SPI Clock Delay Calibration for Accurate Response Sampling
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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 failing to sample portions of the response signal, which can waste processor time and power.
Innovation Solution
A delay circuit is introduced to adjust the SPI clock signal to match the round trip delay, using both coarse and fine calibration methods to ensure the clock is adjusted to the correct timing for accurate signal sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the SPI clock signal is transmitted without delay adjustment, then the communication speed is maintained, but sampling errors occur due to improper timing
Solution Approach 1:
The patent applies preliminary action by calculating and applying the round-trip delay (RTD) compensation value before normal SPI communication occurs. The delay calibration process determines the appropriate delay amount in advance, and this pre-calculated delay is then applied to the SPI clock signal to ensure proper timing alignment for sampling response signals.
2Measurement precision
If a delay circuit is added to compensate for round trip delay, then sampling accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the delay compensation function into discrete, selectable delay values that can be individually calibrated and applied. Rather than implementing a continuous complex delay circuit, the system divides the delay compensation into distinct calibration steps (coarse and fine calibration) with specific delay amounts that can be independently adjusted and optimized.
Solution Approach 2:
The patent changes the timing parameter of the SPI clock signal by applying a calculated delay amount to compensate for round-trip delay. The delay calibration process determines optimal delay values, and these parameter adjustments are applied to align the clock signal timing with the response signal sampling requirements.
3Measurement precision
If delay calibration is performed, then timing accuracy is improved, but processor time and power consumption increase
Solution Approach 1:
The patent performs delay calibration as a preliminary action during system initialization or setup, rather than continuously during normal operation. The calibration process determines the optimal delay value in advance, and once calibrated, the system operates with the pre-determined delay setting, minimizing ongoing processor involvement and power consumption during actual SPI communication.
Solution Approach 2:
The patent employs feedback mechanisms during the calibration process where the system tests different delay values and evaluates sampling accuracy based on received response signals. The calibration process uses feedback from the sampling results to determine when optimal timing alignment is achieved, allowing the system to stop calibration once the correct delay is found rather than continuously adjusting.
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.