SLAA494B May   2011  – September 2023 MSP430AFE221 , MSP430AFE222 , MSP430AFE223 , MSP430AFE231 , MSP430AFE232 , MSP430AFE233 , MSP430AFE251 , MSP430AFE252 , MSP430AFE253

 

  1.   1
  2.   Implementation of a Single-Phase Electronic Watt-Hour Meter Using the MSP430AFE2xx
  3. 1 Trademarks
  4. 2 Introduction
  5. 3 Block Diagram
  6. 4 Hardware Implementation
    1. 4.1 Power Supply
      1. 4.1.1 Resistor Capacitor (RC) Power Supply
      2. 4.1.2 Switching-Based Power Supply
    2. 4.2 Analog Inputs
      1. 4.2.1 Voltage Inputs
      2. 4.2.2 Current Inputs
  7. 5 Software Implementation
    1. 5.1 Peripherals Setup
      1. 5.1.1 SD24 Setup
    2. 5.2 Foreground Process
      1. 5.2.1 Formulas
        1. 5.2.1.1 Voltage and Current
        2. 5.2.1.2 Power and Energy
    3. 5.3 The Background Process
      1. 5.3.1 Voltage and Current Signals
      2. 5.3.2 Phase Compensation
      3. 5.3.3 Frequency Measurement and Cycle Tracking
      4. 5.3.4 LED Pulse Generation
    4. 5.4 Energy Meter Configuration
  8. 6 Energy Meter Demo
    1. 6.1 EVM Overview
      1. 6.1.1 Connections to the Test Setup or AC Voltages
      2. 6.1.2 Power Supply Options
    2. 6.2 Loading the Example Code
      1. 6.2.1 Opening the Project
  9. 7 Results
    1. 7.1 Viewing Results on PC
    2. 7.2 Viewing Results During Debug
  10. 8 Important Notes
  11. 9 Schematics
  12. 10References
  13. 11Revision History

2 Introduction

The MSP430AFE2xx devices belong to the MSP430F2xx family of devices. These devices find their application in energy measurement and have the necessary architecture to support it. The MSP430AFE2xx devices have a powerful 12-MHz central processing unit (CPU) with MSP430 CPUX architecture. The analog front end consists of up to three analog-to-digital converters (ADCs) based on a second-order sigma-delta (ΣΔ) architecture that supports differential inputs. The ΣΔ ADCs (SD24) can output 24-bit results. They can be grouped together for simultaneous sampling of voltage and current on the same trigger. Each SD24 converter supports a common-mode voltage of up to -1 V and enables all sensors to be referenced to ground. In addition, it has an integrated gain stage that supports gains up to 32 for amplification of low-output sensors. A 16-bit x 16-bit hardware multiplier on this chip can be used to further accelerate math-intensive operations during energy computation. The software supports calculation of various parameters for single-phase energy measurement. The key parameters calculated during energy measurements are root mean square (RMS) current and voltage, active and reactive power and energy, power factor, and frequency. This application report has the complete metrology source code provided as a zip file. For new designs, download the Energy Measurement Design Center (EMDC) and software library from MSP-EM-DESIGN-CENTER.