SLYA036B July   2018  – November 2021 DRV5053 , DRV5053-Q1 , DRV5055 , DRV5055-Q1 , DRV5056 , DRV5056-Q1 , DRV5057 , DRV5057-Q1

 

  1.   Trademarks
  2. 1Introduction
  3. 2Overview
    1. 2.1 Types of Magnetization
    2. 2.2 Types of Magnets
  4. 3Device Descriptions
    1. 3.1 2.5-V to 38-V, Bipolar Hall Effect Sensor Family: DRV5053 and DRV5053-Q1
    2. 3.2 High-Accuracy, 3.3-V or 5-V, Ratiometric, Bipolar Hall Effect Sensor Family: DRV5055 and DRV5055-Q1
    3. 3.3 High-Accuracy, 3.3-V or 5-V, Ratiometric, Unipolar Hall Effect Sensor Family: DRV5056 and DRV5056-Q1
  5. 4Methods
    1. 4.1 Uncalibrated Implementations
      1. 4.1.1 Overview
        1. 4.1.1.1 General Implementation
        2. 4.1.1.2 Preferred Magnet Types
        3. 4.1.1.3 General Accuracy and Resolution
        4. 4.1.1.4 Considerations
      2. 4.1.2 One Bipolar Sensor, Uncalibrated
        1. 4.1.2.1 Specific Implementation
        2. 4.1.2.2 Calculating Region
        3. 4.1.2.3 Accuracy
      3. 4.1.3 Two Bipolar Sensors 90° Apart, Uncalibrated
        1. 4.1.3.1 Specific Implementation
        2. 4.1.3.2 Calculating Region
        3. 4.1.3.3 Accuracy
      4. 4.1.4 Two Bipolar Sensors n° Apart, Uncalibrated
        1. 4.1.4.1 Specific Implementation
        2. 4.1.4.2 Calculating Region
        3. 4.1.4.3 Accuracy
      5. 4.1.5 Three or More Bipolar Sensors, Uncalibrated
        1. 4.1.5.1 Specific Implementation
        2. 4.1.5.2 Calculating Region
        3. 4.1.5.3 Accuracy
    2. 4.2 Peak Calibrated Implementations
      1. 4.2.1 Overview
        1. 4.2.1.1 General Implementation
        2. 4.2.1.2 Preferred Magnet Types
        3. 4.2.1.3 General Accuracy and Resolution
        4. 4.2.1.4 Considerations
      2. 4.2.2 One Bipolar Sensor, Peak Calibrated
        1. 4.2.2.1 Specific Implementation
        2. 4.2.2.2 Calculating Angle
        3. 4.2.2.3 Accuracy
      3. 4.2.3 Two Bipolar Sensors 90° Apart, Peak Calibrated
        1. 4.2.3.1 Specific Implementation
        2. 4.2.3.2 Calculating Angle
        3. 4.2.3.3 Accuracy
    3. 4.3 Lookup Table Calibration Implementations
      1. 4.3.1 Overview
        1. 4.3.1.1 General Implementation
        2. 4.3.1.2 Preferred Magnet Types
        3. 4.3.1.3 General Accuracy and Resolution
        4. 4.3.1.4 Considerations
      2. 4.3.2 One Bipolar Sensor, Lookup Table Calibrated
        1. 4.3.2.1 Specific Implementation
        2. 4.3.2.2 Calculating Angle
        3. 4.3.2.3 Accuracy
      3. 4.3.3 Two Bipolar Sensors ≈ 90° Apart, Lookup Table Calibrated
        1. 4.3.3.1 Specific Implementation
        2. 4.3.3.2 Calculating Angle
        3. 4.3.3.3 Accuracy
    4. 4.4 Peak Calibrated Plus Lookup Table Hybrid
      1. 4.4.1 Overview
        1. 4.4.1.1 General Implementation
        2. 4.4.1.2 Preferred Magnet Types
        3. 4.4.1.3 General Accuracy and Resolution
        4. 4.4.1.4 Considerations
      2. 4.4.2 One Bipolar Sensor, Hybrid Calibrated
        1. 4.4.2.1 Specific implementation
        2. 4.4.2.2 Calculating Angle
        3. 4.4.2.3 Accuracy
      3. 4.4.3 Two Bipolar Sensors 90° Apart, Hybrid Calibrated (Recommended High Accuracy Method)
        1. 4.4.3.1 Specific Implementation
        2. 4.4.3.2 Calculating Angle
        3. 4.4.3.3 Accuracy
  6. 5References
  7. 6Revision History

4.2.1.1 General Implementation

With a peak-calibrated system, bipolar sensor data can be normalized to ±1 for use with the arctan2 (two sensors) or arcsin (one sensor) function in order to determine the angle. Arctan2 must be used instead of arctan, because arctan2 accounts for which of the two values are negative. The process for calibration is:

  1. Find the min and max values from each sensor by continuously reading voltages while rotating the magnet 360°. One full rotation is required, but more rotations help make sure that more accurate min and max values are found.
  2. Then, during normal operation, each new measured voltage can be normalized to ±1 using Equation 1.
    Equation 1. NORM=Vmeasured-Vmin-VamplitudeVamplitude where Vamplitude=Vmax-Vmin2
  3. The normalized data is then put directly into the arctan2 (two sensors, 0° to 360° output) or arcsin (one sensor, 0° to ±90° output) function in order to get the angle of the magnet.