Design scheme of LED intelligent street lamp control system based on single chip microcomputer

With the development of digital technology and network technology, the digitalization and networking of street lamps has become an inevitable trend. Saving energy, ensuring lamp life, improving lighting management, beautifying city nights and ensuring urban nighttime travel safety have become a basic requirement for lighting systems. The continuous development of social civilization and the rapid expansion of urban scale, urban lighting is not limited to the lighting of roads, the society's accuracy of lighting, the accuracy of switching lights, the real-time of fault detection and the timeliness of maintenance, energy-saving requirements of street lamps It is also constantly increasing. With the expansion of the city and the rapid growth of the number of street lamps, the manual control method has become less and less suitable for the development of the city in terms of real-time fault monitoring and control, on-demand control, and energy conservation. Therefore, the intelligent control and energy saving measures adopted by the street lamps have been very meaningful.

The LED intelligent street lamp control system designed in this paper uses STC89C58RD single-chip microcomputer as the leading control chip, which can realize the clock timing switch lamp, realize the switch lamp according to the light and dark changes of the environment, automatically adjust the lighting condition according to the traffic situation, and implement the sound and light alarm for the street lamp failure. A series of intelligent behaviors.

1 system overall design

The system uses a photodiode to detect changes in the brightness of the environment. The infrared transmitter is used as a device for automatically adjusting the lighting according to traffic conditions. The infrared emitter is mounted on the street light pole, and the infrared receiver is mounted on the street light bracket. When the photodiode is not detected. When the light source is detected and the infrared receiver detects the infrared signal, the street light will illuminate, otherwise it will not light. Using programming to achieve timing, design the street light to turn off the light and turn off the light, use LCD12864 as the display device, and display accordingly. The system structure block diagram is shown in Figure 1.

2 unit module design

2.1 clock timing part

The STC89C58RD chip we chose has a programmable timer/counter that can be programmed to achieve timing/counting. When the set time is reached, the corresponding timing setting task is executed.

2.2 Photodiode section

The circuit uses a photodiode as the main control element (see Figure 2). When there is no illumination, the reverse resistance is large and the reverse current is small. When there is illumination, the photon hits near the PN junction, so it is generated near the PN junction. Electron-hole pairs, which perform directional motion under the action of an electric field inside the PN junction to form a photocurrent. The stronger the light, the greater the photocurrent. Therefore, different voltage signals are output according to the brightness of the environment.

2.3 Infrared receiving and transmitting part (detecting traffic conditions, street lights are on)

Install the infrared receiver on the two bypass light poles of the road as required (see Figure 3). The receiving end of the signal is connected to the single-chip microcomputer. When the vehicle or pedestrian passes, the receiver detects the infrared, and the signal end detects the high-level input. Control the lighting of the street lights.

2.4 sound and light alarm part

When the street lamp fails, LED0 lights up and the buzzer sounds to achieve the sound and light alarm function (see Figure 4). When the single-chip microcomputer P0.7-one pin gives high frequency, LED0 lights up, and the triode is turned on, and the buzzer sounds.

2.5 display part

This part uses LCD128*64 as the display (see Figure 5). The main reason for using this display is that it can display pictures and characters. It is very powerful and controls the control of the whole circuit through display prompts.

2.6 constant current source part

The circuit provides a constant current (see Figure 6) and Q3 terminates the load to stabilize the load. Increased load will not affect current changes.

The street lamp thus connected can work stably. The output of the current can be changed accordingly by adjusting the voltage at the input. The reference voltage of the collector C of the TIP122 Darlington tube can be l2-20 v.

2.7 street lamp quality detection part

The circuit uses two voltage comparators built by the LM358 to detect the quality of the two street lights at the P1 and P2 terminals. When the street light is turned on, the comparator's 2 pin and 6 pin have voltage, while the comparator's 3 pin and 5 pin pass the sliding resistor to adjust the voltage, and the 3 pin and 5 pin adjust voltages are 2 feet and 6 respectively. The working voltage of the foot is small, but it cannot be adjusted to 0 V. Therefore, when the street lamp works normally, the P0.5 pin and the P0.6 pin of the MCU output low level. When the street lamp is faulty, the P0.5 pin and the P0.6 pin will be The output is high.

3 system software design

The system software block diagram is shown in Figure 7.

4 system test results

LED street light drive current output terminal voltage and current test results (see Table 1 and Table 2).

Table 1 load one (one lamp)

Table 2 Load two (two lights)

5 Conclusion

This paper presents a design scheme of street lamp intelligent control system based on single chip microcomputer, and completes the hardware and software design. The intelligent control device can automatically adjust the lighting state according to traffic conditions: when the vehicle or pedestrian approaches the street light, the street light gradually becomes brighter; when the vehicle or pedestrian is far away, the street light automatically dims and finally goes out. The controller can also independently control the turn-on and turn-off times of each street light. The system is cost-effective overall, low maintenance cost, low power consumption, environmentally friendly process, and meets the requirements of a green economy and a conservation-oriented society.

Edit: Nizi