Program instructions are stored in non-volatile flash memory.
Almost all devices (except the smallest TinyAVR chips) have serial interfaces, which can be used to connect larger serial EEPROMs or flash chips. Some devices have a parallel external bus option to allow adding additional data memory or memory-mapped devices. Device architectureįlash, EEPROM, and SRAM are all integrated onto a single chip, removing the need for external memory in most applications. The instruction set is similar to other RISC cores, but it is not compatible with the original AVR or any of the various ARM cores. This 32-bit family of devices is intended to compete with the ARM-based processors. They include SIMD and DSP instructions, along with other audio- and video-processing features. Main article: AVR32 In 2006 Atmel released microcontrollers based on the 32-bit AVR32 architecture. Basic familiesĪVRs are generally classified into following: The AVR is a modified Harvard architecture machine, where program and data are stored in separate physical memory systems that appear in different address spaces, but having the ability to read data items from program memory using special instructions. By 2003, Atmel had shipped 500 million AVR flash microcontrollers. The AVR 8-bit microcontroller architecture was introduced in 1997. The polarity of the RESET line was opposite (8051's having an active-high RESET, while the AVR has an active-low RESET), but other than that the pinout was identical. Note that the use of "AVR" in this article generally refers to the 8-bit RISC line of Atmel AVR Microcontrollers.Īmong the first of the AVR line was the AT90S8515, which in a 40-pin DIP package has the same pinout as an 8051 microcontroller, including the external multiplexed address and data bus. However, it is commonly accepted that AVR stands for Alf (Egil Bogen) and Vegard (Wollan)'s RISC processor.
The creators of the AVR give no definitive answer as to what the term "AVR" stands for. Atmel says that the name AVR is not an acronym and does not stand for anything in particular. The designers worked closely with compiler writers at IAR Systems to ensure that the instruction set provided for more efficient compilation of high-level languages. When the technology was sold to Atmel from Nordic VLSI, the internal architecture was further developed by Bogen and Wollan at Atmel Norway, a subsidiary of Atmel. It was known as a μRISC (Micro RISC) and was available as silicon IP/building block from Nordic VLSI. The original AVR MCU was developed at a local ASIC house in Trondheim, Norway, called Nordic VLSI at the time, now Nordic Semiconductor, where Bogen and Wollan were working as students. The AVR architecture was conceived by two students at the Norwegian Institute of Technology (NTH), Alf-Egil Bogen and Vegard Wollan.