Introduction to DS18B20 temperature sensor
DS18B20temperature sensor is a commonly used digital temperature sensor. Itsoutput is digital signal. It has the characteristics of small size, lowhardware overhead, strong anti-interference ability and high precision.DS18B20 temperature sensor digital temperature sensor wiring isconvenient, packaging can be applied to a variety of occasions, such aspipeline, threaded, magnet adsorption, stainless steel packaging, avariety of models.
The characteristics of DS18B20 temperature sensor
The encapsulated DS18B20 temperature sensor can be used for cable trench temperature measurement, blast furnace water circulation temperature measurement, boiler temperature measurement, machine room temperature measurement, agricultural greenhouse temperature measurement, clean room temperature measurement, ammunition warehouse temperature measurement and other non-limiting temperature occasions. Wear-resisting and impact-proof, small size, easy to use, various forms of packaging, suitable for all kinds of small space equipment digital temperature measurement and control field.
The working principle of DS18B20 temperature sensor
DS18B20 temperature sensor has the same reading and writing sequence and temperature measurement principle as DS1820 temperature sensor, but the number of bits of temperature value obtained varies with the resolution, and the delay time of temperature conversion is reduced from 2s to 750ms. The principle of DS18B20 temperature sensor temperature measurement is shown in Figure 3. The oscillation frequency of the crystal oscillator with low temperature coefficient in the figure is little affected by temperature. The pulse signal used to generate a fixed frequency is sent to the counter 1. The oscillation frequency of crystal oscillator with high temperature coefficient changes obviously with temperature, and the generated signal is used as the pulse input of counter 2. The counter 1 and the temperature register are preset at a base value corresponding to -55 C. Counter 1 subtracts and counts the pulse signals generated by the cryogenic coefficient oscillator. When the preset value of counter 1 is reduced to zero, the value of the temperature register is added 1, the preset of counter 1 is reloaded, and counter 1 restarts counting the pulse signals generated by the cryogenic coefficient oscillator until counter 2 is counted. When the number reaches zero, the temperature register value is stopped, and the value in the temperature register is the temperature measured. The slope accumulator is used to compensate and correct the nonlinearity in the temperature measurement process, and its output is used to correct the preset value of counter 1.
Application scope of DS18B20 temperature sensor
This product is suitable for temperature measurement and control fields such as refrigeratory, granary, storage tank, telecommunication room, electric power room, cable trough, etc. Bearing bush, cylinder block, textile machine, air conditioning, etc. narrow space industrial equipment temperature measurement and control.Automotive air conditioners, fridges, freezers, and medium and low temperature drying boxes. Heat / refrigeration pipe heat metering, central air conditioning household heat metering and industrial area temperature measurement and control.
DS18B20 temperature sensor wiring
Facing the flat side, the left side is negative and the right side is positive. Once it is reversed, it will immediately become hot and burn up. At the same time, it is also the reason why the sensor always displays 85 degrees. In the actual operation, the positive and negative joints will be inverted, and the sensor will be heated immediately. The LCD screen can not display the reading. After the positive and negative joints are completed, the display temperature will be 85 degrees. In addition, if 51 single-chip microcomputer is used, then the middle pin must be connected with 4.7K-10K pull-up resistance, otherwise, because the high level can not be normal input/output, or immediately after power-on display 85 degrees Celsius, or temperature in a few months after jumping on 85 degrees Celsius and normal value. See the following links for details：DS18B20 temperature sensor wiring