encounters with electron•ics / by flabbergast


For the impatient: the project is hosted on github here: node-llap.

Intrigued by the cheap and easy-to-use radios from Ciseco, I set out to make a sensor data collecting station out of my Raspberry Pi. The goal is to have the Pi act as a central unit, with sensors reporting to it, and the Pi serving the data in a visually pleasant and easily comprehensible way over the net. Plus, it should be reasonably easy to hack, so that modifications to suit particular needs are quick.

I know that there are numerous projects like this on the internets by now, but, well, I wanted to make one myself so that I understand completely what is going on inside and can modify it to my needs without having to dog through someone else’s code.

On the hardware side, I’ve got my Pi, one URF unit (that’s a radio-to-serial-over-USB, ideal for the computer end of the development setup), one XRF radio mounted on a custom PCB with a thermistor and a coin battery (‘the sensor’ transmitting periodically sensor readings over the radio).

For getting off the ground I started off with the Node-LEDS project. So the whole thing is running on a node.js server. More technical details are explained in the readme of the project: node-llap.

Update 2013-11-26

I’ve run into one technical problem, which is not likely to affect anyone else: apart from node-llap, I also run mpd on my Pi. It turns out that whenever mpd is actually playing music and something opens/accesses the serial port created by the URF, kernel oopses. Bummer. So I need to receive llap messages on the Pi in a different way: XRF or Slice of Radio directly to Pi’s serial port.