Bidirectional Communication Clock Synchronization via Test Sequence
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Solution Overview
Problem
Bidirectional communications between electronic units are hindered by unknown and varying time delays due to external conditions like temperature, causing unreliable detection of output signals, especially in JTAG interfaces, where clock synchronization is critical.
Innovation Solution
A method that includes transmitting a test sequence before the response sequence in the output signal, allowing the first electronic unit to account for time delays by recognizing the test sequence and adjusting the clock pulse accordingly, enabling accurate synchronization and analysis of the response sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clock synchronization is used for bidirectional communications, then signal detection reliability is improved, but time delays due to circuit systems and external conditions cause the synchronization to fail
Solution Approach 1:
The patent applies preliminary action by transmitting a test sequence before the actual data sequence. This test sequence allows the receiving unit to measure and determine the time delay in advance, so that when the actual data is transmitted, the clock pulse can be adjusted based on the pre-measured delay, ensuring reliable signal detection despite the time delay.
Solution Approach 2:
The patent implements feedback by using the test sequence response to adjust the clock pulse timing. The receiving unit analyzes the test sequence, determines the actual time delay, and feeds this information back to adjust the clock synchronization for subsequent data transmission, thereby compensating for the time delay and improving reliability.
2Productivity
If the clock pulse frequency is increased to improve communication speed, then productivity is improved, but signal detection becomes unreliable due to time shifts caused by circuit delays
Solution Approach 1:
By performing the time delay measurement using a test sequence before actual high-speed data transmission, the system can establish the correct clock timing relationship in advance. This allows the system to operate at higher clock frequencies for improved productivity while maintaining reliable signal detection through the pre-established timing compensation.
3Reliability
If a test sequence is transmitted before the response sequence, then time delay compensation is enabled, but the communication protocol becomes more complex
Solution Approach 1:
The test sequence serves multiple functions: it acts as a synchronization signal, a time delay measurement signal, and a protocol validation signal. By making the test sequence multi-functional, the patent reduces the need for separate dedicated signals for each function, thereby limiting the increase in protocol complexity while achieving comprehensive time delay compensation.
Data Source
AI summary
In a method for carrying out bidirectional communications between a first electronic unit and a second electronic unit, a clock signal and an input signal synchronized with the clock signal are transmitted from the first electronic unit to the second electronic unit, and the second electronic unit transmits a response sequence in an output signal to the first electronic unit. In addition, an unambiguous test sequence is generated in the second electronic unit and transmitted to the first electronic unit prior to the response sequence in the output signal, a time sequence between the test sequence and the response sequence in the output signal making it possible to take into account a time delay between the first electronic unit and the second electronic unit.