EFB Display Controller for Priority-Based Processor Arbitration
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Solution Overview
Problem
Designing a Class III Electronic Flight Bag (EFB) device that can simultaneously run Type B and Type C software applications while sharing a display screen and keyboard I/O device is constrained by issues like FAA Certified Screen Display De-confliction, Data Separation, and Independent Software Development, where higher priority tasks need to gain control over lower priority tasks for safety, but commercial off-the-shelf software lacks the necessary self-prioritizing features and interoperability for FAA certification.
Innovation Solution
A system with two processors, where one processor runs an FAA-certified Type C application and the other a lower priority Type B application, sharing a common display and I/O port, allowing the first processor to control the display and I/O operations to prioritize critical information, potentially blocking or merging information from both applications, thus reducing the need for costly certification of the second application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single display is shared by two processors running different software applications, then cost is reduced and device complexity is lowered, but the ability of higher priority tasks to gain control of the display and data I/O is compromised
Solution Approach 1:
A display controller serves as an intermediary between two processors and a single display device. The controller receives display data from both processors, determines priority based on control signals, and selectively outputs data from the higher priority processor to the display, enabling priority-based access without requiring multiple displays
Solution Approach 2:
The system dynamically adjusts display output by receiving control signals that indicate priority status of different processors. The display controller dynamically switches between processors based on real-time priority requirements, allowing the higher priority processor to take control when needed while maintaining cost-effective single display architecture
2Ease of manufacture
If commercial off-the-shelf software is used for lower priority tasks, then cost is reduced and ease of manufacture is improved, but the software lacks self-prioritizing features needed for FAA certification
Solution Approach 1:
The display controller acts as an intermediary that implements priority management logic externally, allowing COTS software to run without requiring built-in self-prioritizing features. The controller receives control signals from the system and manages display access accordingly, enabling FAA certification compliance while using cost-effective commercial software
Solution Approach 2:
The system segments priority management functionality from the software applications themselves and places it in the display controller hardware. This allows COTS software to focus on their primary functions while the hardware controller handles priority arbitration, separating concerns and enabling use of commercial software in certified systems
3Reliability
If Type C application controls the display to provide urgent warnings, then safety is improved and reliability is enhanced, but the lower priority Type B application cannot display its information
Solution Approach 1:
The display controller periodically monitors control signals from both processors and dynamically switches display output based on current priority requirements. When urgent warnings are needed, Type C application gains control; when safe, Type B application can display information, creating periodic alternation that ensures safety while minimizing information loss
Solution Approach 2:
The system dynamically adjusts display allocation based on real-time priority signals. The display controller can switch between processors dynamically, allowing Type B application to utilize the display during low-priority periods while ensuring Type C application can immediately take control when urgent warnings are required, balancing information display with safety requirements
Data Source
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AI summary
An electronic flight bag (EFB) system for use on a mobile platform, for example, a commercial or military aircraft. The EFB system includes first and second independent processors that run first and second independent software applications. The first software application may be a Type C application requiring a high level of governmental agency certification for use on an aircraft while the second application may be a commercially available, off-the-shelf software application that requires no certification. The two processors share a common display, although the first processor is provided with control over the display so that use of the display by the second processor can be inhibited or limited by the first processor as may be needed to display more critical flight or aircraft related information. The first processor is also provided with control over a switching subsystem that can interrupt the flow of information from external I/O devices to and from the second processor, if needed.