DS18B20 / DS1822 溫度探頭電纜

DS18B20/ DS1822是常用的數位溫度感測器. 它的輸出是數位訊號, 具有體積小等特點, 硬體開銷低, 抗干擾能力強、精度高. The DS18B20 digital temperature sensor is easy to wire and can be used in a variety of situations after being packaged, 例如管道類型, 螺紋型, 磁鐵吸附式, and stainless steel packaging type. 有各種型號, 包括 LTM8877, LTM8874等. As a digital temperature sensor, the DS18B20 does not require any external components when measuring temperature. It can directly output the measured temperature value of 9~12 bits (including sign bit). The temperature measurement range is -55~+125℃. The measurement accuracy is ±0.5℃ in the range of -10~+85℃, and the output measurement resolution is adjustable, up to 0.0625℃. Supporting "single-wire bus" 科技, only one general-purpose I/O port is required to complete communication with the microcontroller. The on-site temperature is directly transmitted digitally via a "single-wire bus", which greatly improves the system's anti-interference capability.

DS18B20, DS1822 "One-line bus" digital temperature sensor Same as DS1820. DS18B20 also supports "專線巴士" 介面, and the measurement temperature range is -55°C~+125°C, and the accuracy is ±0.5°C in the range of -10~+85°C. The accuracy of the DS1822 is ±2°C. The on-site temperature is directly transmitted digitally via the "專線巴士", which greatly improves the system's anti-interference capability. Suitable for on-site temperature measurement in harsh environments, such as environmental control, equipment or process control, temperature measurement consumer electronics, ETC. The new product supports a voltage range of 3V~5.5V, making system design more flexible and convenient. And the new generation of products is cheaper and smaller. Features of DS18B20 and DS1822 DS18B20 can be programmed with a resolution of 9~12 bits and an accuracy of ±0.5°C. Optional smaller package, wider voltage range. The resolution setting and the user-set alarm temperature are stored in EEPROM and are still saved after power off. The performance of DS18B20 is the best among the new generation products! The price-performance ratio is also excellent! The DS1822 is software compatible with the DS18B20 and is a simplified version of the DS18B20. The EEPROM that stores user-defined alarm temperature and resolution parameters is omitted, and the accuracy is reduced to ±2°C. It is suitable for applications with low performance requirements and strict cost control. It is an economical product. Following the early products of the "One Line Bus", the DS1820 opens up a new concept in temperature sensor technology. DS18B20 and DS1822 provide more choices in voltage, characteristics and packaging, allowing us to build an economical temperature measurement system that suits us.

Internal structure of ds18b20 temperature probe
The internal structure of DS18B20 mainly consists of four parts:
64-位光刻ROM, 溫度感應器, non-volatile temperature alarm trigger TH and TL, configuration register.
The pin arrangement of DS18B20 is as follows
DQ為數位訊號輸入/輸出端; GND是電源地; VDD is the external power supply input terminal (寄生電源接線方式接地).
The 64-bit serial number in the photo etched ROM is photo etched before leaving the factory. 可以看作是DS18B20的位址序碼. 64位元光刻ROM的排列是: 首先 8 位元 (28H) 是產品型號, the next 48 位元是DS18B20本身的序號, and the last 8 bits are the previous 56-bit cyclic redundancy check code (CRC=X8 +X5+X4+1). The purpose of the photolithography ROM is to make each DS18B20 different, 這樣多個 DS18B20 就可以連接到一條總線上.
DS18B20中的溫度感測器可以完成溫度的測量. 以12位轉換為例: it is provided in the form of a 16-bit sign-extended two's complement reading, 以0.0625°C/LSB的形式表示, 其中 S 是符號位.
這是12位元轉換後得到的12位元數據, 儲存在兩個18B20的8位元RAM中. 首先 5 bits in binary are sign bits if the measured temperature is greater than 0. 這些 5 位元是 0. 只需將測量值乘以 0.0625 取得實際溫度. 如果溫度低於 0, 這些 5 位元是 1, 並且需要將測量值取反, 加 1, 然後乘以 0.0625 取得實際溫度.
例如, +125℃數位輸出為07D0H, +25.0625℃數位輸出為0191H, -25.0625℃數位輸出為FE6FH, -55℃數位輸出為FC90H.