This is a project that is based on Sanguinololu. The ATmega644P has been replaced with an Atmel AT90USB1286 MCU. This Microcontroller has on-chip USB, removing the need for the FTDI USB UART. LUFA CDC bootloader preinstalled on the AT90USB1286 allows you to upload the firmware in the Arduino IDE through USB cable . All of the through hole resistors and capacitors have been replaced with 0805 SMT components. Like the Sanguinololu the Teensylu has expansion headers supporting I2C, SPI, UART, and ADC pins. All extra I/O ports of the AT90USB have been broken out to headers for prototyping.
Teensylu v0.8 Hi3D RepRap Prusa Mendel printer driver board - OlMaCe3f