Design and development of intelligent humidifier PCBA
Design and development of intelligent humidifier PCBA
With the development of society, people have higher and higher requirements for comfortable life, and the expectation of smart home is more and more urgent. While air conditioning in summer brings people cool, drying problems also follow. In winter, people in the north will feel uncomfortable due to insufficient humidity in the environment. Research shows that 50% ~ 60% of the ambient air relative humidity is the most beneficial to human health, people's disease resistance is also the strongest, and people will feel comfortable. Therefore, humidifier came into being. However, the traditional humidifier mostly adopts the manual opening mode, with simple structure and single function. It can only manually adjust the amount of fog and can not accurately understand the temperature and humidity in real time, which makes it difficult to achieve the ideal comfort feeling. It can automatically control the working state of the ultrasonic humidifier Intelligent mobile humidifier, which can realize intelligent regulation and humanized quantitative setting, has become people's real demand. The humidifier designed in this paper takes a simple robot as the platform, gets rid of the shackles of the traditional fixed humidifier, 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 in line with the lifestyle of modern people.
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 move freely in the whole room to ensure uniform driving; When the humidifier is about to dry burn, start the audible and visual alarm; Automatically adjust the spray size according to the humidity value monitored. Real time display of indoor humidity; The optimal humidity value can be customized by the user. In order to realize these requirements, the humidifier is mainly divided into seven modules for coordination: central control module with single chip microcomputer as the core, sensor module with DHT11 as the core, intelligent drive module with L298N as the core, display module with LED LCD as the core, audible and visual alarm module, power module and peripheral independent keyboard. The specific structure is shown in Figure 1. The sensor module will monitor the indoor humidity in real time, display it on the LED display screen, 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 a command to stop the humidifier and the bottom trolley; When the indoor humidity drops below the set minimum humidity, the humidifier and the car will work again. During this period, the humidifier will automatically select the appropriate spray size according to the humidity of the room 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 audible and visual alarm module will send an alarm to remind the user to add water in time to prevent dry burning.
2、 Hardware design of intelligent humidifier
(1) Central control module: there are two central control modules based on single chip microcomputer. One is responsible for controlling the humidity monitoring and working state of the humidifier, and the other is to control the relevant functions of the simple car at the bottom, such as obstacle avoidance, turning, start, stop, etc. the two single chip computers are connected and controlled by a relay, mainly the single chip microcomputer on the humidifier, Control the MCU on the simple car to send commands. The selected single chip microcomputer is a new generation 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-way high-speed 10 bit a / D conversion inside, which can directly convert the data of temperature and humidity sensor from analog to digital inside the single chip microcomputer, eliminating the external a / D conversion module.
(2) Intelligent drive module: because the precision of stepping motor is higher than that of ordinary motor and easy to control, the humidifier designed in this paper adopts stepping motor and L298N motor drive chip. L298N is a single integrated circuit with high voltage, high current and four channel drive. It can directly control the motor without isolation circuit. By changing the level of the chip control end through the I / O input of the single chip microcomputer, the motor can be operated forward, reverse and stop. It is very convenient and can also meet the high current requirements of the DC deceleration motor. During debugging, the corresponding action can be realized by inputting the corresponding code value according to the chip manual. The circuit principle of the drive module is shown in Figure 2.
(3) Power module: the power supply used in this design includes 5V single chip microcomputer 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, a 7805 voltage drop circuit needs to be added in the power module to reduce the voltage and maintain the normal operation of the circuit.
(4) Alarm module: the circuit of the alarm module is shown in Figure 3. When the water level sensor detects that the water level in the humidifier drops to the set minimum water level, the central control module sends a command, that is, sends a low level, and the buzzer sends a "tick" alarm sound.
(5) Sensor module: the sensor module takes DHT11 as the core. DHT11 is a temperature and humidity sensor that has stored calibrated digital signals, including a humidity sensing element and a temperature measuring element, which are internally connected with a high-performance 8-bit single chip microcomputer to complete the collection of temperature and humidity.
（6） LED display module: in this design, the LCD is used as the output status display, which has the advantages of good stability and not easy to flash. After receiving the humidity information sent by the temperature and humidity sensor, the central control module uses the existing 8-bit high-speed A / D conversion module to convert the information into digital signals, which are input into the LCD working on the common cathode for display.
3、 Program design of intelligent humidifier
The humidifier introduced in this paper divides the software design into two parts. One part is the bottom simple car: an infrared obstacle avoidance sensor is installed on the left and right sides of the car. When no obstacles are detected on the left and right sides, the car will move forward; if an obstacle is detected on the left and no obstacle is on the right, let the car turn right; if an obstacle is detected on the right and no obstacle is on the left If there are obstacles, let the trolley turn left; when obstacles are detected on both left and right sides, let the trolley stop first and then move back for 50ms; the other part is the humidifier: initialize the LCD screen and startup interface first; scan the keys and work according to the mode selected by the user. 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 mode Regulation mode. In the automatic control mode of monitoring mode, the relay determines whether to humidify and control the humidifier according to the comparison between the upper / lower limit of the preset humidity value and the current humidity value. The system limits the range of the preset humidity value to 0 ~ 100% RH. The 1602LCD is used to display the current humidity and the preset humidity value. In addition, when the water level is lower than the set minimum value, the system will Drive buzzer alarm to prevent dry burning.
epilogue
In this paper, a modularized design method is used to design an intelligent humidifier which can move freely and automatically adjust the spray size in the room. Under the condition of ensuring uniform humidification indoors, it can effectively prevent the humidifier from drying and display the indoor humidity in real time. First, it is programmed in C language, and is debugged and tested by Keil4, AltiumDisgner and other software. It is proved that the humidifier designed in this paper effectively solves the above problems of the traditional humidifier, which makes the humidifier another step towards the direction of smart home, and its low cost, simple operation and certain practical application value.