Spread Clock Reception Timing for EMI-Safe Serial Communication
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Solution Overview
Problem
The use of spread clock signals for serial communication can lead to communication failures due to mismatched data sampling times when the frequency of the clock signal is cyclically increased and decreased, causing issues in establishing synchronization between the receiver and sender.
Innovation Solution
A receiving apparatus that adjusts the change cycle of the spread clock signal based on the receiving time per bit, using a cycle-adjusting section to synchronize the frequency changes with the data sampling process, thereby preventing communication failures and achieving effective EMI reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the frequency of the clock signal is cyclically increased and decreased to scatter radiation energy and reduce EMI, then EMI reduction is improved, but data sampling timing accuracy deteriorates causing communication failures
Solution Approach 1:
The patent applies periodic action by using spread spectrum modulation that cyclically varies the clock signal frequency according to a predetermined pattern. The modulation period is specifically designed to be an integer multiple of the bit reception time, ensuring that frequency variations complete full cycles within each bit period. This periodic modulation scatters EMI radiation energy across a broader frequency spectrum while maintaining synchronized data sampling at regular intervals, thus resolving the contradiction between EMI reduction and communication reliability.
Solution Approach 2:
The patent changes the frequency parameter of the clock signal dynamically through spread spectrum modulation. The frequency is varied within a controlled range according to a modulation pattern, transforming the fixed-frequency clock signal into a time-varying frequency signal. This parameter change approach disperses electromagnetic energy across multiple frequencies (reducing EMI) while the modulation structure ensures that data sampling occurs at consistent effective timing points, preventing communication failures.
2Object-affected harmful factors
If spread spectrum modulation is applied to the clock signal for EMI prevention, then EMI radiation is reduced, but data sampling timing mismatch occurs leading to communication failures
Solution Approach 1:
The modulation period is set as an integer multiple of the bit reception time, creating a periodic structure where frequency variations complete full cycles within each bit period. This ensures that data sampling occurs at consistent effective timing points regardless of the frequency variations, maintaining measurement precision while achieving EMI reduction through spectral spreading.
Solution Approach 2:
The patent incorporates synchronization mechanisms that use feedback to maintain alignment between the modulated clock signal and data sampling timing. The receiver detects synchronization signals and adjusts its sampling timing based on the modulated clock's phase and frequency variations, ensuring accurate data sampling despite the frequency changes used for EMI prevention.
Data Source
AI summary
When receiving data in a unit of frame, each frame including a plurality of bits, based on a spread clock signal, a receiving time per bit of receiving data is calculated based on a receiving rate, and the change cycle of the spread clock signal is adjusted according to the receiving time per bit.