ECU needs to receive data again to confirm the end of a closed-loop control. With the advancement of today’s automotive technology, ECU shoulders more and more burdens. Variable valve timing technologies such as i-VTEC require an additional camshaft position sensor, and the phase of the camshaft is converted through ECU calculations, especially continuously variable valve timing systems such as BMW Double-VANOS, which require more ECU makes precise calculations to control its phase and valve lift. At present, in some mid-to-high-end cars, ECU is not only applied to the engine, but also can be found in many other places. For example, anti-lock braking system, 4-wheel drive system, active suspension system, airbag system, and automatic transmission all require separate control systems. More and more ECUs appear on cars, and many devices added to cars are ECU management is required, and the traditional “Engine Control Unit” can no longer meet the development of the times, and has become a module of the vehicle control system. Therefore, today we prefer to call ECU “Electrical Control Unit” or electronic control system. With the improvement of electronic automation of cars, there will be more and more ECUs, and the circuits will become more and more complicated. In order to simplify the circuit and reduce the cost, the information transmission between multiple ECUs on the car must adopt a communication network technology called multiplexing, and the ECUs of the whole vehicle will form a network system, that is, the CAN data bus.