Intelligent lighting system indoor light collection circuit diagram

The system uses a single-chip microcomputer as the controller, and uses a thermal human body infrared sensor and a light intensity sensing system to detect whether there are people in the room and the indoor light intensity. A schematic block diagram of an intelligent lighting control system is proposed, and based on this, an intelligent lighting system is designed. For some hardware circuits of the control system, the system adopts a modular structure design, which is clearly organized and easy to improve and expand. At the same time, it also has the advantages of small size, convenient control, and high reliability, which can meet the requirements of intelligent lighting control in office spaces to achieve energy saving purposes.

Indoor ambient light collection circuit

The indoor ambient light collection circuit is shown in Figure 2. The working principle is that when the indoor natural light intensity in the office is higher than a certain level (that is, the parameter is set), the phototransistor D5 will show a low resistance state, which is less than 1 kΩ, and the base voltage of the transistor Q1 will increase, causing the saturated conduction of the transistor Q1. If it is turned on, the collector of transistor Q1 will output a low level and will not participate in its work. When the indoor natural light intensity in the office space is less than a certain level (i.e., the parameter is set), the phototransistor D5 shows a high resistance state of greater than 100 kΩ, causing the transistor Q1 to cut off, and the collector of Q1 outputs a high level to participate in its circuit work. Among them, the variable resistor R24 ​​is used as a device to adjust the sensitivity parameters of the indoor ambient light intensity. Its resistance value will cause the transistor Q1 to be turned on under different indoor ambient light intensity parameters, and the circuit composed of R3 and C1 is Designed to prevent external interference, it has the function of preventing interference.

Human body signal acquisition circuit

When detecting whether the human body is indoors in the office, the pyroelectric infrared sensor that detects the presence of the human body must have the functions of high sensitivity, good stability, strong anti-interference, and good delay performance. The selection should be based on the working hours of the office. Depending on other factors, the HT-208 model pyroelectric infrared sensor is usually used. The human body signal acquisition circuit designed based on the functional characteristics of this chip is shown in Figure 3. Among them, the No. 1 pin of the pyroelectric infrared sensor is connected to the external power supply signal, and the No. 2 pin is connected to the external acquisition signal. A capacitor with a capacitance of 6800pF is often connected to the No. 3 pin, and the No. 3 pin The pin is externally grounded, so the pyroelectric infrared sensor is connected to the P3.3 pin of the microcontroller AT89S52 using the No. 2 pin. In order to enhance the stability of signal acquisition, that is, the stability of the pyroelectric infrared sensor detection Reliable, a 100 kΩ pull-up resistor is often connected to the pin port of the microcontroller.

watchdog circuit

This circuit has the functions of watchdog timer, automatic reset, and voltage threshold monitoring. When the system is powered on, powered off, or the supply voltage is insufficient, the logic state of the microcontroller and bus is uncertain, which will cause the RESET trigger of the MAX705 chip. The pin outputs a reset signal to the microcontroller to maintain the microcontroller in the reset state to avoid control errors. The circuit is shown in Figure 4. In order to make the reset more reliable, an external 10 k pull-up resistor is connected to the reset output terminal and connected to the reset terminal of AT89C52. Therefore, when the voltage at the VCC terminal is lower than the reset voltage, the system remains in the reset state. In order to detect the power supply voltage, connect the power supply Vin to the PFI pin. When the voltage at the PFI terminal is lower than 1.24 V, the PFO terminal outputs a warning signal, and the WDI terminal is controlled by an internal timer. When WDI is low level, Only by providing protection for the system can we avoid crashes, program runaways, deadlocks, etc. and make the system work normally.

This system uses the AT89S52 microcontroller as the main control core, and uses ambient light intensity signals and human body conditions as the main input parameters. Driven by relevant circuits, it realizes intelligent control of office lighting and fluorescent lamps. It is better than traditional human-style manual management. The lighting in the office space is more reasonable and effective, which improves the utilization of natural light in the office space and avoids waste of electrical energy. At the same time, this system adds time control parameters to make the lighting control in the office space more consistent with work schedules.