Fully automated sprinkler system

[sbj_ee]

Before I worked on my home security system, there was another house related item that I addressed.  My yard is 1.5 acres and manicured with 15 sprinkler zones.  It had a sprinkler controller that was microcontroller based and one would be turning a dial and pushing buttons to change zones, etc... Then I'd see it raining outside and the sprinklers running and it was driving me batty. So, I decided to design and implement an intelligent sprinkler controller.  At this point, I had no idea how the sprinkler system even worked.

It didn't take me long to figure out the sprinkler controller was simply controlling 24VAC power going to solenoids that opened a valve. I could do this with a Raspberry Pi and some relays. I attached some photos of my quick prototype and a photo of the final design in the enclosure after I created a PCB.

The magic sauce was really in the software design.  I queried nearby airports and the National Weather Service to get the weather information.  Then I'd base run decisions on how much rain has occurred, if it was raining, or if it was expected to rain.  I also considered the temperature and wind.  I also wanted the sprinklers to complete at sunrise, so I calculated the sunrise for my latitude for every run.  Then to top off the automation... I live in Wisconsin and the sprinkler system needs to be winterized, so I had it email the sprinkler company to schedule the winterization the last week of September.

I learned a lot doing this project.  For example, the municipal airport about 3 miles from my house is truly inaccurate with their weather station. Most of my software development was during the Winter and I'd pick some region in the Southern U.S. for testing. Prototyping with whatever you can get your hands on is valuable.

[Aaron Moncur]

Stephen, this is so awesome! I bought a system that does this for my (much smaller) lawn, but you engineered one yourself! So impressive. Seeing these super cool projects you've shared (thank you for doing so, by the way) makes me wonder if you'd consider being a guest on our Being An Engineer podcast to talk about your journey as an engineer - what do you think? You can message me privately if you're interested.