To reset the 51 single-chip microcomputer, it can be realized by connecting a high level to the 9th pin for 2us. How is this process realized? In the single-chip microcomputer system, the system is reset once when it is powered on. When the button is pressed, the system resets again. If it is pressed again after release, the system will reset. Therefore, the reset can be controlled in the running system by opening and closing the button. Why is it reset when power on In the circuit diagram, the size of the capacitor is 10uf and the size of the resistance is 10k. Therefore, according to the formula, it can be calculated that the capacitor is charged to 0.7 times the power supply voltage (the power supply of the microcontroller is 5V, so charging to 0.7 times is 3.5V), and the time required is 10K*10UF=0.1S. That is to say, within 0.1S of the computer startup, the voltage across the capacitor increases at 0~3.5V. At this time, the voltage across the 10K resistor is reduced from 5 to 1.5V (the sum of the voltages across the series circuit is the total voltage). So within 0.1S, the voltage received by the RST pin is 5V~1.5V. In 51 single-chip microcomputers that work normally at 5V, voltage signals less than 1.5V are low-level signals, and voltage signals greater than 1.5V are high-level signals. Therefore, within 0.1S of booting, the SCM system automatically resets (the time of the high level signal received by the RST pin is about 0.1S). Why does it reset when the button is pressed After the microcontroller is started for 0.1S, the voltage across the capacitor C is continuously charged to 5V. This is when the voltage across the 10K resistor is close to 0V, and RST is at low level, so the system works normally. When the button is pressed, the switch is turned on. At this time, a loop is formed at both ends of the capacitor, and the capacitor is short-circuited. Therefore, during the process of pressing the button, the capacitor begins to release the previously charged power. As time goes by, the voltage of the capacitor changes from 5V to 1.5V or even less within 0.1S. According to the voltage of the series circuit as the sum of all parts, the voltage across the 10K resistor at this time is 3.5V or even greater, so the RST pin receives a high level again. The microcontroller system resets automatically. to sum up: 1. The principle of the reset circuit is that the RST pin of the microcontroller receives a level signal above 2US. As long as the charging and discharging time of the capacitor is greater than 2US, the reset can be achieved, so the capacitance value in the circuit can be changed. 2. Press the button to reset the system. The capacitor is in a short circuit, which releases all the electric energy and the voltage across the resistor increases. HA series hood is suitable to small heavy duty connectors, it is widely used in machinery, wind energy, rail transportation, power systems, photovoltaic industry, communications industry, engineering equipment and other fields. Heavy Duty Connector is designed for modular production pre-wiring and satisfying severe environmental conditions, applied in rail transit,industrial automation and equipment manufacturing fields. Compared with traditional wiring methods,use of heavy duty connector can reduce site wiring operation after equipment or vehicle leaves the workshop,enhance production efficiency and reduce quality risk of site wiring. Ha Series Connector,4-Pin Heavy Duty Connector,3 Pin Heavy Duty Connector,Industrial Heavy Duty Kunshan SVL Electric Co.,Ltd , https://www.svlelectric.com