有關單片機的設計

The system of wise traffic light controlled by single-chip microcomputer was studied and designed from the theory on concept of humanization and science. A new traffic light system composed of the minimum system formed by the STC89C51 single-chip microcomputer， crystal oscillating circuit and compound circuit， 74HC245 driving circuit， and press module， the LED digital tube display and E18-D80NK-N infrared sensor was given. This system can detect the number of cars through infrared sensor， the car passing time changes were achieved through that the system voluntarily examines car flow. Through the buzzer， the functions of test and issue a warning sound to the vehicles that pass the red light are achieved. Realizing the LED display of the traffic light conversation time’s automatic countdown， by the integration of two common cathode digital tube display and buttons， set the timing etal. The design model’s actual operation show that every function works well， not only can realize basic function of traffic lights， but also can change the passing time of next period according the vehicles that the infrared sensor detect. The keys can realize the following functions that the model of midnight that all traffic lights will turn yellow; the model of emergency that all traffic lights will turn red when encounter emergency; the model of east-west and the model of south-north， in this situation there will have only one direction’s traffic light is green and the other will become red; the model of determine that press the key the traffic will work base on the before passing time; the model of check， when you press this key， you can look the current passing time and the vehicles that the infrared sensor detect.