## 2 Related Works
This system can automatically turn on the LED lights in the campus classrooms, using the PIR sensor to detect movement and computer processing to control the lights. The function of this system is to turn on the lights automatically when someone enters the classroom and turn off the lights automatically when there is no one in the school. Similar research also appeared in [23]. [PERSON] [24] also studied a similar intelligent lighting system, the working principle of which was that the PIR sensor would detect the presence of people through body temperature and the movement of people in the room. [PERSON] et al. [25] used two PIR sensors to catch people's entry and exit status at the entrance and then determined the brightness of the lighting according to the number of people in the space. The larger the number of people, the brighter the illumination, thereby avoiding energy waste. Although LED lighting is environmentally friendly, it is still not popular due to its higher installation cost than existing lighting. Although LED lighting prices are falling with recent advancements in manufacturing technology, LED lighting is still costly. To this end, researchers have extensively carried out many previous works [31; 32; 33; 34; 35; 36; 37; 38] to improve the economic feasibility of LED lighting through control algorithms based on sensor and network technology. When the user is not in the room or the room is too bright, these systems can reduce energy consumption by reducing the output power of the lighting instead of processing it under the same illuminance. In this article, a low-cost, easy-to-install, Master-Slave intelligent LED lights controlling system is proposed, which is based on Internet of Things (IoT) techniques. Using the proposed system, the brightness of the LED lights in the same zone can be changed simultaneously to save energy consumption. Furthermore, the parameters of the LED lights can be directly set. Therefore, LED lights in the same zone will operate in low-light mode when nobody is passing by. When any LED light in this zone detects that someone is passing by, it will transmit a message via the Wi-Fi 2.4 G wireless transmission module to alert LED lights in the same zone and adjust the brightness to the high-light mode at the same time, instead of sequentially lighting up the LED lights one by one. The LEDs and sensors can be directly connected via the IoT module and the internet to set the parameters of the LED lights, upload the collected data to the cloud, and then use data analysis to make the best settings for the various settings parameters of the LED lights. Similar to the proposed system, some previous works [39; 40; 41; 42] have applied IoT technology to intelligent traffic light systems, and good research results have been achieved. The other previous works [43; 44; 45; 46] have also adopted IoT technology to the intelligent dimming of old houses, reducing lighting energy consumption, healthy lighting, etc. These previous works were discussed how to extend the life of wireless sensor network (WSN) nodes, and privacy issues of the Google Home devices have been leaked. [PERSON] et al. [47] proposed a hierarchical efficient scheme, which was integrated management of heterogeneous platforms for green workload management. Finally, we make a comparison table of related works with the proposed system, as can be seen in Table 1. The adoption of PIR sensors to sense people passing by can be found in [22; 23; 24], but there are only two modes: full dark and full brightness. Compared to [22; 23; 24], the proposed system is improved to such a statement that is two modes (high-light and low-light) are designed in this article. The LED lights in the same zone will be changed to high-light mode at the same time to reduce the number of irritated eyes and minimize the number of light flashes.