Power is supplied via the 12V DC connector. The USB port is used for host communications only, and does not draw current from the host. At the heart of the Atmel AVR ONE! main-board is the ATmega1280 AVR microcontroller, which is coupled to an FPGA for target interface signal processing. The target interface is clocked by an external clock generator capable of providing a frequency in the range of approximately 1kHz to 64MHz. A small external SRAM is connected to the AVR MCU, and is used to store symbolic information during a debug session, while the larger and faster DDR-SDRAM is used by the FPGA as a trace message buffer only.