spi of fpga implementation considerations

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A signal line SCK solely controlled by the master device, the slave device can not control signal line. Similarly, in a SPI-based devices, have at least one master device. Such transmission characteristics: This transmission has an advantage, common serial communication with a different, Common serial communication at least one continuous transfer 8-bit data, and a data transfer allows an SPI allow even suspended because the clock SCK a control line from the master, when no clock transition, from the device does not collect or transmit data. That is, the master device by controlling the clock line SCK can complete control of the communications. SPI protocol data exchange can also be achieved: because the SPI data input and output lines is allowed to separate while completing the input and output data. Different implementations vary different SPI devices, and changing the main data collection time, the rising or falling edge of the clock signal have different definitions collected