Difference between 8051 and AVR

A microcontroller is a small processing device which is primarily designed to perform specific functions within a large system. For example, a microcontroller is used in an air conditioner to automatically control and adjust the temperature of a room.

The main parts that a microcontroller has are: central processing unit (CPU), memory unit, and I/O interfaces. All these components of the microcontroller are formed on a single chip. A microcontroller can be programmed using various programming languages like C language, assembly language, etc. to perform a specific function. Microcontrollers are widely used in a variety of electronic devices, such as medical instruments, manufacturing machinery, robotics, automobiles, home appliances, toys, etc. to automate their operation.

Based on the architecture, there are several different types of microcontrollers. The 8051 and AVR are two different microcontroller architectures. They are absolutely different from each other many aspects like bus width, instruction set architecture, memory architecture, price, clock speed, power consumption, etc.

In this article, we will understand all the important differences between 8051 and AVR microcontrollers. But before discussing the differences, let’s have a look into their basics.

What is an 8051 Microcontroller?

8051 microcontroller is an 8-bit microcontroller developed by Intel in 1980. The 8051 microcontroller is an entry level popular microcontroller used in many embedded systems and automation applications.

  • The 8051 microcontroller supports many advanced features, such as interrupts, serial communication, and timers. The 8051 microcontroller uses Von Neumann Memory architecture.

  • The 8051 microcontroller has an 8-bit microprocessor, a number of built-in peripherals, and on-chip RAM and ROM. Although, the memory space in the 8051 microcontrollers can be extended with an external memory device as needed.

  • The 8051 microcontroller uses a simple instruction set. Therefore, it can be easily programmed using either low-level assembly language or high-level languages like C.

  • The major advantages of the 8051 microcontrollers include simpler design, versatility, low power consumption, low cost, etc. Therefore, the 8051 microcontroller is commonly used in embedded systems, energy management systems, automobiles, medical instruments, etc.

What is an AVR Microcontroller?

AVR is an abbreviation for Alf and Vegard’s RISC processor. It is named in the honor of its developers, Alf-Egil Bogen and Vegard Wollan. AVR is a RISC (Reduced Instruction Set Computer) based microcontroller architecture. It was first produced by Atmel Corporation in the year of 1997. The AT90S8515 was the first microcontroller developed based on the AVR microcontroller architecture.

  • AVR microcontrollers have simple instruction sets, making them fast and efficient.

  • The major advantages of AVR microcontrollers include low power consumption, low cost, and high performance.

  • We can use assemble language as well as high-level languages like C, C++, etc. to program these microcontrollers for a specific function.

  • AVR microcontrollers are widely used in several different applications like robotics, home and office appliances, industrial automation systems, automobiles, etc.

After getting an overview of 8051 and AVR microcontrollers, let us not discuss their differences.

Difference between 8051 and AVR

The following table gives all the important differences between 8051 and AVR microcontrollers −


8051 Microcontroller

AVR Microcontroller


8051 is a simple and low cost 8-bit microcontroller used in several types of embedded system applications.

AVR is a high-performance 8-bit microcontroller used in advanced systems like robotics, industrial control systems, smart home appliances, etc.

Bus width

8051 microcontrollers have a bus width of 8 bits.

AVR microcontrollers have bus width of 8-bit. But, some AVR microcontrollers also have a bus width of 32 bits.


8051 microcontroller was developed by Intel.

AVR microcontroller was produced by Atmel Corporation.

Memory Architecture

8051 microcontrollers have Von Neumann architecture.

AVR microcontrollers have Modified Harvard architecture.

Instruction set architecture

8051 microcontrollers are based on CISC (Complex Instruction Set Computer) architecture.

AVR microcontrollers are based on RISC (Reduced Instruction Set Computer) architecture.


8051 microcontrollers have a smaller number of registers.

AVR microcontrollers have a greater number of registers.

Power consumption

The power consumption for 8051 microcontrollers is average.

AVR microcontrollers consume less power than 8051.

I/O ports

8051 microcontrollers have a smaller number of I/O ports.

AVR microcontrollers have a greater number of I/O ports.


8051 microcontrollers have low clock speed, 1 clock per cycle.

AVR microcontroller have higher clock speed, 12 clocks per cycle.

Built-in peripherals

8051 microcontrollers have fewer built-in peripherals.

AVR microcontrollers have more number of built-in peripherals.

Communication protocols

8051 microcontrollers use UART, USART, I2C, and SPI.

AVR microcontrollers use UART, USART, CAN, LIN, SPI, I2S communication protocols.

Popular microcontrollers

Some popular microcontrollers of 8051 family are P89v51, AT89C51, etc.

Some popular microcontrollers of AVR family are ATmega 8/16/32, Arduino, etc.


The most significant difference between 8051 and AVR is that the 8051 microcontrollers have CISC (Complex Instruction Set Computer) architecture, while the AVR microcontrollers have RISC (Reduced Instruction Set Computer) architecture.

Updated on: 25-Apr-2023


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