TIDUEJ6A January   2019  – July 2022

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  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 Support Resources
  10. 5About the Authors
  11. 6Revision History

3.1.2.4 USS Design Center (PC GUI)

The MSP430 Ultrasonic Sensor Design Center Tool GUI included in this reference design lets developers modify some configuration parameters required to test different transducers, as well as observe the behavior of the system in real time.

The configuration window is shown by default when opening the application (see Figure 4-6).

GUID-5178CC14-04C6-43FF-8835-A8EFFF47BA41-low.pngFigure 4-6 GUI Configuration Parameters Window

The configuration window lets developers configure the parameters detailed in Table 4-2.

Table 4-2 GUI Configuration Parameters Description
ParameterDescription
Transmit Frequency (kHz)Pulse output frequency (kHz) used to excite transducers
Gap between pulse start and ADC capture (µs)Gap in microseconds between the generation of a pulse output and sampling of a received signal using SDHS
Number of PulsesNumber of pulses sent during pulse generation
UPS and DNS Gap (µs)Gap in microseconds between upstream and downstream captures
UPS0 to UPS1 Gap (ms)Gap in milliseconds between captures. This is measured from the end of the downstream capture to the start of the next upstream.
GUI-Based Gain ControlPGA gain setting in dB. This only takes specific values that are supported by the MSP430FR6043 MCU.
Meter ConstantConstant used to calculate the volume flow rate. This static constant is related to the cross section area of the meter that the vendor should provide as a one-time input. This also needs to vary depending on whether lph or gpm is used for the display.

Figure 4-7 shows the Advanced Parameters configuration panel.

GUID-2A59B043-9503-448F-B5E8-2ED35AA70276-low.pngFigure 4-7 GUI Advanced Parameters Configuration Window

The Advanced Parameters Configuration panel lists the parameters in Table 4-3.

Table 4-3 GUI Configuration Advanced Parameters Description
ParameterDescription
USSXT (kHz)Frequency of X1 resonator in kHz connected to MSP430FR6043 on EVM430-FR6043
ADC Sampling Frequency (kHz)Reserved
Signal Sampling Frequency (kHz)Sampling frequency of the received signal in kHz
ADC Oversampling RateOversampling ratio (OSR) of the SDHS. This is 80 for signal sampling frequency in the range of [850 to 1000] kHz, and 40 for sampling frequency in the range of [1.7 to 2.0] MHz.
Delta ToF offset (ps)Offset to compensate the delta ToF in picoseconds for any nonzero bias
Absolute ToF additional delay (ns)Time in nanoseconds to compensate for unaccounted additional delays in absolute ToF
Capture Duration (µs)Duration of the ADC capture in microseconds
Algorithm OptionEnables Lobe or Hilbert based algorithm
Envelope Crossing ThresholdThreshold from peak of AbsTOF correlation
Start PPG Count (ns)Time to start PPG pulse trigger in nanoseconds.
Turnon ADC Count (ns)Time to turn ON the ADC in nanoseconds.
Start PGA and IN Bias Count (ns)Time to turn the PGA and input biasing in nanoseconds
USS XTAL Settling Count (µs)Time allocated for USS crystal settling after initialization
External Amplifier Count (ns)Time allocated for settling of the external amplifier
User Param 8Reserved
Search RangeRange over which AbsTOF is searched
User Param 10Reserved

The MSP430 Ultrasonic Sensor Design Center Tool lets developers observe the behavior of the system in real time by using the Waveforms window, shown in Figure 4-8. This tool plots the delta time of flight (DToF) in the upper panel, the upstream absolute time of flight (AbsToFUPS) and downstream absolute time of flight (AbsToFDNS), and the volume flow rate (VFR). The plots include both the instantaneous measurement as well as the mean value of the measurements.

GUID-F26246EF-DFC1-431B-AFE3-06B38E14412E-low.pngFigure 4-8 USS Design Center GUI Waveforms Window

Additionally, it is also possible to obtain and plot a single capture to validate the integrity of the signal by using the ADC Capture panel (see Figure 4-9). The panel lets users obtain continuous captures of the ADC waveform of contiguous measurements and allows the user to do additional debugging if required.

GUID-BD14E35B-5148-44EA-8319-1392E46170A1-low.pngFigure 4-9 USS Design Center ADC Waveform Capture Window