Introduction to AVR Microcontroller

      Single-chip microcomputer, also known as single-chip microcontroller, integrates a computer system into one chip. In short, one chip becomes a computer. Single-chip microcomputer technology is a branch of computer technology and the core component of simple robots. In
      1997, Mr. A and Mr. V from ATMEL's Norwegian Design Center used ATMEL's new Flash technology to jointly develop a high-speed 8-bit single-chip microcomputer with a RISC reduced instruction set, referred to as AVR.


Advantages and features of AVR single-chip microcomputer Single-chip
      microcomputers have been widely used in military, industrial, household appliances, smart toys, portable smart instruments and robot production, which greatly improves product functions, precision and quality, and has simple circuits, low failure rates, high reliability and low cost. There are many types of single-chip microcomputers. Why choose AVR single-chip microcomputers in simple robot production and innovation?

      1. Easy to learn and low cost
      First of all, for non-professionals, the main reason for choosing AVR single-chip microcomputers is that the threshold for entering the development of AVR single-chip microcomputers is very low. As long as you can operate a computer, you can learn the development of AVR single-chip microcomputers. Microcontroller beginners only need an ISP download line to write the edited and debugged software program directly into the AVR microcontroller online, and then they can develop various packaged devices in the AVR microcontroller series. Therefore, AVR microcontrollers are known as "one-line conquering the world" in the industry.
      Secondly, AVR microcontrollers are easy to upgrade. AVR program writing is to modify and burn programs directly on the circuit board, which is convenient for product upgrades.
Thirdly, AVR microcontrollers are inexpensive. To learn AVR microcontrollers, you can use the ISP online download programming method (that is, write the compiled program on the PC into the program memory of the microcontroller). You don't need to buy emulators, programmers, erasers, chip adapters, etc., and you can develop and apply all AVR microcontrollers, which can save a lot of development costs. The program memory can be erased and written more than 10,000 times, and no scrapped products will be produced.

      2. High speed, low power consumption, and confidentiality
      First, the AVR microcontroller is a high-speed embedded microcontroller:
      1. The AVR microcontroller has the function of pre-fetching instructions, that is, when executing an instruction, the next instruction is taken in advance, so that the instruction can be executed within one clock cycle.
      2. Multi-accumulator type, fast data processing speed. The AVR microcontroller has 32 general working registers, which is equivalent to 32 overpasses for fast passage.
      3. Fast interrupt response speed. The AVR microcontroller has multiple fixed interrupt vector entry addresses, which can respond to interrupts quickly.
      Secondly, the AVR microcontroller has low energy consumption. For typical power consumption, it is 100nA when the WDT is turned off, which is more suitable for battery-powered application equipment. Some devices can work at a minimum of 1.8 V.
      Thirdly, the AVR microcontroller has good confidentiality performance. It has an unbreakable bit encryption lock Lock Bit technology, and the confidentiality bit unit is hidden deep inside the chip and cannot be seen with an electron microscope.

      3. The I/O port is powerful and has A/D conversion circuits.
      1. The I/O port of the AVR microcontroller is a real I/O port, which can correctly reflect the real situation of the I/O port input/output. It is an industrial-grade product with a large current (sink current) of 10-40 mA, which can directly drive the thyristor SSR or relay, saving peripheral driver devices.
      2. The AVR microcontroller has an analog comparator inside, and the I/O port can be used for A/D conversion, which can form a cheap A/D converter. Devices such as ATmega48/8/16 have 8-channel 10-bit A/D.
      3. Some AVR microcontrollers can form a zero peripheral component microcontroller system, so that this type of microcontroller can work without external components, which is simple, convenient and low-cost.
      4. The AVR microcontroller can reset the startup reset to improve the reliability of the microcontroller. There is a watchdog timer for safety protection, which can prevent the program from going out of control (flying) and improve the product's anti-interference ability.

      4. Powerful timer/counter and communication interface
      The timer/counter T/C has 8-bit and 16-bit, which can be used as a comparator. The counter external interrupt and PWM (can also be used as D/A) are used to control the output. Some models of AVR microcontrollers have 3 to 4 PWMs, which are ideal devices for stepless motor speed regulation.
      The AVR microcontroller has a serial asynchronous communication UART interface, which does not occupy the timer and SPI synchronous transmission function. Because of its high-speed characteristics, it can work at a general standard integer frequency, and the baud rate can reach 576K.



Model identification analysis of AVR microcontrollers

      1. The letter following the model indicates the voltage operating range. With "V": 1.8-5.5V; if it is default, without "V": 2.7-5.5V.
　　　　Example: ATmega48-20AU, without "V" means the operating voltage is 2.7-5.5V.
　　2. The digital part of the suffix indicates the highest system clock supported.
　　　　Example: ATmega48-20AU, "20" means that it can support a system clock of up to 20MHZ.
　　3. The first (second) letter of the suffix indicates the package. "P": DIP package, "A": TQFP package, "M": MLF package.
　　　　Example: ATmega48-20AU, "A" indicates TQFP package.
　　4. The last letter of the suffix indicates the application level. "C": Commercial grade, "I": Industrial grade (lead), "U" Industrial grade (lead-free).
　　　　Example: ATmega48-20AU, "U" indicates lead-free industrial grade. ATmega48-20AI, "I" indicates lead-free industrial grade.