Google Calendar Interface for Your Internet of Lawns

If you live somewhere where summers are hot and dry, you can instantly tell which homes don’t have automatic sprinklers installed. Or they may have them installed, but like the blinking “12:00” on that VCR of yore, the owners may not have mastered the art of programming the controller. To be fair, the UI on most residential irrigation controllers is a bit wanting, which is the rationale behind letting Google Calendar tell your sprinklers when it’s time to water.

Granted, someone who is mystified by setting a digital clock is not likely to pull off [ClemRz]’s build. It’s still pretty simple stuff, though, centered around an ESP8266 as it is. And calling the result an “irrigation system” is a little bit of a stretch, given that it could only support a single zone with a solenoid valve harvested from a defunct sprinkler timer. But as a proof-of-concept, or to water a small area, it hits all the marks. The ESP8266 drives the latching solenoid valve through an H-bridge chip after reading your Google Calendar and looking for upcoming events to open or close the valve. The Google Script and the ESP8266 code default to failsafe so that a mistake doesn’t leave the valve open and run up your water bill or drain your well.

It’s easy to see how this can be expanded to control a multi-zone irrigation system and support a smartphone UI for instant control of the valves. Overrides based on weather forecasts would be a nice feature too. Or you could just read the soil moisture levels directly with backscatter sensors.

8 thoughts on “Google Calendar Interface for Your Internet of Lawns

  1. I have a sprinkler system, but who can afford that, if I let it run as much as it would like to its ~500$/mo in water. I need to figure out how to use rain barrels to supply it…

  2. I think lot of people don’t realize how INSANELY POWERFUL a tool google scripts is.You can write code that runs entirely in the could, for free, and does whatever you want it to do. Not only can you make it hit any API on programableweb.com (there’s a Scripts API for making requests) but you have easy, free integration with everything from Gmail to GOOGLE TRANSLATE.

    Since google translate is now a paid service if you want to use it directly, I wrote a script which exposes the Scripts API for GT through a simple REST-ish API and let’s me translate anything I want for free anywhere I have an internet connection. (now working on an automatic manga/comic translator)

    I also made something like this last summer (but never got around to writing to HaD about it) where an ESP8266 would read a temp and humidity sensor, and do a POST to a script’s URL, triggering the doPost() method. The parameters were then extracted and logged with a timestamp to a google sheet.

    The only issue I’ve had is with google constantly changing their certificate fingerprint, since this is over https when talking to google scripts, and I haven’t figured out how to make the ESP ignore the fingerprint. Hopefully this will be resolved when the people behind the ESP libraries for platformio get CA Certs working.

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