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

2.2 Differences between ADC Approach and TDC Approach

The fundamental difference between those two approaches is about the signal processing.

  • ADC approach (cross-correlation using the ADC captured signal): samples four times in each cycle of the signal. The correlation method gives the digital filtering to suppress the noise down.
  • TDC approach (zero-crossing using a time-to-digital converter (TDC): samples two times in each cycle near the zero crossing point. Noise affects each zero crossing time with no digital filtering possible in TDC approach for noise suppression.

The ADC approach has a benefit of being approximately 3-4 times lower of the standard deviation data of the dTOF. The ADC is robust to signal amplitude variations. The algorithm is insensitive to the received signal amplitude as in high flow rates, transducer to transducer variation, temperature variation, different gas compositions (air, methane). And, since the envelope of signal is obtained naturally in ADC approach, users can implement more customize functions.