Configure SPI controller with the SPI mode and operating frequency

def configure(self):
        """
        Configure SPI controller with the SPI mode and operating frequency
        """

        # Convert standard SPI sheme to USBISS scheme
        lookup_table = [0, 2, 1, 3]
        mode = lookup_table[self._mode]

        # Add signal for SPI switch
        iss_mode = self._usbiss.SPI_MODE + mode

        # Configure USB-ISS
        self._usbiss.mode = [iss_mode, self.sck_divisor]