The main function of an MCU is to control all aspects of an embedded system, from performing specific tasks and functions such as sensor data acquisition, processing, communication, controlling motors, or executing specific algorithms. It is widely used in various fields including home appliances, automotive electronics, industrial automation, medical devices, smartphones, IoT devices, etc.
The MCU can be viewed as a mini-computer, but it is more focused on specific tasks and domains and usually has more limited resources than a general-purpose computer. This makes it ideal for embedded system design as it strikes a balance between cost, power consumption, and performance for specific applications.