When the SPI_EN pin is disabled (driven LOW), the system controller’s SPI outputs are tri-stated, and the external processor can drive the SPI pins to program the SPI flash. Neither the system controller nor the fabric can drive the SPI interface. The external processor can drive the SPI_EN pin LOW to program the external SPI flash. The SPI_EN pin can also be configured external to the device using the jumpers on the board. The SPI flash is programmed using an external processor SPI master SCK frequency. The SCK frequency is configured using external processor application. The following figure shows the connections required for programming the SPI flash using an external processor.
