Dear Sirs,
I need to connect mentioned HCZ-H8 humidity sensor to MSP430-based system.
In brief:
HCZ-H8 is a resistive AC-rated sensor ( http://www.fenghua.com/pdf/humidsensor/HCZ-H8.pdf ). To measure the humidity using the one, you should power it with a sinewave 1kHz, 1Vrms, pure AC without DC component, to obtain it's impedance |Z|. The sensor is resistive, not capacitive, so the main goal of AC supply is not to degrade the sensor with DC. 1KHz is used as it's datasheet already contains calibration table "impednace-humidity" @ 1KHz .
The similar sensor is well described in this document: http://www.produktinfo.conrad.com/datenblaetter/175000-199999/182630-da-01-en-Feuchtesensor.pdf
I'm going to solve my problem this way:
1)Set voltage of current sinewave's step (1KHz) using DAC
2)Pass DAC output through the filters (remove DC)
3)Split filtered sine between:
a)ADC CH0 directly
b)Humidity sensor then to ADC CH1
4)From CH0, CH1 calculate |Z|
5)From tables obtain humidity
Am I on the right way? Any ideas how to make this in a simpliest way?
Regards,
Ilia V. Davidov