Hard Disk Hot-Plug Detection Circuit Using Signal Delay

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Solution Overview

Problem

The existing hybrid hard disk driver backplane technology faces mis-determination issues when hard disks are hot-plugged due to asynchronous changes in IFDET and PRSNT signal levels, leading to incorrect identification of hard disk status and type.

Innovation Solution

A hard disk detecting device with a control circuit and connector that outputs specific signals to determine the presence and type of hard disks, using a latch circuit and delay circuit to synchronize signal changes and correctly identify SAS, SATA, and NVME hard disks during hot insertion and removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the CPLD determines hard disk status based on IFDET and PRSNT signal levels, then the detection method is simple, but mis-determination occurs during hot-plugging due to asynchronous signal level changes

Engineering Contradiction:

Improvedetection logic complexityVSAvoidhard disk status detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces a delay circuit that delays the PRSNT signal by a predetermined time before it reaches the CPLD. This preliminary action ensures that the PRSNT signal level changes are synchronized with the IFDET signal level changes, preventing mis-determination during hot-plugging operations. The delay circuit pre-adjusts the timing of signal arrivals at the detection logic.

Inventive Principle:

Principle #10Preliminary action

2Speed

If signal level changes are used to detect hard disk hot-plugging, then the detection method is fast, but asynchronous changes cause incorrect identification of hard disk type

Engineering Contradiction:

Improvehot-plugging detection speedVSAvoidhard disk type identification accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent introduces a delay circuit as an intermediary element between the PRSNT signal source and the CPLD detection logic. This intermediary component synchronizes the arrival times of signal level changes, ensuring that both IFDET and PRSNT signals are processed simultaneously by the CPLD, thereby eliminating incorrect identification of hard disk types during asynchronous hot-plugging events.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12002494B2Method and device for detecting hard disk connection and disconnection during a computer session

Publication Date: 2024.06.04 FULIAN PRESION ELECTRONICS (TIANJIN) CO LTD

AI summary

A device to detect hot-plugging and hot-unplugging of hard disk and the hard disk type includes a connector and a control circuit. When hot-plugged, the hard disk is coupled to the connector, the control circuit comprises delay circuit and latch circuit. The delay circuit delays a falling edge of the third signal and outputs a delay signal, the latch circuit processes the first and second signals and outputs a logical result as a latch signal. The control circuit determines the connected or disconnected status and type of the hard disk according to the respective levels of the first and second signals, the delay signal, and the latch signal. The delay signal and the latch signal work to correct error of the control circuit in determining connectivity and non-connectivity during a session due to asynchronous changes in signal levels of the first and second signals.