Overview
The ATmega164/324/644 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega164/324/644 achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.
The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected tothe Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.

FEATUREs
• High-performance, Low-power AVR® 8-bit Microcontroller
• Advanced RISC Architecture
– 131 Powerful Instructions – MostSingle-clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 20 MIPS Throughput at 20 MHz
– On-chip 2-cycle Multiplier
• Nonvolatile Program and Data Memories
– 16/32/64K Bytes of In-System Self-Programmable Flash
   Endurance: 10,000 Write/Erase Cycles
– Optional Boot Code Section with Independent Lock Bits
   In-System Programming by On-chip Boot Program
   True Read-While-Write Operation
– 512B/1K/2K Bytes EEPROM Endurance: 100,000 Write/Erase Cycles
– 1/2/4K Bytes Internal SRAM
– Programming Lock for Software Security
• JTAG (IEEE std. 1149.1 Compliant) Interface
– Boundary-scan Capabilities According to the JTAG Standard
– Extensive On-chip Debug Support
– Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface
• Peripheral Features
– Two 8-bit Timer/Counters with Separate Prescalers and Compare Modes
– One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture Mode
– Real Time Counter with Separate Oscillator
– Six PWM Channels
– 8-channel, 10-bit ADC Differential mode with selectable gain at 1x, 10x or 200x
– Byte-oriented Two-wire Serial Interface
– One/Two Programmable Serial USART (ATmega644, ATmega164/324)
– Master/Slave SPI Serial Interface
– Programmable Watchdog Timer with Separate On-chip Oscillator
– On-chip Analog Comparator
– Interrupt and Wake-up on Pin Change
• Special Microcontroller Features
– Power-on Reset and Programmable Brown-out Detection
– Internal Calibrated RC Oscillator
– External and Internal Interrupt Sources
– Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby and Extended Standby
• I/O and Packages
– 32 Programmable I/O Lines
– 40-pin PDIP, 44-lead TQFP, and 44-pad QFN/MLF
• Operating Voltages
– 1.8 - 5.5V for ATmega164/324/644V
– 2.7 - 5.5V for ATmega164/324/644
• Speed Grades
– ATmega164/324/644V: 0 - 4MHz @ 1.8 - 5.5V, 0 - 10MHz @ 2.7 - 5.5V
– ATmega164/324/644: 0 - 10MHz @ 2.7 - 5.5V, 0 - 20MHz @ 4.5 - 5.5V
• Power Consumption at 1 MHz, 3V, 25°C for ATmega644
– Active: 240 µA @ 1.8V, 1MHz
– Power-down Mode: 0.1 µA @ 1.8V