Serial Peripheral Interface (SPI) is a high-speed synchronous serial input/output port IP that allows a serial bit stream of programmed length (2 to 16 bits) to be shifted into and out of the device at a programmed bit-transfer rate. The SPI is normally used for communication between the device and external peripherals. SPI module connects to the DMA Engine. It has an AXI bus interface on the other side for the configuration and control registers of the
Host Controller. The SPI Flash controller is provided to allow direct PIO access to SPI flash devices for BIOS boot up.