Difference between 8051 Vs AVR Microcontrollers

8051 Microcontroller

AVR family controller

• Utilizes a Complex Instruction Set Computing (CISC) architecture, offering a diverse set of instructions to accommodate various operations within a single instruction.

• Less number of register 

• Multiple instruction sizes and formats.

• it doesn't have inbuilt EEPROM, ADC. It requires an ADC IC. 

• Generally, few versions of the 8051 family supports UART only.

• instructions take a varying amount of cycle time. so, pipelining is difficult. 

• Offers respectable performance metrics but may lag behind AVR in terms of execution speed and efficiency.

• Slower processing due to CISC architecture. 

• Primarily 8-bit data bus, limited built-in peripherals. 

• Traditionally expensive development tools, evolving with open-source options. 

• The 8051 microcontroller has a Harvard architecture with separate address spaces for program memory and data memory. It has a total of 128 bytes of internal RAM and can address up to 64 KB of external data memory.
  
  

• 8051 microcontrollers are commonly used in embedded systems, industrial control, automation, robotics, and consumer electronics due to their reliability and ease of use.

• It uses SPI, I2C, UART, USART communication protocol.
  
  

• It uses ROM, SRAM, FLASH memory.
  Its speed is 12 clock per instruction cycle.

• Popular microcontrollers are AT89C51, P89v51, etc.

• Employs a Reduced Instruction Set Computing (RISC) architecture, executing simpler instructions often in a single clock cycle, promoting efficiency and speed.

• More number of register

• Instruction of the same set with formats.

• it has inbuilt EEPROM, ADC. 

• supports SPI, UART and I2C. 

• instruction takes one cycle time. so, pipelining is easy.

• Excels in performance with superior execution speed and efficiency, thanks to its RISC architecture. It also boasts low power consumption, extending battery life and reducing overall power usage.

• Faster processing and higher efficiency with RISC architecture.

• Offers 8-bit, 16-bit, and even 32-bit options, wider range of peripherals (timers, ADCs, communication protocols).

• Vibrant open-source community, free compilers like AVR-GCC readily available

• AVR microcontrollers use a modified Harvard architecture with a unified address space for both program memory and data memory. It typically has more internal RAM compared to the 8051 and can address larger external memory spaces.

• AVR microcontrollers are widely utilized in applications such as IoT devices, wearable technology, smart appliances, automotive systems, and scientific instruments that require higher performance and advanced features.
  
  

• It uses UART, USART, LIN, CAN, Ethernet, SPI, I2S communication protocols.

• It uses Flash, SRAM, EEPROM memory.

• Its speed is 1 clock per instruction cycle.

• Popular microcontrollers are Atmega8, 16, 32, Arduino Community.

Features

8051

AVR

Architecture

8-bit

8-bit or 32-bit

CPU Speed

Up to 33 MHz

Up to 20 MHz

Power Consumption

Higher Power Need

Low power required

Instruction Set

Limited Instruction Set

Complex and diverse Instruction Set

On-chip memory

Limited memory

Larger on-chip memory

On-chip peripherals

Limited peripherals

More and diverse on-chip peripherals

Interrupt handling

Simple and limited handling of interrupt

More complex and efficient Interrupt handling

Cost

Lower

Lower (compared to some ARM and MSP430)