Safety I&C FPGA Circuit with Switch Matrix for Predictable Timing
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Solution Overview
Problem
The nuclear industry faces challenges in adopting FPGA-based safety I&C systems due to unpredictable timing characteristics and the need for electronics experts, as existing partial reconfiguration tools are complex, unstable, and not well-suited for nuclear applications, which require predictable and stable solutions.
Innovation Solution
The approach involves developing pre-qualified FPGA designs with a superset of logic blocks and using a programmable switch matrix or crossbar switch to connect these blocks in a project-specific way, allowing for a diagram-based engineering flow without requiring electronics experts, and utilizing CPLDs or FPGAs with a dedicated tool chain for predictable timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If FPGA-based safety I&C systems are used, then flexibility and parallel signal handling are improved, but timing predictability and tool chain stability deteriorate
Solution Approach 1:
The system is divided into two distinct parts: a fixed, pre-qualified FPGA design that provides timing predictability, and a programmable switch matrix that provides flexibility. This segmentation allows each part to optimize for its specific function without compromising the other.
Solution Approach 2:
A programmable switch matrix is introduced as an intermediary component between the fixed FPGA design and the external interfaces. This mediator provides the needed flexibility for different applications while the fixed FPGA core maintains timing predictability and has already undergone qualification.
2Ease of operation
If diagram-based engineering approach is used, then ease of operation is improved, but applicability to FPGA systems deteriorates
Solution Approach 1:
The programmable switch matrix acts as an intermediary that translates high-level diagram-based specifications into concrete FPGA configurations. This allows nuclear engineers to use familiar diagram-based tools without needing to master complex FPGA design methodologies.
Solution Approach 2:
The fixed FPGA design serves as a proven template or copy that has already been qualified. Instead of creating new FPGA designs from scratch for each project, the same proven design is reused with different switch matrix configurations, maintaining both ease of operation and FPGA compatibility.
3Adaptability or versatility
If partial reconfiguration is implemented, then adaptability is improved, but device complexity and qualification difficulty increase
Solution Approach 1:
The complex partial reconfiguration functionality is extracted and replaced with a simpler programmable switch matrix. This extraction removes the unnecessary complexity of dynamic reconfiguration tools while retaining the essential adaptability needed for different nuclear applications.
Solution Approach 2:
Instead of using dynamic partial reconfiguration to achieve adaptability, the invention inverts the approach by using a fixed design with a programmable routing layer. This inversion simplifies the tool chain while maintaining adaptability through the switch matrix.
4Reliability
If fixed FPGA designs are reused, then qualification effort is reduced, but project-specific adaptability deteriorates
Solution Approach 1:
The system segments functionality into a fixed qualified core and a configurable interface layer. The fixed core maintains its qualification status while the programmable switch matrix provides project-specific adaptability without requiring re-qualification of the entire system.
Solution Approach 2:
Different parts of the system have different qualities: the FPGA core is fixed and highly qualified for reliability, while the switch matrix is programmable and tailored to specific project needs. This local differentiation allows each part to optimize for its primary function.
Data Source
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AI summary
A circuit arrangement, in particular for a safety I&C system (4) of a nuclear power plant (6), is to keep the proven diagram-centric project-specific engineering approach known from CPU-based systems while reaping the benefits of FPGA technology. To this end, the circuit arrangement according to the invention comprises • a generic FPGA (18) with a number of logic blocks (20), and • at least one dedicated PLD (22) which operates as an application-specific switch-matrix for said logic blocks (20).