In order to enhance system communication efficiency and reduce costs, modern automotive designs extensively utilize serial bus communication protocols. I2C and SPI are commonly used for inter-chip communication within electronic control units (ECUs), while CAN, LIN, and FlexRay are the most widely adopted serial buses in the automotive industry for long-distance communication between various vehicle subsystems such as comfort systems, anti-theft mechanisms, transmissions, and engine controls.
LIN buses, which operate on a master-slave architecture, are typically used in non-critical applications like seat and window control. In contrast, the CAN bus employs differential signaling with event-triggered communication, offering better noise immunity compared to the single-ended LIN bus. This has made CAN the dominant control bus in vehicles for over two decades. FlexRay, an emerging technology, uses differential time-triggered communication and a deterministic schedule. It is primarily found in high-end vehicles, where high performance and security are essential.
Despite their reliability, serial bus communications can be affected by signal integrity issues caused by the complex and noisy environment inside a vehicle. These issues include interference from the ignition system and random electrical noise, which can lead to errors during critical communication cycles. While serial bus protocol analyzers are excellent tools for testing and monitoring data at higher protocol and application layers, they lack the ability to assess the physical layer quality of the serial bus signals.
To address this, some mid-to-high-performance digital storage oscilloscopes (DSOs) now offer decoding and triggering capabilities for LIN, CAN, and FlexRay buses. This allows engineers to establish a time-correlated link between the protocol layer and the physical layer, providing deeper insights into bus behavior.
Figure 1 illustrates the Agilent 3000 X-Series oscilloscope capturing and decoding both CAN and FlexRay buses simultaneously. At the bottom of the display, you can see time-correlated decoding traces for each bus, positioned directly below the corresponding physical layer waveform. The top portion of the screen features the industry’s only time-crossing “list†display, also known as an event table. This format closely resembles that of a traditional protocol analyzer, making it more intuitive for users familiar with such tools.
Jiangmen Pengjiang Guanqi Trading Co., Ltd. , https://www.kwunkeeindustry.com