[SOLVED] adc reading and calculation of humidity

[key_]

hai all
I need to know how to convert 10bit adc value for a humidity sensor SY-HS-220 ......pls give any formula for converting that adc value to relative humidity value........

 

[errakeshpillai]

This sensor will give humidity in percentage. So the count of 1023 means 100% humidity.
Hence you can derive the humidity from count by this formula:

Humidity(in %) = (adc_val * 100) / 1023;

 

[key_]

thanks for your replay ......
I have doubted because the data sheet shows its working in 30-90% RH and it give output 2970mv at 90%RH .........??? and I calculated the value

%RH= adc_val*90/(2970mV/4.8mV)
but i didn't get the correct value ....so pls clear my doubt

 

[Raady Here]

Your datasheet shows a straight-line for Characterstics curve.
Straight line has equation y=mx+c

slope (Δy/Δx) = (2.970-0.990)/(90-30) = 0.033 // from Standard characterstics table.
so, m=0.033

check with substitutions,
x=30, y=0.990
0.990=(0.033)(30)+c
c = 0

x=90 y=2.970
2.970=(0.033)(90)+c
c = 0

Both of passing through origin.

so, output voltage (RH) 0.033 V or 33 mV.

Now apply the reference voltage in the above equation.