Include delay until data is expected to be ready

Without this delay the host is sending continuous read requests to the sensor. However the sensor is busy producing the data and does not respond to those requests. Observations with an oscilloscope indicate that each request deteriorates the SDA and SCL and potentially affects the sensor's and potentially the hosts' life time. SCA and SCL signal high level decreases and fluctuates when 0x40(R) is produced, indicating that hosts can not maintain a stable signal level on the i2c bus.

Author: uutzinger

adafruit_htu21d.py

@@ -97,13 +97,15 @@ def relative_humidity(self):
         """The measured relative humidity in percent."""
         self.measurement(HUMIDITY)
         self._measurement = 0
+        time.sleep(0.016)
         return self._data() * 125.0 / 65536.0 - 6.0
 
     @property
     def temperature(self):
         """The measured temperature in degrees Celcius."""
         self.measurement(TEMPERATURE)
         self._measurement = 0
+        time.sleep(0.050)
         return self._data() * 175.72 / 65536.0 - 46.85
 
     def measurement(self, what):