I’ve been there, and let me tell you, it was not fun. But everything changed when I switched to the Rachio smart sprinkler ...

Ok, software done; on to the relay controller box! [danman]’s sprinkler system has four 12V AC valves that need wrangling, and no data cables, necessitating the wireless setup. Initially ...

The brains of the operation is handled by a Moteino, which is a Arduino compatible micro controller board with WiFi on board. In order to interface with the sprinkler system, an interface PCB is made.