The sonic bikes use sonicbike software system, a development by Tom Keene on the original swamp software system that was made in 2008 (more below).
The sonicbike system was created in 2015 for Finding Song Home when the sonic bikes moved onto the Raspberry Pi2 platform,. This was done so as to enable more interaction possibilities in the future, that the Raspberry Pi2 is capable of running.
A fully working version of the current software can be found on github: https://github.com/sonicbikes
In 2012 the swamp system was redesigned and developed by Dave Griffith for The swamp that was… when the sonic bikes were swapped onto Beagleboards. It ran on Beagleboards with an adapted version of the Ångström linux distribution. The software is written in Lua and periodically polls the GPS device for location, looks up where it is on the map and triggers samples to play based on it's previous state. The map is stored in JSON format, as exported from the map tool and contains zones, which consist of names, polygons and sample parameters. The code is available here under the GPL licence. The build & development of the original 'swamp' system(2012), built on a Beagleboard, is at https://gitorious.org/swamp-bikeopera
In 2013 swamp was completed for performance by Dave
In 2014 the Beagleboards were no longer being sold and so we swapped to the Beaglebone Black for 2nd ward - a bicycle opera. We continued to use the swamp system on the Beaglebone blacks.
In 2015 Tom developed the swamp system into the new sonicbike system that we currently use, in order to pave the way for future sonic bike interaction. Tom found that the Beaglebones weren't capable of supporting new software and so the sonic bikes were swapped onto Raspberry Pi2s instead. This was done for Finding Song Home during an interaction residency at Q-02. The sonicbike system does also work on the Beaglebone black, the software repository also contains full instructions for getting up and running on a Beaglebone Black too.