If you are referring to the deep debugging protocol (used on devices like the AVR32), you need the AVR32 Software Framework.

Significant "bloat" compared to AVR Studio 4; requires a 1.6GHz processor and at least 1GB of RAM (2GB for x64). Notable Improvements in 5.1

To download and set up AVR Studio 5.1 , you can use the official archives provided by