This is the 78th original long article!
A few days ago, I wrote a summary of embedded system hardware systems, discussing the components of hardware systems, as well as an overview of several units besides processors and storage.
I do not plan to introduce these overviews in detail right now, as they are not very useful for PMs.
If you are interested, here is an old article: Overview of Embedded System Hardware Systems
Components of Embedded Hardware Systems:
Processors, memory (RAM/ROM), I/O devices, analog/digital conversion (A/D, D/A) units, communication modules, power modules.
Today, let’s discuss the core unit of embedded hardware systems: the processor
In previous articles, I always mention at the beginning: Embedded systems are customizable dedicated computer systems designed to meet specific needs.
Embedded systems originated from computer architecture and were born in the era of microcomputers. With the development of science and technology, they have gone through a long evolutionary path.
We can understand them through time and functionality as two evolutionary attributes.
From a temporal perspective, embedded processors have gone through three main stages: microcontrollers, microcontrollers, and system-on-chip.
From a functional perspective, embedded processors can be classified into four types: MPU, MCU, SOC, DSP.
Actually, understanding this is best done by first studying computer architecture principles, which I have recommended before. Once you have this foundation, the myriad variations become easier to understand.
This article will not delve into this part; if possible, we can discuss the bus structure of embedded processing later, namely Von Neumann architecture, Harvard architecture, and extended Harvard architecture. I personally believe that understanding this may facilitate understanding this part.
1. Microcontroller (SCM, Single Chip Microcomputer)
SCM integrates the CPU and peripheral circuits onto a single chip, configured with external buses, serial communication interfaces, special function register modules, and Boolean instruction systems.
SCM is typically centered around 4-bit and 8-bit microprocessors.
As a result:
In hardware, the structure and function are relatively simple, processing efficiency is low, and storage capacity is small.
In software, the structure is relatively simple, and an embedded operating system is not required.
It is suitable for scenarios with simple functions, small data processing volumes, and low real-time requirements, such as controlling a light switch.
2. Microcontroller (MCU, Micro Controller Unit)
MCU integrates more external interface functions, such as high-speed I/O, watchdog, PWM, A/D conversion, etc., and is configured with serial buses between chips.
MCU usually centers around 8-bit and 16-bit processors.
In hardware, it is more complex compared to SCM.
In software, the structure is more complex, and the number of programs has significantly increased.
It is suitable for simple real-time tasks, such as IMU navigation in robotic vacuum cleaners, automotive airbags, and ABS systems.
What we often refer to as