TIDUC26A April   2022  – April 2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Inductive Touch Buttons
      2. 2.2.2 Sensor Coil Placement
      3. 2.2.3 Collecting Data from Multiple LDCs
      4. 2.2.4 Magnetic Dial Implementation
      5. 2.2.5 CORDIC Algorithm
    3. 2.3 Highlighted Products
      1. 2.3.1 LDC3114-Q1
      2. 2.3.2 TMAG5273
      3. 2.3.3 DRV2605
      4. 2.3.4 TLV75518
      5. 2.3.5 TCA9534
      6. 2.3.6 PCA9543
      7. 2.3.7 Sensor Control Board
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Firmware and Programming
      1. 3.1.1 Operational Mode 1
      2. 3.1.2 Operational Mode 2
      3. 3.1.3 Operational Mode 3
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 ABS Force Response
      2. 3.3.2 ABS Gain Corrected
      3. 3.3.3 Nylon Force Response
      4. 3.3.4 Nylon Gain Corrected
  10. 4Hardware Components
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6Revision History

1 System Description

Human-machine interfaces are a common part of many applications and typically require electromechanical components for implementing buttons and dials. Many push buttons use a mechanical switch that has an electrical contact that connects when the button is pressed. This interaction provides a point of wear and tear that can breakdown overtime. Implementing buttons with switches like this also means having to seal the button surface in applications that operate in harsher environments such as industrial or automotive applications. Otherwise, this also allows for dirt or dust to get inside the mechanical button which can further reduce the product lifetime.

Other HMI components like dials also suffer from wear and tear. Dials traditionally use an encoder or potentiometer to determine the rotational change of the input. These components have mechanical components that can breakdown over time similar to push buttons.

In this reference design, inductive sensing is used to implement seamless touch buttons that provide a contact free implementation while also enabling variable force touch functionality. Additionally, Hall-effect sensing is used to implement a contactless dial to reduce the wear and tear that comes with devices like potentiometers and rotary encoders. This design includes a 3D-printed housing that provides the button surface and rotational push-button dial.

Since buttons and dials are a common component on many human-machine-interfaces, these technologies can be used in a wide variety of applications. For automotive applications, inductive touch buttons provide a force sensitive response that works with gloves on. Additionally, being able to design with a button on different surfaces provides flexibility to the overall design. These same benefits also apply to other implementations such as industrial HMI and appliances.