DS18B20数字温度传感器技术规格

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"DS18B20是一款数字温度传感器，由 Dallas Semiconductor（现Maxim Integrated）制造。该器件以其独特的1-Wire接口而闻名，仅需一条数据线就能实现通信，简化了分布式温度传感应用的设计。它不需要外部组件，可以从数据线上获取电源，供电范围在3.0V至5.5V之间，且在待机状态下不消耗功率。" DS18B20的主要特性包括： 1. **1-Wire接口**：这种接口允许一个主机与多个DS18B20设备通过单个数据线进行通信，显著减少了硬件需求。 2. **多滴功能**：支持多设备连接，使得在同一个系统中可以部署多个DS18B20来监控不同位置的温度。 3. **无需外部组件**：DS18B20内置所有必要的电路，简化了系统集成。 4. **电源管理**：可以从数据线直接取电，电源电压范围宽泛，适应性强。 5. **零待机功耗**：在非工作状态时，DS18B20几乎不消耗电力。 6. **温度范围**：可测量-55°C到+125°C的温度，相当于-67°F到+257°F，适用于宽温环境。 7. **精度**：在-10°C到+85°C范围内具有±0.5°C的高精度。 8. **分辨率**：用户可编程设置温度计的分辨率，从9位到12位不等，提供更多灵活性。 9. **快速转换**：能够在750毫秒内将12位温度值转换为数字信号。 10. **温度报警**：用户可以设定非易失性温度报警阈值，当温度超出设定范围时，设备会响应特定的命令。 11. **报警搜索命令**：通过此命令，可以快速识别并定位那些处于温度报警状态的设备。 DS18B20的应用非常广泛，包括但不限于： - **恒温控制系统**：如空调、暖气系统的温度控制。 - **工业系统**：如过程控制、环境监测等。 - **消费产品**：例如智能家电、电子设备的热管理。 - **各类温度计**：如室内/室外温度计、食品储存监控等。 - **任何对温度敏感的系统**：如实验室设备、数据中心的冷却系统等。在硬件布局上，DS18B20有三个引脚： - **GND**：接地。 - **DQ**：数据输入/输出，用于1-Wire通信。 - **VDD**：电源输入，提供工作电压。 - **NC**：无连接，不使用的引脚。 DS18B20是一种功能强大、易于使用的数字温度传感器，适合各种需要精确温度测量的场合。

DS18B20

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64-BIT LASERED ROM

Each DS18B20 contains a unique ROM code that is 64-bits long. The first 8 bits are a 1-Wire family

code (DS18B20 code is 28h). The next 48 bits are a unique serial number. The last 8 bits are a CRC of

the first 56 bits. (See Figure 4.) The 64-bit ROM and ROM Function Control section allow the DS18B20

to operate as a 1-Wire device and follow the 1-Wire protocol detailed in the section “1-Wire Bus

System.” The functions required to control sections of the DS18B20 are not accessible until the ROM

function protocol has been satisfied. This protocol is described in the ROM function protocol flowchart

(Figure 5). The 1-Wire bus master must first provide one of five ROM function commands: 1) Read

ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM, or 5) Alarm Search. After a ROM function

sequence has been successfully executed, the functions specific to the DS18B20 are accessible and the

bus master may then provide one of the six memory and control function commands.

CRC GENERATION

The DS18B20 has an 8-bit CRC stored in the most significant byte of the 64-bit ROM. The bus master

can compute a CRC value from the first 56-bits of the 64-bit ROM and compare it to the value stored

within the DS18B20 to determine if the ROM data has been received error-free by the bus master. The

equivalent polynomial function of this CRC is:

CRC = X

+ X

+ 1

The DS18B20 also generates an 8-bit CRC value using the same polynomial function shown above and

provides this value to the bus master to validate the transfer of data bytes. In each case where a CRC is

used for data transfer validation, the bus master must calculate a CRC value using the polynomial

function given above and compare the calculated value to either the 8-bit CRC value stored in the 64-bit

ROM portion of the DS18B20 (for ROM reads) or the 8-bit CRC value computed within the DS18B20

(which is read as a ninth byte when the scratchpad is read). The comparison of CRC values and decision

to continue with an operation are determined entirely by the bus master. There is no circuitry inside the

DS18B20 that prevents a command sequence from proceeding if the CRC stored in or calculated by the

DS18B20 does not match the value generated by the bus master.

The 1-Wire CRC can be generated using a polynomial generator consisting of a shift register and XOR

gates as shown in Figure 6. Additional information about the Dallas 1-Wire Cyclic Redundancy Check is

available in Application Note 27 entitled “Understanding and Using Cyclic Redundancy Checks with

Dallas Semiconductor Touch Memory Products.”

The shift register bits are initialized to 0. Then starting with the least significant bit of the family code,

1 bit at a time is shifted in. After the 8th bit of the family code has been entered, then the serial number is

entered. After the 48

bit of the serial number has been entered, the shift register contains the CRC

value. Shifting in the 8 bits of CRC should return the shift register to all 0s.

64-BIT LASERED ROM Figure 4

8-BIT CRC CODE 48-BIT SERIAL NUMBER

8-BIT FAMILY CODE

(28h)

MSB LSB MSB LSB MSB LSB

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