防水水温DS18B20仅返回-127摄氏度

如何解决防水水温DS18B20仅返回-127摄氏度

对于大学中的一个项目，我必须测量各种水质，包括温度。温度传感器是DS18B20，我使用Arduino Mega板进行了整个展示。与DS18B20一起运行的个人只能返回任何有意义的数字。而不是25C（或类似的温度），它返回-127。

下面的代码来自达拉斯温度（变化很小，例如有延迟和删除一些注释行）

// Include the libraries we need
#include <OneWire.h>
#include <DallasTemperature.h>

// Data wire is plugged into port 2 on the Arduino
#define ONE_WIRE_BUS 48

// 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);


void setup(void)
{
  // start serial port
  Serial.begin(9600);
  Serial.println("Dallas Temperature IC Control Library Demo");

  // Start up the library
  sensors.begin();
}

void loop(void)
{ 
  delay(500);
  sensors.requestTemperatures(); // Send the command to get temperatures
  Serial.println("DONE");
  Serial.print("Temperature for the device 1 (index 0) is: ");
  Serial.println(sensors.getTempCByIndex(0));  
  delay(2500);
}

这实际上是来自Wiki page of DFRobot（我的传感器的来源）

#include <OneWire.h>

int DS18S20_Pin = 48; //DS18S20 Signal pin on digital 48

//Temperature chip i/o
OneWire ds(DS18S20_Pin);  // on digital pin 48

void setup(void) {
  Serial.begin(9600);
}

void loop(void) {
  float temperature = getTemp();
  Serial.println(temperature);

  delay(100); //just here to slow down the output so it is easier to read
}

float getTemp(){
  //returns the temperature from one DS18S20 in DEG Celsius

  byte data[12];
  byte addr[8];

  if ( !ds.search(addr)) {
      //no more sensors on chain,reset search
      ds.reset_search();
      return -1000;
  }

  if ( OneWire::crc8( addr,7) != addr[7]) {
      Serial.println("CRC is not valid!");
      return -1000;
  }

  if ( addr[0] != 0x10 && addr[0] != 0x28) {
      Serial.print("Device is not recognized");
      return -1000;
  }

  ds.reset();
  ds.select(addr);
  ds.write(0x44,1); // start conversion,with parasite power on at the end

  byte present = ds.reset();
  ds.select(addr);
  ds.write(0xBE); // Read Scratchpad


  for (int i = 0; i < 9;  i++  ) { // we need 9 bytes
    data[i] = ds.read();
  }

  ds.reset_search();

  byte MSB = data[1];
  byte LSB = data[0];

  float tempRead = ((MSB << 8) | LSB); //using two's compliment
  float TemperatureSum = tempRead / 16;

  return TemperatureSum;

}

此特定代码每次都会返回-1000，我认为是与上面的-127等价。

解决方法

来自图书馆：

// Error Codes
#define DEVICE_DISCONNECTED_C -127

https://github.com/milesburton/Arduino-Temperature-Control-Library/blob/b34be08d603242bb534e7b717dac48baf60c5113/DallasTemperature.h#L36

因此您的设备未连接/未通信。检查您的接线和引脚号。