Identification circuit for ILDE-state clock polarity of clock port of SPI slave device

The invention provides a circuit for identifying the ILDE-state clock polarity of a clock port of SPI slave equipment, and the circuit comprises a clock synchronization unit which is used for synchronizing a host clock sent by SPI master equipment with a reference system clock, the first clock after synchronization of the host clock and the second clock after synchronization and phase reversal of the host clock are output; the polarity determining unit is used for selecting the first clock or the second clock to output, and the polarity determining unit outputs an effective clock from the initial moment when the polarity of the first clock or the polarity of the second clock is matched with the polarity of an ILDE state clock of a clock port of the SPI slave device; and the output unit is used for outputting a slave effective clock by referring to the host clock and the effective clock, and the host effective clock of the host clock after the initial moment is matched with the slave effective clock, so that t