BL4.EU, or Blinkenlights for Europe, is an open source art project,
or experiment, intended to draw the attention of clever and curious people with an open mind.



You may have got here after discovering a mysterious lightsource somewhere IRL, sending out a "secret message" consisting of long and short flashes of light. This made you curious and since it reminded you of good old morse code you decided to check it up. After decoding the message you may have got a text something like this: "WWW.BL4.EU" Offcourse you entered that text as an URL to your web-browser and that´s why you are here now! Well done my friend! Now you can settle with this and feel good about your achievement. But why not take it one step further by becoming a member of the BL4.EU project? You can help with the development or by deploying light-beacons. You can actually have your own webpage pointed out by your beacons.
The concept of BL4.EU may be suited for individuals,
for geocaching but also for marketing.

Here´s a video clip of a beacon based on ATtiny44 with the V1.3 software. (LED used as light sensor, battery saving sleepmodes and altered morse code timing for easier reading. There´s a tiny glitch when I insert the battery, making the first "W" look like a "U". Also note that I now use the morse code special character for "." instead of spelling it out as "DOT" and using extra pauses. These modifications makes the message a lot easier to read.


The inventor of BL4.EU also have the ambition of handing out a number of rewarding prizes to those who decode a BL4.EU beacon and properly describe it´s location in the real world. This is however a non-commercial project on hobby basis so the number of rewarding prizes is unfortunately limited.


The beacon messages are based on standard morse code but the timining have been altered to a better fit for messages sent by light. A skilled morse operator can copy an audible message of about 40 words per minute but messages transmitted by light are much slower to read due to persistence of vision. It is however a truly minimalistic way of sending a message.

A BL4.EU light-beacon may be as small as a keyring LED-lamp, containing only a battery, a microcontroller and an LED. By using the single LED as a light sensor the unit is kept in sleep-mode during daylight. This feature also make it possible for a non-tech user to program their own morse code message. Such a beacon can operate for months without replacing it´s tiny battery. There´s offcourse no upper limit for how advanced or powerful a beacon can be built.

Since the transmission of a message has to be slow it should contain a minimum of characters. At least in the beginning of this project, before the concept gets well known, it is best to send "WWW" before the actual website URL. This will make transmission take longer time but also to make it obvious what it all is about. The true power of the concept is that individual messages can be created to point out a specific webpage. A complete message pointing out an individual sub-page may be: "WWW.BL4.EU/PX".
To get there, enter "" in your browseer.


To read detailed tech-stuff about the software/hardware and to download the BL4 beacon sourcecode, click here!



The whole concept of using a light-beacon to give out a morse coded website URL is provided freely to the public by it´s inventor John Ahlberg. All that is required is to remember who came up with the idea and give the inventor some credits for it. It´s not wrong to make money out of the concept in general or BL4.EU in particular, but attempting to apply for a patent or claim copyright definitely is. Information wants to be free and BL4.EU is just about that,
-free information in the open air for anybody to read!

Anyone is free to copy both the hardware, program code, the purpose of the website etc. BL4.EU have the intention to hand out wiring diagrams, bill of material, sourcecode and hex-file to make it easy for other electronics DIY:ers to build their own light-beacons. It man also be possible that the inventor can set up a small scale production for completely assembled units. While kept at a small scale, BL4.EU will also provide a small space for a personal webpage to the individual light-beacon messages.



The inventor of BL4.EU have spent many hours designing minimalistic projects around the AVR microcontrollers. "What may be the absolute minimum for a user interface" he have often asked himself and realised that a single LED offers a lot more complex communication than simple on/off status. The fact that the single LED also can act as a light sensor open up the possibilities for complex bi-directional communication. While working with a project family named "Cyclops Serial Timekeeper" - a minimalistic wristwatch - the good old morse code became a source of inspiration. The CST is not based on morse code but share the same "dit and dah´s". So why not try sending something both more basic, yet more interesting than actual time?

The idea of giving out a short website URL in a "mysterious" or unusual way in real life have been in the inventor´s mind for years but it was the Cyclops Serial Timekeeper that gave the idea of the perhaps most interesting way of doing it.

The website name "Blinkenlights for Europe" is inspired by the term "Blinkenlights" which derives from the last word of the famous blackletter-Gothic sign in mangled mock German that once graced about half the computer rooms in the English-speaking world. Blinkenlights is a hacker's neologism for diagnostic lights on old mainframe computers and modern network hardware.
Visit Wikipedia to read more about Blinkenlights!



Within the BL4.EU-concept is the posibility to have a "mobile app" that can record and decode the messages from a ligth-beacon via the cellphone video camera. Unfortunately, the inventor of BL4.EU don´t have the skills needed for creating such an application that is the key to take the concept from something of a geeky adventure to the wide public. By implementing a mobile application to the concept, a function similar to that of the popular matrix barcodes may be possible. If you have the proper skills for creating such a smartphone application you are warmly invited to take part in this project!
-It´s all about the glory of creating something realy different!



The creator of this website, John Ahlberg, disclaims any responsibility for the deployed light-beacons pointing at this website. The full responsibility for any light-beacon is taken by the person who placed it. Please carefully consider the consequences of each placement!

The idea of deploying tiny light-beacons may have some similarities with "LED-throwies" and it´s important to consider legal aspects before placing them. Take into account environmental issues, traffic safety, and individuals. Batteries may contain poisonous chemicals and people can get annoyed or distracted by the flashing light. Putting a light-beacon at a public place may be considered littering by law.
Help us make BL4.EU become a big phenomenon but please do it in a clever and responsible way!




Text and concept by John Ahlberg, Stockholm, Sweden 2012