Project Description
Unfortunately, the automated sprinkler controllers sold in hardware stores are simply fixed-function microcomputers programmed to turn on relays that activate your sprinkler valves at specified times. Few people install the available rain sensors, which would let the systems avoid the public stupidity of watering while it rains, but even with a rain sensor the systems are too simplistic to detect and eliminate the wet or dry spots. The duration each valve stays on is fixed unless you adjust the program yourself for changing conditions and soil moisture.
Fat chance. If you were going to be that meticulous, you could just turn manual valves on and off yourself.
On the other hand, sensors exist that can tell you how much moisture is in the soil — for example, visit the garden shop at your local hardware store and find the watering meters, the ones that indicate how wet the soil is. The ones we can find are usually cheap and not very durable, but imagine what you could do if you hooked up similar sensors to your PC. Combine the sensors with some relays to control the sprinkler circuits and software to control the system, and you could dynamically control how much water your garden gets.