ESPHome firmware for the LILYGO T-Higrow WIFI Plant Sensor

How to install esphome to the lilygo T-HiGrow wifi plant sensor

You can use the blue button “connect” below to install the pre-built firmware directly to your device via USB from your web browser.

Afterwards you can set up Wi-Fi and add your device to Home Assistant from this same web page. Make sure that it is on the same network as home-assistant is and it will connect automatically with the api of the plantsensor.

To enable the flower-card in home-assistant:

1. Get - OpenPlantBook API
2. Install HACS
3. Install Homeassistant Plantbook intergration
4. Install Homeassistant Plantbook api intergration
5. Install Homeassistant Flower card

How to calibrate the lilygo T-HiGrow wifi plant sensor

First make sure you can flash your current sensor, otherwise you cannot continue. Start with opening the plantsensors.yaml file to change some settings.

Find the following comments:

# comment when calibrating

Place a comment in front of that line. For example:

unit_of_measurement: '%' # comment for calibration

will become:

# unit_of_measurement: '%' # comment for calibration

Do this for every line you find.

Find the # uncomment for calibration line and change it. For example:

# unit_of_measurement: "V" # uncomment for calibration

Becomes:

unit_of_measurement: "V" # uncomment for calibration

Now do this for every line you find in plantsensors.yaml.

After you did this, it is time to generate the configuration again, for this you need ESPHOME. You can do this in the addon in home assistant or, much quicker, on your own PC with the following command, but first insert your sensor with USB to your PC.

esphome run LILYGO-T-Higrow-ESP32.yaml

This will compile and flash the file. While it is compiling, get some glass with water. After you have flashed the file you will see a log output. This is great! We need it for the measurements. Make sure to clean the sensor and make sure it is totally dry as we need a dry measurement first.

After drying the sensor look in the log file for the measurements, look for the following 2 lines:

[15:46:50][D][sensor:127]: 'lilygo_higrow_plant_sensor Soil Conductivity': Sending state 0.07500 V with 2 decimals of accuracy
[15:46:46][D][sensor:127]: 'lilygo_higrow_plant_sensor Soil Moisture': Sending state 2.83500 V with 2 decimals of accuracy

Note the: 0.07500 V and 2.83500 V

Now let the sensor run for at least 10 minutes and leave it untouched!

After 10 minutes check the measurements again. In my case: conductivity stayed: 0.07500 V and moisture stayed: 2.83500 V we can write that in our yaml.

Open LILYGO-T-Higrow-ESP32.yaml and find the following:

moisture_min: "2.82"
moisture_max: "1.39"
conductivity_min: "0.075"
conductivity_max: "0.25"

This means, 2.82 and 0.075 are the minimum values that we measuret when it is actually 0%. We adjust this to what we found during our calibration.

Now we have to change the max reading of the sensor, this means it is water time! Put the sensor in the water up till the white line. So make very sure not to put it in too much!

So we now look for the higher numbers when it is (half) submerged, again look in the log files and note the voltage readings as previously explained:

[16:22:22][D][sensor:127]: 'lilygo_higrow_plant_sensor Soil Conductivity': Sending state 0.24400 V with 2 decimals of accuracy
[16:22:25][D][sensor:127]: 'lilygo_higrow_plant_sensor Soil Moisture': Sending state 1.37300 V with 2 decimals of accuracy

So we write them down in the LILYGO-T-Higrow-ESP32.yaml again but now the higher numbers.

After you written down the correct numbers it is time to uncomment the commented section again, for example:

  # Fertilizer sensor
  - platform: adc
    pin: GPIO34
    name: '${devicename} Soil Conductivity'
    icon: 'mdi:flower'
    update_interval: ${update_interval}
    accuracy_decimals: 2 # comment for calibration
    unit_of_measurement: 'µS/cm' # comment when calibrating
    # unit_of_measurement: "V" # uncomment for raw data
    filters: # comment when calibrating
      - calibrate_linear: # comment when calibrating
          # Map 0.0 (from sensor) to 0.0 (true value)
          - ${conductivity_min} -> 0.0 # comment when calibrating
          - ${conductivity_max} -> 100.0 # comment when calibrating

Reflash it again with the previous command: esphome run LILYGO-T-Higrow-ESP32.yaml and it is now calibrated!

You can also calibrate the temperature and humidity sensors, please read the dht.yaml or bme280.yaml to set the correct offsets.