Sync Lane State Signaling for Serial Interface Startup
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Solution Overview
Problem
Existing point-to-multi-point serial communication systems, such as those used in video displays, require a multi-state startup procedure that results in a slow start-up due to the varying initialization times of clock and data recovery (CDR) circuits, necessitating a longer clock pattern transmission to ensure reliable initialization.
Innovation Solution
A system and method utilizing a sync lane for state information communication between the transmitter and receivers, where the transmitter pulls the sync lane to a 'not ready' state and receivers follow suit during initialization, transitioning to 'ready' states to synchronize and enable efficient data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the TCON transmits the clock pattern for a long interval to ensure all DIC CDRs are initialized, then the reliability of display startup is improved, but the startup time becomes relatively slow
Solution Approach 1:
The patent implements a feedback mechanism where each receiver monitors the sync lane and notifies the transmitter when its CDR circuit is initialized. The transmitter receives feedback from all receivers before transitioning from clock pattern transmission to data transmission, ensuring reliable startup while minimizing wait time.
Solution Approach 2:
Each receiver independently monitors its own CDR initialization status and actively pulls the sync lane low when ready, without requiring the transmitter to poll or wait for each receiver individually. This self-service approach allows parallel initialization detection across all receivers.
2Reliability
If the TCON waits for all DIC CDRs to initialize before transitioning to data transmission, then the system reliability is improved, but the productivity of the startup process deteriorates
Solution Approach 1:
The transmitter begins transmitting the clock pattern immediately upon power-up, performing the CDR initialization in parallel across all receivers before the data transmission phase. This preliminary action allows all CDR circuits to initialize simultaneously rather than sequentially, improving startup speed while maintaining reliability through the sync lane coordination.
Solution Approach 2:
The sync lane provides real-time feedback from each receiver to the transmitter about CDR initialization status. This feedback mechanism allows the transmitter to transition to data transmission as soon as all receivers are ready, rather than using a fixed conservative timeout period, thus optimizing startup speed while ensuring reliability.
3Reliability
If a sync lane is added to communicate state information between transmitter and receivers, then the startup reliability is improved, but the device complexity increases
Solution Approach 1:
The sync lane serves multiple functions: it communicates CDR initialization status from receivers to the transmitter, provides a ready signal for state transitions, and enables coordinated synchronization across the entire system. This multi-functionality reduces the need for separate dedicated control lines for each function.
Solution Approach 2:
The patent combines multiple control and status signaling functions into a single sync lane, merging what could have been multiple separate control lines into one shared communication channel. This reduction in the number of physical lines decreases device complexity while maintaining comprehensive control over the startup sequence.
Data Source
AI summary
A system for starting a point-to-multi-point serial communications system. The system includes a transmitter having a sync connection and a plurality of data outputs and a plurality of receivers, each of the plurality of receiver having a sync connection and a data input; the data input of each of the plurality of receivers being connected to a respective one of the plurality of data outputs of the transmitter; and the sync connection of the transmitter being connected, by a conductor, to the sync connection of each of the plurality of receivers, each of the plurality of receivers comprising a first impedance and a first switch, the first impedance and the first switch configured to establish, when the first switch is closed, a current path between the sync connection of the receiver and a first voltage source in the receiver.