DS18B20数字温度计技术详解：1-Wire接口与典型应用

DS18B20

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DS18B20技术文档详细介绍了这款独有的一线（1-Wire）接口温度传感器，它在现代电子系统中的应用具有显著优势。该设备的主要特点包括： 1. 接口简化：DS18B20仅需一个引脚（DQ）进行通信，这极大地节省了硬件资源，使得在分布式温度监控系统中实现多点连接变得简单易行。 2. 无外部组件需求：该传感器内置所有必要功能，无需额外添加电阻器、电容器或其他外部元件，提高了设计的简洁性和可靠性。 3. 电源灵活性：DS18B20可以从数据线上获取电源，工作电压范围为3.0V至5.5V，这意味着它可以适应多种电源条件，且在休眠状态下几乎不消耗电流，有助于节能。 4. 宽温范围：温度测量范围覆盖-55°C到+125°C，相当于-67°F至+257°F，适用于各种环境下的温度监控，如家用、工业和科研设备。 5. 高精度：在-10°C至+85°C的温度区间内，提供±0.5°C的准确度，确保测量结果的精确性。 6. 可编程分辨率：用户可以根据需求设置温度分辨率，从9位到12位，这增加了数据的精细化程度。 7. 快速转换：12位温度数据转换成数字信号的速度最快可达750毫秒，提高了数据采集的实时性。 8. 自定义报警设置：允许用户设置非易失性的温度警报阈值，当温度超出预设范围时，传感器会发送报警信号，方便系统进行相应处理。 9. 报警搜索功能：通过执行命令，可以搜索并定位那些温度超出设定范围（温度报警条件）的设备，增强了系统的智能化管理。 10. 广泛应用领域：DS18B20适用于各种场景，如家庭自动控制、工业自动化设备、消费电子产品、实验室温度计以及任何对温度敏感的系统。在实际应用中，为了正确使用DS18B20，需要了解引脚分配，例如GND（接地）、DQ（数据输入/输出）和VDD（电源供应）。根据这些信息，设计者可以构建完整的电路，并通过编写相应的软件程序来读取、解析和响应温度变化。通过结合这些特性，DS18B20成为了许多温控项目中的理想选择，提供了高效、精确和经济的解决方案。

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DS18B20

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OPERATION - MEASURING TEMPERATURE

The core functionality of the DS18B20 is its direct-to-digital temperature sensor. The resolution of the

DS18B20 is configurable (9, 10, 11, or 12 bits), with 12-bit readings the factory default state. This

equates to a temperature resolution of 0.5°C, 0.25°C, 0.125°C, or 0.0625°C. Following the issuance of

the Convert T [44h] command, a temperature conversion is performed and the thermal data is stored in

the scratchpad memory in a 16-bit, sign-extended two’s complement format. The temperature

information can be retrieved over the 1-Wire™ interface by issuing a Read Scratchpad [BEh] command

once the conversion has been performed. The data is transferred over the 1-Wire™ bus, LSB first. The

MSB of the temperature register contains the “sign” (S) bit, denoting whether the temperature is positive

or negative.

Table 2 describes the exact relationship of output data to measured temperature. The table assumes 12-bit

resolution. If the DS18B20 is configured for a lower resolution, insignificant bits will contain zeros. For

Fahrenheit usage, a lookup table or conversion routine must be used.

Temperature/Data Relationships Table 2

-1

-2

-3

-4

LSB

MSb

(unit = °C)

LSb

SSSSS2

MSB

TEMPERATURE DIGITAL OUTPUT

(Binary)

DIGITAL

OUTPUT

(Hex)

+125°C 0000 0111 1101 0000 07D0h

+85°C 0000 0101 0101 0000 0550h*

+25.0625°C 0000 0001 1001 0001 0191h

+10.125°C 0000 0000 1010 0010 00A2h

+0.5°C 0000 0000 0000 1000 0008h

0°C 0000 0000 0000 0000 0000h

-0.5°C 1111 1111 1111 1000 FFF8h

-10.125°C 1111 1111 0101 1110 FF5Eh

-25.0625°C 1111 1110 0110 1111 FF6Fh

-55°C 1111 1100 1001 0000 FC90h

*The power on reset register value is +85°C.

OPERATION - ALARM SIGNALING

After the DS18B20 has performed a temperature conversion, the temperature value is compared to the

trigger values stored in TH and TL. Since these registers are 8-bit only, bits 9-12 are ignored for

comparison. The most significant bit of TH or TL directly corresponds to the sign bit of the 16-bit

temperature register. If the result of a temperature measurement is higher than TH or lower than TL, an

alarm flag inside the device is set. This flag is updated with every temperature measurement. As long as

the alarm flag is set, the DS18B20 will respond to the alarm search command. This allows many

DS18B20s to be connected in parallel doing simultaneous temperature measurements. If somewhere the

temperature exceeds the limits, the alarming device(s) can be identified and read immediately without

having to read non-alarming devices.

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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 eighth 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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DS18B20数字温度计技术详解：1-Wire接口与典型应用

DS18B20代码51单片机代码

DS18B20.C和ds18b20.h怎么写

解释代码。void DS18B20_Start(void) { DS18B20_Rst(); DS18B20_Check(); DS18B20_Write_Byte(0xcc); DS18B20_Write_Byte(0xee); }

DS18B20.H和DS18B20.C是什么

用stm32f10x.h去写ds18b20.h和ds18b20.c的程序

stm32f10x.h编写ds18b20.c和ds18b20.h

DS18B20 模块驱动程序

void Ds18b20Write(unsigned char infor) { unsigned int i; Ds18b20OutputInitial(); for(i=0;i<8;i++) { if((infor & 0x01)) { Ds18b20IO = 0; Ds18b20Delay(6); Ds18b20IO = 1; Ds18b20Delay(50); } else { Ds18b20IO = 0; Ds18b20Delay(50); Ds18b20IO = 1; Ds18b20Delay(6); } infor >>= 1; } }

ds18b20的头文件

#ifndef __DS18B20_H__ #define __DS18B20_H__ void DS18B20_ConvertT(void); float DS18B20_ReadT(void); #endif

DS18B20代码流程

ds18b20.h内容

ds18b20校验代码

ds18b20c语言代码

最新资源

#ifndef __DS18B20_H #define DS18B20_H__ void DS18B20_ConvertT(void); float DS18B20_ReadT(void); #endif