Capacitive Soil Moisture sensors with Nodemcu-ESP32, ESPhome, MCP3008 ADC, Pinotech soilwatch 10

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All links to Hardware, Software and reference docs are here. (I’m not allowed to have more than 2 links in this post)

To automate my Opensprinkler setup I settled on using a soil moisture sensor a while back. I tried a Vegtrug (Bluetooth Soil Moisture sensor ) and found it going through a new CR3032 battery every few months. I had a raspberry pi reading the BLE data and pushing it via MQTT to HA.

Hardware
After some research of wired systems I settled on a NodeMCU-ESP32 (though an ESP8266 would have been fine too) and a capacitive soil moisture sensor from Pinotech. I also ended up using an MCP3008 for the Analog to Digital readings as the ESP32 ADC’s were quite noisy.

Software
I planned to use Tasmota though couldn’t get the ESP32 to boot, I suspect the model I chose is not supported yet. I was then pleasantly surprised by ESPhome and how easy it was to get going, which is what I settled on.

Reference "docs"
For reference here is the ESP32 pinouts and the youtube clip of wiring up the MCP3008. Also the wiring diagram for the MCP3008.

Here is how I wired it up:

2021-08-12 21.45.37
2021-08-12 21.45.374016×3008 1.11 MB

And here is the esphome config:

esphome:
  name: moisturesensors
  platform: ESP32
  board: nodemcu-32s

spi:
  clk_pin: GPIO14
  miso_pin: GPIO12
  mosi_pin: GPIO27
  
mcp3008:
  - id: 'mcp3008_hub'
    cs_pin: GPIO13

sensor:
  - platform: mcp3008
    update_interval: 5s
    mcp3008_id: 'mcp3008_hub'
    id: garden_moisture_1
    name: "Garden Moisture Sensor 1"
    number: 0
    accuracy_decimals: 2
    filters:
      - calibrate_linear:
          # Map 0.0 (from sensor) to 0.0 (true value)
          - 0.08 -> 0.0
          - 2.91 -> 100.0
      - exponential_moving_average:
          alpha: 0.1
          send_every: 5
    unit_of_measurement: "%"
  - platform: mcp3008
    update_interval: 5s
    mcp3008_id: 'mcp3008_hub'
    id: garden_moisture_2
    name: "Garden Moisture Sensor 2"
    number: 1
    accuracy_decimals: 2
    filters:
      - calibrate_linear:
          # Map 0.0 (from sensor) to 0.0 (true value)
          - 0.08 -> 0.0
          - 2.91 -> 100.0
      - exponential_moving_average:
          alpha: 0.1
          send_every: 5
    unit_of_measurement: "%"
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