Clock circuit

The invention provides a clock circuit. The clock circuit comprises a clock source selection module, a system clock generation module, a peripheral clock generation module and a clock domain crossing synchronization module, wherein the clock source selection module is used for selecting one clock from a low-frequency external clock, a low-frequency crystal oscillator clock, a high-frequency external clock and a high-frequency crystal oscillator clock as a source clock to be output according to a final selection control signal; the system clock generation module is connected with the output end of the clock source selection module and is used for carrying out frequency division on a source clock and generating a system clock; the peripheral clock generation module is connected with the output end of the system clock generation module and is used for generating a peripheral clock according to the system clock; and the cross-clock domain synchronization module is connected between the system clock generation mod