Serial Chip Baud Rate Calibration Using Low-Level Pulse Counting
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Solution Overview
Problem
Existing methods for calibrating baud rates in serial port communication systems are not suitable for fast-changing environments, as they rely on default bytes and cannot calibrate in real time, leading to unreliable data transmission due to internal clock offsets.
Innovation Solution
A circuit comprising a first counter, a second counter, a divider, and a selector, which records low-level durations and bit sampling pulses to dynamically calculate and update the baud rate, allowing for real-time calibration without relying on default bytes, and ensures accurate baud rate matching between communication ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional baud rate calibration methods using default bytes are used, then the communication system can maintain simplicity in implementation, but the baud rate calibration cannot be performed in real-time in fast-changing communication environments
Solution Approach 1:
The patent implements dynamic baud rate calibration by continuously monitoring the actual baud rate during data transmission and adjusting it in real-time. The calibration is no longer static based on pre-agreed default bytes, but dynamically adapts to changing communication conditions through continuous feedback from the communication process itself.
Solution Approach 2:
The patent introduces a feedback mechanism where the receiving end monitors the actual baud rate during data transmission, compares it with the expected baud rate, and sends calibration information back to the sending end. This closed-loop feedback enables real-time baud rate synchronization without requiring pre-agreed default bytes.
2Reliability
If real-time baud rate calibration is implemented, then data transmission reliability in dynamic environments is improved, but the system complexity increases due to additional calibration circuits and protocols
Solution Approach 1:
The patent enables the communication system to perform self-calibration by having each end independently monitor and detect baud rate deviations during normal data transmission. The system uses its own communication traffic to generate calibration information, eliminating the need for separate calibration phases or external calibration equipment.
Solution Approach 2:
The patent makes the data transmission channel serve dual purposes: both for transmitting actual data and for performing baud rate calibration simultaneously. The same communication channel and processing circuits used for data transmission are also utilized for calibration, avoiding the need for dedicated calibration hardware.
3Adaptability or versatility
If default byte-based calibration is used, then the implementation remains simple and compatible with existing protocols, but the calibration cannot adapt to internal clock offsets between communication ends
Solution Approach 1:
The patent performs preliminary baud rate detection and calibration during the initial stages of communication or during idle periods before actual data transmission begins. This preliminary action ensures that the baud rate is synchronized before critical data exchange, maintaining simplicity while improving adaptability.
Solution Approach 2:
The patent introduces calibration information as an intermediary element that mediates between the sending and receiving ends. This calibration data, extracted from the communication stream itself, serves as a mediator to convey baud rate deviation information without requiring complex additional signaling protocols.
Data Source
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AI summary
The present disclosure relates to communication technologies, and provides a circuit for calibrating a baud rate and a serial port chip. The circuit includes: a first counter which is connected to a receiving module of a serial port chip and configured to record a first low level duration of a data frame received by the receiving module; a second counter which is connected to the receiving module and configured to: receive a bit sampling pulse, and record a quantity of the bit sampling pulse in the first low level duration, where the bit sampling pulse is generated from sampling the data frame by the receiving module according to a current baud rate of the receiving module; a divider, which is connected to the first counter and the second counter and configured to calculate a calibration baud rate according to the first low level duration and the quantity of the bit sampling pulse in the first low level duration; and a selector, which is connected to the receiving module and the divider and configured to output the calibration baud rate to the receiving module.