ATmega168 Introduction

ATmega168 is a low-power 8-bit CMOS microcontroller based on an enhanced AVR RISC architecture. Due to its advanced instruction set and single-clock cycle instruction execution time, ATmega168 has a data throughput of up to 1 MIPS/MHz, which can alleviate the contradiction between power consumption and processing speed in the system.

The ATmega168 AVR core has a rich instruction set and 32 general-purpose working registers. All registers are directly connected to the arithmetic logic unit (ALU), allowing one instruction to access two independent registers simultaneously in one clock cycle. This structure greatly improves code efficiency and has a data throughput rate up to 10 times higher than that of ordinary CISC microcontrollers.

ATmega168 has the following features: 16K bytes of in-system programmable Flash (with simultaneous read and write capabilities, i.e. RWW), 512 bytes of EEPROM, 1K bytes of SRAM, 23 general-purpose I/O lines, 32 general-purpose working registers, DebuyWIRE interface for boundary scan, support for on-chip debugging and programming, three flexible timers/counters (T/C) with compare mode, on-chip/external interrupts, programmable serial USART, universal serial interface with start condition detector, 8-channel 10-bit ADC with optional differential input stage and programmable gain (TQFP package), programmable watchdog timer with on-chip oscillator, an SPI serial port, and five power saving modes that can be selected by software. 

When working in idle mode, the CPU stops working, while USART, two-wire interface, A/D converter, SRAM, T/C, SPI port and interrupt system continue to work; in power-down mode, the crystal oscillator stops oscillating, and all functions except interrupts and hardware resets stop working; in power-saving mode, the asynchronous timer continues to run, allowing the user to maintain a time base, while the other functional modules are in a dormant state; in ADC noise suppression mode, the CPU and all I/O modules except the asynchronous timer and ADC are terminated to reduce the switching noise during ADC conversion; in Standby mode, only the crystal or resonant oscillator runs, and the other functional modules are in a dormant state, so that the device consumes very little current and has fast startup capability; in extended Standby mode, the oscillator and asynchronous timer are allowed to continue working.

This chip is produced with Atmel's high-density non-volatile memory technology. The on-chip ISP Flash allows the program memory to be programmed through the ISP serial interface, or a universal programmer, or through the boot program running in the AVR core. The bootloader can use any interface to download the application to the Application Flash Memory. The program in the Boot Flash Memory continues to run while the Application Flash Memory is updated, thus implementing RWW operation. By integrating the 8-bit RISC CPU with the in-system programmable Flash in one chip, the ATmega168 becomes a powerful single-chip microcomputer, providing a flexible and low-cost solution for many embedded control applications. The ATmega168 has a complete set of programming and system development tools, including: C language compiler, macro assembler, program debugger/software emulator, emulator and evaluation board.

ATmega168 Product Features
· High-performance, low-power 8-bit AVR microprocessor
· Advanced RISC architecture
– 131 instructions
– Most instructions are executed in a single clock cycle
– 32 8-bit general-purpose working registers
– Fully static operation
– Up to 20MIPS at 20MHz
– Hardware multiplier with only two clock cycles
· Non-volatile program and data memory
– 16K bytes of in-system programmable Flash, erase and write life: 10,000 times
– Optional Boot code area with independent lock bits, in-system programming through on-chip Boot program, true simultaneous read and write operation
– 512 bytes of EEPROM, erase and write life: 100,000 times
– 1024 bytes of on-chip SRAM
– The lock bits can be programmed to encrypt user programs
· Peripheral features
– Two 8-bit timer/counters with independent prescaler and comparator functions
– One 16-bit timer/counter with prescaler, compare function and capture function
– – Real-time counter (RTC) with independent oscillator
– Six-channel PWM
– Eight-channel 10-bit ADC (TQFP and MLF packages)
– Six-channel 10-bit ADC (PDIP package)
– Two programmable serial USARTs
– SPI serial interface that can operate in master/slave mode
– Programmable watchdog timer with independent on-chip oscillator
– On-chip analog comparator
– Interrupt and wake-up of MCU on pin change
· Special processor features
– Power-on reset and programmable brownout detect
– On-chip calibrated RC oscillator
– On-chip/external interrupt sources
– Five sleep modes: idle mode, ADC noise suppression mode, power-saving mode, power-down mode, standby mode
· I/O and package
– 23 programmable I/O ports
– 28-pin PDIP package, 32-pin TQFP package, and 32-pin MLF package
· Operating voltage:
– ATmega168V: 1.8 - 5.5V
– ATmega168: 2.7 - 5.5V
· Speed ​​grades
– ATmega168V: 0- 10MHz 
– ATmega168 : 0- 20MHz 
· Extremely low power consumption
– Normal mode: 1 MHz, 1.8V: 250μA 
　　　　　 32 kHz, 1.8V: 15μA (including oscillator)
– Power-down mode: 1.8V , 0.1 μA