Serial Port Baud Rate Calibration Circuit for Real-Time Reception
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Solution Overview
Problem
Existing baud rate calibration methods in serial port communication systems are not suitable for fast-changing environments, as they rely on default data frames 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, connected to a serial port chip's receiving module, dynamically calculates and updates the baud rate by recording data frame low level durations and bit sampling pulses, allowing for real-time calibration without relying on default bytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing baud rate calibration methods using default data frames are used, then the system structure is simple, but the baud rate cannot be calibrated in real time and reliability deteriorates in fast-changing communication environments
Solution Approach 1:
The receiving end performs self-calibration by automatically measuring the low level duration of received data frames and calculating the actual baud rate using internal counters and dividers, eliminating the need for external calibration equipment or pre-agreed default data frames. The system serves itself by using its own receiving resources to generate calibration data.
Solution Approach 2:
The calibration circuit continuously monitors the received data frames, measures their low level durations, compares the measured baud rate with the current working baud rate, and dynamically adjusts the working baud rate based on this feedback. This closed-loop feedback mechanism ensures real-time adaptation to communication environment changes.
2Measurement precision
If real-time baud rate calibration is implemented using counters and dividers, then calibration accuracy is improved, but device complexity increases
Solution Approach 1:
The first counter and second counter are not dedicated solely to calibration functions but are integrated with the normal data receiving process. The same counters used for counting data bits are also utilized for measuring low level duration and calculating baud rate, making the calibration circuit share existing receiving resources rather than adding completely separate measurement hardware.
Solution Approach 2:
The calibration function is merged with the data receiving function. The low level duration measurement is combined with the existing start bit detection mechanism, and the baud rate calculation is integrated into the data processing pipeline. This merging avoids duplicating hardware resources and reduces overall circuit complexity.
Data Source
AI summary
The present disclosure relates to a circuit for calibrating a baud rate. The circuit includes: a first counter 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 configured to: receive a bit sampling pulse generated from sampling the data frame according to a current baud rate of the receiving module, and record a quantity of the bit sampling pulse in the first low level duration; a divider, connected to the first counter and the second counter and 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, connected to the receiving module and the divider and configured to output the calibration baud rate to the receiving module.