JAJU680A January   2019  – July 2022

 

  1.   概要
  2.   Resources
  3.   特長
  4.   アプリケーション
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Flow Measurement
      2. 2.2.2 ToF Measurement
        1. 2.2.2.1 ADC-Based Acquisition Process
        2. 2.2.2.2 Ultrasonic Sensing Flow-Metering Library
      3. 2.2.3 Low-Power Design
        1. 2.2.3.1 Energy-Efficient Software
        2. 2.2.3.2 Optimized Hardware Design
        3. 2.2.3.3 Efficient Use of FRAM
        4. 2.2.3.4 The LEA Advantage
    3. 2.3 Highlighted Products
      1. 2.3.1 MSP430FR6043
      2. 2.3.2 OPA836 and OPA838
      3. 2.3.3 TS5A9411
    4. 2.4 System Design Theory
      1. 2.4.1 Signal Processing for ToF
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Required Hardware and Software
      1. 3.1.1 Hardware
        1. 3.1.1.1 EVM430-FR6043
      2. 3.1.2 Software
        1. 3.1.2.1 MSP Driver Library (MSP DriverLib)
        2. 3.1.2.2 Ultrasonic Sensing Flow Metering Library
        3. 3.1.2.3 Application
          1. 3.1.2.3.1 Application Customization
          2. 3.1.2.3.2 LCD Stand-Alone Mode
        4. 3.1.2.4 USS Design Center (PC GUI)
      3. 3.1.3 Transducer and Meter
        1. 3.1.3.1 Frequency Characterization of Transducer and Meter
    2. 3.2 Testing and Results
      1. 3.2.1 Test Setup
        1. 3.2.1.1 Connecting Hardware
        2. 3.2.1.2 Building and Loading Software
          1. 3.2.1.2.1 Using Code Composer Studio IDE
          2. 3.2.1.2.2 Using IAR Embedded Workbench IDE
        3. 3.2.1.3 Executing Application
        4. 3.2.1.4 Configure Device and Observe Results Using GUI
        5. 3.2.1.5 Customization and Optimization
      2. 3.2.2 Test Results
        1. 3.2.2.1 Single-Shot Standard Deviation
        2. 3.2.2.2 Zero-Flow Drift
        3. 3.2.2.3 Absolute Time of Flight Measurements
        4. 3.2.2.4 Variability in Zero Flow Drift Across Transducers
        5. 3.2.2.5 Flow Measurements
        6. 3.2.2.6 Average Current Consumption
        7. 3.2.2.7 Memory Footprint
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 Bill of Materials
      3. 4.1.3 PCB Layout Recommendations
        1. 4.1.3.1 Layout Prints
      4. 4.1.4 Altium Project
      5. 4.1.5 Gerber Files
      6. 4.1.6 Assembly Drawings
    2. 4.2 Software Files
    3. 4.3 Related Documentation
    4. 4.4 Terminology
    5. 4.5 Trademarks
    6. 4.6 サポート・リソース
  10. 5About the Authors
  11. 6Revision History

3.1.3.1 Frequency Characterization of Transducer and Meter

Different meters and transducers have different responses; consequently, it is important to characterize the frequency response of the meter to obtain an optimal performance.

The MSP430 Ultrasonic Sensor Design Center Tool GUI provided in this reference design can be used for this purpose. The GUI includes a Frequency Sweep panel. Ultrasonic Sensing Design Center User's Guide describes the detailed operation, but a brief description is provided here for completeness.

To start a sweep, do the following:

  1. Set the F1 Parameter on the Configuration tab, and then set the Number of Captures parameter in the Frequency Sweep tab to determine the range in which to sweep.
  2. Click on the Frequency Sweep button and navigate to the desired location in the file system where the Frequency Sweep data is saved, and then click the Save button.

The Frequency Sweep tool helps to determine at which transducer excitation frequency the ADC capture achieves the maximum amplitude. The frequency at which the peak amplitude is reached should be used as the new F1 parameter to achieve the strongest signal for the meter configuration. For the example, in Figure 4-11 a value of 170 to 180 should be placed into the F1 parameter.

GUID-DD525697-E257-4F08-B1EC-3D91FB6264E1-low.png Figure 4-11 Frequency Response Test Results