TIDUF98A October   2024  – February 2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 End Equipment
      1. 1.1.1 Electricity Meter
    2. 1.2 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 ADS131M03
      2. 2.2.2 MSPM0L2228
      3. 2.2.3 THVD1400
      4. 2.2.4 ISO6731
      5. 2.2.5 DRV5032
    3. 2.3 Design Considerations
      1. 2.3.1 Design Hardware Implementation
        1. 2.3.1.1 Analog Inputs
          1. 2.3.1.1.1 Voltage Measurement Analog Front End
          2. 2.3.1.1.2 Current Measurement Analog Front End
      2. 2.3.2 Energy Metrology Software
        1. 2.3.2.1 Software Architecture
        2. 2.3.2.2 Setup
          1. 2.3.2.2.1 Clocking Scheme
          2. 2.3.2.2.2 SPI
          3. 2.3.2.2.3 UART Setup for GUI Communication
          4. 2.3.2.2.4 Real-Time Clock
          5. 2.3.2.2.5 LCD Controller
          6. 2.3.2.2.6 Direct Memory Access
    4. 2.4 Hardware, Software, Testing Requirements, and Test Results
      1. 2.4.1 Required Hardware and Software
        1. 2.4.1.1 Cautions and Warnings
        2. 2.4.1.2 Hardware
          1. 2.4.1.2.1 Connections to the Test Setup
          2. 2.4.1.2.2 Power Supply Options and Jumper Settings
        3. 2.4.1.3 Calibration
      2. 2.4.2 Testing and Results
        1. 2.4.2.1 Test Setup
          1. 2.4.2.1.1 Viewing Metrology Readings and Calibration
            1. 2.4.2.1.1.1 Viewing Results From LCD
            2. 2.4.2.1.1.2 Viewing Results From PC GUI
        2. 2.4.2.2 Electricity Meter Metrology Accuracy Testing
        3. 2.4.2.3 Electricity Meter Metrology Accuracy Results
  9. 3Design Files
    1. 3.1 Schematics
    2. 3.2 Bill of Materials
    3. 3.3 PCB Layout Recommendations
      1. 3.3.1 Layout Prints
    4. 3.4 Altium Project
    5. 3.5 Gerber Files
    6. 3.6 Assembly Drawings
  10. 4Related Documentation
    1. 4.1 Trademarks
  11. 5About the Authors
  12. 6Revision History

1.1.1 Electricity Meter

As the accuracy requirements and amount of processing expected from electricity meters rapidly increase, it becomes more and more difficult to solve these issues with a single metrology system-on-chip (SoC). A dual-chip approach with a standalone ADC and a host microcontroller (MCU) helps overcome the limitations of electricity meter SoCs and enables system designs, better tailored to the needs of specific markets or regions of the world. Combining a high-accuracy cost-optimized non-isolated standalone ADC, such as the ADS131M03, and a cost-optimized MSPM0L2228 MCU with LCD controller and a Backup (VBAT) power domain enables a new generation of cost-optimized electricity meters for single-phase with multiple advantages:

  • Achieving 0.5S accuracy requirements with a shunt current sensor at an attractive cost point with 3- (or only 2) channel simultaneous-sampling, delta-sigma ADC
  • MSPM0L2228 host MCU drives segmented LCD displays with up to 8×51 and 4×55 software definable COM and SEG lines for easier and more compact PCB
  • The VBAT island in MSPM0L2228 includes the low frequency clock system (LFOSC, LFXT), the real-time clock, the tamper detection and time-stamping logic, an independent watchdog timer, and a 32-byte backup memory
  • Support for external SPI FLASH memory and two UART interfaces: one for IrDA Optical port as per EN 62056-21 and second one for isolated RS-485 communication

The TIDA-010940 firmware specifically supports calculation of various metrology parameters for single-phase energy measurement by processing continuously the incoming ADS131M03 data samples. The most relevant parameters, that can be viewed from the calibration GUI or through the ACT and REACT pulsed outputs, connected to a reference metrology test system, are:

  • Active (kWh), reactive (kvarh), and apparent energy (kVAh) with pulse-generation outputs
  • RMS line current and RMS line voltage
  • Power factor
  • Line frequency

In addition, the MSPM0L2228 drives the liquid crystal display (LCD) of the board and communicates to a personal computer (PC) graphical user interface (GUI) through the isolated RS-485 circuitry on the board.