Serial Port Squelch Circuit Using Timer-Based State Machine

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Solution Overview

Problem

Current technologies lack a solution to suppress serial port ingress traffic effectively, particularly in raw socket implementations, where continuous bad data from serial devices causes 'jamming' due to the absence of squelching and unsquelching mechanisms at the serial port itself.

Innovation Solution

A circuit and method utilizing timers and a state machine to enable squelching and unsquelching of serial port ingress traffic, including a squelch timer, idle timer, and auto-clear timer, configured with user-adjustable parameters, to detect and manage continuous data streams and prevent data path failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If serial port ingress traffic is allowed to flow continuously, then the serial device can send data without interruption, but the network becomes jammed when bad character data is transmitted continuously

Engineering Contradiction:

Improveserial data transmission continuityVSAvoidnetwork jamming from bad character data

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary mechanism (squelch/unsquelch function with timers and state machine) between the serial port and the network to filter out bad character data. This intermediary monitors the serial data stream, detects continuous bad data patterns, and selectively blocks them before they can jam the network, while allowing legitimate data to pass through normally.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If squelching is implemented at the far-end of C-Pipe with framing, then serial data can be filtered, but the solution cannot be applied to raw socket implementations where TDM frames are not used

Engineering Contradiction:

Improveserial data filtering capabilityVSAvoidcompatibility with raw socket implementation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the operational parameters of the squelch function by removing its dependency on framed data structures and TDM protocols. Instead, it operates directly on raw character streams from serial ports using timer-based detection mechanisms, making it adaptable to both framed and unframed (raw socket) implementations without requiring protocol-specific infrastructure.

Inventive Principle:

Principle #35Parameter changes

3Loss of information

If the entire bit stream including idle data is transferred over C-Pipe, then complete serial data is transmitted, but network bandwidth consumption increases significantly

Engineering Contradiction:

Improvecompleteness of serial data transmissionVSAvoidnetwork bandwidth consumption

Core Design Contradiction:

Loss of informationVSLoss of energy

Solution Approach 1:

The patent extracts and removes unnecessary idle data and bad character data from the serial bit stream before transmission over the network. By selectively filtering out these non-essential elements while preserving legitimate data, the system reduces network bandwidth consumption without sacrificing the completeness of meaningful serial data transmission.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10164887B2Circuit and method for squelching and unsquelching serial port ingress traffic

Publication Date: 2018.12.25 ALCATEL LUCENT CANADA INC

AI summary

Various embodiments relate to an apparatus and method for squelching and unsquelching serial port ingress traffic, including a squelch timer, an idle timer and a state machine which is configured to enable squelch and enable a data path, load and start the squelch timer when a character is received by the serial port, load and start the idle timer, activate a squelch state when the squelch timer expires before the idle timer and disable the data path.