The reset circuit is composed of polar capacitors and resistors, as shown in Figure 3-3. The microcontroller is reset at a high level. After the clock circuit starts to work, when the high level time exceeds about 2us, the reset can be realized. The reset circuit has both manual reset and power-on reset functions. The power-on reset occurs at power-on and is automatically completed by the system. Manual reset is realized by pressing the button. When the program is running, if there is a crash, infinite loop or program "flight", it can be restarted by manual reset.