The ATMEGA644-20MU is a high-performance, low-power 8-bit 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 timers/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 1MIPS per MHz, balancing power consumption and processing speed.
Advanced RISC architecture
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
131 Powerful instructions-most single clock cycle execution
32 x 8 General purpose working registers
Fully static operation
Up to 20MIPS throughput at 20MHz
JTAG (IEEE std. 1149.1 compliant) interface
Programmable watchdog timer with separate on-chip oscillator
On-chip analog comparator
Interrupt and wake-up on pin change
Two 8-bit timers/counters with separate prescaler and compare mode
One 16-bit timer/counter with separate prescaler, compare mode and capture mode
