SPI Delay Circuit Calibration for Round-Trip Sampling Timing
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Solution Overview
Problem
Existing SPI communication systems face errors due to improper timing of the SPI clock signal reception, leading to issues such as sampling line noise or missing data, caused by round trip delays in short-range communications.
Innovation Solution
A delay circuit is implemented in the SPI main to adjust the SPI clock signal based on measured round trip delay, using both coarse and fine calibration methods to ensure the clock signal is synchronized with the response signal, reducing errors by aligning the clock signal with the data reception timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SPI clock signal is transmitted without delay adjustment, then the communication speed is maintained, but timing errors occur causing line noise sampling or data loss
Solution Approach 1:
The patent applies preliminary action by measuring the round trip delay before normal communication operations, and pre-adjusting the clock signal timing through delay circuits. The system performs calibration sequences that determine the actual delay characteristics of the communication interface, then configures appropriate delay values in advance so that when normal high-speed communication occurs, the timing is already optimized, preventing data sampling errors without sacrificing communication speed.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the clock signal delay parameter based on measured round trip delay characteristics. The system varies the delay amount through calibration sequences, testing different delay values to find the optimal setting that synchronizes clock edges with data arrival times. This parameter optimization ensures reliable data sampling while minimizing unnecessary delay that would reduce communication throughput.
2Measurement precision
If a delay circuit is added to adjust clock signal timing, then timing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by implementing automatic calibration sequences that measure the round trip delay and self-adjust the clock signal timing without external intervention. The system includes built-in test modes that automatically determine the delay characteristics of the communication interface and configure the delay circuits accordingly. This self-calibrating approach eliminates the need for manual timing adjustment while achieving precise synchronization, thereby reducing operational complexity despite the added hardware.
Solution Approach 2:
The patent implements feedback mechanisms by using calibration sequences that measure the actual round trip delay and use this information to adjust the clock signal timing. The system continuously monitors timing accuracy through pattern comparison between transmitted and received signals, and automatically adjusts delay parameters based on measured performance. This closed-loop feedback ensures optimal timing accuracy while minimizing the need for complex manual configuration.
3Reliability
If calibration sequences are performed to measure round trip delay, then timing synchronization is improved, but communication overhead increases
Solution Approach 1:
The patent applies preliminary action by performing the delay measurement and calibration sequences during system initialization or setup phases, before normal communication operations begin. By completing the timing characterization work in advance, the system establishes optimal delay parameters that can be used for extended periods without re-calibration, minimizing the impact on overall communication throughput while ensuring accurate timing synchronization for all subsequent data transfers.
Data Source
AI summary
In described examples, a device includes a transmitter, a receiver, and a control circuit. The transmitter transmits a clock signal, and the receiver receives a response signal. The control circuit is coupled to the transmitter and the receiver. The control circuit causes the transmitter to transmit a first clock signal with a first clock period, and to transmit a second clock signal with a second clock period greater than the first clock period. The control circuit determines whether a first pattern of a signal responsive to the first clock signal is the same as a second pattern of a signal responsive to the second clock period. If the patterns are the same, the control circuit delays the clock signal with a delay responsive to the first clock period to generate a delayed clock signal. The receiver samples response signals using the delayed clock signal during normal operation of the device.