Design scheme of two-way temperature controller based on 51 single chip microcomputer
This paper proposes a design scheme based on 51 single-chip two-way temperature controller. The design adopts two DS18B20 temperature sensors to collect the temperature in two different places. It is processed by AT89C51. The measured temperature is measured by four LED digital tubes. Two are the temperature of the first temperature sensor and the last two are the temperature of the second temperature sensor. The highest and lowest temperature settings are achieved with three buttons, and the buzzer and motor are used to achieve over- or under-temperature alarms.
1 Introduction
At present, the problem with temperature controllers is how to reduce costs, reduce power consumption, accuracy of temperature measurement and simultaneous display of multiple temperatures. The realization of this scheme is based on the two-way temperature controller of C51 single-chip microcomputer, which achieves the lowest cost and high precision. The display and control of two-way temperature can start the electric fan to cool down when the temperature exceeds the set maximum temperature. When the temperature is lower than the set minimum temperature, the buzzer alarm is activated, and the user can set the highest and lowest temperature.
2. System structure
The temperature controller system includes the following main parts: temperature sensor, alarm circuit, LED display circuit, keyboard control, 89C51 control part. as the picture shows:
The system is designed and implemented: after the temperature controller is started, the green light is on, the first two digits of the four LED digital display are the ambient temperature measured by the temperature sensor 1, and the last two are the ambient temperature measured by the temperature sensor 2.
3. Hardware structure
3.1 Temperature sensor
This design uses DS18B20 as the temperature sensor. Compared with the traditional thermistor, DS18B20 has the advantages of high precision, small measurement error and convenient multi-point temperature measurement. Therefore, DS18B20 is used as temperature sensor.
3.2 Alarm circuit
This design uses a buzzer and an electric fan alarm circuit. The buzzer alarm circuit consists of a triode and a buzzer. When the temperature is lower than the set minimum temperature, the buzzer will alarm. The electric fan alarm circuit is composed of a triode and an electric fan. When the temperature is higher than the set maximum temperature, the electric fan will alarm.
3.3 display circuit
The system adopts LED digital display tube display, and the LED has high brightness and high viewing angle. The LCD has a low viewing angle, low brightness, and high price. Considering that this temperature sensor is mainly used in environments with low brightness such as greenhouses, LEDs are selected as displays from an economical and practical point of view.
3.4 Keyboard Control
The system uses three independent buttons as the keyboard control circuit. Keyboards are generally divided into stand-alone and matrix keyboards. The stand-alone keyboard has a simple structure, but it occupies more resources; the matrix keyboard structure is more complicated, but it occupies less lines. Considering that the number of buttons required for this design is small, three temperature sensors are used to set the temperature of the two temperature sensors.
3.5 89C51 Control Section
This system uses AT89C51, 51 for small electronic products, and the hardware design circuit is shown in Figure 1.
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