ds18b20为什么发烫 ds18b20接电阻是为什么

DS18B20单线数字温度传感器，“一线设备”具有独特的优点。

(1)使用单总线接口连接到微处理器时，只要有一个端口，微处理器和DS18B20之间就可以双向通信。

（ 2 ）测量温度范围宽，测量精度高 DS18B20 的测量范围为 -55 ℃ ~+ 125 ℃ ； 在 -10~+ 85°C 范围内，精度为 ± 0.5°C 。

（ 3 ）持多点组网功能 多个 DS18B20 可以并联在惟一的单线上，实现多点测温。

（ 4）供电方式灵活 DS18B20 可以通过内部寄生电路从数据线上获取电源。因此，当数据线上的时序满足一定的要求时，可以不接外部电源，从而 使系统结构更趋简单，可靠性更高。

（ 5 ）测量参数可配置 DS18B20 的测量分辨率可通过程序设定 9~12 位。

DS18B20 具有体积更小、适用电压更宽、更经济、可选更小的封装方式，更宽的电压适用范围，适合于构建自己的经济的测温系统，因此也就被设计者们所青睐。

产品封装

时序图

典型应用电路

寄生供电方式

支持命令集

复位时序

读写时序

具体操作：

1、打开IDE，项目-加载库-管理库，搜索下载安装相应的库，不然程序写好了，编译时会报错；

搜索 18B20 ，看到18B20相关的库，点击 安装好，

打开 文件-示例，第三方库刚安装好的库，找到第一个例子Alarm；

看到除了Dalla，还需要另一个库OneWire.h，再按之前步骤，搜索 OneWire 安装即可；ONE_WIRE_BUS 2 意思是 数据口连接开发版引脚pin 2；

2、Arduino 开发版用USB连接电脑，选择对应的开发版和端口，编译上传烧录，

3、接线，必须加电阻，不加电阻检测不到设备；

管脚定义：面朝印字面，左为GND，右为VCC，中间为数字输出引脚（须接上4.7K—10K的上拉电阻）本例4.7K电阻；

BOM表

Arduino Uno *1

18B20温度传感器 *1

4.7K电阻*1

接线

Arduino Uno <------> 18B20温度传感器 颜色

Pin 2 <------> DO 白色

5V <------> VCC 红色

GND <------> GND 黄色

Arduino接线图

4、接好线后，再用USB连接电脑，打开串口监视器查看结果；

Alarm案例代码，可根据需要自行修改：

#include <OneWire.h>//引用单总线头文件

#include <Dalla>//引用18b20驱动文件

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

#define ONE_WIRE_BUS 2//定义2脚为数据脚

// 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的意思是串口数据以10进制的格式输出

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);

}

*/

}