PXI Express Controller Power State Machine
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Solution Overview
Problem
PXI Express controllers face challenges in handling scenarios without a chassis power button, where auxiliary power is not provided, leading to difficulties in automatically booting up or maintaining the main power supply in an off state when inserted into a chassis with always-present auxiliary power.
Innovation Solution
A state-machine configured PXI Express controller that supports three conditions for turning on, including automatically asserting the power button signal when auxiliary power is present, and preventing the main power supply from turning on when inserted into a chassis with always-present auxiliary power, by programming the chipset to maintain the power off state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the controller uses standard PC chipset power management, then the controller can automatically boot up when power button is pressed, but the controller cannot handle scenarios where power button is absent or auxiliary power is not provided
Solution Approach 1:
The controller monitors its own power state and automatically asserts the power button signal to the chipset when auxiliary power is present but main power is off, enabling self-boot functionality without external intervention or mechanical power buttons
Solution Approach 2:
The controller continuously monitors the power state through power good signals from the power supply and uses this feedback to automatically assert or de-assert the power button signal, ensuring reliable power management across different configurations
2Ease of operation
If the controller automatically asserts power button signal to enable booting, then the controller can boot up without mechanical power button, but the controller may incorrectly turn on main power supply when inserted into chassis with always-present auxiliary power
Solution Approach 1:
The controller dynamically adjusts its power management behavior based on detected conditions: when auxiliary power is present without main power, it asserts power button signal for booting; when both auxiliary and main power are present, it de-asserts the signal to prevent incorrect power-on
Solution Approach 2:
The controller changes the state of the power button signal (asserted/de-asserted) based on the detected power state parameters, allowing flexible adaptation to different power configuration scenarios
3Reliability
If the controller prevents main power supply from turning on when auxiliary power is present, then the controller remains off when inserted into chassis, but the controller cannot automatically boot up when power is switched on
Solution Approach 1:
The controller dynamically responds to power state changes: when main power is switched on while auxiliary power is present, it detects this change and automatically asserts the power button signal to enable booting, overcoming the prevention mechanism
Data Source
AI summary
A PXI Express controller may be configured to support at least three different conditions under which the controller may be turned on. If a chassis (e.g. a PXI Express chassis) interfacing with the controller has a power button, the first condition (which may be considered normal operation) may be met when the power button is being pressed at a time auxiliary power is present. When the chassis does not have a power button, the second condition may be met when the power is switched on at a time auxiliary power is present, and the third condition may be met when the power is switched on at a time auxiliary power is not present. A state-machine comprised in the PXI Express controller may be configured to interface with a chipset equally comprised in the PXI Express controller, to perform the control functions required to provide the support for the three different conditions.