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This version (13 Nov 2014 19:34) was approved by Walt_Kester.The Previously approved version (23 Jun 2014 15:58) is available.Diff

Magneto Resistive Angle Measrement (CN0323)

Overview

This circuit provides a contactless, AMR (Anisotropic Magneto Resistive) based angle measurement solution providing 1° angular accuracy over a 180° range.

The circuit is ideal for applications where high speed, accurate, non-contact angle measurements are critical. A rotating magnetic field stimulates the sensor, creating an output voltage of ±70mV. The circuit provides an industry leading angle measurement solution suitable for machine tool speed control, crane angle control, motor speed measurement, and other industrial or automotive applications.

General Setup

  • One EVAL-CN0323-SDPZ Evaluation Board
  • EVAL-SDP-CB1Z Evaluation board
  • One USB Type-A plug to USB Mini-B plug cable.
  • One diametrically magnetized Neodymium magnet
  • One of the following:
    • 6V DC wallwart. (EVAL-CFTL-6V-PWRZ)
    • DC power supply with a 0-6V output. (HP6236B)

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 CN0323 SDP Eval Software.zip and open the file setup.exe. It is recommended that you install the CN0323 SDP Evaluation Software to the default directory path C:\Program Files\Analog Devices\CN0323\ and all National Instruments products to C:\Program Files\National Instruments\
  2. Press “Next”.
  3. Press “Next”.
  4. Press “Next”.
  5. Upon completion of the installation of the CN0323 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.
  6. Press “Next”.
  7. It is recommended that you install the drivers to the default directory path C:\Program Files\Analog Devices\SDP\Drivers\
  8. Press “Install” to install the Drivers and complete the installation of all software necessary to evaluate the EVAL-CN0323-SDPZ

Opening and Enabling the Evaluation Software

  1. Launch the executable found at C:\Program Files\Analog Devices\CN0323 and press the “Connect“ button.

Step by Step Instruction for Calibrating the System

  1. The following is a step by step guide for manual or automatic calibration of the calibrating the EVAL-CN0323-SDPZ.
    1. A manual calibration requires the user to input the maximum and minimum ADC code for each channel of the ADC.
    2. An automatic calibration allows the software to identify the maximum and minimum ADC code for each channel of the ADC. This method is easier to use than the manual method, however, it may introduce errors if the magnet is spinning with an un-smooth or non-periodic nature.
  2. Step 1: Begin by selecting manual or automatic calibration.
  3. Step 2: Press the 'Click to Sample' button to begin data conversion.
  4. Step 3: Rotate the magnet and observe the changing ADC codes.
  5. Step 4: If manual calibration was selected, you must input the maximum and minimum codes (seen in step 3) in the boxes provided. If automatic calibration was selected, you must simply spin the magnet through several complete revolutions to allow the software to identify the necessary codes.
    1. The calibration coefficients can be modified to produce a better end result. For example, if one of the maximum ADC codes is mis-represented on the high side, the output angle will never reach +90 degrees or -90 degrees depending on the channel.
    2. Once the calibration is complete, proceed to the second tab 'Final Angle(Needle)' to observe the angle information.
resources/eval/user-guides/circuits-from-the-lab/cn0323.txt · Last modified: 13 Nov 2014 19:33 by Walt_Kester