DS18B20單線數(shù)字溫度傳感器，“一線設備”具有獨特的優(yōu)點。

(1)使用單總線接口連接到微處理器時，只要有一個端口，微處理器和DS18B20之間就可以雙向通信。

單總線具有經(jīng)濟性好，抗干擾能力強，適合于惡劣環(huán)境的現(xiàn)場溫度測量，使用方便等優(yōu)點，使用戶可輕松地組建傳感器網(wǎng)絡，為測量系統(tǒng)的構(gòu)建引入全新概念。

（ 2 ）測量溫度范圍寬，測量精度高 DS18B20 的測量范圍為 -55 ℃ ~+ 125 ℃ ； 在 -10~+ 85°C 范圍內(nèi)，精度為 ± 0.5°C 。

（ 3 ）持多點組網(wǎng)功能 多個 DS18B20 可以并聯(lián)在惟一的單線上，實現(xiàn)多點測溫。

（ 4）供電方式靈活 DS18B20 可以通過內(nèi)部寄生電路從數(shù)據(jù)線上獲取電源。因此，當數(shù)據(jù)線上的時序滿足一定的要求時，可以不接外部電源，從而 使系統(tǒng)結(jié)構(gòu)更趨簡單，可靠性更高。

（ 5 ）測量參數(shù)可配置 DS18B20 的測量分辨率可通過程序設定 9~12 位。

DS18B20 具有體積更小、適用電壓更寬、更經(jīng)濟、可選更小的封裝方式，更寬的電壓適用范圍，適合于構(gòu)建自己的經(jīng)濟的測溫系統(tǒng)，因此也就被設計者們所青睞。

產(chǎn)品封裝

時序圖

典型應用電路

寄生供電方式

支持命令集

復位時序

讀寫時序

具體操作：

1、打開IDE，項目-加載庫-管理庫，搜索下載安裝相應的庫，不然程序?qū)懞昧?，編譯時會報錯；

搜索 18B20 ，看到18B20相關(guān)的庫，點擊 安裝好，

打開 文件-示例，第三方庫剛安裝好的庫，找到第一個例子Alarm；

看到除了Dalla，還需要另一個庫OneWire.h，再按之前步驟，搜索 OneWire 安裝即可；ONE_WIRE_BUS 2 意思是 數(shù)據(jù)口連接開發(fā)版引腳pin 2；

2、Arduino 開發(fā)版用USB連接電腦，選擇對應的開發(fā)版和端口，編譯上傳燒錄，

3、接線，必須加電阻，不加電阻檢測不到設備；

管腳定義：面朝印字面，左為GND，右為VCC，中間為數(shù)字輸出引腳（須接上4.7K—10K的上拉電阻）本例4.7K電阻；

BOM表

Arduino Uno *1

18B20溫度傳感器 *1

4.7K電阻*1

接線

Arduino Uno <------> 18B20溫度傳感器 顏色

Pin 2 <------> DO 白色

5V <------> VCC 紅色

GND <------> GND 黃色

Arduino接線圖

4、接好線后，再用USB連接電腦，打開串口監(jiān)視器查看結(jié)果；

Alarm案例代碼，可根據(jù)需要自行修改：

#include <OneWire.h>//引用單總線頭文件

#include <Dalla>//引用18b20驅(qū)動文件

// Data wire is plugged into port 2 on the Arduino

#define ONE_WIRE_BUS 2//定義2腳為數(shù)據(jù)腳

// Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)

OneWire oneWire(ONE_WIRE_BUS);

// Pass our oneWire reference to Dallas Temperature.

DallasTemperature sensors(&oneWire);

// arrays to hold device addresses

DeviceAddress insideThermometer, outsideThermometer;

void setup(void)

{

// start serial port

Serial.begin(9600);

Serial.println("Dallas Temperature IC Control Library Demo");

// Start up the library

();//初始化器件

// locate devices on the bus

Serial.print("Found ");

Serial.prin(), DEC);//DEC的意思是串口數(shù)據(jù)以10進制的格式輸出

Serial.println(" devices.");

// search for devices on the bus and assign based on an index.

if (!(insideThermometer, 0))

Serial.println("Unable to find address for Device 0");

if (!(outsideThermometer, 1))

Serial.println("Unable to find address for Device 1");

// show the addresses we found on the bus

Serial.print("Device 0 Address: ");

printAddress(insideThermometer);

Serial.println();

Serial.print("Device 0 Alarms: ");

printAlarms(insideThermometer);

Serial.println();

Serial.print("Device 1 Address: ");

printAddress(outsideThermometer);

Serial.println();

Serial.print("Device 1 Alarms: ");

printAlarms(outsideThermometer);

Serial.println();

Serial.println("Setting alarm temps...");

// alarm when temp is higher than 30C

(insideThermometer, 30);

// alarm when temp is lower than -10C

(insideThermometer, -10);

// alarm when temp is higher than 31C

(outsideThermometer, 31);

// alarn when temp is lower than 27C

(outsideThermometer, 27);

Serial.print("New Device 0 Alarms: ");

printAlarms(insideThermometer);

Serial.println();

Serial.print("New Device 1 Alarms: ");

printAlarms(outsideThermometer);

Serial.println();

}

// function to print a device address

void printAddress(DeviceAddress deviceAddress)

{

for (uint8_t i = 0; i < 8; i++)

{

if (deviceAddress[i] < 16) Serial.print("0");

Serial.print(deviceAddress[i], HEX);

}

}

// function to print the temperature for a device

void printTemperature(DeviceAddress deviceAddress)

{

float tempC = (deviceAddress);

Serial.print("Temp C: ");

Serial.print(tempC);

Serial.print(" Temp F: ");

Serial.print(DallasTemperature::toFahrenheit(tempC));

}

void printAlarms(uint8_t deviceAddress[])

{

char temp;

temp = (deviceAddress);

Serial.print("High Alarm: ");

Serial.print(temp, DEC);

Serial.print("C/");

Serial.print(DallasTemperature::toFahrenheit(temp));

Serial.print("F | Low Alarm: ");

temp = (deviceAddress);

Serial.print(temp, DEC);

Serial.print("C/");

Serial.print(DallasTemperature::toFahrenheit(temp));

Serial.print("F");

}

// main function to print information about a device

void printData(DeviceAddress deviceAddress)

{

Serial.print("Device Address: ");

printAddress(deviceAddress);

Serial.print(" ");

printTemperature(deviceAddress);

Serial.println();

}

void checkAlarm(DeviceAddress deviceAddress)

{

if (deviceAddress))

{

Serial.print("ALARM: ");

printData(deviceAddress);

}

}

void loop(void)

{

// call () to issue a global temperature

// request to all devices on the bus

Serial.print("Requesting temperatures...");

();

Serial.println("DONE");

// Method 1:

// check each address individually for an alarm condition

checkAlarm(insideThermometer);

checkAlarm(outsideThermometer);

/*

// Alternate method:

// Search the bus and iterate through addresses of devices with alarms

// space for the alarm device's address

DeviceAddress alarmAddr;

Serial.println("Searching for alarms...");

// resetAlarmSearch() must be called before calling alarmSearch()

();

// alarmSearch() returns 0 when there are no devices with alarms

while (alarmAddr))

{

Serial.print("ALARM: ");

printData(alarmAddr);

}

*/

}