View source for I2C Humidity Sensor

=General description=
The [http://www.sensirion.com/de/01_humidity_sensors/05_humidity_sensor_sht21/00_humidity_sensor_sht21.htm SHT21] from Sensirion is a digital humidity and temperature sensor with a easy to use I2C interface. It connects to your Freerunner just like the [[I2C Pressure Sensor]].

A simple kernel driver is already available from [http://gitorious.org/freerunner-navigation-board/sht21 here].

=Mounting=
The relative humidity depends on the ambient temperature. This makes it rather difficult to find the best mounting place for the sensor. The requirements are:
* contact with fresh air
* minimize errors introduced through heat from other electronic components.

==Possible mounting places==
* next to the GPS antenna
* inside the GSM antenna
* behind the speaker holes
* ...

I tried the first two options. After drilling small holes both places can be used, but even without top cover I was able to measure a temperature difference of about one degree celsius between the inside and outside of the case.

[[Category:Accessories]]