An Electronic Control Unit (ECU) is a small device inside a vehicle that controls one or several electrical systems in that vehicle. It tells the electrical systems what to do and how to operate ECU's core. An ECU core is a microcontroller and it is controlled by software.
How does it work?
An ECU receives input from several parts of the vehicle and uses that information to take action if needed. For e.g. - An airbag ECU receives information from crash sensors and seat sensors. When the car crash, the ECU decides which airbag to deploy depending on where passengers are seating. Then it tells the actuators to deploy them.Types of ECUs
- Body Control Modules (BCM) which handle functionalities like wiper control, automatic/adaptive lighting control, seating control, power window, automatic windshield control etc.
- Climate Control Modules (CCM) which handle the functionalities of sun/heat sensors, humidity sensors, ambient sensors etc.
- Electronic Brake Control Module (EBCM) which handles the anti brake lock system, electronic brake force distribution and brake assistance system.
- Power Steering Module (PSM) which handles the power steering mechanism.
- Suspension Control Module (SCM) which handles and collect information about the wheel suspensions.
- Battery Management System (BMS) which gives information about the battery lifecycle. Very useful in EVs.
- Advanced Driver Assistance Systems (ADAS) which assists the driver on seamless driving, responsible for in vehicle connectivity and vehicle to vehicle connectivity, cloud data computing and over the air updates, handles infotainment/display application system and a lot more.
etc...
Note- These are the important ECUs which are mentioned above. There are a lot more ECUs which are used in vehicles depending on their types, size, use case and cost. All these ECUs work, based on the software component (SWC) allocated to each ECUs. These software are mostly written in Embedded C, C++ & Python using various other cross platform frameworks and libraries mostly suitable for RTOS such as Linux.
A basic diagram showing different ECUs in a high-end car
