With the rapid development of urbanization, the intelligent construction of public lighting systems is an important part of urban construction. Currently, there are two common problems in the public and on the road in the use of lighting:
(1) People often keep lighting when they do not need to use lights, resulting in waste of energy;
(2) In the middle of the night, many public places are closed, which brings a lot of inconvenience to pedestrians.
The Doppler Smart LED Light Control System controls the switching of street lights and public lighting systems by detecting the movement of objects. There are many large and small cities in China, and the demand for lighting systems in street lamps and public places is large. The application of Puller intelligent LED lighting control system has effectively improved the use rate of light, bringing convenience to people while avoiding energy waste, reflecting contemporary environmental protection and energy conservation. Concept.
1 Doppler intelligent LED lighting control system design
The intelligent LED lighting control system based on Doppler effect uses the photoresistor to detect the brightness of the environment. When the surrounding environment is dark, the light-sensitive detection signal is transmitted to the single-chip microcomputer. The single-chip microcomputer detects whether there are objects such as pedestrians or vehicles according to the microwave sensor of HB100. The situation of the movement intelligently controls the number of lights turned on. The delay is set by the single-chip STC89C52 to realize the illumination replacement between the lights. As shown in Figure 1, the system consists of an intelligent control module and a 'normally bright' module. The intelligent control module consists of HB100 microwave sensor detection, light sensing, STC89C52 microcontroller, power supply and lED driver module.
Figure 1: Schematic diagram of Doppler intelligent LED lighting control system
In order to adapt to various environments, the system sets the 'normally bright' module. 'Normally bright' module, as long as the light
The sensitizer detects that the ambient environment is dark, and the 'normally bright' module will illuminate. The 'Changliang' module is designed to facilitate the maintenance of the entire system while avoiding the use of darkness in environments where there is no object movement. The 'Changliang' module improves the applicability of the intelligent light control system with Doppler effect. At the same time, the number of LED lights in the 'Changliang' module is much less than the number of LED lights in the intelligent control part, which saves a lot of electricity compared to the general control system.
The Doppler-based lamp control system we studied has a great improvement in detection control, and the control of the device and the monitoring of the refinement to each lamp have good stability and energy saving. In the current situation of energy shortage, the program embodies its advantages of energy saving, low manufacturing cost and stability in practical applications, including reliability, stability of data transmission, anti-interference of communication lines, etc. It is believed that in the near future It can be applied to real life in the future, and will bring good development opportunities and market prospects.
2 control system hardware design
2.1 HB100 microwave sensor detection module
The HB100 microwave sensor detection module mainly includes the HB100 Doppler microwave sensor and signal processing part. The principle of the Doppler effect is that when the transmitting end moves in the direction of the radius of the receiving end, the frequency of the received signal deviates with respect to the frequency of the transmitted signal.
Equation 1 is the Doppler frequency formula, which is the speed of relative motion, λ is the operating wavelength, and φ is the initial phase. When the moving end moves in the direction in which the sensor approaches, the value of the Doppler frequency is positive; otherwise, the value of the Doppler frequency is negative.
The sensor operates in the X-band and operates at a frequency of 10.52 GHz. The pulse wave and the simple continuous wave make up the emission waveform of the sensor. The sensor works on the principle of DOPPLER and is capable of transmitting low-power microwave signals and receiving energy reflected from objects. When moving an object, the frequency of the received signal is deviated relative to the frequency of the transmitted signal. The two microwaves are mixed with each other, and a low-frequency voltage is generated at the output end. After being processed by the signal processing part, the input to the single-chip microcomputer realizes some functions of the intelligent control system. . The sensor has good stability in high temperature environment and high accuracy during detection. It is suitable for contactless motion and object detection applications.
2.2 regulated DC power supply module
The regulated DC power supply module consists of four parts, which are the transformer, rectifier, filter and voltage regulator circuit of the power supply. The regulated DC power supply module can convert 220V AC power into a adjustable voltage of 1.22 to 9.3V, which is convenient for power supply control and meets the control system voltage.
2.3 Light detection module
The light sensing module is used for illumination measurement, and the core device of the module is a photoresistor. The working principle of the photoresistor is the internal photoelectric effect, which consists of a photosensitive semiconductor material with wires on both ends. In a matte environment, the dark current of the photoresistor is small, and if the applied voltage is applied, the current passing therethrough will increase as the intensity of the illumination incident thereon increases. Thereby the effect of illumination measurement is realized, and part of the intelligent control function of the system is further realized.
2.4 STC89C52 microcontroller
STC89C52 MCU plays an important role in this system. The STC89C52RC/RD+ series of single-chip microcomputers have the characteristics of fast operation speed and good anti-interference ability. They are compatible with the code of the traditional single-chip 8052 instruction in the code of the application instruction. The MCU has 8k bytes of storage space and can be directly downloaded using the serial port for simpler operation and wider application range.
2.5 LED driver module
The Doppler intelligent LED lighting control system uses LED luminaire illumination. The LED driver is a driver with a constant current value output from the driver circuit to ensure stable brightness of the LED lamp. Compared with the same type of constant current driver, the PAM2842 has a large output power and meets the requirements of output regulation and constant current. As a constant current driver dedicated to LED drivers, the PAM2842's input voltage is 5.5V to 40V, and its built-in MOSFET (Gold Oxygen Half Field Effect Transistor) can output up to 30W.
The PAM2842 chip has a high efficiency and a wide constant current characteristic voltage range, so the drive circuit can be operated normally in a higher temperature environment or a sudden drop in input voltage. The PAM2842 chip also features high current, high temperature protection, which helps protect the LED luminaires and extends the life of the LED luminaires.
3 control system software design
The programming of Doppler intelligent LED lighting control system is written in assembly language and imported into the microcontroller through software to realize intelligent functions. Doppler intelligent LED lighting control system in the STC89C52 microcontroller environment to complete the light detection signal analysis, HB100 microwave sensor detection module generated signal analysis and LED driver start command output control.
3.1 HB100 microwave sensor detection program design
As shown in Figure 2, the HB100 microwave sensor detects the program's main program initialization resources, with external interrupt 0 as the level trigger mode, when its pin P3.2 is low, interrupts, enters the interrupt program; Calculate whether the number of low pulses in the subroutine reaches more than three within 10ms. If it is reached, the LED is lit; the timer T1 is used for timing, and the difference between the time of starting the non-initial external interrupt and the time of the initial external interrupt is Compared to 10ms, there is a time limit for the number of external interrupts.
Figure 2: HB100 Microwave Sensor Detection Program Design
3.2 Light detection program design
The light detection program collects the signal through the photoresistor, the converter ADC converts the signal, inputs the single-chip microcomputer, and inputs the signal of the single-chip microcomputer to compare with the set value, and makes the next decision. Through A/D conversion, it is converted into a digital signal, which is convenient for the judgment of the single chip microcomputer. After the entire circuit is powered on, the ADC is initialized, the ADC is converted, and the input values ​​are compared to make a judgment to realize the light detection function.
4 system debugging
After completing the software and hardware design of the Doppler intelligent LED lighting control system, in order to perfect the Doppler intelligent LED lighting control system, the entire system was debugged. In the IDE software environment, the code is written, compiled, and debugged until the debugging is successful, and then written into the microcontroller. Through the IDE, the MCU can be controlled to know the value of the MCU's registers in real time, and further monitor and debug all aspects of the functions of the MCU until the entire LED lighting control system is intelligently controlled.
4.1 HB100 microwave sensor detection program debugging
Before debugging the HB100 microwave sensor detection program, when the microcontroller pin P3.2 is low, it is interrupted. Connect the circuit of the HB100 microwave sensor detection module to test whether each circuit is conducting. The MCU is connected to the computer to facilitate real-time monitoring of measurement data and debugging during testing. When no object moves, the frequency at which the microwave sensor emits the microwave does not shift from the frequency of the microwave reflected back through the moving object, and a high voltage signal is detected at this time. When an object movement is detected, the LED light is illuminated. With the timer T1 timing, the difference between the time when the non-initial external interrupt arrives and the time of the first external interrupt is 10 ms. The HB100 microwave sensor detection function is debugged by calculating the low pulse number within 10ms by calculating the subroutine.
4.2 Light detection program debugging
Before the light detection program is debugged, set the contrast value according to the requirements of the light intensity of different environments. In the connection circuit, the signal is converted by the analog/digital converter ADC, input to the single chip microcomputer, and the next step function is determined by comparing the input value and the set value of the single chip microcomputer. Use IDE debugging in debugging, different debugging programs, and finally achieve the results that the system needs.
4.3 System overall test
After testing each module, each module is connected according to the overall design system. In the IDE environment, first step through the steps to determine the data for each step. After each set of data is reasonable, the overall operation is carried out. After determining the normal operation of the system, the light intensity set by the single-chip microcomputer is turned on. When an object passes, the light fixture is automatically turned on to realize the intelligence. However, in order to further debug the performance of the intelligent control system, the controller's lamp control angle range is tested as follows, and the test angle range is shown in FIG. It can be seen from the results of the controller's light control angle range test that the lamp can not be lit only when there is an object passing through the position of 7, 9 and the lamp can be illuminated when the object passes through other test positions, which is in accordance with the sensor. Test Range.
Figure 3: Schematic diagram of the angle test point
5 Conclusion
With the shortage of energy, the concept of energy conservation and systematization, the intelligent lighting control system has received the attention of the society. Doppler intelligent LED lighting control system is mainly composed of Changliangzi control system and intelligent control subsystem. It detects double control through light detection module and HB100 microwave sensor. After processing by single chip, it outputs signal information and passes LED driver module to illuminate LED lamps. The function of the intelligent LED light control system is realized. The system has simple operation, good control performance, high energy-saving efficiency and low cost. It can be used in public places such as parks, campuses, communities, stairs, etc., and has broad market and application value.
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