add VPD

tweak SCD40 temperature offset
set i2c to 10kHz

growbox.yaml

@@ -10,3 +10,4 @@ packages:
   yieryi2178: !include packages/yieryi3178.yaml
   scd40:      !include packages/scd40.yaml
   mlx90614:   !include packages/mlx90614.yaml
+  vpd:        !include packages/vpd.yaml

packages/esp32.yaml

@@ -4,3 +4,4 @@ esp32:
 i2c:
   sda: 21
   scl: 22
+  frequency: 10khz

packages/scd40.yaml

 sensor:
 - platform: scd4x
   update_interval: 5s
+  temperature_offset: 4.85
   ambient_pressure_compensation_source: bme280_pressure
   co2:
     id: scd40_co2

packages/vpd.yaml

+sensor:
+- platform: template
+  id: vpd
+  name: "Vapor Pressure Deficit"
+  update_interval: 5s
+  accuracy_decimals: 2
+  unit_of_measurement: 'kPa'
+  lambda: |-
+    float temperature = (id(mlx90614_temperature_object).state - 32) * 5/9;
+    float humidity = id(bme280_humidity).state;
+    float vpSaturation = 610.7 * pow(10, (7.5 * temperature / (temperature + 237.3)));
+    float vpDeficit = ((100.0 - humidity) / 100.0) * vpSaturation;
+    return vpDeficit / 1000;
+
+prometheus:
+  relabel:
+    vpd:
+      id: vpd
+      name: "Vapor Pressure Deficit"