Irrigation Controller Uses Google Calendar To Make Things Easy

Irrigation controllers have been around for a long time, often using similar hardware inside that would be familiar to the average maker. However, many of the products on the shelf at your local hardware store can be quite expensive for what amounts to a microcontroller, display, and relay board. [oscillatory] had such a rig, but wanted to bring it into the 21st century, IOT style.

The existing Holman irrigation system consisted of a control box, hooked up to four solenoid valves controlled by relays. [oscillatory] decided that replacing this with something fancier would thus be straightforward. A relay board packing an ESP8266 was sourced, and flashed with the Tasmota firmware. This was then hooked up to run off the Holman’s 24 VAC supply via a CCTV power supply, allowing the new controller to be run in parallel with the existing hardware, just in case. Scheduling is then controlled by Google Calendar, in concert with Home Assistant.

[oscillatory] now has a watering system that can be controlled over the web, and without the need to install any custom apps. Simply creating a calendar entry is enough for the system to spring into action. We’ve seen others use a similar approach, too.  It’s a great example of using off-the-shelf parts to whip up a useful custom home automation setup!

16 thoughts on “Irrigation Controller Uses Google Calendar To Make Things Easy

    1. Hi Thorsten. I only really use the calendar for scheduling watering events in the future or on a recurring basis. If I want to quickly test something right now, it’s easy to turn the stations on and off through the Home Assistant WebGUI (provided I have my phone), or issue voice commands via Google Home/Assistant. If that is too hard, then with this setup I can also turn stations on and off using the old irrigation controller, which runs in parallel with the new one I built.

  1. I’ve never used google colander but I would take a guess that it is infinitely easier to schedule an event than the woeful UI that comes with most sprinkler systems.

    Nice addition

  2. Tasmota is the bomb with Home assistant. It would be really easy to set up the timer in Node-Red, you could also set up automation that checks the weather for precipitation via Darksky API that could override the schedule.

    1. Yes, I agree Troy; both Tasmota and Home Assistant are amazing. I’m continually impressed by what they can do. I haven’t experimented with Node Red yet, and have been writing my automatons manually. I do have a darksky feed set up in Home Assistant though; I just need to decide on an appropriate algorithm to control the watering times.

  3. I need a different kind of irrigation controller, one that only drops out a live AC cable strung around the garden or embedded in the soil about every 3 or 4 days for half an hour.

    I suffer from “helpful” people who will overwater the bijazuz out of anything I plant. I have actually had to ban anything from being planted. Sure call me the ass, but ain’t nobody volunteering to pay the $200 they put on the water bill, replace all the soil that getting washed out, dig all the weeds that are enjoying the copious runoff, or even replace foundations of buildings they’re likely to wash out. And again you’re all going, “but what’s the harrrrrrrm, let them help grow things if they want tooooooo” NO, you’re seriously not getting it, everything is ruined, the tomatoes, cucumbers etc split and burn, the brassiccas and lettuces bolt and burn, what they’re doing is not help, it’s anti-help, nothing useful is produced.

    1. always a fear for any google service, ANY… sometime in the dystopian future… okay a MORE than inevitably dystopian future… “Google sh*tcans search, says predictive algorithms are now good enough to serve results as paid ads 5 seconds before you need them, without requiring text input.”

  4. Last month I built mine with a Omega2. Used a 24 volt transformer and built a 5v power supply to control the low voltage. From there it went from the gpio to relays. I currently have Cron setup to run my system on Wednesdays and Sundays. I also got the Hunter rain sensor to work as well, this just makes a relay to open that kills the power to the level shifter circuit. I also have the Omega2 running a web server so I can use bash scripts over php to manually control the solenoids.

    1. Sounds like a cool project TCPMeta. I’ve been considering trying to get the rain sensor working with my system as well, bit the sensor is a bit unreliable, and I think there might be more value in me trying to get an ESP8266 set up with a tipping rain gauge instead. That’s a project for another day.

  5. I built mine with ESPeasy on a Wemos D1 Mini Pro. Just hooked up 6 GPIOs to six relays and wrote some simple code in the Rules engine.

    I’m currently triggering it with Domoticz, but anything could be used.

    I included a local timer in the rules so that the GPIOs will be turned off after 45 minutes if there is no further interaction from the scheduler. Also, enforcing that only one relay can be on at any time is done locally too.

    The power supply is a 24Vac plugpack inside an exterior-grade housing. This powers the relays, and a 24Vac to 5Vdc module powers the micro.

    This replaces the PoS Hunter controller, which has the world’s worst UI.

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