Clock-Detecting Circuit Using AC Zero-Crossing for Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional brushless DC motor controllers face issues due to low clock precision in microprocessors, leading to inefficiencies, increased power consumption, and potential damage, with existing solutions being complex and costly.
Innovation Solution
A clock detecting circuit comprising a microprocessor, a zero-cross detecting circuit, and a clock circuit that utilizes utility power AC to detect zero crossing points and count oscillation periods, eliminating the need for special watchdog chips and simplifying the structure while reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high precision clock circuits and special watchdog chips are used to detect clock precision, then clock precision and reliability are improved, but circuit structure complexity and production cost increase
Solution Approach 1:
The microprocessor uses its own internal resources (timer unit and register) to detect clock precision, eliminating the need for external watchdog chips. The system self-monitors by counting clock cycles between AC power zero-crossing points, making the detection function integrated within the existing microprocessor architecture.
Solution Approach 2:
The microprocessor's timer unit, originally designed for general timing functions, is utilized for clock precision detection. This multi-functional use of existing components avoids adding specialized detection hardware, reducing circuit complexity while maintaining detection capability.
2Reliability
If high precision clock circuits and special watchdog chips are used to detect clock precision, then reliability is improved, but production cost increases
Solution Approach 1:
The microprocessor performs self-diagnosis of clock precision using built-in timer resources, eliminating the need to purchase and integrate expensive external watchdog chips. This self-service approach maintains reliability while significantly reducing component costs and manufacturing complexity.
Solution Approach 2:
Instead of using a separate physical watchdog chip to monitor clock precision, the system creates a virtual monitoring mechanism using software-based counting of clock cycles in the microprocessor's existing timer register, achieving the same functional effect at lower cost.
3Device complexity
If the microprocessor counts clock oscillation periods between AC zero crossing points, then clock precision detection is achieved without special chips, but the detection method requires AC power reference
Solution Approach 1:
The AC power zero-crossing points serve as an external reference mediator to measure clock precision. By using the stable 50Hz AC power frequency as a time reference, the system can accurately count clock cycles without requiring complex internal reference oscillators, simplifying the overall detection architecture.
Data Source
AI summary
A clock-detecting circuit, containing at least a microprocessor, a clock circuit, and a zero-cross detecting circuit. The clock circuit is connected to the microprocessor. The input end of the zero-cross detecting circuit is connected to the utility power AC input. The output end of the zero-cross detecting circuit is connected to the input end of the microprocessor. The zero-cross detecting circuit operates to detect zero crossing points of the utility power AC input. The microprocessor operates to count the number of oscillation periods of the clock circuit in a time interval between two adjacent zero crossing points of the utility power AC input and to detect clock precision of the microprocessor according to the counted number. The circuit according to the invention features simple structure and low production cost, and is reliable and easy to be implemented.