27-Air conditioning temperature control system based on 51 single chip microcomputer

Specific implementation functions

The system consists of STC89C51 microcontroller + LCD1602 liquid crystal display + L298N control module + DC motor + DS18B20 temperature sensor.

Specific functions:

(1) Realize L298N to control the motor and use LCD1602 to directly and clearly display the temperature;

(2) Control the motor speed based on the measured temperature (using the motor to simulate the air conditioning variable frequency system);

(3) In automatic mode, the higher the temperature, the higher the duty cycle and the faster the speed. In manual mode, the motor speed can be controlled by pressing buttons.

design background

In recent years, with the rapid development of the air conditioning industry, it has greatly occupied the market. Compared with fans, air conditioners have powerful cooling functions and can quickly and effectively reduce the ambient temperature. However, there are also many problems with air conditioning. For example, it is easy to get air conditioning disease if you blow it for a long time in summer, and it is easy to catch a heat cold due to the imbalance of indoor and outdoor temperatures; at the same time, because it is forced cooling, the elderly and children are not able to bear it, and it is easy to breed bacteria when the air is not circulated indoors for a long time when using air conditioning, and the air conditioning consumes a lot of energy. Therefore, it is very important to reasonably control and use air conditioning. With the development of science and technology and the improvement of people's living standards, household electrical appliances tend to be automated, intelligent, low-power, environmentally friendly and humanized, and intelligent temperature-controlled air conditioners controlled by microcomputers have emerged.

In order to solve the above problems, this paper designs an air conditioning temperature control system based on a single-chip microcomputer, taking advantage of the characteristics of the single-chip microcomputer, which is small and multifunctional, can realize a variety of design requirements, and is applied in many fields. This system uses a high-precision integrated temperature sensor, controlled by a single-chip microcomputer, can display the real-time temperature, and adjust the frequency conversion system of the air conditioner according to the temperature to realize air conditioning control, improve the intelligence and humanity of the air conditioner, and save electricity.

hardware design

The figure shows the hardware design of this system. Specifically, the hardware circuit consists of the following modules:

(1) Single-chip microcomputer minimum system. It is used to drive and control other modules to achieve the overall function. It uses the AT89C51 single-chip microcomputer as the core chip, supplemented by a reset circuit and a crystal oscillator circuit;

(2) Button module. It consists of three buttons to switch between automatic and manual modes and control the motor speed (acceleration and deceleration).

(3) Display module. The real-time temperature value measured by DS18B20 is displayed on the LCD1602 liquid crystal display;

(4) Motor and its drive module. The operation of the air conditioner inverter is simulated by the number of revolutions of the motor.

software design

According to the design requirements of this article, on the basis of hardware circuit design, the specific functions that need to be implemented through software programming are:

(1) Drive each module to work and realize clear display of LCD1602;

(2) Button setting function. The interactive single-pole double-throw switch is used to switch between automatic and manual states, and the other two button switches are used to control the motor speed (acceleration and deceleration);

(3) Realization of temperature detection function. Realize real-time detection and display of ambient temperature;

(4) Motor drive and control. Realize motor speed control based on temperature.

The specific design process is shown in the figure.

Schematic

The schematic diagram of this system was designed using Altium Designer19, as shown in the figure.

program

This design uses KEIL5 software to implement program design, as shown in the figure.

Simulation Implementation

This design uses protues8.7 software to implement simulation design, as shown in the figure.