Solar street light design scheme based on AT89S52 microcontroller

1. Solar street light controller design

The working principle of the street light control system: photovoltaic cells charge the battery during the day, and the battery provides power for street lighting at night. So the battery will form a charge and discharge cycle. The solar street light lighting control circuit includes four parts: photovoltaic cells, batteries, street lights and controllers. The AT89S52 microcontroller is used in the design and is used as an intelligent core module. The peripheral circuits mainly include solar cell voltage sampling module, battery voltage sampling module, keyboard circuit module, LED display module, charge and discharge control module, etc. Figure 1 is the structural design diagram of the solar street light controller.

2. Single chip intelligent control module

The solar street light controller chooses ATMEL's 8-bit microcontroller AT89S52 as the core intelligent control module, which has the characteristics of low power consumption and high performance as a whole.

2.1. Microcontroller oscillation circuit

The microcontroller oscillation circuit is shown in Figure 2.

2.2. Reset circuit

The reset circuit is shown in Figure 3. The circuit structure is simple, stable and reliable.

3. Power circuit module design

The normal operating voltage of the system is 5V. The system uses a 12V/24V lead-acid battery for power supply. The battery voltage is unstable, so the power supply needs to be stabilized. This system uses the LM7805 three-terminal voltage regulator, which can ensure a stable output of +5V when the input voltage is 5~24V. The LM7805 regulated power supply requires only a few peripheral components, is very convenient to use, and works stably and reliably. The system power circuit is shown in Figure 4.

4. Sampling module design

Solar cell sampling and battery sampling play a very important role in the normal operation of the system. The solar street light controller needs to reasonably control the charge and discharge of the battery, that is, it needs to sample the voltage of the battery and solar panel. To this end, the AT89S52 microcontroller must be connected to an external A/D conversion module to convert the voltage into a digital signal. The system uses the v/F conversion chip LM331 to form a digital-to-analog conversion circuit. In the system sampling design, in order to prevent the AT89S52 program from running away or crashing due to external factors and improve system stability, a single-channel high-speed photoelectric isolator 6n137J needs to be added between the LM331 and the microcontroller. Figure 5 is a solar panel sampling circuit diagram. The system battery sampling and solar panel sampling circuits are the same.