Design scheme of automotive electronic control system unit

Figure 6 FlexRay data receiving flow chart

C. Data receiving program

The FlexRay data slot receiving node can be trained in either rotational drive mode or interrupt drive mode. The electronic control unit set in this paper works in interrupt drive mode to receive data, for example [7]. The flowchart of FlexRay receiving data is shown in Figure 6.

IV. Analysis of the communication test results of automotive electronic control system units

In the design of the automotive electronic control system unit, two electronic control system units are connected to the FlexRay node through the FlexRay communication module to implement the data transmission and reception test of the FlexRay bus. When the +12V voltage is given to make it work, the two electronic control system units in the FlexRay bus node send and receive the corresponding test data according to the set ID and CRC.

In the FlexRay communication of these two electronic control system units, the waveform using the oscilloscope has a node bus. Because the FlexRay bus is a twisted pair, the FlexRay bus connections of the two BM and BP are differential signals. A dual-track oscilloscope is provided to compare these two tests. The waveform diagram is shown in Figure 7 below.

Figure 7 FlexRay communication node waveform

In a short period of time, a partial waveform as shown in FIG8 is obtained.

Figure 8 Partial waveform of FlexRay bus communication data frame

V. Conclusion

Practice has proved that the automobile body electronic control system unit based on FlexRay bus technology and MC9S12XF512 as the core is small in size, low in power consumption, high in stability and low in price. In particular, FlexRay data communication has higher transmission speed, higher reliability and stability, and better anti-interference ability.

The microcontroller is designed with a co-processor that can serve any peripheral module, which undoubtedly reduces the workload of the CPU and enables the electronic control system unit to operate normally under heavy load. However, the electronic control system unit still needs further research and improvement. If it is put into actual automotive applications, the application of communication networks, data monitoring and dynamic parts of data storage also need further research and improvement.