Student ID : 201710319 NAME: MengYang
一、 DESCRIPTION：
DS18B20 is a first-line digital temperature sensor produced by Dallas company. The DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20 communicates over a 1-Wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor. It has an operating temperature range of -55°C to +125°C and is accurate to ±0.5°C over the range of -10°C to +85°C. In addition, the DS18B20 can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply. 二、 FEATURES:
1. Can Be Powered from Data Line; Power Supply Range is 3.0V to
5.5V.
2. Measures Temperatures from -55°C to +125°C (-67°F to +257°F) 3. ±0.5°C Accuracy from -10°C to +85°C.
4. Thermometer Resolution is User Selectable from 9 to 12 Bits. 5. Converts Temperature to 12-Bit Digital Word in 750ms (Max). 6. Each Device has a Unique -Bit Serial Code Stored in an On-Board
ROM
7. Another feature of the DS18B20 is the ability to operate without an
external power supply. Power is instead supplied through the 1-Wire pullup resistor via the DQ pin when the bus is high. The high bus signal also charges an internal capacitor (CPP), which then supplies power to the device when the bus is low. 三、 Application scope:
The product is suitable for temperature measurement and control fields such as freezer, granary, storage tank, telecommunication room, power room, cable trough, etc. 四、 Wiring method
Facing the flat side, the left side is negative and the right side is positive. If it is reversed, it will immediately heat up and may burn! At the same time, the reverse connection is also the reason why the sensor always displays 85 ℃. In the actual operation, the positive and negative will be reversed, the sensor will immediately heat up, the LCD screen can
not display the reading, after the positive and negative are connected, the display will be 85 ℃. In addition, if 51 single chip microcomputer is used, then the middle pin must be connected with a 4.7k-10k pull-up resistor, otherwise, because the high level cannot be normally input / output, either 85 ℃ will be displayed immediately after power on, or the temperature will jump on the normal value at 85 ℃ after several months.
