The working principle of the clock circuit is that the oscillator (or internal oscillator) is connected to the outside of the single-chip microcomputer to provide high-frequency pulse. After the frequency division processing, the clock signal becomes the internal clock signal of the single-chip microcomputer, which is the control signal for the coordinated work of the components in the chip. The function is to cooperate with the external crystal to realize the oscillation circuit, which can provide the running clock for the single chip microcomputer.