I/O Pins

Maximum Pull-up on SPI/JTAG header	1kΩ
Maximum Pull-down on SPI/JTAG header	10kΩ
Maximum Source Current VCC header	Up to total 300mA

Note:

The Atmel AVR Dragon requires a USB port that can deliver up to 500mA. (Self-powered USB hub.)

Programmers and Debuggers