TIDUE74F April   2018  – March 2026

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 C2000™ Real-Time MCU LaunchPad™ Development Kit
      2. 2.2.2 SN65HVD78
      3. 2.2.3 TLV702
      4. 2.2.4 TPS22918-Q1
    3. 2.3 Design Considerations
      1. 2.3.1 Tamagawa T-Format Protocol
      2. 2.3.2 C2000 T-Format Encoder Interface Overview
      3. 2.3.3 TIDM-1011 Board Implementation
      4. 2.3.4 MCU Resource Requirements
      5. 2.3.5 Device-Specific Resource Usage
        1. 2.3.5.1 CRC Calculations
        2. 2.3.5.2 Input, Output Signals, and CLB Tiles
      6. 2.3.6 CLB T-Format Implementation Details
        1. 2.3.6.1 Transaction Waveforms
          1. 2.3.6.1.1 IDLE State
          2. 2.3.6.1.2 TRANSMIT_DATA State
          3. 2.3.6.1.3 WAIT_FOR_START State
          4. 2.3.6.1.4 RECEIVE_DATA State
        2. 2.3.6.2 Communication Tile Design
        3. 2.3.6.3 Logic View
      7. 2.3.7 CLB Receive Data CRC Implementation
      8. 2.3.8 PM T-Format Encoder Interface Library
        1. 2.3.8.1 PM T-Format Reference Implementation Commands
        2. 2.3.8.2 Functions Supported in PM T-Format Reference Implementation
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware
      1. 3.1.1 TIDM-1011 Jumper Configuration
    2. 3.2 Software
      1. 3.2.1 C2000 Driver Library (DriverLib)
      2. 3.2.2 C2000 SysConfig
      3. 3.2.3 C2000 Configurable Logic Block Tool
      4. 3.2.4 Installing Code Composer Studio™ and C2000WARE-MOTORCONTROL-SDK
      5. 3.2.5 Locating the Reference Software
    3. 3.3 Testing and Results
      1. 3.3.1 Hardware Configuration
      2. 3.3.2 Building and Loading Project
      3. 3.3.3 Running Code
      4. 3.3.4 Cable Length Validation
      5. 3.3.5 Benchmarks
      6. 3.3.6 Troubleshooting
  10. 4Design Files
  11. 5Related Documentation
    1. 5.1 Trademarks
  12. 6Terminology
  13. 7About the Authors
  14. 8Revision History

1 System Description

Industrial drives, like servo drives, require accurate, highly-reliable, and low-latency position feedback. The T-Format protocol, from Tamagawa, is designed for serial transfer of digital data between a sensor and a controller. The sensor can be an encoder (linear, rotary, or angle), a touch probe, or an accelerometer. The subsequent electronics, or controller, includes numerical controls, servo amplifiers, and programmable-logic controllers.

The TIDM-1011 design implements a T-Format encoder interface to a C2000 LaunchPad. T-Format is a pure-serial, digital interface, based on the RS-485 standard. T-Format is capable of transmitting position values, along with other physical quantities, and allows reading and writing of the internal memory of the encoder. The transmitted-data types include absolute position, turns, temperature, parameters, and diagnostics. Commands transmitted to the encoder from the interface select the response-data types.

Figure 1-1 shows a T-format encoder connected to a BOOSTXL_POSMGR plus F28379D LaunchPad encoder interface.

TIDM-1011 Industrial Servo Drive With T-Format Position Encoder Interface Figure 1-1 Industrial Servo Drive With T-Format Position Encoder Interface

The position encoder with T-Format connects to the TIDM-1011 device through a single, 4-wire, shielded cable. RS-485 is used as the physical layer for T-Format encoders. The four wires used are:

  • DATA+ and DATA- : differential signals for communication data
  • Power and Ground: encoder power supply and ground

The Texas Instruments C2000 T-Format (PM_tformat) encoder interface implementation enables interfacing a T-Format encoder to a C2000 device without external hardware such as an FPGA or CPLD. The reference implementation features:

  • 2.5 MBPS clock frequency as required by the T-Format protocol
  • Integrated cable-propagation delay compensation to enable variable cable length, verified up to 100 m
  • Software driver functions:
    • Perform a transaction with the encoder. This consists of sending a request and receiving the response.
    • Calculate a CRC
    • Compare CRC received with a calculated CRC
    • Packing and unpacking the data

This reference implementation includes all the source code. Any changes needed for the implementation can be made by users as needed by their application.

Note: Only the basic interface drivers for the commands defined in the T-Format specification are provided. All the higher-level application software must be developed by users using the basic interface provided by this implementation.