This version (29 Jul 2021 07:32) was approved by Harvey John De Chavez.The Previously approved version (25 Jan 2021 11:06) is available.Diff

Relative Humidity Measurement System (CN0346)


This circuit provides a contactless, capacitive based, relative humidity (RH) measurement solution with 2% relative humidity accuracy from 0% RH to 100% RH and replaces bulky hygrometer based methods. This circuit is ideal for applications where accurate, temperature controlled, noncontact humidity measurements are critical, such as HVAC, telecommunication cabinets, infant incubators, and other industrial or medical applications.

General Setup

Minimum PC/System Requirements

  • One PC with the following
    • Windows XP SP2, Windows Vista or Windows 7 Business/Enterprise/Ultimate editions
    • Intel Pentium processor (x86 compatible), 1GHz or faster
    • 512 MB RAM and 2 GB available hard disk space
    • .NET 3.5 Framework

How to Install the Evaluation Software

  1. Extract the files within the file CN0341 SDP Eval and open the file setup.exe. It is recommended that you install the CN0341 SDP Evaluation Software to the default directory path C:\Program Files\Analog Devices\CN0341\ and all National Instruments products to C:\Program Files\National Instruments\
  2. Press “Next”.
  3. Press “Next”.
  4. Upon completion of the installation of the CN0341 SDP Eval Software, the installer for the ADI SDP Drivers will execute. Follow the on-screen prompts to install the drivers. It is recommended that you close all other applications before clicking “Next”. This will make it possible to update relevant system files without having to reboot your computer.
  5. Press “Next”.
  6. It is recommended that you install the drivers to the default directory path C:\Program Files\Analog Devices\SDP\Drivers\
  7. Press “Install” to install the Drivers and complete the installation of all software necessary to evaluate the EVAL-CN0341-SDPZ

Opening and Enabling the Evaluation Software

  1. Launch the executable found at C:\Program Files\Analog Devices\CN0346 and press the “Connect“ button.

Step by Step Instruction for Calibrating the System

  1. The following is a step by step guide for calibrating the EVAL-CN0346-SDPZ.
    1. Calibration requires the user to identify and input the maximum and minimum values of humidity and sensor capacitance.
    2. Place the PCB into a humidity controlled environment and adjust the environment to the desired minimum humidity value.
    3. Use an external LCR meter to measure the sensor capacitance.
    4. Place both values into the calibration tab shown below.
    5. Repeat these steps for the desired maximum humidity value and enter the values into the software.
    6. Input the calculated CAPDAC value into the box found at the bottom of the Calibration tab.


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resources/eval/user-guides/circuits-from-the-lab/cn0346.txt · Last modified: 29 Jul 2021 07:32 by Harvey John De Chavez