DE4001 DEICO Onyx is an I²C bus and SPI bus host adapter which allows to communicate with any I²C or SPI devices via USB. DEICO Onyx is powered directly from the PC’s USB port. DEICO Onyx can be used as a master or slave for I²C and SPI. I²C and SPI pins can also be used as GPIO or combined with I²C or SPI functionality.