Preamble Detection Circuit for Asynchronous Signal Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Programmable logic devices (PLDs) face challenges in handling asynchronous clock signals from external devices, leading to data loss or errors due to unknown timing, which existing techniques have not adequately addressed.
Innovation Solution
An apparatus and method involving a delay evaluation section that receives signals, stores expected time delays, and adjusts based on signal occurrences to synchronize data transfer, using a preamble detection circuit to accurately time data capture and transition between different clock domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing asynchronous signal handling techniques are used, then device complexity is reduced, but data reliability deteriorates due to data loss and errors from unknown timing
Solution Approach 1:
The patent applies preliminary action by detecting the preamble signal before the actual data transfer begins. The delay evaluation section pre-measures the time delay between the first signal and the second signal during a calibration phase, storing this information for later use. This allows the system to establish timing relationships in advance, ensuring reliable data capture without adding complex real-time timing logic during normal operation.
Solution Approach 2:
The patent uses an intermediary approach by introducing a preamble detection circuit as a mediator between the asynchronous clock domains. This circuit includes a delay evaluation section that acts as an intermediate measurement stage, separating the complex asynchronous timing problem into manageable parts: preamble detection, delay measurement, and then using the stored delay information to guide subsequent data capture operations.
2Measurement precision
If precise timing synchronization is implemented, then data capture accuracy is improved, but device complexity increases due to additional synchronization circuitry
Solution Approach 1:
The delay evaluation section performs preliminary timing measurements during a calibration phase before actual data transfer. It stores the measured time delay information, which is then reused for multiple subsequent data capture operations. This approach achieves precise timing synchronization without requiring complex real-time synchronization circuitry during normal data transfer.
Solution Approach 2:
The system uses self-service by having the delay evaluation section automatically measure and store its own timing characteristics during calibration. The stored delay information is then used by the same system to synchronize subsequent data capture operations, eliminating the need for external timing reference or complex continuous synchronization mechanisms.
3Reliability
If delay measurement and adjustment is performed, then data transfer reliability is improved, but processing time increases due to calibration sequence
Solution Approach 1:
The delay measurement and adjustment is performed as a preliminary calibration action before normal data transfer begins. The delay evaluation section measures and stores the timing characteristics during this initial phase, enabling fast and reliable data capture in subsequent operations without repeated calibration overhead.
Solution Approach 2:
The patent applies partial action by performing delay evaluation only during the initial calibration phase and not continuously during normal operation. The system measures timing characteristics once (or periodically) and reuses the stored information, rather than continuously measuring and adjusting, thereby reducing time loss while maintaining reliability.
Data Source
AI summary
An embodiment of a technique to determine an expected occurrence of a signal is disclosed. The technique includes receiving first and second signals, and storing delay information representing an expected time delay from an occurrence of the first signal to a point in time corresponding approximately to an expected occurrence of the second signal. The technique further includes responding to an occurrence of the first signal by: waiting for a time interval equivalent to the expected time delay, evaluating the second signal at approximately the end of the time interval, and adjusting the stored delay information if the second signal occurred outside a time window associated with the end of the time interval.