Slave Device Pass-Through Mode for Serial Communication Phase Error Reduction
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Solution Overview
Problem
In daisy chain serial communications systems, phase difference errors occur during time synchronization between a master device and slave devices due to the accumulation of delays through multiple slave devices, leading to inaccuracies in synchronization.
Innovation Solution
Implementing a slave device with a communications circuit capable of switching between a communication mode and a pass through mode, allowing data to be transmitted directly without relying on its own clock pulse signal, thereby reducing the effective number of intervening slave devices and minimizing phase difference errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is transmitted through multiple slave devices in communication mode, then the data can be processed and transmitted by each slave device using its own clock pulse signal, but the delay time accumulates proportionally to the number of slave devices, causing phase difference errors
Solution Approach 1:
The patent extracts the harmful function of intermediate slave devices (which cause delay accumulation) by introducing a pass-through mode that bypasses their processing functions. When a slave device operates in pass-through mode, it directly transmits received data to the next device without using its own clock pulse signal, thereby removing the source of delay accumulation while maintaining the daisy-chain communication structure.
Solution Approach 2:
The patent makes the communication mode dynamic by allowing slave devices to switch between communication mode and pass-through mode based on whether they are the target of time synchronization. This dynamic switching enables the system to adapt its behavior: intermediate devices use pass-through mode to minimize delay, while the target slave device uses communication mode to perform synchronized processing.
2Measurement precision
If time synchronization is performed between master device and a slave device that is not adjacent to the master device, then the synchronization can be achieved, but phase difference errors occur due to the accumulation of delays through multiple slave devices
Solution Approach 1:
The patent introduces pass-through mode as an intermediary state for intermediate slave devices. These devices act as mere conduits for synchronization data, neither processing nor generating clock-based delays. This intermediary function allows the synchronization signal to pass through multiple devices without accumulating phase errors, effectively making the number of intervening devices irrelevant to measurement precision.
3Ease of operation
If slave devices operate in communication mode, then each device can process and transmit data using its own clock pulse signal, but the delay time in each device accumulates, leading to synchronization errors
Solution Approach 1:
The patent applies different operational qualities to different parts of the system: intermediate slave devices operate in pass-through mode with minimal processing to maintain synchronization precision, while the target slave device operates in communication mode to perform necessary data processing. This local differentiation of operational modes allows the system to maintain both ease of operation and synchronization precision where needed.
Data Source
AI summary
A slave device is equipped with a communications circuit that carries out serial communications in a communication mode in which received data is transmitted in synchronism with its own clock pulse signal, a communications line that carries out serial communications in a pass through mode in which received data is directly transmitted without depending on its own clock pulse signal, a switching unit that switches from the communication mode to the pass through mode, and a control unit that controls the switching unit.