I have an expanding network of water related sensors, via arduino (Moteino) to a central RPi. I have sensors for water level in my cistern and for the house water pressure (on a well). Your product would seem a natural extension for a more sophisticated irrigation controller. What approach would you suggest for getting this other data fed to your controller to be used with additional control logic (switch off from cistern as it’s about empty; don’t use house water as Pressure is too low – other usage in place, etc)? I also have a couple of flow meters ordered to monitor appropriate flow rates. I gather there is an option for a radio (using RFM69 on current setup). Can your controller receive input data via its ethernet connection? A novice but learning arduino/rpi hacker.
The easiest way to get started, without modifying the firmware, is probably to make use of the available HTTP GET command to send control commands to OpenSprinkler. Please check the PDF in this section of the user manual for a complete list of HTTP GET commands: http://rayshobby.net/?page_id=730#httpget