Just 9 days to go until Pachube hosts the first global Internet of Things Hackathon - a 24 hour event commencing in London and with sister events happening in several different countries.
In preparation for the event, to provide suitable web connected microcontroller hardware - I am putting together a small batch of Nanodes - a low cost target board designed for Internet of Things sensor applications and built to be compatible with Arduino technology.
For under £20, the Nanode offers a platform to develop intelligent sensor network node applications, capable of communicating via the Internet and Pachube or locally with other nodes on a low cost wired serial network. It can act as a web server, a web client or communicate with other web connected Nanodes using a publisher/subscriber messaging protocol.
Nanodes can also be connected together using a simple "multidrop" serial bus - made from low cost telephone extension cable. This carries power and data and allows Nanodes to be distributed around the home for tasks such as home heating control, home automation and energy (electricity and gas) monitoring.
Slave Nanodes can be cheaper still, by not fitting the ethernet components, yet still communicate with a master device connected to the internet.
Last summer, a pair of early prototype Nanodes successfully communicated with each other using Pachube as a publisher/subscriber service for short messages. A message left on the Pachube feed by one Nanode, would be picked up by a second Nanode which subscribed to that feed, decoded and used to perform some local action - such as switching a relay or changing colour on a RGB LED lamp.
For the example of the RGB LED, the publisher would send a short message consisting of comma separated arguments to Pachube b,1,255,255,255 This would be interpreted by the subscribing Nanode as a command to set the brightness (b) of the red, green and blue PWM channels of the LED (number 1) to full brightness (255) resulting in a white colour.
The publishing Nanode might have a temperature sensor connected to one of its analogue inputs, and change the arguments of the brightness command according to the temperature. Any Nanode subscribing to this feed, and equipped with the RGB LED would change the colour space accordingly in response to temperature.
This is a trivial example of how two Nanodes can communicate via Pachube. The publisher pushes the message, with no regard to whether it is received or acted upon. It might be possible to use a second Pachube feed as a "back-channel" to allow the publisher to be informed if the message has been received and acted upon.
At the Hackathon it is hoped that we have 5 pairs of Nanodes distributed around the country at various sister events - Nottingham Hackspace, OpenEnergyMonitor.org, North Wales, London Hackspace, Thatcham and at Pachube's own event.
Anyone with an Arduino and NuElectronics Ethernet Shield, could participate with nearly the same firmware. Following that, the intention is to make a batch of 100 boards and offer them at discount to interested parties. Bare boards will be offered at £5, and complete kits for under £20.