-sheet.pdf
• micro-cheat-sheet.svg

If you like it, you will also like the Tod’s cool Arduino chip sticker.

Update 2010/01/24

The new version includes the pinout of the Bus Pirate. Thanks Philipp for the update.

Here is the second incarnation of a Braitenberg vehicle. This one is almost half of the size of the previous one and it is programmed to “love”. That means it sticks to the light source and does not try to overrun it, as the “aggressive” first one.

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This is another breadboard compatible header board, that I am working on. This one is for all 28-pin AVR devices, ATmega48, ATmega88, ATmega168 and the latest ATmega328. Component count is low and there is no voltage regulator on board. That makes it easy to power it from various sources.

As a bonus, this board is a hybrid of through hole and SMT components. It has two SMD LEDs under the hood. Great to learn how to solder surface mounted devices.

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The Arduino can talk over a wide range of networks. Ethernet, Bluetooth, Wifi, XBEE and GPRS to name the most known. I had a Telit GM862-GPS module laying around, unused for some time already. It has GPRS and GPS capabilities, both accessible with AT commands. So I decided to port some of my code to the Arduino.

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If you want to play some retro arcade games, you will install the amazing MAME and run your favorite ROM. One of my best-of-all-times is Bomb Jack.

But you have to play it with the keyboard. Bah!

Or an USB game pad. Better, but still — bah!

Nothing compares to real arcade controls. And with a bit of tinkering, you can get a tiny step closer to the real gaming experience.

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Jonathan asked me, if I would like to do a project with him on Braitenberg vehicles. After some research and reading the first couple of chapters in Vehicles: Experiments in Synthetic Psychology, I was hooked in. Here is the first version of a Braitenberg vehicle, powered with two RC-Servos and an Arduino as its brain.

Best of all, it needs no soldering, drilling or hot glue. And if you’ve played already with Arduinos, there is a good chance, that you have already most of the needed parts at home..

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Jonathan bought a 64pixels kit and modded it into a green version. The three solar cells, that he uses are rated with: 2.7 volts (open circuit) @ 15mA (short circuit). He writes, it works well in bright sun light. His desktop lamp shines with 60 Watts and that seems to work as well.

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In this post I will try to show, why it’s a good idea to use a current limiting resistor for an LED. And when it’s save to drive the LED without any resistor.

If you read about LEDs, you will notice that everyone tells you, that you need a current limiting resistor. But mostly they do not tell you why.

LED with current limiting resistor

If you look at a datasheet of an LED, you will notice that graphs shown are not linear. An LED is a diode, a semiconductor and behaves differently compared to a resistor.

If you apply a specific voltage to a resistor, you can compute the resulting current with:


I = V / R Example: I = 5 Volt / 100 Ohm = 50 mA


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I love Blinkenlights. And all kinds of other blinking and flashing LED stuff. I think, it’s already a form of addiction. When I ran across an LED matrix with square pixels, I thought it would be cool to build a small animated display with it. To keep things simple, the display is attached directly to the microcontroller the “Evil-Mad-Scientist-way”.

The display performs really well, the pixels are bright and the batteries last for over two weeks running non-stop. The microcontroller has 2 k flash RAM. That’s enough for three simple animations and a couple of messages.

If you want to see the guts, then follow me to the 64pixels howto.

And grab a 64pixels kit from the Tinker Store, if you want to build your very own.