• Menu
  • Product
  • Email
  • PDF
  • Order now

  • Interface to Sin/Cos Encoders With High-Resolution Position Interpolation

    • TIDUA05B June   2015  – March 2025

       

  • CONTENTS
  • SEARCH
  • Interface to Sin/Cos Encoders With High-Resolution Position Interpolation
  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1 System Description
    1. 1.1 Design Overview
    2. 1.2 Analog Sin/Cos Incremental Encoder
      1. 1.2.1 Sin/Cos Encoder Output Signals
      2. 1.2.2 Sin/Cos Encoder Electrical Parameter Examples
    3. 1.3 Method to Calculate High-Resolution Position With Sin/Cos Encoders
      1. 1.3.1 Theoretical Approach
        1. 1.3.1.1 Overview
        2. 1.3.1.2 Coarse Resolution Angle Calculation
        3. 1.3.1.3 Fine Resolution Angle Calculation
        4. 1.3.1.4 Interpolated High-Resolution Angle Calculation
        5. 1.3.1.5 Practical Implementaion for Non-Ideal Synchronization
        6. 1.3.1.6 Resolution, Accuracy, and Speed Considerations
    4. 1.4 Sin/Cos Encoder Parameters Impact on Analog Circuit Specification
      1. 1.4.1 Analog Signal Chain Design Consideration for Phase Interpolation
      2. 1.4.2 Comparator Function System Design for Incremental Count
  8. 2 Design Features
    1. 2.1 Sin/Cos Encoder Interface
    2. 2.2 Host Processor Interface
    3. 2.3 Evaluation Firmware
    4. 2.4 Power Management
    5. 2.5 EMC Immunity
  9. 3 Block Diagram
  10. 4 Circuit Design and Component Selection
    1. 4.1 Analog Signal Chain
      1. 4.1.1 High-Resolution Signal Path With 16-Bit Dual Sampling ADC
        1. 4.1.1.1 Component Selection
        2. 4.1.1.2 Input Signal Termination and Protection
        3. 4.1.1.3 Differential Amplifier THS4531A and 16-Bit ADC ADS8354
      2. 4.1.2 Analog Signal Path With Single-Ended Output for MCU With Embedded ADC
      3. 4.1.3 Comparator Subsystem for Digital Signals A, B, and R
        1. 4.1.3.1 Non-Inverting Comparator With Hysteresis
    2. 4.2 Power Management
      1. 4.2.1 24-V Input to 6-V Intermediate Rail
      2. 4.2.2 Encoder Supply
      3. 4.2.3 Signal Chain Power Supply 5 V and 3.3 V
    3. 4.3 Host Processor Interface
      1. 4.3.1 Signal Description
      2. 4.3.2 High-Resolution Path Using 16-Bit Dual ADC ADS8354 With Serial Output
        1. 4.3.2.1 ADS8354 Input Full Scale Range Output Data Format
        2. 4.3.2.2 ADS8354 Serial Interface
        3. 4.3.2.3 ADS8354 Conversion Data Read
        4. 4.3.2.4 ADS8354 Register Configuration
    4. 4.4 Encoder Connector
    5. 4.5 Design Upgrades
  11. 5 Software Design
    1. 5.1 Overview
    2. 5.2 C2000 Piccolo Firmware
    3. 5.3 User Interface
  12. 6 Getting Started
    1. 6.1 TIDA-00176 PCB Overview
    2. 6.2 Connectors and Jumper Settings
      1. 6.2.1 Connector and Jumpers Overview
      2. 6.2.2 Default Jumper Configuration
    3. 6.3 Design Evaluation
      1. 6.3.1 Prerequisites
      2. 6.3.2 Hardware Setup
      3. 6.3.3 Software Setup
      4. 6.3.4 User Interface
  13. 7 Test Results
    1. 7.1 Analog Performance Tests
      1. 7.1.1 High-Resolution Signal Path
        1. 7.1.1.1 Bode Plot of Analog Path from Encoder Connector to ADS8354 Input
        2. 7.1.1.2 Performance Plots (DFT) for Entire High-Resulation Signal Path
        3. 7.1.1.3 Background on AC Performance Definitions With ADCs
      2. 7.1.2 Differential to Single-Ended Analog Signal Path
      3. 7.1.3 Comparator Subsystem With Digital Output Signals ATTL, BTTL, and RTTL
    2. 7.2 Power Supply Tests
      1. 7.2.1 24-V DC/DC Input Supply
        1. 7.2.1.1 Load-Line Regulation
        2. 7.2.1.2 Output Voltage Ripple
        3. 7.2.1.3 Switching Node and Switching Frequency
        4. 7.2.1.4 Efficiency
        5. 7.2.1.5 Bode Plot
        6. 7.2.1.6 Thermal Plot
      2. 7.2.2 Encoder Power Supply Output Voltage
      3. 7.2.3 5-V and 3.3-V Point-of-Load
    3. 7.3 System Performance
      1. 7.3.1 Sin/Cos Encoder Output Signal Emulation
        1. 7.3.1.1 One Period (Incremental Phase) Test
        2. 7.3.1.2 One Mechanical Revolution Test at Maximum Speed
    4. 7.4 Sin/Cos Encoder System Tests
      1. 7.4.1 Zero Index Marker R
      2. 7.4.2 Functional System Tests
    5. 7.5 EMC Test Result
      1. 7.5.1 Test Setup
      2. 7.5.2 IEC-61000-4-2 ESD Test Results
      3. 7.5.3 IEC-61000-4-4 EFT Test Results
      4. 7.5.4 IEC-61000-4-5 Surge Test Results
  14. 8 Design Files
    1. 8.1 Schematics
    2. 8.2 Bill of Materials
    3. 8.3 PCB Layout Guidelines
      1. 8.3.1 PCB Layer Plots
    4. 8.4 Altium Project
    5. 8.5 Gerber Files
    6. 8.6 Software Files
  15. 9 References
  16. 10About the Author
    1.     Recognition
  17. 11Design Files
    1. 11.1 Schematics
    2. 11.2 Bill of Materials
    3. 11.3 PCB Layout Guidelines
    4. 11.4 Altium Project
    5. 11.5 Gerber Files
  18. 12Support Resources
  19.   Trademarks
  20. 13About the Author
    1.     Recognition
  21. 14Revision History
  22. IMPORTANT NOTICE
search No matches found.
  • Full reading width
    • Full reading width
    • Comfortable reading width
    • Expanded reading width
  • Card for each section
  • Card with all content

 

Design Guide

Interface to Sin/Cos Encoders With High-Resolution Position Interpolation

Description

This reference design is an EMC compliant industrial interface to Sin/Cos position encoders. Applications include industrial drives, which require accurate speed and position control. The design uses a 16-bit dual sample ADC with drop-in compatible 14- or 12-bit versions available, allowing for optimization of performance and cost. TIDA-00176 is also provides a simple to connection to external processors using SPI and QEP interfaces and allows for the use of optional, embedded ADCs. For quick evaluation an example firmware for Piccolo™ F28069M MCU LaunchPad™ is provided, which outputs the measured angle from the Sin/Cos encoder with up to 28-bit resolution through the MCU’s USB virtual COM port.

Resources

TIDA-00176 Design Folder
ADS8354, THS4531A Product Folder
TLV3202, OPA2365 Product Folder
REF2033, TPS54040A Product Folder
TIPD117 Tool Folder
Piccolo F28069M MCU LaunchPad Tool Folder
TIDA-00176 Ask our TI E2E™ support experts

Features

  • EMC-Compliant Industrial Interface Design for Sin/Cos Encoders With 1-VPP Differential Output at 2.5-V Offset, Input Frequencies up to 500 kHz
  • High-Resolution Interpolated Position, up to 28-bit Resolution, Cable Length Tested up to 70 m
  • Dual Analog Signal Chain for Simultaneous Use of 16-bit Dual SAR ADC and MCU Embedded ADCs Allows for Evaluation of Both Paths and Optimization of One Path for Increased Noise Immunity With Reduced Bandwidth
  • Easy to Connect to MCU With SPI and QEP Interface and Option for Cost Optimization Pending Resolution Requirements, Thanks to Drop-in Compatible 14- or 12-bit ADC
  • Example Firmware for C2000™ MCU With High-Resolution Angle Calculated at 16-kHz and Angle Data Send Through USB Virtual COM Port for Easy Performance Evaluation
  • Tested for IEC61000-4-2, 4-4, and 4-5 (ESD, EFT, and Surge EMC Immunity Requirements)

 
Texas Instruments

© Copyright 1995-2025 Texas Instruments Incorporated. All rights reserved.
Submit documentation feedback | IMPORTANT NOTICE | Trademarks | Privacy policy | Cookie policy | Terms of use | Terms of sale