Signature-Based Shadow Memory Checking for Fault Detection
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Solution Overview
Problem
Conventional shadow memory validation methods, relying on parity checkers, have limited fault detection coverage, which is inadequate for performance-critical systems like automotive and aerospace, where data integrity is paramount.
Innovation Solution
An integrated circuit (IC) with a multiplexor, shift register, signature storage, and comparator circuit is used to generate and compare signatures from non-volatile and shadow memories, sending an error flag or reload command when discrepancies are detected, ensuring high fault detection coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a parity checker is used to validate shadow memory data, then the validation process is simple and fast, but the fault detection coverage is limited
Solution Approach 1:
The patent creates a shadow memory that is a complete copy of the primary memory, and generates a shadow signature that is a copy of the primary signature. This copying approach allows for comprehensive fault detection by comparing the shadow copy against the primary, enabling detection of faults that simple parity checks would miss while maintaining manageable system complexity through the use of established copying mechanisms
Solution Approach 2:
The patent introduces a signature register and signature comparison logic as an intermediary between the memory structures and the fault detection process. Instead of directly checking individual memory bits with complex circuits, the signature intermediary condenses the memory state into a compact representation that can be efficiently compared, thereby improving fault detection coverage without proportionally increasing checking mechanism complexity
2Reliability
If signature-based checking is implemented, then fault detection coverage is enhanced, but the device complexity increases due to additional components
Solution Approach 1:
The patent segments the memory validation function into distinct components: a primary memory with its signature register, and a shadow memory with its own signature register. This segmentation allows the complex validation task to be divided into manageable parts that can operate independently and be compared, enhancing data integrity while keeping each component's complexity manageable through clear functional separation
Solution Approach 2:
The signature register serves multiple functions: it stores the signature of the primary memory, enables shadow memory validation, and provides a mechanism for detecting faults. This multi-functionality reduces the need for separate dedicated components for each validation task, thereby enhancing data integrity without proportionally increasing the number of components in the system
Data Source
AI summary
In one aspect, an integrated circuit (IC) includes a multiplexor configured to receive data from a non-volatile memory and configured to receive data from a shadow memory, a shift register configured to generate a first signature from the data received from the non-volatile memory and configured to generate a second signature from the data received from the shadow memory; a signature storage configured to store the first signature; and a shadow memory checking controller configured to enable the multiplexor to send the data from the non-volatile memory to the shift register, and send a command to reload the shadow memory with data from the non-volatile memory in response to receiving an error flag. The IC also includes a comparator circuit configured to compare the first signature and the second signature and configured to send the error flag in response to the first signature and the second signature being different.