Update bme680.rst - add indoor air quality index and IAQ label (#3272)

components/sensor/bme680.rst

@@ -103,6 +103,68 @@ configure this amount. Possible oversampling values:
 -  ``8x``
 -  ``16x`` (default)
 
+.. _bme680-advanced-configuration:
+
+Advanced Configuration
+----------------------
+
+Add indoor air quality (IAQ) calculation and IAQ label, based on the values in the `BME680 BSEC component </components/sensor/bme680_bsec.html?highlight=bme680#index-for-air-quality-iaq-measurement>`__ index.
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    sensor:
+      - platform: bme680
+        temperature:
+          name: "BME680 Temperature"
+          oversampling: 16x
+        pressure:
+          name: "BME680 Pressure"
+        humidity:
+          id: "humidity"
+          name: "BME680 Humidity"
+        gas_resistance:
+          id: "gas_resistance"
+          name: "BME680 Gas Resistance"
+        address: 0x77
+        update_interval: 60s
+      - platform: template
+        name: "BME680 Indoor Air Quality"
+        id: iaq
+        icon: "mdi:gauge"
+        # caulculation: comp_gas = log(R_gas[ohm]) + 0.04 log(Ohm)/%rh * hum[%rh]    
+        lambda: |-
+          return log(id(gas_resistance).state) + 0.04 *  id(humidity).state;
+    text_sensor:
+      - platform: template
+        name: "BME680 IAQ Classification"
+        icon: "mdi:checkbox-marked-circle-outline"
+        lambda: |-
+          if (int(id(iaq).state) <= 50) {
+            return {"Excellent"};
+          }
+          else if (int(id(iaq).state) <= 100) {
+            return {"Good"};
+          }
+          else if (int(id(iaq).state) <= 150) {
+            return {"Lightly polluted"};
+          }
+          else if (int(id(iaq).state) <= 200) {
+            return {"Moderately polluted"};
+          }
+          else if (int(id(iaq).state) <= 250) {
+            return {"Heavily polluted"};
+          }
+          else if (int(id(iaq).state) <= 350) {
+            return {"Severely polluted"};
+          }
+          else if (int(id(iaq).state) <= 500) {
+            return {"Extremely polluted"};
+          }
+          else {
+            return {"unknown"};
+          }
+
 See Also
 --------