Interrupt Handling Circuit for Slow Peripheral Clock Domains
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Solution Overview
Problem
Conventional interrupt handling techniques in electronic circuits with differing clock speeds suffer from significant delays and latency, particularly when servicing interrupts from slow clock domain circuits by fast clock domain circuits, leading to potential missed interrupt events due to synchronization challenges.
Innovation Solution
An interrupt handling circuit and method that includes an interrupt generator circuit and an interrupt clear circuit, which generate and clear interrupt signals asynchronously with respect to the slower clock signal, using flip-flops and AND gates to synchronize signals with the faster clock domain, thereby reducing synchronization delays and facilitating timely interrupt servicing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interrupt handling techniques synchronize clear requests to the slow clock signal, then the interrupt clear operation is reliable and coordinated with the slow peripheral circuit, but the interrupt clearance delay increases significantly (at least two slow clock cycles)
Solution Approach 1:
The patent introduces a handshaking mechanism with acknowledge signals as an intermediary between the fast CPU and slow peripheral circuit. The CPU sends a clear request, and the peripheral circuit responds with an acknowledge signal after clearing the interrupt, mediating the interaction between different clock domains to reduce delay while maintaining reliability
Solution Approach 2:
The patent implements preliminary synchronization of the clear request signal to the slow clock domain before executing the clear operation. By pre-synchronizing the request signal, the system prepares the slow peripheral circuit in advance, reducing the overall interrupt clearance delay while ensuring proper coordination
2Reliability
If the fast clock domain CPU waits for interrupt clearance to avoid re-entry, then interrupt handling reliability is maintained, but the CPU productivity decreases due to waiting time
Solution Approach 1:
The patent implements a feedback mechanism where the slow peripheral circuit sends an acknowledge signal back to the fast CPU after clearing the interrupt. This feedback allows the CPU to immediately proceed with other tasks rather than waiting, maintaining reliability through proper synchronization while improving overall CPU productivity through better resource utilization
Solution Approach 2:
The handshaking mechanism enables continuous useful action by allowing the CPU to maintain productivity through overlapping operations. While one interrupt is being cleared in the slow domain, the CPU can continue executing other tasks, ensuring continuous productive work rather than idle waiting
3Stability of the object's composition
If interrupt requests are generated based on rising slow clock edges, then the interrupt generation is synchronized with the slow peripheral circuit operation, but further delays are introduced in servicing interrupt events
Solution Approach 1:
The patent applies preliminary synchronization by pre-aligning the clear request signal with the slow clock domain before the actual interrupt clear operation. This advance preparation reduces the overall latency in servicing interrupt events while maintaining proper synchronization with the slow peripheral circuit's operational rhythm
Data Source
AI summary
Disclosed examples include interrupt handling circuitry and methods for managing interrupts of a fast clock domain circuit operated according to a first clock signal by a slow clock domain circuit operated according to a second clock signal in which an interrupt generator circuit generates an interrupt input signal synchronized to the second clock signal, and an interrupt clear circuit selectively resets the interrupt generator circuit in response to an acknowledgment signal from the first circuit asynchronously with respect to the second clock signal.