Home » Embedded Systems

What is AVR (Advanced Virtual Risc)?

In this article, we are going to learn about AVR which stands for Advanced Virtual Risc, AVR is a microcontroller developed by the ATMEL. Here, we will learn its architecture, categories.
Submitted by Suryaveer Singh, on June 13, 2018

AVR is the family of microcontroller which was developed by the ATMEL in the year 1996. These are the modified Harvard Architecture 8-bit RISC Single Microcontroller Chip.

The architecture of AVR was developed Alf-EgilBogen and VegardWollan. The name of the AVR is derived from the name of the people who developed it i.e. Alf-EgilBogen VegardWollan RISC microcontroller, and is also known as "Advanced Virtual Risc".

The Diagram above shows the basic Architecture of the AVR where,

• ADC: Analog to Digital Conversion
• USART: Universal Synchronous Asynchronous Receiver Transmitter
• TIMERS: Provides delay to the microcontroller

AVR is one of the first Microcontrollers that uses on-chip flash memory for program storage. The first Microcontroller based on AVR architecture was AT90S8515.

These Microcontrollers are available in three categories:

• TinyAVR
  Less memory, small size and suitable only for simpler applications.
• MegaAVR
  These are the most popular ones, they have good amount of memory (upto 256 KB), higher number of inbuilt peripherals and is suitable for moderate to complex applications.
• XmegaAVR
  It is mostly used commercially for complex applications, which require large program memory and high speed.

The program instructions in the AVR are stored in a non-volatile flash memory. The size of the program memory is indicated in the naming of the device itself. Example the ATmega64x line has 64 kb of flash and the ATmega16 has a 16 kb of a flash memory.

Reference: Atmel AVR