last update:

I backed a recent Kickstarter project to allow Sabernetics to create and sell small I2C powered OLED displays – the small number of IO lines required by I2C makes it an excellent bus for embedded stuff, and I love things with blue LEDs so backing the project was a no-brainer :) The boards just arrived, so I decided to have a play by wiring one up to an Arduino and giving it a poke.

I’ve had a cacti server for some time, but I recently decided to experiment with collectd. In this post, I’ll talk about how I ported my CurrentCost monitoring code to work with collectd. What’s wrong with cacti? For a home user who just wants to monitor my router, power usage, and the odd arduino controlled thermometer, cacti is fine, but the limitations are fairly obvious: Cacti is buggy – really buggy.

In the last year or so there’s been a fair amount of coverage of the excellent Ubertooth project. Ubertooth One is an open source 2.4 GHz experimentation device, designed for messing with bluetooth, but with a lot of flexibility which gives rise some other very cool features, like spectrum monitoring. I installed the Kismet Spectrum-Tools on a Backtrack Linux box to play with, and thought I’d share a brief howto, along with some images.

The TinyAlarm came about because my brother needed a simple alarm for his drum practice garage - something which will scare someone away, but not go off all night, as he doesn’t live near it. I decided to use an ATTiny45 chip as I had some spare, and thought it was high time I wrote some proper (non-arduino) microcontroller code. Naturally, I decided to use avr-gcc (and friends!). Programming microcontrollers is mostly a matter of manipulating registers; having the correct datasheet for the device you’re using is absolutely essential, and knowing a little about bitwise arithmetic is very useful.

Last year (in my last post!), I had fun scanning for bluetooth devices on a busy road in Bath, UK (where I happen to live), so this year I decided to repeat the experiment. This year, instead of running btscanner, which logs results as a directory per device, I decided to go with running hcitool inq on my debian server, and catting the results into a text file. This unsophisticated approach has the advantages that I get timestamps along with my data, and generate less radio chatter (which was interfering with my wireless network :().