I’ve been playing with my spark module, which is based on the arduino and got to wondering if coupling it with the relay module would make for a good sprinkler controller.
What’s great about it is the built in wifi module. So this might make a great all in one device. I am starting to plan a central house “brain” controlled with a nexus 7 tablet. So being able to control my sprinkler system would fit very well with this vision.
I think you’ve covered the key components — microprocessor, WiFi, solenoid drivers (i.e. relays). There are other comopnents that OpenSprinkler has, but you may or may not need them, such as the 24V AC to 5V DC switching regulator (you dont’ need it if you are ok with using two separate power supplies, one for the microprocessor and one for sprinkler valves), real-time clock, buttons, LCD, microSD slot.