Clock Controller for Shared External Oscillator Failover
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Solution Overview
Problem
In microcontroller-based systems, especially those with RF transceivers, sharing a crystal oscillator between RF transceiver circuits and microcontrollers can lead to instability and race conditions, particularly when the oscillator is external and used concurrently, resulting in potential failures and performance issues.
Innovation Solution
A system and method that includes an oscillator control circuit coupled to an external oscillator, a clock controller, and a security circuit to manage and select a system clock, with a detection block to identify failures and interrupt the external oscillator clock signal, ensuring safe and stable execution by switching to alternative clock sources when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the external oscillator is shared between RF transceiver circuit and microcontroller, then resource utilization is improved, but system stability and reliability deteriorate due to race conditions and concurrent access failures
Solution Approach 1:
A clock controller is introduced as an intermediary component between the external oscillator and the microcontroller. This mediator manages clock signal distribution, handles failure detection, and coordinates access between RF transceiver and microcontroller, preventing direct race conditions while enabling shared resource utilization.
Solution Approach 2:
The system implements feedback mechanisms where the clock controller continuously monitors the external oscillator signal and provides feedback about clock status. When failures are detected, the feedback loop triggers automatic switching to internal oscillators, ensuring continuous stable operation without manual intervention.
2Device complexity
If the external oscillator clock signal is directly coupled to the microcontroller, then device complexity is reduced, but the risk of race conditions and execution failures increases
Solution Approach 1:
The clock controller serves as a protective intermediary that sits between the external oscillator and microcontroller. It absorbs the complexity of failure detection and clock switching logic, preventing direct coupling risks while avoiding duplication of control logic in the microcontroller itself.
Solution Approach 2:
The clock management function is segmented into a dedicated clock controller module separate from the main microcontroller. This segmentation isolates the complex failure detection and switching logic into a specialized component, reducing overall system risk while maintaining functional integration.
3Reliability
If failure detection and automatic switching mechanisms are implemented, then system reliability is improved, but device complexity increases due to additional security circuit and detection block
Solution Approach 1:
The failure detection block and clock switching logic are merged into a single integrated clock controller unit. This consolidation combines multiple functions (detection, decision-making, switching) into one cohesive component, reducing overall device complexity while maintaining high reliability through automated failure response.
Data Source
AI summary
In accordance with an embodiment, a system includes an oscillator equipped circuit having an oscillator control circuit configured to be coupled to an external oscillator and a processing unit comprising a clock controller. The clock controller includes an interface circuit configured to exchange handshake signals with the oscillator control circuit, a security circuit configured to receive the external oscillator clock signal and configured to select the external oscillator clock signal as the system clock, and a detection block configured to detect a failure in the external oscillator clock signal. Upon detection of the failure, a different clock signal is selected as the system clock and the interface circuit to interrupts a propagation of the external oscillator.