Introduction to the characteristics of AVR microcontroller

RISC (Reduced Instruction Set Computer) is relative to CISC (Complex Instruction Set Computer). RISC does not simply reduce instructions, but improves the computing speed by making the computer structure simpler and more reasonable. RISC gives priority to simple instructions with the highest frequency of use and avoids complex instructions: it also fixes the instruction width, reduces the types of instruction formats and addressing modes, thereby shortening the instruction cycle and improving the operating speed. Because AVR adopts this structure of RESC, the AVR series of microcontrollers have a high-speed processing capability of 1MIPS/MHz (million instructions per second/megahertz).

The AVR microcontroller absorbs the characteristics of the DSP dual bus and adopts the Harvard bus structure. Therefore, the program memory and data memory of the microcontroller are separated, and the program memory and data memory with the same address can be addressed independently.

In the AVR microcontroller, when the CPU executes the current instruction, it fetches the next instruction to be executed and puts it into the register, thus avoiding the occurrence of multiple instruction cycles in the traditional MCS51 series microcontrollers.

All data processing of traditional MCS51 series microcontrollers is based on an accumulator, so the data conversion between the accumulator and the program memory and data memory becomes the bottleneck of the microcontroller; in the AVR microcontroller, the registers are composed of 32 general working registers, and any register can act as an accumulator, which effectively avoids the bottleneck effect of the accumulator and improves the performance of the system.

AVR microcontrollers have good integration performance. AVR series microcontrollers all have online programming interfaces, and the Mega series also has JTAG simulation and download functions; they all contain on-chip watchdog circuits, on-chip program Flash, and synchronous serial interface SPI; most AVR microcontrollers also have built-in AD converters, EEPROM, analog comparators, PWM timer counters and other functions; the I/O interface of AVR microcontrollers has strong driving capabilities, and the current can directly drive relays, LEDs and other devices, thereby eliminating the need for drive circuits and saving system costs.

AVR microcontrollers are manufactured using low-power, non-volatile CMOS technology. In addition to having the characteristics of low power consumption and high density, they also support low-voltage online Flash and EEPROM writing functions.

AVR microcontrollers also support programming in high-level languages ​​such as Basic and C. Using high-level languages ​​to develop microcontroller systems is the development trend of microcontroller applications. Programming microcontrollers in high-level languages ​​can easily achieve system transplantation and speed up the software development process.

AVR microcontrollers have multiple series, including ATtiny, AT90, and ATmega. Each series includes multiple products, which are very different in function and memory capacity, but the basic structure and principle are similar, and the programming method is also the same.

AVR microcontroller series are complete and can be applied to various occasions. AVR microcontrollers are divided into three series:

Low-end: ATtiny

Mid-range: AT90

High-end: ATmega