Using an MSO Oscilloscope To Debug an Automotive CAN Bus
Application Notes
Introduction
To improve efficiency of system communication and to reduce cost, all of today’s automotive designs employ a variety of serial bus communication protocols. The I2C and SPI protocols are most often used for chip-to-chip communication within electronic control units (ECUs). For long-haul serial communication between various automotive subsystems such as anti-lock brakes, airbag deployment, engine control, and GPS navigation, the CAN, LIN, MOST and FlexRay protocols are the most popular serial buses implemented in today’s vehicles, as shown in Figure 1. Unfortunately, long-haul communication is often susceptible to signal integrity problems caused by the naturally harsh environment found in automobiles, including signal interference from ignition systems and random system noise, which can sometimes create errors during critical communication cycles.