userial is an Free project building an USB to I2C/SPI/GPIO bridge, using the Atmel AT90USB647 chip. Hardware and Software are released under an Open Source licence. It supports the following interfaces:
* USB interface (serial emulation)
* JTAG
* I2C (TWI)
* SPI
* 8 General purpose digital I/O
* 4 Analog to Digital converters (currently no firmware support)
