I2C Humidity Sensor

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(SHT21 digital humidity sensor)
 
 
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The SHT21 is a digital humidity and temperature sensor with a easy to use I2C interface. With just four wires it's rather easy to connect it to your Freerunner. For details see [[I2C]] and [[I2C Pressure Sensor]].
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=General description=
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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].
 
A simple kernel driver is already available from [http://gitorious.org/freerunner-navigation-board/sht21 here].
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=Mounting=
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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:
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* contact with fresh air
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* minimize errors introduced through heat from other electronic components.
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==Possible mounting places==
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* next to the GPS antenna
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* inside the GSM antenna
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* behind the speaker holes
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* ...
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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.
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[[Category:Accessories]]

Latest revision as of 16:49, 9 September 2010

[edit] General description

The 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 here.

[edit] 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.

[edit] 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.

Personal tools

The SHT21 is a digital humidity and temperature sensor with a easy to use I2C interface. With just four wires it's rather easy to connect it to your Freerunner. For details see I2C and I2C Pressure Sensor.

A simple kernel driver is already available from here.