Simplify USB to SPI connectivity by using this app note from FTDI.
The FT2232H and FT4232H are the FTDI’s first USB 2.0 Hi-Speed (480Mbits/s) USB to UART/FIFO ICs. They also have the capability of being configured in a variety of serial interfaces using the internal MPSSE (Multi-Protocol Synchronous Serial Engine).
This application note introduces the SPI synchronous serial communication interface, and illustrates how to implement SPI with the FT2232H. The FT2232H will be used to write and read data to a SPI serial EEPROM.