Stephan wrote in to let us know how he’s building a connected light project through Europe with Fona at the re:publica web conference:
We want to support the beautiful motto of re:publica #9 „Finding Europe“ with the project „Finding Europe with lights“. 28 light-sensors equipped with a mobile internet connection will be sent to 28 hosts in the 28 european member-states. You will be able to follow their path to the destination because they will send GPS-coordinates while on their journey. When re:publica opens it’s doors on May 5th, you will find 28 hand-made lamps on the ground that are connected to these sensors. These lamps will show the colors of Europe. If the sun is shining in Portugal, the lamp will shine bright, if France is seeing the sun rising later than Bulgaria the lamp will show that difference to early visitors of the trade-faire.
It can hook up Adafruits Fona and talk to it and also turn it on and off etc. On the right hand side it has an additional circuit which works as an external watchdog as i figured out that the internal one is not reliable enough to operate the board autonomously in the wild. You can read the considerations behind that guy in this earlier post, but the general principle is easy – if the board turns on the 555 circuit gets also turned on and the capacitor starts to load. If the operation of the board would take too long the 555 would switch and trigger the reset-pin of the Arduino. If everything goes fine the Arduino turns off the 555-watchdog before going to sleep.