Time domain analysis of the physical wiring for a star-like topology in high-speed controller area networks

Abstract

The high-speed controller area network protocol supports a linear wiring topology. However, owing to productivity and cost concerns, actual networks in automotive applications may be configured in a star-like topology using joint connectors, with multiple stubs diverging from one point on the main bus; this type of configuration may lead to increased signal reflection and requires careful design of the physical wiring. In this study, the time response in a star-like joint-connector-based controller area network bus topology is analysed, and design guidelines for the physical wiring are presented. The effects of the number of stubs connected to a joint connector on the signal transmission are described and evaluated through experiments. Then, the time response through a joint connector with a diverse number of stubs is estimated, which gives a timing reference for designing the physical wiring in a star-like bus topology. Additionally, the effects of reflection between adjacent joint connectors are analysed together with the distance between joint connectors to ensure that no propagation delay degradation occurs.