Bi-Directional Bus Repeater Control to Prevent Self-Locking
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Solution Overview
Problem
The existing bi-directional bus repeater systems suffer from a self-locking problem, where high-to-low transitions on the bus lines can lead to continuous pull-down of voltages, locking the communication bus and preventing data transfer between communication units.
Innovation Solution
The proposed bi-directional bus repeater design includes pulldown controllers that activate only after simultaneously detecting a high-to-low transition at one input terminal and a logical high at the other input terminal, preventing self-locking by ensuring coordinated activation of pulldown elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-to-low transition occurs on bus line 5A, then data transfer from first communication unit to second communication unit is enabled, but pull-down transistor Q4 activates and causes continuous pull-down of bus line 6A, leading to self-locking
Solution Approach 1:
The patent introduces a control mechanism that mediates between the pull-down transistors Q3 and Q4 and the bus lines. The control inputs of these transistors are governed by pulldown controllers that detect transition conditions before activating the transistors. This intermediary control layer prevents direct, uncoordinated activation that causes self-locking, while still enabling data transfer when conditions are met.
Solution Approach 2:
The pulldown controllers perform preliminary detection of transition conditions (high-to-low transitions) before activating the pull-down transistors. By detecting the transition state first and then coordinating activation, the system prevents the self-locking condition from occurring in the first place, rather than attempting to resolve it after it occurs.
2Ease of operation
If pull-down transistor Q1 is activated to transfer data on bus line 5A, then voltage transition occurs for data communication, but this triggers Q4 activation which in turn triggers Q3 activation, creating a feedback loop that locks the bus
Solution Approach 1:
The patent implements feedback mechanisms where the state of one bus line is monitored to control the activation of transistors on the other bus line. The pulldown controllers continuously monitor the voltage states and only activate pull-down transistors when appropriate transition conditions are detected, creating a controlled feedback loop that prevents uncontrolled self-locking while enabling communication.
3Power
If both Q3 and Q4 are activated simultaneously, then both bus lines 5A and 6A are pulled down, but this creates a self-locking state that prevents further communication
Solution Approach 1:
The pulldown controllers are designed to detect transition conditions and coordinate activation in advance, preventing the harmful self-locking effect from occurring. By monitoring bus line states and only activating transistors when appropriate conditions are met (high-to-low transitions), the system counteracts the potential for self-locking before it can manifest.
Data Source
AI summary
The present disclosure relates to a bi-directional bus repeater. The present disclosure further relates to a communication bus including a bi-directional bus repeater, and to a communication system including the communication bus. The bi-directional bus repeater includes a first input terminal, a second input terminal, a first pulldown element connected to the first input terminal, and a second pulldown element connected to the second input terminal. By ensuring that the activation of the first and second pulldown elements is dependent on the state of the corresponding input terminal and the detection of a high-to-low transition of the corresponding other input terminal, the problem of self-locking can be avoided or at least minimized.