Internal structure and functional modules of automotive ECU

General function modules

① Power supply: Provides stable voltage (5V, 3V, etc.) to each module in the ECU and is connected to the 12V battery in the engine compartment; it can also be used as the standard voltage for the AD converter, which can achieve higher accuracy.
② Input buffer: Converts digital input signals into signal levels (signal levels) that can be input to the microcontroller.
③ AD converter: Converts analog input signals into digital values ​​that can be input to the microcontroller.
④ Microcontroller: Calculates the control amount based on various input signals and outputs it.
⑤ EEPROM: Electrically Erasable and Programmable Read Only Memory, which can store data to be memorized even when the power supply is no longer supplied after the engine stops.
⑥ Output driver: Converts the output signal of the microcontroller into a signal form that can be driven by the actuator, or amplifies the voltage.
⑦ Communication driver/receiver: The communication driver converts the output data of the microcontroller into a communication signal that meets the communication protocol; the communication receiver converts the signal sent by other ECUs into a signal level that can be input to the microcontroller.

1. The input/output
   
   
   ECU is an interface for external communication. In order to achieve optimal control that matches the actual state through microcontroller calculations, it is necessary to have an input means for detecting the external state and an output means for actual control drive. In recent years, in order to meet the close coordination control between multiple ECUs, communication means have also been set up in ECUs.
   

1. Microcontroller

Basic structure of microcontroller

Although the microcontroller in the vehicle ECU is used in the vehicle, its basic structure is the same as that of an ordinary microcontroller.

In order to cope with the regulations in recent years, ROM (Read Only Memory) has gradually changed to a flash memory type, and the contents stored in the ROM in module units can be changed.

The timing controller is a control device related to time and moment. When the set moment is consistent with the internal timing (the value of the timer), it has a matching function to change the set output and a capture function to memorize the edge input moment of the external signal. The matching function is used to determine the injection signal output timing, etc. The capture function cooperates with the interrupt controller to detect the engine speed signal output, etc.

The communication interface is a device that communicates with the input/output expansion IC inside the ECU and other ECUs. In recent years, in order to cope with the in-vehicle LAN (Local Area Network), the number of microcontrollers with built-in CAN functions has gradually increased.

4. ECU and controller mounting locations

The actual form of the ECU varies depending on where it is installed in the vehicle. The structural design of the ECU needs to correspond to its installation environment.

When cars were first electrified, ECUs were installed in car cabins with better environmental conditions because electronic components were less able to withstand harsh environments such as heat, humidity, and vibration. Later, as the reliability of electronic components including circuit boards and installation technology improved, ECUs began to be gradually installed in engine compartments with harsher environmental conditions, and some were even installed directly on the engine. From a design perspective, ECU hardware must be able to be installed anywhere in the vehicle, which is the concept of "free installation."