Irrigation controller using Openhab and the ESP8266 module
Hardware
Raspberry Pi running Openhab
NodeMCU ESP8266 development boards (frontyard and backyard zones)
8-channel relay boards
24VAC transformer
5VDC power supply (USB)
System
ESP8266
Controls sprinkler valves via 8 channel relay board
Does not execute sprinkler timing logic, scheduling done in Openhab
Receives open / close commands from Openhab
Provides status updates to Openhab via MQTT
Has "watchdog" timer limiting runtime of any zone, preventing lawn flooding if comms are lost
Only one zone can run at a time
Openhab
Allows for manual on / off via sitemap
Provides (4) programs
Provides weather compensation, via wunderground (or weather binding of your choice)