The high-performance, low-power Microchip 8-bit AVR RISC-based microcontroller combines 16KB ISP flash memory with read-while-write capabilities, 512B EEPROM, 512 bytes SRAM, 22 general purpose I/O lines, 32 general purpose working registers, two flexible timer/counters with compare modes and PWM, USART, programmable watchdog timer with internal oscillator, SPI serial port, debugWIRE interface for on-chip debugging and programming, and five software selectable power saving modes. The device operates between 2.7-5.5 volts.