ATMEGA644-20PU Datasheet PDF - Microchip

The ATMEGA644-20PU is a 8-bit high-performance low-power 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, real time counter, three flexible timer/counters with compare modes and PWM, 2 USARTs, byte oriented 2-wire serial interface, 8-channel/10-bit A/D converter with optional differential input stage with programmable gain, programmable watchdog timer with internal oscillator, SPI serial port, JTAG (IEEE 1149.1 compliant) test interface for on-chip debugging and six software selectable power saving modes. The device operates between 2.7 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.