Aiming at the problem of poor maneuverability of human-machine interface of existing intelligent lighting system, a design scheme of intelligent lighting controller with touch human-machine interface is proposed.Intelligent lighting controller connects Internet of Things cloud platform through WiFi module, which can realize remote control of APP, dimming and color adjustment, switch timing. At the same time, an independent capacitive touch dimming and color adjustment circuit is designed on the controller, which can be separated from the mobile phone, manual touch dimming and color adjustment on the spot, and scene switching.In this paper, the lamp belt is used as illumination source, and the driving logic of remote control and touch operation is explained in detail, which realizes the organic combination of remote intelligent management and real-time touch control.The results show that the human-machine interface of intelligent lighting controller is friendly, and the practical experience of intelligent lighting products is improved significantly.As a subsystem of smart home, intelligent lighting technology will be an important technical means to strengthen green functions such as energy saving and health management in the future.And LED solid-state lighting is very convenient to realize intelligent control [2], which is also the mainstream of lighting technology at present.
Traditional wired control technologies based on DMX [3] bus and DALI [4] bus, wireless control technologies based on WiFi [5], ZigBee [6], Bluetooth [7], RF? 433MHz [8], and wireless control system based on wired bus protocol [9], have been applied in intelligent lighting systems to varying degrees.In recent years, the rapid development of Internet of Things technology, combined with intelligent lighting applications, and further integration of voice control technology [12], began to use artificial intelligence to recognize voice [13] in the cloud to achieve lighting scene control.Many existing wireless intelligent lighting controllers have single design function, complicated operation of APP, poor protocol compatibility, and do not let users experience real convenience and speed in their real life.Li Yan et al. realized the intelligent lighting system based on WiFi [14], but did not consider the problem of remote control.Wang Yonghui and Hu Yanrui have designed the App of Android terminal, which is the wireless control function of the local area network and has no access to the Internet of Things [15?16]. The interface of APP is too complex to be operated by users.Wang Min proposed an intelligent lighting system architecture based on the Internet of Things, but the system is complex and not practical [17]. Cao Yang proposed a lighting design scheme for touch control to achieve dimming, but did not consider networking control [18].This paper presents the design of an intelligent lighting controller. The characteristics of the system are that it combines wired capacitive touch and wireless WiFi connection to realize the intelligent lighting control of wired and wireless combination, which increases the flexibility of the controller application and improves the actual operation experience of users.In the process of wireless communication, the system realizes remote intelligent control of LED lighting by combining WiFi module with LED lighting, wireless WiFi network and Internet of Things cloud platform.At the same time, under the control of Android mobile phone client, LED lighting device achieves the functions of dimming, color adjustment, timing, scene switching and so on.At the same time, in the process of wired connection, the system provides manual control operation of dimming and color adjustment through capacitance touch panel, which achieves the effect of fast and convenient operation and real-time control.The intelligent lighting controller designed in this paper is composed of power supply module, WiFi module, MCU module, capacitor touch input module and mobile phone APP. It can be connected with RGB color light belt driven by 12 V DC to realize intelligent lighting control.The power supply uses SY8292 power IC to realize DC? DC voltage conversion. It supplies power for MCU module, WiFi module and capacitor touch chip WTC401.In wireless connection design, the WiFi module uses ESP8266 single chip system.According to the research status and application of WiFi LAN control and the operation mode of WiFi WLAN, the basic WiFi mode LAN environment based on Java language control is established.Using Java language to program, a smart phone client application software with simple operation, complete functions and friendly interface is developed, which can send command signals to target hardware system accurately and timely, communicate with intelligent lighting controller, and realize real-time control of brightness and color of RGB full-color LED lamp band.In the design of wired connection, an independent capacitor touch-controlled dimming and color-adjusting circuit is set up, which makes use of the characteristics of capacitor touch-controlled switch, such as easy to use, long life and low cost. It achieves the effect of fast response in manual control of lighting and simplifies the operation process.The overall architecture of the controller is shown in Figure 1.The system is powered by a 12 V power adapter. After voltage reduction by SY8292 power supply circuit, the output voltage is 3.3 V stable DC voltage.The output 3.3 V DC voltage will not fluctuate significantly with the grid voltage, which provides a good guarantee for the power supply of the main logic circuits of ESP8266 module and controller.The ESP8266 wireless WiFi module in the system is the communication bridge of the whole control system. Its functions include: communicating with the smart phone terminal, receiving control signals and returning relevant state information; communicating with STM8 controller through serial port according to received control instructions, and then outputting different PWM (Pulse Width Modulation) by STM8 controller. Width Modulation (WM) signal drives the LED lamp band to control the color temperature, brightness and color of the LED lamp band.RGB tri-color LED is chosen as the main illumination device in the system, which can realize arbitrary combination of different colors and change brightness and color according to user’s needs.The smart phone terminal of the system is equivalent to remote control equipment. The application software is developed based on Andriod operating system. The program is written with Eclipse software. After compiling, the. APK file is generated and downloaded to the smart phone terminal. After installation, the APP software is controlled.App on mobile phone sends control data to WiFi module through wireless network, WiFi module reports status data to mobile phone through wireless network, and APP displays to mobile phone screen.The STM8 controller processes the data received from ESP8266, translates and responds the received control signal in time, and outputs the corresponding PWM modulation signal [19] to the three output ports to realize the control of the three primary color LED lamp.In addition, the controller also has a wired input mode and a capacitive touch panel with eight touch switches on it.When the human finger touches the surface of the touch panel, it encodes the detection information of the 8-way touch switch, realizes the position detection, and sends the relevant information to the STM8 MCU for judgment, and then controls the RGB lamp belt.Finally, both WiFi module and mobile APP can access the cloud platform of the Internet of Things to realize remote wireless connection and remote control.The hardware design of intelligent lamp belt controller includes power module, MCU module, LED driver module, WiFi module and capacitor touch module.Among them, the power module is responsible for the voltage distribution of the whole controller, the MCU module is responsible for information processing and output control, the LED driver module ensures the brightness and color control of the LED lamp, the WiFi module is responsible for information exchange between the system and the mobile phone, and the capacitive touch module realizes finger touch sensing.In the circuit and equipment included in the hardware system, ESP8266 module, MCU module and touch module all need stable 3.3 V DC power supply.In the design of power module, SY8292 power IC is used to realize DC? DC step-down conversion, and the energy conversion rate can reach 97%.This system provides 12 V voltage input by power adapter. 12 V voltage is converted to 3.3 V DC voltage by SY8292 power IC. It directly provides stable DC voltage for ESP8266 module and STM8 microcontroller circuit.As shown in Figure 2, the output voltage can be obtained by adjusting the values of resistance R20 and R1 2.This system is based on STM8S103F3P6 single chip computer as the main control chip, as shown in Figure 3, the working voltage is 2.95-5.
5V.The chip has abundant internal resources, powerful functions, low power consumption, low price, good stability, and good timeliness and accuracy for the transmission and processing of control signals.In this design, three PWM signals are output by STM8 MCU. PWM_R/PWM_G/PWM_B corresponds to RGB three-color LED lights.Figure 4 takes a PWM_B as an example. PNP small signal transistor S8050 realizes the conversion of 3.3 V switch level of single chip computer to 12 V level driving NMOS power transistor AP60T03, realizes the current on-off control of RGB three-way LED lamp.In the process of adjusting the light of LED lamp band, PWM realizes brightness control by changing the ratio of on-off time of LED.There is a special hardware PWM signal generator in STM8 MCU. Through high-resolution counter, the output PWM square wave frequency and duty cycle are modulated. Through high-speed switch, the LED lamp is switched on and off continuously, and the brightness of the LED lamp is adjusted.Because the load current of PWM dimming is only full load and no load, it will not interfere with the performance of LED such as color temperature and color deviation.Therefore, PWM dimming is the main dimming mode of this design system.In this design example, the working frequency of PWM is 1 kHz, the duty cycle is 256, and the number of RGB synthetic colours is 256 x 256 x 256 = 16 million colours.In order to meet the user’s requirement of self-adjusting illumination color, brightness and color temperature, the illumination source of the system uses a set core of encapsulated full-color red, green and blue three-color LED, and three LED chips are integrated on a 5 mm *5 mm size ceramic base. The mixing effect is good.The control reference voltages of LED chips are R (red), 1.8-2.0 V, G (green), 3.2-3.4 V, B (blue), 3.2-3.4 V, respectively.For the proportion of the luminous intensity of three small LED beads, red, green and blue, the general choice is: 3 (red):6 (green):1 (blue), which can be combined to get white.
Therefore, users can adjust the color and brightness according to their own needs, that is, by changing the proportion of driving current of the small beads of various colors in the packaged three-color LED, the brightness and color temperature of the LED light source can be adjusted.Because the LED light spectrum used in the system is very flexible, its color rendering and radiation are affected by three single beads, so the packaged three-color LED lamp has good stability, and its luminance and color adjustment is very convenient.The system uses WiFi module directly, and the circuit design is shown in Fig. 5.WiFi module can join WiFi wireless communication network to realize controller access network.App and ESP8266 wireless control modules of smart phone client are added to the preset WiFi network respectively. The relevant control signals of APP are transmitted to the intelligent lighting controller via WiFi network.When ESP8266 wireless control module receives the corresponding control signal, it is transmitted to STM8 MCU through UART serial port for processing. Different control instructions enable three PWM output ports of MCU to output PWM control signals with different duty cycles, so as to adjust the brightness of three different color beads of three primary color LED lamp belts, thus combining them. The color and brightness required by the user.The ESP8266 module is connected with the single chip computer. While transmitting the user’s control signal to the single chip computer in real time, the single chip computer reports the status of the intelligent lighting controller to the user’s mobile phone, so that the data can be transmitted stably and monitored in real time.
Using the capacitance effect of human body, finger touch detection can be realized.As shown in Fig. 6, thermostatic element the capacitive touch circuit of the system adopts WTC401 special touch chip and sets up eight touch switch inputs.In the formula, e is the dielectric constant, K is the static constant, S is the positive area of the capacitor plate, and D is the distance between the two plates.When S and D change, the capacitance value between the induction electrode and the circuit ground changes. WTC401 catches the change and processes the signal, generates the touch input position information, then transmits the data to the single chip computer. Finally, the single chip computer controls the duty cycle of three PWM output according to the touch switch press, and then controls the LED lamp with illumination. Ming.In practical use, eight touch button layouts are designed on the circular touch panel, which cross each other by wedge and connect the head and the tail to form a touch ring.The touch area can be quantified to 64 physical touch location information. The single chip computer continuously queries WTC401 through SPI interface, acquires finger touch location information in real time, and converts it to 64 color codes to control PWM dimming and color adjustment.Based on the embedded development platform, the system compiles the program of STM8 MCU in C language.The software can be divided into the following parts: system initialization, touch key recognition, logic judgment, PWM output, watchdog reset, WiFi module driver and transmission protocol parsing.The flow chart of the main program is shown in Figure 7.This design is based on Android software development platform on the mobile client, and a mobile phone software is compiled. This software mainly cooperates with the hardware system for wireless control and real-time state monitoring.Eclipse has the characteristics of free, open source code and unlimited scalability, which provides convenient conditions for the software writing of the system.This system uses Eclipse software and Java language to compile the control program. After compiling and compiling, A. APK file can be generated and downloaded to the mobile phone, and a mobile phone APP software can be obtained. With this software, it can communicate with ESP8266 module under WiFi network, and then transfer data with the single chip computer system, and compile the mobile phone APP software. The main interface of APP light control is shown in Figure 8.The cloud platform workflow of intelligent lighting is shown in Figure 9.Guangzhou Smart Cloud Internet of Things Technology Co., Ltd. provides a cloud service platform for self-development of intelligent hardware. This system chooses the Smart Cloud as the cloud access platform of the Internet of Things.In WiFi module, the cloud-compiled firmware of smart cloud system has been built in.
The hardware part communicates with smart cloud through WiFi module and uploads device status data.The smart cloud communicates with the WiFi module to send the mobile phone APP control command to the controller for execution.If the controller and the mobile phone are connected to the same LAN, then the mobile phone APP can interact directly with the system hardware without passing through the smart cloud.Smart Cloud supports devices accessing via HTTPS and MQTT.HTTPS access scenarios mainly include: acquisition of device configuration information, acquisition of equipment upgrade information and so on.MQTT access scenarios include subscription device control instructions, publishing device status, etc.After debugging the software, the intelligent lighting controller is connected to the scheduled WiFi network, and the smart phone is connected to the same WiFi network.The real-time control of the lamp band can be realized by adding equipment to APP software.The circuit board of intelligent lighting controller is shown in figs. 10-12.The display effect of the color light strip under the input control of the APP interface and touch panel is shown in Figure 13.The parameters of intelligent lighting controller and color lamp band are: controller power supply, DC 12 V/1A; lamp band power, 6W (30 *0.2W/LED); PWM output, 1kHz, 256 duty cycle; color matching capability, 16 million colors; touch resolution, 64 points@8 key loop; WiFi standard, 2.4 GHz IEEE 802/11b/g/n.This paper provides a design scheme of intelligent lighting controller with touch control function, and describes the scheme in detail.
The lighting system is controlled by wireless WiFi network environment, which is convenient for users to control the lighting system in a long distance.In order to further improve the user experience, the system enhances the flexibility and practicability of the controller through the cable capacitance touch mode, realizes the brightness and color adjustment of the LED lamp band in the function, and finally brings the user a new experience, and promotes the popularization of the application of intelligent lighting system technology.