TIDUF35A June   2023  – October 2024 AM6442

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Terminology
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1  AM6442 Microprocessor
      2. 2.3.2  DP83867 gigabit Ethernet Physical Transceiver
      3. 2.3.3  DP83TD510E Single-Pair Ethernet Physical Transceiver
      4. 2.3.4  MSPM0G1107 Microcontroller
      5. 2.3.5  LMK1C1106 6-Channel Output LVCMOS 1.8V Buffer
      6. 2.3.6  LMK6C Low-Jitter, High-Performance, Bulk-Acoustic-Wave (BAW) Fixed-Frequency LVCMOS Oscillator
      7. 2.3.7  TLVM13630 High-Density, 3V to 36V Input, 1V to 6V Output, 3A Step-Down Power Module
      8. 2.3.8  LM74700-Q1 Reverse-Polarity Protection Ideal Diode
      9. 2.3.9  TPS62825A Synchronous Step-Down DC-DC Converter
      10. 2.3.10 LMR36006 Ultra-Small Synchronous Step-Down Converter
      11. 2.3.11 TLV62568A High-Efficiency Step-Down Buck Converter With Forced PWM
  9. 3System Design Theory
    1. 3.1 Power Subsystem
    2. 3.2 AM6442 System on Module Subsystem
    3. 3.3 Ethernet Subsystem
    4. 3.4 Power Over Data Line (PoDL) Subsystem
    5. 3.5 Additional Subsystems
      1. 3.5.1 USB 3.1 Interface
      2. 3.5.2 Micro SD Card Interface
      3. 3.5.3 SimpleLink CC3301 Wi-Fi 6 and Bluetooth Low-Energy BoosterPack Interface
      4. 3.5.4 AM6442 UART Interface
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
      1. 4.1.1 Board Interface
        1. 4.1.1.1 Boot Switch Configuration
        2. 4.1.1.2 Starting up the Reference Design
    2. 4.2 Software Requirements
      1. 4.2.1 PoDL PSE Protocol Programming
      2. 4.2.2 Create an SD Card Image With U-Boot and Linux
    3. 4.3 Test Setup and Procedure
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Documentation Support
    3. 5.3 Support Resources
    4. 5.4 Trademarks
  12. 6About the Author
  13. 7Revision History

2.2 Design Considerations

This reference design shows the implementation of the digital back of four single-pair Ethernet (SPE) 10BASE-T1L ports with the option for powering the remote sensors or actuators through Power over Data Line (PoDL). PoDL is standardized by IEEE802.3cg. The PoDL is implemented including serial communication classification protocol (SCCP) to negotiate the desired power class between the power sourcing equipment (PSE) and a powered device (PD).

To implement SPE together with PoDL, on the data side the design needs an Ethernet PHY such as the DP83TD510E, for translating the interface from the media access controller (MAC) to the medium-dependent interface (MDI) on the single pair Ethernet cable. One the MAC side, a media-independent interface (MII) such as the reduced gigabit MII (RGMII) is used.

To add power and SCCP communication to the single pair Ethernet cable, two things are needed: a coupling network to separate power and data on the line, and a device for adding the required communication protocol. The coupling network can be seen as a frequency filter, where the low-frequency component (especially the DC) is going to the power part and the high-frequency components are treated as data going to the PHY. The communication protocol plays an important role, similar to Power over Ethernet (PoE), the PSE needs to make sure to properly power only the PD requesting power. Otherwise the equipment that is connected to SPE can get damaged. The reference design supports four ports of SPE with PoDL, but required only a single microcontroller (MCU) for the SCCP communication.

The reference design uses an AM6442-based system-on-module (SOM) and also supports a gigabit Ethernet port for cloud connection. The Arm Cortex-A53 cores operate the Linux® operating system (OS).

The reference design offers Joint Test Action Group (JTAG) access and an isolated Universal Serial Bus (USB) Universal Asynchronous Receiver or Transmitter (UART) interface to simplify bring up and debug. For storing an application, use either an onboard micro Secure Digital (SD) card connector, a NOR flash, or an eMMC on the module. The boot mode switches allow selection of which peripheral to start from.