Pad Configuration Register Save and Restore Logic
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Solution Overview
Problem
Switching off the power supply to a core power domain results in loss of information from pad configuration registers, leading to routing congestion and high power leakage in conventional D flip-flop implementations, which require software interactions for restoration.
Innovation Solution
A hardware save and restore logic component in the core power domain automatically saves and restores pad configuration registers in a memory within an always-on power domain, reducing power leakage and congestion by enabling autonomous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power supply to the core power domain is switched off to reduce power leakage, then power consumption is reduced, but information in the pad configuration registers is lost
Solution Approach 1:
The hardware save and restore logic component automatically saves the pad configuration register data to external memory before the core power domain is switched off, and restores it after power is switched on. This preliminary action ensures information preservation across power cycles without requiring software intervention.
2Loss of information
If conventional D flip-flop implementations are used to retain pad configuration information, then information can be maintained, but power leakage increases to as high as 5.6 μW
Solution Approach 1:
The pad configuration registers are extracted from the core power domain and placed in an always-on power domain, while only the hardware save and restore logic component remains in the core power domain. This separation allows the configuration data to be retained without continuous power to the core domain, eliminating the need for high-power D flip-flops.
3Loss of information
If pad configuration registers are placed in the always-on power domain to avoid information loss, then information is preserved, but place and route congestion occurs
Solution Approach 1:
The system is segmented into two parts: the pad configuration registers placed in the always-on power domain for information retention, and the hardware save and restore logic component placed in the core power domain for automated management. This segmentation resolves routing congestion by allowing limited I/O at the domain boundary while maintaining functionality.
4Loss of information
If software interactions are used to restore pad configuration registers, then restoration can be achieved, but system complexity and operation time increase
Solution Approach 1:
The hardware save and restore logic component automatically performs the save and restore operations without requiring software intervention. The component detects power domain state changes and autonomously manages the configuration register data, reducing system complexity and operation time.
Data Source
AI summary
According to various illustrative embodiments, an apparatus, system, and method for automatically saving and restoring pad configuration registers implemented in a core power domain are described. In one aspect, the apparatus comprises a save and restore logic component implemented in the core power domain and coupled to the pad configuration registers. The apparatus also comprises a memory instantiated in an always-on power domain and coupled to the save and restore logic component, the save and restore logic component implemented in the core power domain to automatically save the pad configuration registers in the memory in a pad configuration save process before a power supply to the core power domain is switched off and to automatically restore the pad configuration registers from the memory in a pad configuration restore process after the power supply to the core power domain is switched on.