Baud Rate Generator Hardware Correction Circuit

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Solution Overview

Problem

Conventional baud rate correction methods in serial communication systems, such as those using the LIN protocol, impose a significant CPU load and deteriorate transfer speed due to the need for software-based calculations and timer operations, leading to inaccuracies and increased wait times.

Innovation Solution

A baud rate generator system that includes a counter, timer, and baud rate correcting circuit to measure and correct the baud rate based on a reference clock signal, reducing CPU load and improving transfer speed by dynamically adjusting the baud rate using a synch field measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If software-based arithmetic operations are used for baud rate correction, then the baud rate can be corrected, but the CPU load increases significantly

Engineering Contradiction:

Improvebaud rate correction accuracyVSAvoidCPU load

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces software-based arithmetic operations with a hardware-based baud rate correcting circuit that uses a counter and timer to automatically measure and correct baud rate. The counter counts the number of clock cycles in the synch field, and the timer measures the time duration, allowing the baud rate to be corrected through hardware computation rather than CPU software calculations, thereby significantly reducing CPU load while maintaining correction accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If software-based timer operations are used for baud rate correction, then the baud rate can be corrected, but the transfer speed deteriorates

Engineering Contradiction:

Improvebaud rate correction accuracyVSAvoidtransfer speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent replaces software-based timer operations with a hardware timer that simultaneously measures the time duration of the synch field. This hardware timer operates in parallel with the counter, enabling concurrent measurement without blocking the communication stream. The hardware-based approach eliminates software context switching and processing delays, thereby maintaining high transfer speed while achieving accurate baud rate correction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If baud rate correction is performed frequently, then synchronization is maintained, but wait times increase

Engineering Contradiction:

Improvesynchronization maintenanceVSAvoidwait time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent implements a hardware-based baud rate correcting circuit that continuously monitors the synch field and automatically performs corrections without requiring CPU intervention. The counter and timer operate continuously to measure baud rate deviations, and the correcting circuit automatically adjusts the baud rate when deviations are detected. This continuous hardware-based correction maintains synchronization without the wait times associated with software-based correction cycles.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS7620075B2Serial communication system with baud rate generator

Publication Date: 2009.11.17 RENESAS ELECTRONICS CORP

AI summary

A baud rate generator includes a first counter, a timer and a baud rate correcting circuit. The first counter is configured to count bits of an inputted serial data. The timer is configured to measure a time for which the first counter counts a predetermined number of bits based on a reference clock signal. The baud rate correcting circuit is configured to output a baud rate correction value based on the measurement time by the timer such that a baud rate in a serial communication is corrected based on the baud rate correction value.