Sensor Clock Synchronization for Reduced Bus Lines
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Solution Overview
Problem
In decentralized systems, reducing the number of bus lines for communication between sensors and control units is necessary to lower costs, while maintaining reliable decoding without external hardware, especially when the clock and transmission start need to be encoded within the data.
Innovation Solution
A sensor with a local clock generator, such as an RC oscillator, sends a synchronization signal based on its internal clock, allowing the control unit to determine the clock period between edges, enabling efficient data sampling and reducing the need for precise clock tolerance matching between sensors and control units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the clock and transmission start are encoded within the data itself to reduce the number of bus lines, then the number of bus lines is reduced, but the decoding complexity increases and requires external hardware
Solution Approach 1:
The sensor performs self-synchronization by generating a synchronization signal based on its own internal clock. The control unit determines the clock period by measuring the time between edges of this self-generated signal, eliminating the need for external decoding hardware while maintaining reliable data transmission
Solution Approach 2:
The invention changes the parameter of clock tolerance by allowing sensors to operate with relaxed clock tolerance (e.g., ±10% or more) instead of requiring precise matching. The control unit adapts to the actual clock period by measuring it from the synchronization signal, enabling communication despite parameter variations
2Reliability
If low-tolerance local clock generators are used in sensors to ensure precise clock matching, then decoding reliability improves, but the manufacturing cost increases
Solution Approach 1:
Each sensor uses its own internal clock to generate the synchronization signal, making the system independent of precise clock matching between sensor and control unit. The control unit measures the actual clock period from the received signal and uses it for sampling, eliminating the need for expensive low-tolerance clock generators in sensors
Solution Approach 2:
The invention changes the acceptable range of clock frequency parameters by allowing significant tolerance (e.g., ±10% or more) instead of requiring precise matching. The system compensates for parameter variations through adaptive measurement of the actual clock period at runtime
3Reliability
If a common system clock is used in embedded systems to coordinate data transmission, then data transmission reliability improves, but the system complexity and cost increase
Solution Approach 1:
The invention extracts the clock synchronization function from the control unit and places it in the sensor itself. The sensor generates and transmits the synchronization signal based on its own internal clock, eliminating the need for a common system clock and reducing system complexity
Solution Approach 2:
Instead of the control unit providing the clock signal to the sensor (traditional approach), the sensor generates its own clock signal and provides it to the control unit. This inversion allows the sensor to operate independently with relaxed clock tolerance while maintaining reliable communication
Data Source
AI summary
A sensor may include a clock generator configured to generate a clock. A receiver may be configured to receive signals from a control unit, and a transmitter they be configured to send signals to the control unit. In one implementation, the transmitter is configured to send a synchronization signal based on the clock. A period between a first edge and a second edge of the synchronization signal may be dependent on the clock and both edges are either rising or falling.