1: What is soc
SOC is called system-on-chip, also known as chip-on-chip, which is a product of a proprietary integrated circuit, which includes a complete system and has all the contents of embedded software. At present, SOC has more integrated processors (including CPU, GPU, DSP), memory, baseband, various interface control modules, various interconnection buses, etc., which are typically represented by mobile phone chips.
2: What is a CPU
The CPU (central processing unit) is a large-scale integrated circuit, which is the computing core and control core (calculator + controller) of a computer. Its function is mainly to interpret computer instructions and process data in computer software.
The CPU mainly includes an arithmetic unit (ALU), a cache register and a bus that implements data, control and status between them. It is known as the three core components of an electronic computer together with internal memory and input/output (i/o) devices
What ARM produces is CPU, it sells its own CPU design to other companies, and other companies add various peripheral controllers they need according to the CPU provided by ARM, which is SOC.
The controllers used by different companies are not necessarily the same, because different companies need different performances, so they will want to customize the controllers they need from semiconductor companies.
In daily work and life, the so-called CPU refers to the SoC, just like the memory has NandFlash and ordinary memory.
Our learning of bare metal programs is to learn the interoperation between the CPU and various peripheral controllers.
It can be simply understood that the SOC includes the CPU, and the development of the chip is from the CPU to the SOC.
3: The main function of the CPU
Processing instructions
English Processing instructions; this refers to the execution order of the instructions in the control program. There is a strict sequence between the instructions in the program, and must be executed in strict accordance with the sequence specified in the program to ensure the correctness of the computer system.
perform action
English Perform an action; the function of an instruction is often realized by a series of operations performed by components in the computer. The CPU needs to generate corresponding operation control signals according to the functions of the instructions and send them to the corresponding components, so as to control these components to act according to the requirements of the instructions .
control time
English Control time; time control is to implement time timing for various operations. During the execution of an instruction , what operations are performed at what time should be strictly controlled. Only then can the computer work in an orderly manner.
Data processing
That is to perform arithmetic and logical operations on data , or perform other information processing .
Its function is mainly to interpret computer instructions , process data in computer software , and execute instructions. Also known as microprocessor in microcomputer, all operations of the computer are controlled by the CPU, and the performance index of the CPU directly determines the performance index of the microcomputer system . The CPU has the following four basic functions: data communication , resource sharing, distributed processing, and providing system reliability. The operating principle can be basically divided into four stages: Fetch, Decode, Execute and Writeback.
4: The working process of the CPU