5.1 Interfacing the AT25128B/AT25256B on the SPI Bus

Communication to and from the AT25128B/AT25256B must be initiated by the SPI Host device, such as a microcontroller. The SPI Host device must generate the serial clock for the AT25128B/AT25256B on the Serial Data Clock (SCK) pin. The AT25128B/AT25256B always operates as a client due to the fact that the SCK is always an input.