Control Module for Configuration Retention via Hardware Interrupt
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Solution Overview
Problem
Existing power gating technologies in battery-supplied devices lose circuit state information when power is cut off, leading to increased development costs and power consumption due to the use of retention flip-flops, which are area-intensive and consume current in the power-on state.
Innovation Solution
A control module with a storage unit, state machine unit, and event detector that uses a system bus to store and retrieve configuration information via a hardware interrupt signal, reducing area and current consumption by utilizing high-density storage and efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retention flip-flop cell is adopted to keep configuration information, then the circuit state can be retained during power gating, but the area and current consumption increase in the power-on state
Solution Approach 1:
The patent extracts the configuration information retention function from the traditional retention flip-flop cell and relocates it to an external memory device. The control module manages the transfer of configuration information between the peripheral unit and the memory device, allowing the retention function to be performed outside the power-gated circuit block, thus reducing the area occupied within the chip while maintaining reliability.
Solution Approach 2:
The patent introduces a control module as an intermediary between the peripheral unit and the memory device. This control module coordinates the storage and retrieval of configuration information, enabling the system to retain state information without requiring dedicated retention flip-flop cells within the peripheral unit itself, thereby reducing area consumption while preserving the required functionality.
2Reliability
If a retention flip-flop cell is adopted to keep configuration information, then the circuit state can be retained during power gating, but the current consumption increases in the power-on state
Solution Approach 1:
The retention function is extracted from the power-on circuitry and moved to an external memory device that remains in a low-power state. The control module only consumes significant current during the brief periods when configuration information is being transferred, rather than continuously consuming current as retention flip-flop cells would require while powered on.
Solution Approach 2:
The system uses periodic action by only activating the control module and transferring configuration information when mode changes occur (from active to idle or from idle to active). During normal operation, the memory device remains in a low-power state, and the control module enters sleep mode, significantly reducing current consumption compared to continuous operation of retention flip-flop cells.
3Loss of energy
If power gating is used to achieve low leakage, then power consumption is reduced, but the circuit state information is lost
Solution Approach 1:
The control module performs preliminary action by detecting when a mode change is about to occur and proactively transferring the configuration information from the peripheral unit to the memory device before power gating is activated. This ensures that the state information is preserved in a non-volatile or externally maintained location before the power cut-off, preventing information loss while enabling power leakage reduction.
Solution Approach 2:
The system uses feedback through the event detector and control module to monitor system state changes. When the system transitions to idle mode, the control module receives feedback and automatically triggers the backup of configuration information to memory. When transitioning back to active mode, the control module retrieves the information, ensuring continuous state preservation without requiring the peripheral unit to remain powered on.
Data Source
AI summary
A control module used with a peripheral unit having configuration information through a system bus includes a storage unit, a state machine unit and an event detector. The storage unit is configured to store a program. The state machine unit is configured to operate under the program. The event detector is configured to receive a hardware interrupt signal from the peripheral unit via an additional wire, wherein the event detector triggers the state machine to perform one of storing and retrieving the configuration information respectively to and from the storage unit via the system bus.