What is the difference between CPU and MCU?

When we mention the CPU, what comes to mind most often is the central processing unit of a computer. The performance of a CPU is very powerful. However, in many cases, such as refrigerators, air conditioners, and washing machines, such high performance is not necessary because their functions are very simple. If the latest 12th-generation Intel Core processors were installed in these products, it would be a waste. For these situations, people have invented the younger brother of the CPU, the MCU, each with its own advantages.

MCU stands for Micro Controller Unit, commonly known as a single-chip microcomputer. Compared with the CPU, the MCU has greatly reduced performance but has also added many features.

Let’s talk about the difference between CPU and MCU. The operation of the CPU depends on many peripheral components, such as the motherboard, memory module, and hard drive, to form a computer. The MCU itself is a mini version of a computer, with an integrated central processing unit, ROM, RAM,¬†interrupt system, timer, and IO interface. Because it needs to cope with various situations, there are many types of MCUs. The main CPU manufacturers are Intel and AMD, while there are many manufacturers of single-chip microcomputers, such as Infineon, NXP, Microchip, Cypress, and Texas Instruments.

Intel CPU
Intel CPU
STM32 MCU
STM32 MCU

The mainstream CPU price ranges from $150 to $400. The price of single-chip microcomputers is very low, and the price of commonly used MCUs is usually between $1 and $10. The CPU frequency is mostly 3-4 GHz, while the mainstream frequency of the MCU is between 8 MHz and 72 MHz, differing by hundreds of times. In terms of power, the power of the CPU is mainly concentrated between 65 and 150 watts, while the normal working power of commonly used single-chip microcomputers is about 0.1 watts. In terms of storage, the external RAM of the CPU is mostly 8 to 32 GB, while the RAM of the MCU is built-in, roughly between 2 and 256 KB. The ROM of the CPU is now generally a solid-state hard drive of 512 KB to 2 KB, while the built-in ROM of the MCU is usually between 16 KB and 2 MB.

Internal detail of CPU
Internal detail of CPU

Almost all modern computers are 64-bit, while MCUs are mainly 8-bit and 32-bit. Although 32-bit single-chip microcomputers have been popular for many years, they have not yet shaken the position of 8-bit single-chip microcomputers. In 2018, 8-bit single-chip microcomputers still accounted for 41% of the market share, with sales reaching $7.8 billion. Finally, in terms of communication interfaces, the CPU’s communication interfaces mainly include USB, Thunderbolt, and Ethernet ports, while the single-chip microcomputer uses I2C, serial communication, SPI, and others.

Internal detail of MCU
Internal detail of MCU
FeatureCPUMCU
PerformanceVery powerfulMuch lower, but still suitable for many tasks
Peripheral componentsRequires many external components, such as motherboard, memory, and hard driveIntegrated, self-contained system with CPU, RO interrupt system, timers, and I/O interface
Variety of models and brandsFew main brands, such as Intel and AMDMany manufacturers, such as Infineon, NXP, Microchip, and Texas Instruments
PriceHigher, usually ranging from $150 to $400Lower, typically ranging from $1 to $10
FrequencyUsually 3-4 GHzMainstream frequency ranges from 8 MHz to 72 MHz
PowerTypically ranges from 65 to 150 wattsTypically uses very little power, around 0.1 watt when operating normally
MemoryExternal RAM usually ranges from 8 to 32 GBIntegrated RAM usually ranges from 2 to 256 KB
StorageExternal ROM usually ranges from 512 KB to 2 GBIntegrated ROM usually ranges from 16 KB to 2 MB
Word sizeTypically 64-bitMostly 8-bit and 32-bit
Communication interfacesUSB, Thunderbolt, EthernetI2C, Serial communication, SPI

These are some differences between CPU and MCU. Do you know any other major differences? Feel free to leave a comment below.

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