Introduction to LIN Bus

For the traditional point-to-point connection method, we can see that the ECU-related sensors and actuators are directly connected to the ECU. When the number of sensors and actuators is small, this connection method can meet the requirements. However, with the continuous increase in the number of automotive electronic control functions, the number of sensors and actuators has increased. As you can imagine, if this connection method is adopted, the number of wires will increase. Due to the increase in the number of wires, the cost of wire processing, wires and connectors will increase, which will lead to an increase in the cost of the car. Then there is the increase in the weight of the wires, which leads to an increase in the weight of the car. Of course, the space for the arrangement of the wires is also a problem. At the same time, due to the increase in the number of wires and connector terminals, it will also have an adverse effect on the reliability of the car, and it is also difficult to diagnose the resulting faults. In addition, when we need to add sensors or actuators, we must require the ECU to have the corresponding hardware interface, which is very unfavorable for the expansion of a system. Therefore, we need new solutions to deal with these problems. The first solution is to connect the sensors and actuators directly to the CAN bus where the ECU is located. This solution brings new problems.

First of all, this method requires that both sensors and actuators must have interfaces, including transceivers and controllers. This will lead to a significant increase in the cost of sensors and actuators. At the same time, too many nodes on the bus will also lead to an increase in bus load. The second solution is to connect sensors and actuators to another CAN bus. The ECU in the middle can act as a gateway to complete the data exchange between other ECUs and sensors and actuators.

In this way, although the load rate of the above bus is not affected, it still cannot solve the cost problem caused by the interface. Therefore, a new solution is proposed. In this solution, the CAN bus connecting the sensor and actuator is replaced with a low-cost bus.

Then, the ECU in the middle can realize the function of the gateway and realize the data exchange between this low-cost bus and the CAN bus. This method can solve some of the problems mentioned above. This low-cost bus is the LIN bus to be discussed in this article.

After adopting the LIN bus, the previous point-to-point connection method is switched to this bus network connection method. We can see that sensors and actuators are connected to the ECU through a common communication medium, that is, the LIN bus. This connection method has the following advantages. First, the cost is reduced, and then the requirements for the layout space of the number of lines and the weight of the number of lines will also be reduced. At the same time, due to the reduction in the number of lines and connectors, reliability will also be improved. Through the bus connection method, faults are easier to diagnose. Finally, the system can be flexibly expanded. For example, if we need to add a sensor now, we can hang this sensor on the bus without making corresponding changes to the ECU hardware. The above is a brief introduction to the LIN bus.