Environmental Sensing Service

Implements the BLE Environmental Sensing Service.

When subscribing to one of the characteristics, the BME680 gets triggered every 3 seconds to produce a new measurement. I chose 3 seconds as this will also the the rate at which a future BSEC MR will read data from the sensor.

Together with this https://phyphox.org/ "experiment" you can get graphs on your phone:

Documentation/bluetooth/ess.rst

+Environmental Sensing Service
+========================
+
+.. warning::
+    This service will be available in version v1.17
+
+The Environmental Sensing Service (ESS) implements access to
+the BME680 environmental sensor of the card10.
+
+It provides:
+
+- Temperature
+- Relative humidity
+- Pressure
+
+
+If notifcations are enabled a measurement of all values is performed every 3 seconds. For each measurement a notification is sent for the characteristics which have notifications enabled.
+
+
+A measurement can also be triggered by reading from a characteristic. A measurement takes roughly 200 ms. A notifciation will be sent to all characteristics which have notifications enabled except the one which was used to trigger the measurement.
+
+
+BLE Service
+-----------
+
+- Service
+
+  UUID: ``181A``
+
+- Temperature characteristic:
+
+  UUID: ``2A6E``
+  read and notify
+
+- Humidity characteristic:
+
+  UUID: ``2A6F``
+  read and notify
+
+- Pressure characteristic:
+
+  UUID: ``2A6D``
+  read and notify
+
+Temperature characteristic
+---------------------------------
+
+- 16 bit little endian value representing the measured temperature.
+
+- Unit: 0.01 deg C
+
+
+Humidity characteristic
+---------------------------------
+
+- 16 bit little endian value representing the measured relative humidity.
+
+- Unit: 0.01%
+
+Pressure characteristic
+---------------------------------
+
+- 32 bit little endian value representing the measured pressure.
+
+- Unit: 0.1 Pa (0.001 hPa)