Intelligent humidifier PCBA design and development

With the development of society, people's requirements for a comfortable life are getting higher and higher, and their expectations for smart homes are becoming more and more urgent. While air-conditioning in summer brings coolness to people, drying problems also follow. In winter, people in the north will feel uncomfortable due to insufficient humidity in the environment. Studies have shown that: 50%~60% ambient air relative humidity is harmful to human body. People's health is the most beneficial, people's disease resistance is also the strongest, and people will feel comfortable. Therefore, humidifiers came into being. However, most of the traditional humidifiers use the manual opening mode, which has a simple structure and a single function. It can only manually adjust the amount of mist, and it is impossible to accurately understand the temperature and humidity conditions in real time, making it difficult to achieve the ideal comfort. One can automatically control the ultrasonic wave The working status of the humidifier and the intelligent mobile humidifier that can realize intelligent regulation and humanized quantitative setting have become people's real needs. The humidifier designed in this paper uses a simple robot as a platform to get rid of the shackles of traditional fixed humidifiers, and uses the principle of embedded single-chip microcomputer to realize the intelligent work of the humidifier, which can keep the indoor humidity uniform and conform to the modern lifestyle.

1. Working principle of intelligent humidifier

According to the analysis of user needs, the humidifier designed in this paper meets the following requirements: automatically start or stop working after monitoring the corresponding humidity range; it can realize free movement in the whole room to ensure uniform driving; when the humidifier is about to dry out , start the sound and light alarm; automatically adjust the spray size according to the monitored humidity value; display the indoor humidity in real time; the optimal humidity value can be customized by the user. In order to achieve these requirements, the humidifier is mainly divided into 7 modules for coordination: the central control module with the single-chip microcomputer as the core, the sensor module with the DHT11 as the core, the intelligent drive module with the L298N as the core, and the LED LCD screen as the core. The specific structure of the display module, sound and light alarm module, power supply module and peripheral independent keyboard is shown in Figure 1. The sensor module will monitor the indoor humidity in real time, display it on the LED display, and transmit the data to the central controller. Once the indoor humidity reaches the optimal relative humidity set by the user, the central controller will send commands to make the humidifier and The bottom trolley stops working; when the indoor humidity drops below the set minimum humidity, the humidifier and the trolley will work again. During this period, the humidifier will automatically select the appropriate spray size according to the indoor humidity to ensure indoor comfort; When the water level in the humidifier drops to the preset minimum water level, the humidifier will stop humidifying, and the sound and light alarm module will send out an alarm to remind the user to add water in time to prevent dry heating.

2. Hardware design of intelligent humidifier

(1) Central control module: There are two central control modules based on single-chip microcomputers, one is responsible for controlling the humidity monitoring of the humidifier and the working status of the humidifier, and the other is for controlling the related functions of the simple car at the bottom, such as obstacle avoidance, turning, Start, stop, etc., are connected and controlled by a relay between the two single-chip microcomputers. The single-chip microcomputer on the humidifier is the main one, and the single-chip microcomputer on the simple car is controlled to send commands. The selected single-chip microcomputer is a new generation of 51 single-chip microcomputer with high speed, low power consumption and super anti-interference. The working voltage is 5.5~3.5V. There are 8 high-speed 10-bit A/D conversions inside, which can directly transfer the data of the temperature and humidity sensor to the single-chip microcomputer. The conversion from analog to digital is carried out internally, eliminating the need for external A/D conversion modules.

(2) Intelligent drive module: Since the stepper motor has higher precision than ordinary motors and is easy to control, the humidifier designed in this paper uses a stepper motor and L298N motor driver chip. L298N is a monolithic integrated circuit, high voltage, high current, four-channel driver, which can directly control the motor without isolation circuit. By changing the level of the control terminal of the chip through the I/O input of the single-chip microcomputer, the motor can be operated in forward, reverse and stop, which is very convenient and can also meet the high current requirements of the DC geared motor. When debugging, follow the chip manual and use the program Input the corresponding code value to realize the corresponding action. The circuit principle of the drive module is shown in Figure 2.

(3) Power supply module: The power supply used in this design includes 5V single-chip power supply, 5V motor drive chip power supply and 7.2V motor power supply, but only two 3.6V lithium batteries are used for power supply. Therefore, in the power supply module It is also necessary to add a 7805 voltage drop circuit to reduce the voltage and maintain the normal operation of the circuit.

(4) Alarm module: the circuit of the alarm module is as shown in Figure 3. After the water level sensor detects that the water level in the humidifier drops to the set minimum water level, the central control module sends an order, that is, sends a low level, and then buzzes The device emits a "beep" alarm sound.

(5) Sensor module: The sensor module takes DHT11 as the core, and DHT11 is a temperature and humidity sensor that has stored a calibration digital signal, including a humidity sensing element and a temperature measuring element, and these two elements are internally connected with a high-performance 8 The single-chip microcomputer is connected to complete the collection of temperature and humidity.

(6) LED display module: In this design, a liquid crystal display is used as the output status display, which has the advantages of good stability and not easy to flicker. After the central control module receives the humidity information sent by the temperature and humidity sensor, it converts the information into a digital signal by using the existing 8-bit high-speed A/D conversion module inside the single chip microcomputer, and then inputs it into a common-cathode working liquid crystal display for display.

3. Program design of intelligent humidifier

The humidifier introduced in this article divides the software design into two parts, one part is a simple car at the bottom: an infrared obstacle avoidance sensor is installed on the left and right sides of the car. When no obstacle is detected on the left and right sides, the car will move forward; if an obstacle is detected on the left side and no obstacle is on the right side, the car will turn right; if an obstacle is detected on the right side but there is no obstacle on the left side, Let the car turn left; when obstacles are detected on the left and right sides, let the car stop first, and then move back for 50ms; the other part is the humidifier: first initialize the LCD screen, boot interface, etc.; scan the button, according to the mode selected by the user working. The working mode of the humidifier is divided into monitoring mode and humidity preset mode, and its adjustment mode is divided into automatic mode and manual adjustment mode. In the automatic control mode of the monitoring mode, the relay determines whether to perform humidification according to the comparison result of the upper/lower limit of the preset humidity value and the current humidity value, and controls the work of the humidifier. This system limits the range of the preset humidity value to 0~100%RH. Use 1602LCD to display the current humidity and preset humidity value. In addition, when the water level is lower than the set minimum value, the system will drive the buzzer to alarm to prevent dry burning.

epilogue

This paper uses a modular design method to successfully design an intelligent humidifier that can move freely indoors and automatically adjust the size of the spray. Under the condition of ensuring uniform indoor humidification, it can also achieve effective early warning to prevent the humidifier from drying out. Real-time display of indoor humidity. First use C language programming, after simulation debugging and actual testing of Keil4, AltiumDisgner and other software, it is proved that the humidifier designed in this paper effectively solves the above problems of traditional humidifiers, making the humidifier a step closer to the direction of smart home, and its The method has low cost, simple operation and certain practical application value.

The above is an example of the design and development of a mobile smart humidifier introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have humidifier development and design needs, you can trust us. We represent a variety of single-chip microcomputers, voice chips, dual-mode Bluetooth ICs, and wifi chips. Brands include Songhan MCU, Yingguang MCU, Jerry Bluetooth, Ankai Bluetooth, Allwinner, and Realtek. Our technical services include: PCB design, MCU development, Bluetooth solution, software and hardware custom development, APP development, small program development, WeChat official account development, etc. It can also undertake the design of intelligent electronic products, the development of living appliances, the research and development of beauty equipment, the application of Internet of things platform, the smart home control system, the development of TWS earphones, Bluetooth earphone speakers, the development of children's educational toys, the design of electronic education products, etc.