example_leaf_vpd.yaml

substitutions:
  friendly_name: Microfire Leaf VPD
  device_name: leaf-vpd
esphome:
  name: $device_name
  platformio_options:
    board_build.flash_mode: dio
esp32:
  board: esp32dev
  framework:
    type: arduino
logger:
api:
ota:
wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  ap:
    ssid: $device_name
    password: !secret wifi_failover
#captive_portal:

# import the mod-ec component
external_components:
  - source:
      type: git
      url: https://github.com/u-fire/ESPHomeComponents/

# https://esphome.io/components/i2c.html
i2c:
  sda: 22
  scl: 21

sensor:
  - platform: mlx90614
    id: mlx
    ambient:
      name: Ambient Temperature
    object:
      id: mlx_object
      name: Leaf Temperature

  - platform: sht3xd
    temperature:
      id: sht_air_temp
      name: "Air Temperature"
    humidity:
      id: sht_air_rh
      name: "Air Humidity"

  - platform: template
    name: "VPD"
    unit_of_measurement: kPa
    accuracy_decimals: 2
    icon: "mdi:leaf"
    state_class: measurement
    lambda: |-
      float _object_temp_c = id(mlx_object).state;
      float _ambient_temp_c = id(sht_air_temp).state;
      float _RH = id(sht_air_rh).state;
      float l_vpd;
      float a_vpd;

      l_vpd = 0.61078 * exp((17.2694 * _object_temp_c) / (_object_temp_c + 237.3));
      a_vpd = 0.61078 * exp((17.2694 * _ambient_temp_c) / (_ambient_temp_c + 237.3)) * (_RH / 100);
      return (l_vpd - a_vpd);