Editing AVR microcontrollers (section)

=== AT90USBKey ===
This small board, about half the size of a business card, is priced at slightly more than an AVR Butterfly. It includes an AT90USB1287 with [[USB On-The-Go]] (OTG) support, 16&nbsp;MB of [[DataFlash]], LEDs, a small joystick, and a temperature sensor. The board includes software, which lets it act as a [[USB mass storage device class|USB mass storage device]] (its documentation is shipped on the DataFlash), a USB joystick, and more. To support the USB host capability, it must be operated from a battery, but when running as a USB peripheral, it only needs the power provided over USB.

Only the JTAG port uses conventional 2.54&nbsp;mm pinout. All the other AVR I/O ports require more compact 1.27&nbsp;mm headers.

The AVR Dragon can both program and debug since the 32&nbsp;KB limitation was removed in AVR Studio 4.18, and the JTAGICE mkII is capable of both programming and debugging the processor. The processor can also be programmed through USB from a Windows or Linux host, using the USB "Device Firmware Update" protocols. Atmel ships proprietary (source code included but distribution restricted) example programs and a USB protocol stack with the device.

[[LUFA]]<ref>{{cite web|url=http://www.fourwalledcubicle.com/LUFA.php|title=LUFA (Formerly MyUSB)|publisher=Four Walled Cubicle|access-date=2012-09-19}}</ref> is a third-party [[free software]] ([[MIT license]]) USB protocol stack for the USBKey and other 8-bit USB AVRs.