SLAAES9 March   2025 MSP430FR5043 , MSP430FR6005 , MSP430FR6007 , MSP430FR6043 , MSP430FR6045 , MSP430FR6047

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Flow Meter Measurement Theory
    1. 2.1 TOF Measurement Algorithm Implementation
      1. 2.1.1 AbsTOF Calculation Method – Lobe
      2. 2.1.2 AbsTOF Calculation Method – Hilbert Wide
      3. 2.1.3 dTOF Calculation Method - Cross-Correlation
        1. 2.1.3.1 Get a High-Precision dTOF Result
        2. 2.1.3.2 Optimization in Cross-Correlation Method
    2. 2.2 Differences between ADC Approach and TDC Approach
  6. 3MSP430 MCUs for USS Application
    1. 3.1 USS Module
    2. 3.2 Differences Between USS and USS_A Module
    3. 3.3 Software Implementation on MSP430 MCUs
  7. 4Hardware Design Flow
    1. 4.1 Schematics
      1. 4.1.1 Water Meter Schematic – MSP430FR6047 and MSP430FR6007
      2. 4.1.2 Water Meter Schematic – MSP430FR6043 and MSP430FR5043
      3. 4.1.3 Gas Meter Schematic – MSP430FR6043 and MSP430FR5043
    2. 4.2 PCB Layout Guide
  8. 5Software Design Guide
    1. 5.1 USS Demo Projects and Related Resources
    2. 5.2 Demo Project Instruction
      1. 5.2.1 Files in Demo Project
      2. 5.2.2 Properties Setting in Demo Project
  9. 6Summary
  10. 7References

4.1.2 Water Meter Schematic – MSP430FR6043 and MSP430FR5043

This is a highly integrated design using the MSP USS MCUs for water meter applications. For more details, refer to the TIDM-02005.

There are only a few points which need to be highlighted.

  1. Before evaluating water meter applications on the EVM430-FR6043 board, there are changes that need to be made on the board to fit for water meter applications. Refer to the Hardware Modifications for Water Meter Operation section in the Optimized Ultrasonic Sensing Metrology Reference Design for Water Flow Measurement design guide.
  2. For the USSXT, TI recommends to choose the load capacitor value through Equation 10.
    Equation 10. C c r y s t a l + C l o a d + C l a y o u t = 34 p F

    Since the ADC approach is used in the USSLib, the measurement accuracy is barely affected by crystal oscillator accuracy. Therefore, use a resonator on the EVM boards for demonstration with good performance. A resonator also consumes less current than a crystal. If users do not care about the current consumption and have a wide temperature range in the application, then users can consider using a crystal to replace the resonator. Users need to modify the USS_HSPLL_INPUT_CLK_TYPE and USS_HSPLL_USSXTAL_SETTLING_USEC in the software.

  3. For the CHx_IN, OUT circuit, TI recommends to use 1% resistors and 1% NP0 capacitors for a better USS performance. Users can change the value of the resistor and capacitor if this can help to get a better performance on the meter. As a note, TI tested several combinations with different transducers and took the value with 200Ohm and 1000pF for the best performance.
  4. For the power supply, TI recommends to use a dedicate LDO, DCDC power supply for the MCU. A good load transient response performance is important for the ultrasonic application.
  5. For the USS GUI connection, TI recommends to keep the I2C connection port (COMM_SDA, COMM_SCL and COMM_IRQ) on the board at first. To debug issues with USS GUI at the evaluation stage is easy.
  6. For evaluating with MSP430FR5043, the default MSP430FR5043 linker file must be modified to meet the memory configuration required for the USS library. Please uses the one lnk_msp430fr6043.cmd in the MSP430FR6043EVM_USS_Water_Demo. Change the name to FR5043 and start evaluation. A comparison of the linker file is shown in Figure 4-1.
Linker File Differences on Water Meter Demo for MSP430FR5043 MCU Figure 4-1 Linker File Differences on Water Meter Demo for MSP430FR5043 MCU

The MSP430FR5043 does not support LCD module, so the software must be modified to disable the LCD and any related functions. This is handled in hal_lcd.h.