Automatic Watering Controller

A cheap WiFi watering controller costing 40 yuan that can control solenoid valves or water pumps to switch water flow, and can integrate a soil humidity sensor for automatic watering

Completely relies on Home Assistant and ESPHome, with no physical buttons, interaction is only possible via HA's web or mobile application. The enclosure has no exposed ports, (hopefully) providing some water resistance

Features

Without relying on a humidity sensor, you can use HA's built-in automation features for timed watering, similar to commercial controllers (except the connection between the controller and HA must not be broken). Furthermore, by integrating a weather forecast plugin into HA, features like not watering on cloudy or rainy days can be achieved

Accessories

If you are in mainland China, clicking the price links will directly take you to Taobao/Pinduoduo, these are the cost-effective links I purchased from at the time

• DC 12V solenoid valve (11 yuan). Be sure to choose a normally closed type to prevent flooding the flowerbed in case of control part failure

  

• ESP32C3 development board (10 yuan)

  

• 12V to 5V step-down module (2.2 yuan)

  

• 5V relay module (3.8 yuan). Also ensure wiring to the normally closed terminal to prevent failure

  

• Temperature and humidity sensor (3 yuan). Only for measuring air temperature and humidity, optional. AHT20

  

• 12V power supply (6 yuan) arbitrary, 1A is enough. You can buy a used dismantled router power supply. The DC female connector should be purchased according to the power supply specifications or directly soldered in place

• Soil sensor (2.5 yuan). Be sure to choose a capacitive type, corrosion-resistant. Seal the component part with 704 silicone rubber, and seal the PCB side of the soil insertion part with AB glue to prevent water seepage

  

• Silicone wire/electronic wire (1 yuan). The enclosure volume is made relatively compact, so soft silicone wire can be used for easier installation
• Several M2*8 countersunk self-tapping screws (1 yuan). If you have built BMUC, these are its enclosure fixing screws

The total above is approximately 40 yuan

• Irrigation kit (28 yuan) for reference only. I bought 8/12 tubes with irrigation drippers from Taobao. The kit comes with a 4-point inlet pipe adapter, which can be directly connected to the solenoid valve outlet. If your faucet has a 4-point thread, it can also be directly connected to the solenoid valve inlet. If extension is needed, you can buy a toilet inlet extension pipe (female on both ends)

  

Installation

Firmware configuration: https://github.com/krrr/esphome_va/tree/main/watering

Deploy ESPHome using Docker, then upload the configuration to flash the development board. The first time requires wired flashing, subsequent firmware updates can be done wirelessly

For the first time, you need to calibrate the humidity sensor according to the comments in the configuration by burying it in completely dry soil and in water, and noting down the raw voltage readings