Half-Duplex Data Link Frame Structure for Direction Reversal Control
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Solution Overview
Problem
Existing half-duplex wired communications links face inefficiencies due to transmission delays, requiring complex circuitry to manage synchronization and data transfer direction reversals, which affects the utilization of available time for data transfer between master and slave devices.
Innovation Solution
A method and device configuration for transferring data over a half-duplex wired communications link using two wires, where a clock signal and payload data are transmitted in one direction, and control data is transmitted in the opposite direction, with a frame structure that allows only one pair of data transfer direction reversals per frame, optimizing data transfer efficiency by minimizing overhead and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bidirectional data transfer is implemented on a single wire with multiple direction reversals per frame, then data communication flexibility is improved, but transmission time is wasted due to multiple reversals and complex synchronization circuitry is required
Solution Approach 1:
The data transfer is segmented into distinct phases within each frame: a first phase for transferring first data in a first direction, and a second phase for transferring second data in a second direction. This segmentation allows controlled direction reversal with minimal overhead, resolving the contradiction by limiting reversals to essential transitions while maintaining bidirectional communication capability.
Solution Approach 2:
The system employs periodic frame structures where direction reversals occur at predetermined intervals (once per frame). This periodic approach regularizes the transmission pattern, eliminating the need for complex synchronization circuitry while ensuring efficient use of transmission time through predictable, timed direction changes.
2Productivity
If bidirectional data transfer is implemented on a single wire, then wire usage efficiency is improved, but device complexity increases due to synchronization requirements
Solution Approach 1:
By implementing periodic frame structures with predetermined direction reversals, the system eliminates the need for complex continuous synchronization circuitry. The periodic nature of the frames provides inherent timing references that simplify the receiver's ability to synchronize, thus reducing device complexity while maintaining efficient wire usage.
Solution Approach 2:
The frame structure itself carries the synchronization information needed for operation. The predetermined reversal pattern embedded in the frame structure allows the receiving device to self-synchronize without requiring additional complex external synchronization circuitry, enabling the system to serve its own synchronization needs.
3Productivity
If direction reversals are minimized to one pair per frame, then transmission efficiency is improved, but control over data transfer flexibility is reduced
Solution Approach 1:
The frame is segmented into distinct phases with predetermined reversal points, which maintains transmission efficiency by limiting reversals to essential transitions. Within this segmented structure, the system retains flexibility by allowing different types of data (synchronization data, command data, status data) to be transferred in different phases, preserving control adaptability despite the reduced number of reversals.
Solution Approach 2:
The frame structure with predetermined reversals serves multiple functions: it enables bidirectional communication, provides synchronization references, and accommodates various data types (commands, status, payload). This multi-functionality maintains data transfer flexibility despite the simplified reversal pattern, as the same structural framework supports diverse communication needs.
Data Source
AI summary
A method is used for transferring data over a half-duplex wired communications link, wherein the wired communications link comprises first and second wires. The method comprises, in each of a plurality of frames: transferring a clock signal on the first wire in a first direction; transferring first payload data on the second wire in the first direction; transferring second payload data on the second wire in a second direction opposite to the first direction; and transferring control data on the second wire, wherein the format of the frame is such that, irrespective of whether the control data is transferred in the first direction or in the second direction, there is only one pair of reversals of a direction of data transfer in each frame.