TIDUF25 june   2023 ADS131M08 , MSPM0G1507

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 End Equipment
    2. 1.2 Electricity Meter
    3. 1.3 Power Quality Meter, Power Quality Analyzer
    4. 1.4 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 External Supply Voltage Supervisor (SVS) With TPS3840
      2. 2.2.2 Magnetic Tamper Detection With TMAG5273 Linear 3D Hall-Effect Sensor
      3. 2.2.3 Analog Inputs
        1. 2.2.3.1 Voltage Measurement Analog Front End
        2. 2.2.3.2 Current Measurement Analog Front End
    3. 2.3 Highlighted Products
      1. 2.3.1  ADS131M08
      2. 2.3.2  MSPM0G3507
      3. 2.3.3  MSP430FR4131 for Driving Segmented LCD Displays
      4. 2.3.4  TPS3840
      5. 2.3.5  THVD1400
      6. 2.3.6  ISO6731
      7. 2.3.7  ISO6720
      8. 2.3.8  TRS3232E
      9. 2.3.9  TPS709
      10. 2.3.10 TMAG5273
  9. 3System Design Theory
    1. 3.1  How to Implement Software for Metrology Testing
    2. 3.2  Clocking System
    3. 3.3  UART Setup for GUI Communication
    4. 3.4  Real-Time Clock (RTC)
    5. 3.5  LCD Controller in MSP430FR4131
    6. 3.6  Direct Memory Access (DMA)
    7. 3.7  ADC Setup
    8. 3.8  Foreground Process
      1. 3.8.1 Formulas
    9. 3.9  Background Process
    10. 3.10 Software Function per_sample_dsp()
      1. 3.10.1 Voltage and Current Signals
      2. 3.10.2 Frequency Measurement and Cycle Tracking
    11. 3.11 LED Pulse Generation
    12. 3.12 Phase Compensation
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Required Hardware and Software
      1. 4.1.1 Hardware
      2. 4.1.2 Cautions and Warnings
    2. 4.2 Test Setup
      1. 4.2.1  Connecting the TIDA-010243 to the Metering Test Equipment
      2. 4.2.2  Power Supply Options and Jumper Settings
      3. 4.2.3  Electricity Meter Metrology Accuracy Testing
      4. 4.2.4  Viewing Metrology Readings and Calibration
        1. 4.2.4.1 Viewing Results From LCD
        2. 4.2.4.2 Calibrating and Viewing Results From PC
      5. 4.2.5  Calibration and FLASH Settings for MSPM0+ MCU
      6. 4.2.6  Gain Calibration
      7. 4.2.7  Voltage and Current Gain Calibration
      8. 4.2.8  Active Power Gain Calibration
      9. 4.2.9  Offset Calibration
      10. 4.2.10 Phase Calibration
      11. 4.2.11 Software Code Example
    3. 4.3 Test Results
      1. 4.3.1 SVS Functionality Testing
      2. 4.3.2 Electricity Meter Metrology Accuracy Results
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout Recommendations
      4. 5.1.4 Layout Prints
      5. 5.1.5 Gerber Files
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

3.8 Foreground Process

The foreground process includes the initial setup of the MSPM0+ MCU hardware and software and the ADS131M08 registers immediately after a device RESET. Figure 3-2 shows the flowchart for this process.

GUID-20230518-SS0I-CP27-9DWL-BJHDLHT1CVPW-low.svgFigure 3-2 Foreground Process

The initialization routines involve the setup of the MSPM0G3507:

  • General purpose input/output (GPIO) port pins
  • Clock system (MCLK or CPU clock, RTC clock, SPI clock, I2C clock, CLK_OUT pin)
  • 4 UART ports for UART functionality
  • Two DMA channels, one per SPI receive and transmit
  • ADS131M08 registers
  • Metrology variables

After the hardware is setup, any received frames from the GUI are processed. If RS-485 is selected for communication to the PC GUI, the THVD1400 device must have the RE and DE pins driven to enable the receiver and driver during the proper points in time to receive packets from the PC GUI and send responses back to the GUI. After any packet is sent from the MSPM0+ MCU to the PC GUI, the foreground process is responsible for asserting the RE and DE pins after the packet has been completely sent out from the MSPM0+ MCU but before the GUI sends out the next packet.

Subsequently, the foreground process checks whether the background process has notified the foreground process to calculate new metering parameters for any voltage-current mappings. This notification is accomplished through the assertion of the "PHASE_STATUS_NEW_LOG" status flag whenever a frame of data is available for processing. The data frame consists of the processed dot products that were accumulated for approximately one second in the background process. This is equivalent to an accumulation of 50 or 60 cycles of data synchronized to the incoming voltage signal. In addition, a sample counter keeps track of how many samples accumulate over this frame period. This count can vary as the software synchronizes with the incoming Mains frequency.

The processed dot products include the VRMS, IRMS, active power, and reactive power. These dot products are used by the foreground process to calculate the corresponding metrology readings in real-world units. Processed voltage dot products, current dot products, active energy dot products, and reactive energy dot products are accumulated in separate 64-bit registers to further process and obtain the RMS and mean values. Using the calculated values of active and reactive power of the foreground process, the apparent power is calculated. The frequency (in Hz) and power factor are also calculated using parameters calculated by the background process using the formulas in Section 3.8.1.

For the 3-phase configuration, there are three voltage-current mappings, where each voltage-to-current mapping has a different voltage and current channel. Specifically, the line-to-neutral voltage measurement for line A and the line A current measurement are associated with each other for one mapping and the line-to-neutral voltage measurement for line B and the line B current measurement are associated with each other for the other mapping and the same for Line C. For simplicity, note that each voltage-to-current mapping is referred to as a phase in the rest of this documentation as well as in the PC GUI.

The foreground process also updates the LCD. The LCD display item is changed every two seconds. See Section 4.2.4.1 for more information about the different items displayed on the LCD.