Automotive electronics overall test solution

Most automotive electronic buses are CAN and LIN buses, and some high-end models use FlexRay. In terms of speed, the latter is faster and is mainly used in high-end models such as BMW. Since the German BOSCH company invented the CAN bus, it has been widely used in automobiles and various means of transportation due to its reliable communication and low cost, and even in some aerospace fields. The speed is generally within 1M, and the bus frame structure is not complicated. CAN nodes share the bus and negotiate freely between nodes. ECUs (electronic control units) send and receive CAN signals according to the designed algorithm, coordinating the communication and priority between various structural units.

The frame structure is relatively simple, mainly including identification area, control area, data area, check area, and ACK response area. From the actual application, in the process of automotive electronics development, physical layer signals need to be evaluated in many occasions. Due to the judgment of error frames and the location of errors, it is usually necessary to collect the original signal. With the help of special triggering methods, this set of oscilloscopes takes all the needs into consideration.

1. Trigger

For example, data frames, error frames, remote frames, and specific data bits in the frame structure may all be called trigger conditions to capture the frames we need or are interested in.

Second, decoding

The decoding process is relatively simple and intuitive. The CAN physical layer analog signal is decoded into the protocol layer data represented by hexadecimal. Different color areas distinguish different fields of the data frame, and the error frame type is identified and marked. These are all displayed and refreshed in real time on the oscilloscope.

3. Measurement

For the measurement of CAN signals, it is more about timing measurement, which can quickly understand the timing relationship of CAN signals. With the help of the parameter statistics function of the oscilloscope itself, the trend statistics of bus parameters can be performed to determine the stability of the parameters. Ensure the result measurement of the bus and exclude potential faults from the design.

In short, for automotive electronic bus testing, physical layer signal capture and signal quality analysis are not difficult for oscilloscopes. The difficulty lies in how to find the corresponding design fault from the signal fault, and often if you treat the symptoms but not the root cause, you cannot solve the fundamental problem. The overall solution of automotive electronics, the coordinated debugging and observation of the three major systems of safety and assistance systems, infotainment systems, and electromagnetic compatibility can thoroughly create a safe, stable, and comfortable vehicle electronic system.