Lambertus Gorter Gives a Low-Cost Robot Mower a Home Assistant Overhaul with an Espressif ESP8266
Attached to the battery pack and tapping into the rain sensor, this clever add-on board delivers remote control and monitoring on the cheap.
Developer Lambertus Gorter has taken a low-cost robotic lawnmower and given it an Espressif ESP8266-powered upgrade, connecting it to Home Assistant for monitoring and remote control.
"This project was made for my own Parkside PMRA 20-Li A1 mower, but it might just work with your mower as well," Gorter explains of the build. "From Home Assistant (or any system supporting ESPHome) you can keep track of your mower's status, command it to mow and set the mowing time. This project hooks into the (analog) rain sensor of the mower. It will also detect whether the mower is moving and whether the charger is connected."
Robotic mowers are increasingly popular for their ability to take the drudgery out of lawn maintenance, automatically keeping the grass trimmed to your preferred height. While there are plenty of devices on the market with all kinds of smarts, those at the cheaper end of the spectrum tend to be basic self-contained systems — which is where Gorter's project comes in.
A perfboard add-on comprised of a low-cost Espressif ESP8266-based Wemos D1 Mini development board, a TDK InvenSense MPU-6050 accelerometer breakout, and a DC/DC converter taps into the mower's electronics, mounting directly to its battery pack. A wire runs from the microcontroller to the mower's built-in rain sensor through a 270 Ohm resistor — using a faked positive rain signal to control whether or not the mower is running.
Once connected to Home Assistant, the add-in board allows for monitoring of the mower's status, whether or not it's in-motion, and its battery voltage and charging status. Mowing can also be manually triggered, and the mowing time configured as required. "Timekeeping is performed on the mower itself," Gorter explains. "This ensures that the mower always returns when the time is up, even if Wi-Fi is out of range or when Home Assistant is down."
A circuit diagram and YAML configuration file for the project have been published to GitHub under the permissive MIT license.