41-Intelligent water heater control system based on 51 single chip microcomputer

Specific implementation functions

The system consists of STC89C52 single chip microcomputer + water level detection sensor + DS18B20 temperature probe sensor + button module + relay module + alarm and indication module + LCD1602 display module + power supply.

Specific functions:

1. The first line of the LCD1602 display shows the temperature and timing time, and the second line shows the upper and lower temperature limits;

2. The buttons can be used to set the upper and lower limits of the temperature and the timing time; heating starts when the timing time is reached

3. Use two water level detection sensors to detect the water level: when the lower limit sensor detects water, the relay starts to control water addition; when the upper limit sensor detects water, the water addition stops;

4. When the temperature is lower than the set lower limit temperature value, the relay starts to control heating; when the temperature is higher than the set upper limit temperature value, the heating stops.

design background

According to incomplete statistics, electric water heaters are the main type of water heaters used in urban households in our city, accounting for more than 60% of the total; the gas water heaters that were once so popular have gradually lost their luster, with a market share of less than 20%; although the emerging solar water heaters are limited by installation conditions, their safety and environmental protection performance are widely favored by consumers, and their development trend is rapid, with a market share of about 15%. For safety reasons, urban residents choose electric water heaters and solar water heaters more. The ventilation effect of commercial housing is not good nowadays, and the pollution generated by gas cannot be eliminated in time, while electric water heaters and solar water heaters basically have no worries in this regard. Advantages of electric water heaters: easy installation, not affected by weather, not restricted by floors and water supply pipes, and low investment cost. With the advancement of technology and the development of new products, electric water heaters with various installation forms such as bottom-mounted and embedded have been launched one after another, completely getting rid of the limitations of room space. In today's society, science and technology are changing with each passing day, water heater technology is developing rapidly, and more and more scientific and technological achievements are being applied to the manufacture of water heaters. Today's water heater products are definitely not a simple heater, but a modern home appliance with high technological content. With the gradual improvement of people's living standards in my country, their living conditions have been greatly improved, and the types of water heaters closely related to family life are emerging in an endless stream. It is in this context that this design chooses the design and research of intelligent electric water heaters based on STC89C51 single-chip microcomputer.

The significance of this topic lies in the intelligent improvement of the water heater. The single-chip microcomputer is used to control its water temperature and water level parameters, which improves the working stability of the water heater. At the same time, the temperature sensor DS18B20 is introduced to collect water temperature data, which improves the control accuracy of the system. The control structure of the water level is simple and easy to implement, and has strong practical application value. Although it is an improvement on the water heater, this intelligent improvement method can also be applied to various water temperature and water level control environments in industry and life, and it also has certain reference significance for the improvement of the control of other related parameters. The water temperature and water level measurement and control system based on the single-chip microcomputer is an improved intelligent product. With its unique advantages of high control accuracy, good stability and low cost, it will have a wide range of practical value in the future. Its improvement method based on the single-chip microcomputer also has a wide range of application significance.

hardware design

This topic is the design of a controller for an intelligent electric water heater based on the STC89C51 single-chip microcomputer. The control requirements to be achieved are: (1) Use LCD1602 liquid crystal to display water temperature, set upper and lower limits and timing time, (2) The water temperature detection display range is 00~99℃, and the accuracy is ±1℃. (3) The temperature preset range is 0~99℃. When the detected temperature is lower than the preset temperature, heating starts; when the detected temperature is higher than the preset temperature, heating stops. (4) Set 4 program buttons. They are set button, plus button, minus button, and confirm.

software design

The software design consists of three parts: the main program, the key scanning subroutine and some other functional module subroutines. The main controller subroutine includes the A/D conversion subroutine (water level, water temperature), keyboard processing and display subroutine, temperature control subroutine (using output comparison function), leakage protection subroutine, etc. The main program must first initialize the working mode parameters of the microcontroller's timer, COP module, A/D conversion, port, key interrupt, etc. After that, the system's main program loop can call the subroutines of each functional module, and the processing of related events is achieved by relying on flags and judgment flags.

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.