The use of DS18B20 digital temperature and humidity sensor and performance is introduced

We all know that DS18B20 digital temperature and humidity sensor can be applied in various fields, the correct use method can provide the performance of the instrument, due to the performance requirements for digital humidity sensor is also very high, so the following project is to introduce specific questions about the use of digital temperature and humidity sensor and performance are introduced.

digital temperature and humidity sensor is the temperature and humidity quantity, physical quantities by temperature, humidity sensor and the corresponding circuit into a convenient data acquisition equipment such as computer, PLC and intelligent instrument directly read digital sensors. The sensor data output format is likely to be RS232 and RS485 data, a data bus, CAN bus data, ZIGBEE data, TCPIP data and duty ratio data.

host control digital temperature and humidity, temperature and humidity change before each time to read and write, will be to reset of digital temperature and humidity sensor, and the CPU to the reset request data offline pull 500 mu s, and then release. Digital temperature and humidity sensor will wait for 16 - after receiving signal After about 60 mu s, a 60 - again 240 mu s low pulse. The CPU receives the signal indicates that the reset successfully. In fact, small hardware overhead need relatively complex software to compensate. Due to the digital temperature and humidity sensor with microprocessor adopts serial data transmission method, therefore, in the programming of digital temperature and humidity sensor, speaking, reading and writing, must be strictly guaranteed to read and write timing, otherwise, will not be able to read correctly temperature measurement results.

for hanging in single bus digital temperature and humidity sensor, the number of people will think you can hang any number of digital temperature and humidity sensor, and is not the case in practice. If hang on single bus digital temperature and humidity more than eight, you need to solve the problem of the bus driver of the microprocessor, therefore, when making battery monomer multi-point temperature measurement system design the questions to pay attention.

to connect digital temperature and humidity sensor bus cable length limitation. Experiment, when using common signal cable and the transmission length of more than 50 m, read the temperature measurement data error will occur. And take bus cable instead of twisted pair shielded cable, normal communication distance is 150 m, such as belt shielding layer and twisted per meter more twisted-pair cable, the normal communication distance can be extended further. This kind of situation is mainly caused by bus distributed capacitance makes signal waveform distortion, therefore, in using digital temperature and humidity sensor for temperature measurement system design should fully consider long distance bus distributed capacitance and impedance matching problem.

in the digital temperature and humidity sensor temperature programming, when the order to send a temperature and humidity conversion to digital temperature and humidity sensor, program total want to wait for the return of digital temperature and humidity sensor signal. So, once a digital temperature and humidity sensor is bad or break line contact, when the program to read the digital temperature and humidity sensor, there is no return signal, so as to make the program into the infinite loop. Therefore, in the digital temperature and humidity sensor hardware connection and software design, should be given enough attention.

compared with analog, digital temperature and humidity sensor has many advantages, the anti-interference ability of the sensor, signal transmission distance, improve the stability of the sensor, but also improves the precision and reliability of integrated sensor, electromagnetic compatibility performance will be much better.

that's project for everyone about the use of digital temperature and humidity sensor and performance problems, you can according to the above content for reference, hope that the above details can help users better instrumentation, through the above description, we should take more attention on instrument performance.

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key words: thermal resistance, thermocouple, thermal resistance, platinum resistance, PT100, PT1000, pressure sensor and digital temperature sensor