Power-Collapsible Boundary Scan Bypassing Unpowered Interfaces
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Solution Overview
Problem
Portable computing devices often have unused off-chip interfaces, leading to power leakage and inefficiencies in boundary scan testing, as unpowered interfaces disrupt the boundary scan chain, preventing comprehensive testing of operational interfaces.
Innovation Solution
The implementation of a bypass control signal and multiplexer system that allows selective bypassing of off-chip interfaces in the boundary scan chain, enabling testing of powered interfaces while excluding unpowered ones, thereby maintaining the integrity of the scan chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unpowered off-chip interfaces are included in the boundary scan chain, then comprehensive testing coverage is improved, but power leakage increases and testing reliability deteriorates
Solution Approach 1:
The patent extracts unpowered off-chip interfaces from the boundary scan chain by introducing bypass control signals that enable the scan chain to skip over interfaces whose power domains are not active. This allows the testing system to focus only on powered interfaces, eliminating power leakage from unpowered interfaces while maintaining testing reliability.
Solution Approach 2:
The patent implements dynamic control of the boundary scan chain through bypass control signals that can be activated or deactivated based on the power state of different interfaces. The scan chain configuration changes dynamically to include only active interfaces during testing, adapting to varying power domain states without requiring physical reconfiguration.
2Adaptability or versatility
If all off-chip interfaces are included in the boundary scan chain, then testing completeness is improved, but device complexity increases due to power management requirements
Solution Approach 1:
The patent introduces bypass control signals as intermediary elements between the boundary scan chain and unpowered interfaces. These control signals act as mediators that automatically determine whether to include an interface in the scan chain based on its power state, eliminating the need for complex manual power management configuration while maintaining testing completeness.
Solution Approach 2:
The bypass control mechanism serves multiple functions: it manages power leakage, determines test coverage, and automatically adapts to different power domain states. This universal approach consolidates multiple management requirements into a single control mechanism, reducing overall device complexity.
3Use of energy by moving object
If unpowered interfaces are bypassed in the boundary scan chain, then power efficiency is improved, but scan chain integrity may be compromised
Solution Approach 1:
The patent segments the boundary scan chain into functional sections by introducing bypass control signals that can independently activate or deactivate specific interface segments. This segmentation allows the scan chain to maintain integrity within powered sections while safely excluding unpowered sections, preserving overall chain stability without requiring continuous physical connectivity.
Data Source
AI summary
Physical or off-chip interfaces may be selectively bypassed in a boundary scan chain. A bypass control signal may be produced that indicates whether to bypass a selected one of the interfaces. In response to a first state of a bypass control signal, a multiplexer may couple the scan chain output of an interface boundary scan cell to the scan chain input of a successor boundary scan cell of the interface boundary scan cell. In response to a second state of the bypass control signal, the multiplexer may couple the scan chain output of a predecessor boundary scan cell of the interface boundary scan cell to the scan chain input of the successor boundary scan cell, bypassing the interface boundary scan cell.