Circuit design of intelligent lighting control system using single chip microcomputer

Single chip microcomputer STM32L151CCU6

The system is mainly composed of a light detecting circuit, a pyroelectric infrared sensor and a processing circuit, a single chip system and a control circuit. During operation, the light detection circuit and the pyroelectric infrared sensor collect information such as the intensity of the light, whether the room is present, or the like, and the information is sent to the single-chip microcomputer, and the single-chip microcomputer performs the switching operation on the lighting device through the control circuit according to the information, thereby realizing the lighting control to achieve energy saving. purpose.

System hardware design

The system hardware circuit constructed according to Figure 1 is shown in Figure 1. In order to make the system function more perfect, a time display circuit can be added in the system for displaying the current time. At present, the more popular single-chip microcomputers have AVR and 51 single-chip microcomputers. From the functional requirements and cost of system design, 51 single-chip microcomputers have higher cost performance. The AT89C52 is a microcontroller with two external interrupts, two 16-bit timers, and two programmable serial UARTs. The central control module adopts AT89C52 single-chip microcomputer to fully meet the design needs and realize the whole system control. When the ambient light is strong, the resistance of the photoresistor R13 is small, then the level of the A point is low; when the ambient light is weak, the resistance of the photoresistor R13 is large, then the level of the A point is higher, this level is Sended to the microcontroller, controlled by the program to achieve lighting.

Pyroelectric infrared sensor

Pyroelectric infrared sensors detect the infrared radiation emitted by the human body in a non-contact manner and convert it into a voltage signal. Pyroelectric sensors have the characteristics of low cost, no need for infrared or electromagnetic waves, high sensitivity, and flowable installation. In actual use, a Fresnel lens should be installed before the pyroelectric sensor, which can greatly improve the receiving sensitivity and increase the detection distance and range. Experiments show that if the pyroelectric infrared sensor is not equipped with a Fresnel lens, the detection distance is only about 2 m; and with the Fresnel lens, the detection distance can be increased to more than 10 m. Since the signal output from the pyroelectric sensor changes slowly and the amplitude is small (less than 1 mV), it cannot be directly used as the control signal of the illumination system. Therefore, the output signal of the sensor must pass through a special signal processing circuit to make the output signal of the sensor irregular. The waveform is converted into a digital signal suitable for processing by the microcontroller.

Signal processing circuit

This design uses BIS0001 to complete the processing of the pyroelectric sensor output signal. BIS0001 is a high performance pyroelectric sensor signal processing integrated circuit, which is mainly composed of an operational amplifier, a voltage comparator, a state controller, a delay time timer, and a lockout time timer. A signal processing circuit composed of BIS0001 is shown in FIG.

In Figure 2, the S-pole output signal of the pyroelectric sensor is sent to the 14-pin of BIS0001. After being amplified by the internal first-stage operational amplifier, it is amplified by C3 from the 12-pin input to the internal second-stage operational amplifier, and then passed through the voltage comparator. After the constituted discriminator is processed, the valid trigger signal is detected to start the delay time timer, and finally the 12-pin output signal (Vo) is sent to the single-chip microcomputer for illumination control.

The intelligent lighting control system designed for this time is suitable for lighting control of large-area indoor places such as schools and shopping malls, and can effectively control the lighting equipment to achieve scientific management and energy saving. The experiment proves that the system has simple structure, convenient installation, stable operation and high reliability. The automatic alarm function can also be implemented if an alarm device is added to the system.