The ATMEGA644PA-AU is a 8-bit high-performance picoPower AVR RISC-based Microcontroller combines 64kB ISP flash memory with read-while-write capabilities, 2kB EEPROM, 4kB SRAM, 32 general purpose I/O lines, 32 general purpose working registers, a real time counter, three flexible timer/counters with compare modes and PWM, two USARTs, a byte oriented 2-wire serial interface, an 8-channel 10-bit A/D converter with optional differential input stage with programmable gain, programmable watchdog timer with internal oscillator, SPI serial port, a JTAG (IEEE 1149.1 compliant) test interface for on-chip debugging and programming and six software selectable power saving modes. The device operates between 1.8 to 5.5V. By executing powerful instructions in a single clock cycle, the device achieves throughputs approaching 1 MIPS per MHz, balancing power consumption and processing speed.