TIDUF72 August   2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
    2. 1.2 End Equipment
    3. 1.3 Electricity Meter
    4. 1.4 Power Quality Meter, Power Quality Analyzer
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Magnetic Tamper Detection With TMAG5273 Linear 3D Hall-Effect Sensor
      2. 2.2.2 Analog Inputs of Standalone ADCs
      3. 2.2.3 Voltage Measurement Analog Front End
      4. 2.2.4 Analog Front End for Current Measurement
    3. 2.3 Highlighted Products
      1. 2.3.1 AMC131M03
      2. 2.3.2 ADS131M02
      3. 2.3.3 MSPM0G1106
      4. 2.3.4 TMAG5273
      5. 2.3.5 ISO6731
      6. 2.3.6 TRS3232E
      7. 2.3.7 TPS709
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
      1. 3.1.1  Software Requirements
      2. 3.1.2  UART for PC GUI Communication
      3. 3.1.3  Direct Memory Access (DMA)
      4. 3.1.4  ADC Setup
      5. 3.1.5  Foreground Process
      6. 3.1.6  Formulas
        1. 3.1.6.1 Standard Metrology Parameters
        2. 3.1.6.2 Power Quality Formulas
      7. 3.1.7  Background Process
      8. 3.1.8  Software Function per_sample_dsp()
      9. 3.1.9  Voltage and Current Signals
      10. 3.1.10 Pure Waveform Samples
      11. 3.1.11 Frequency Measurement and Cycle Tracking
      12. 3.1.12 LED Pulse Generation
      13. 3.1.13 Phase Compensation
    2. 3.2 Test Setup
      1. 3.2.1 Power Supply Options and Jumper Setting
      2. 3.2.2 Electricity Meter Metrology Accuracy Testing
      3. 3.2.3 Viewing Metrology Readings and Calibration
        1. 3.2.3.1 Calibrating and Viewing Results From PC
      4. 3.2.4 Calibration and FLASH Settings for MSPM0+ MCU
      5. 3.2.5 Gain Calibration
      6. 3.2.6 Voltage and Current Gain Calibration
      7. 3.2.7 Active Power Gain Calibration
      8. 3.2.8 Offset Calibration
      9. 3.2.9 Phase Calibration
    3. 3.3 Test Results
      1. 3.3.1 Energy Metrology Accuracy Results
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
      3. 4.1.3 PCB Layout Recommendations
      4. 4.1.4 Layout Prints
      5. 4.1.5 Altium Project
      6. 4.1.6 Gerber Files
      7. 4.1.7 Assembly Drawings
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  11. 5About the Authors

3.1 Hardware Requirements

This reference design can be powered by connecting 3.3V and GND to the board connector J8.

The MSPM0G1106 device provides the minimum resources for running the metrology library and has the required peripherals to interface to the standalone ADCs and the PC GUI.

The required MCU peripheral modules are:

  • HF Clocking subsystem using external XTAL
  • SPI with DMA (data transfer between stand-alone ADCs and MSPM0 MCU)
  • SPI for external SPI flash memory device
  • UART with DMA (data transfer between external PC GUI and MSPM0 MCU for calibration and metrology values read out)
  • GPIOs (inputs with interrupts or outputs for LEDs and ADCs control)
  • I2C for TMAG5273 interface
  • RTC (calendar mode based off 32.768kHz from internal LFOSC)

All the above peripherals or MCU modules are configured through the TIDA-010944.syscfg file in the MSPM0-SDK middleware, utilizing the graphical SysConfig tool, which enables intuitive MCU configuration changes over a GUI interface.

  1. The M0+ clocking scheme is derived from the external 16.384MHz XTAL, which is feeding the PLL module and is being multiplied and divided with specific factors to generate the MCLK frequency (the CPU clock speed) of 79.87MHz. The same external 16.384MHz XTAL is divided by 2 and output to a GPIO pin with high-drive capability to create the 8.192MHz output frequency for M0_CLKOUT.
  2. The SPI bus is shared between both ADCs and the MCU features an SPI controller with two separate CS (Chip Select) lines, one of each connecting to an ADC. The SPI bus runs at 19.968 or 13,312MHz data rate with DMA support using two channels, one for transmit and one for receive. The SPI PICO and POCI data lines are shared, as these are driven sequentially with only one CS line active at a time. The SPI clock from the M0+ MCU SPI peripheral is wired to both ADCs.
  3. The MSPM0G1106 is configured to communicate to the PC GUI through a non-isolated UART connection at maximum 115,200 baud with 8N1. The UART driver supports a bidirectional transfer (two DMA channels are used, one for transmit and one for receive) with a minimum MCU interrupt load.
  4. The two DRDY lines (one from each ADC) are wired to two GPIO inputs of MSPM0+ MCU with interrupt enabled on the falling edge. Three MCU GPIO outputs are needed: the SYNC_RESET line to trigger all ADCs simultaneously, which is shared by all ADCs, and ACT and REACT outputs. These pulsed outputs are for the Active and Reactive energy, being calculated by the metrology middleware and are used to measure the TIDA-01044 accuracy using an external test system, which reads the pulses.
  5. An I2C interface is used to connect the TMAG5273 3D-Hall sensor device, with the MCU being the I2C transmitter.
  6. The RTC module supports calendar mode, which is a common requirement for an electricity meter. The M0+ MCU internal 32.768kHz LFOSC is used as the clock source for the auxiliary clock (RTCCLK) of the device.
  7. Due to the need to have a synchronous clock to both ADCs, the CLKIN signals are wired to the 8.192MHz M0_CLKOUT output pin.