Self-Calibrating Differential Bus Measuring Amplifier
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Solution Overview
Problem
Existing methods for auto-addressing in differential CAN-BUS systems are time-consuming and inflexible, particularly when integrating a large number of participants, and require high accuracy measurements that are challenging to reproduce across different machines and temperature ranges.
Innovation Solution
A method for self-calibration of the measuring arrangement in differential CAN-BUS systems, which involves measuring differential voltage values and compensating for individual offset and gain errors using a correction factor, allowing for location-accurate automatic addressing without the need for additional components or complex adjustment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If automated test systems are used for calibration during production, then measurement precision is improved, but manufacturing complexity and time consumption increase
Solution Approach 1:
The system performs self-calibration using the common-mode voltage from the bus master as an internal reference, eliminating the need for external automated test systems. The bus participants automatically determine their addresses by measuring voltage drops during normal bus operation, achieving both precision and manufacturing simplicity.
Solution Approach 2:
The common-mode voltage signal serves dual purposes: it functions as the differential communication signal for data transmission and simultaneously serves as the reference for auto-addressing calibration. This multi-functionality eliminates the need for separate calibration hardware while maintaining measurement precision.
2Measurement precision
If automated test systems are used for calibration during production, then measurement precision is improved, but production time increases
Solution Approach 1:
The calibration data (auto-address) is determined during initial system startup rather than during manufacturing. This preliminary action during operation eliminates time-consuming production calibration steps while maintaining precision through the self-calibration mechanism using common-mode voltage references.
Solution Approach 2:
The system automatically calibrates itself during normal operation without requiring external test equipment or manual intervention, thereby eliminating production time losses associated with calibration while ensuring measurement precision through the inherent stability of the common-mode voltage reference.
3Measurement precision
If fixed individual addresses are assigned to devices, then addressing accuracy is improved, but adaptability decreases
Solution Approach 1:
The system dynamically determines addresses based on the physical position of devices on the bus using voltage drop measurements during operation. This dynamic addressing scheme provides both accurate position-based addressing and adaptability, allowing devices to be added, removed, or moved without requiring manual reconfiguration or fixed address assignments.
Solution Approach 2:
The address parameter is derived from physical electrical characteristics (voltage drop) rather than being fixed. This allows the addressing system to adapt to changes in bus configuration while maintaining accuracy, as the address automatically reflects the current physical position of each device on the bus.
4Extent of automation
If additional line resistances are inserted for auto-addressing, then addressing functionality is improved, but interference immunity deteriorates
Solution Approach 1:
The common-mode voltage on the differential bus serves dual functions: it is the normal communication signal carrier and simultaneously provides the reference for auto-addressing measurements. No additional resistances or components are required, thereby maintaining interference immunity while achieving full auto-addressing functionality through the existing bus signal structure.
Data Source
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AI summary
The present invention relates to the fields of electrical engineering and electronics and concerns a method for the application-oriented self-calibration of the differential BUS interfaces used for auto-addressing in a differential BUS system and a measuring amplifier, which can be used, for example, to calibrate the control system for the auto-addressing of intelligent LED strips in vehicles. The invention is based on the objective of providing a method that eliminates the need for a time-consuming adjustment procedure during the manufacturing process.The problem is solved by a method and a measuring amplifier in which three differential voltage values are measured at each BUS participant during a dominant BUS state, wherein a first differential voltage value from GND to GND is measured simultaneously at each BUS participant, a second differential voltage value is measured simultaneously at each BUS participant, a third differential voltage value is measured simultaneously at each BUS participant, an individual offset error and an individual gain error for each BUS participant are compensated, and a self-calibrated differential voltage value is determined by each BUS participant.