SPLA002 July   2026 CC2755R10

 

  1.   1
  2.   Abstract
  3. 1Introduction
  4. 2Profile of CC2755
  5. 3Demonstration of the TI Door Lock Solution
  6. 4Overview of Channel Sounding Technology
    1. 4.1 Basic Principles
    2. 4.2 Ranging method
    3. 4.3 Accuracy and Reliability
  7. 5Overall System Design
    1. 5.1 Overall System Architecture
      1. 5.1.1 Power Design Guidance
        1. 5.1.1.1 Linear Regulator Architecture
        2. 5.1.1.2 Buck Converter Architecture
      2. 5.1.2 Motor Driver Design Guidance
  8. 6CC2755-Based Ranging Implementation
    1. 6.1 Keyless Entry Logic
      1. 6.1.1 Basic Configuration and Calibration
      2. 6.1.2 Real-Time Ranging Process
      3. 6.1.3 Frictionless Unlocking Decision Logic
        1. 6.1.3.1 Intent Judgement
      4. 6.1.4 Unlock Execution and Feedback
      5. 6.1.5 Exception Handling
    2. 6.2 RF Hardware Design
      1. 6.2.1 Key End Solution Selection
      2. 6.2.2 Door Lock End Solution Selection
    3. 6.3 Hardware Reference Design
    4. 6.4 Single Antenna and Multi-Antenna
      1. 6.4.1 Impact of Antenna Quantity on Channel Sounding Ranging Performance
      2. 6.4.2 The Role of Antennas in Phase-Based Ranging
      3. 6.4.3 Analysis of Advantages and Disadvantages of Single-Antenna Configuration
        1. 6.4.3.1 Advantages: Simplicity and Low Cost
        2. 6.4.3.2 Disadvantages: Limited by Multiple Interference Factors
      4. 6.4.4 Analysis of Advantages and Disadvantages of Multi-Antenna Configuration
        1. 6.4.4.1 Advantage 1: Anti-Multipath Capability Brought by Spatial Diversity
        2. 6.4.4.2 Advantage 2: Alleviating Antenna Orientation Sensitivity Issues
        3. 6.4.4.3 Advantage 3: Dual Enhancement of Accuracy and Robustness
        4. 6.4.4.4 Disadvantages: Increased Hardware Complexity and Cost
      5. 6.4.5 Precautions for Dual-Antenna Design
    5. 6.5 Test results
      1. 6.5.1 Hardware configuration
      2. 6.5.2 Software Configuration:
      3. 6.5.3 Environment Setup:
    6. 6.6 Power consumption simulations
  9. 7Summary
  10. 8References

1 Introduction

Throughout the evolution of the smart door lock industry, a "safer, more reliable, and more frictionless" unlocking experience has always been the core objective of technological advancement. The frictionless unlocking feature of traditional Bluetooth smart door locks typically uses the Received Signal Strength Indicator (RSSI) as the distance criterion, triggering the unlock logic via path loss calculations. However, RSSI signals fluctuate drastically due to factors such as walls, human body obstruction, and metallic reflections; its accuracy is usually on the order of several meters, making it difficult to accurately determine whether a user is truly approaching the door lock, and it carries security risks such as relay attacks.

The Channel Sounding feature introduced in the Bluetooth 6.0 specification fundamentally resolves this issue. No longer relying on signal strength, this feature calculates the physical distance between devices through precise measurements of phase changes and round-trip times of wireless signals, achieving centimeter-level ranging accuracy while integrating security mechanisms against relay attacks.

The TI SimpleLink™ CC2755 series devices are the industry's first wireless MCU product line to receive Bluetooth Channel Sounding certification and enter mass production; they support the Bluetooth® 6.0 specification and integrate an Algorithm Processing Unit (APU) and a Neural Processing Unit (NPU-CDE) dedicated to Channel Sounding post-processing, capable of running high-resolution ranging algorithms such as MUSIC and network models to handle post-processing in complex application scenarios like Line of Sight (LOS) and Non-Line of Sight (NLOS). Taking the smart door lock keyless entry application as the scenario, this paper introduces the system implementation solution based on the CC2755.