need help for humidity sensor calibration

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saidutt

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hi friends,

i am working on humidity and temperature sensor(HSM- 20G). i want to calculate
relative humidity in % using temperature and ADC output because at different temperature the RH(%) will vary. i am unable to figure it out the formula of RH(%).
so please help me out with it.
 

Hi,

The simplest way will be to use a lookup table for your humidity adc value, but if you are using C etc then using more complex forumla will be easier than assembler.

You can calibrate the humidity sensor at 70% using the damp salt box method - just google it.

This thread might give you some coding clues

**broken link removed**
 

because at different temperature the RH(%) will vary
Click to expand...
By specification, the sensor (as most usual rH sensors) measures relative humidity independant of temperature. Some
variation can be expected of course, but the manufacturer doesn't tell about a systematic relation. So, if your accuracy requirements
aren't very high, you may want to use the sensor based on the given typical characteristic, without individual calibration. if you
do a calibration, you should be sure, that the accuracy is better than the initial sensor accuracy.
 

Some of them gives you a relation to compensate the RH measures at diferent temperatures, as you can see in the datasheet of this one: **broken link removed**.
Take a look at page 2, "Temperature Compensation":

\[V_{out}=(0.0305+0.000044*T-0.0000011*T^{2})*(Sensor RH)+(0.9237-0.0041*T+0.000040*T^{2})\]

Regards.
 
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