Preface

The AVR enhanced microcontrollers are based on a new RISC architecture that has been developed to take advantage of semiconductor integration and software capabilities in the 1990s. The resulting microcontrollers offer the highest MIPS/mW capability available in the 8-bit microcontroller market.

High-level languages are rapidly becoming the standard programming methodology for embedded microcontrollers because of improved time-to-market and simplified maintenance support. The AVR architecture was developed together with C language experts to ensure that the hardware and software work hand-in-hand to develop highly efficient, high-performance code.

To optimize code size, performance, and power consumption, the AVR architecture has incorporated a large fast-access register file and fast single-cycle instructions.

The AVR architecture supports a complete spectrum of price performance from simple small-pin-count controllers to high-range devices with large on-chip memories. The Harvard-style architecture directly addresses up to 8 Mbytes of data memory. The register file is dual mapped and can be addressed as a part of the on-chip SRAM memory to enable fast context switching.

The AVR enhanced RISC microcontroller family is manufactured with ATMEL’s low-power nonvolatile CMOS technology. The on-chip in-system-programmable (ISP) downloadable flash memory allows the program memory to be reprogrammed in-system through an SPI serial port or conventional memory programmer. By combining an enhanced RISC architecture with downloadable flash memory on the same chip, the AVR microcontroller family offers a powerful solution to embedded control application.

This book describes the new AVR architecture and the program development for those microcontrollers of the family available in early 1997. Some tools from ATMEL and third-party companies help to give a first impression of the AVR microcontrollers. Thus, the evaluation of hardware and programming in Assembler and C of that type of microcontroller is supported very well. A simulator makes program verification possible without any hardware.

The development of the AVR microcontroller family by ATMEL shows clearly that remarkable results are not limited to high-end microcontrollers that are often the focus of consideration.

I thank ATMEL for the development of this interesting microcontroller family, because studying these new devices and their development environment was very interesting and made writing this book enjoyable.

Finally, I wish to thank ATMEL Norway and IAR Sweden for their support of this project and my wife, Jutta, for her continued understanding during the preparation of this book.