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In my current project I am reading temperature through sensor which is having only two wires.

Temperature Sensor

To read sensor values, I have used below schematic which I have found on Arduino Project Hub site.

ds1820b connection

In my project I am using below Arduino program.

#include <OneWire.h>
#include <DallasTemperature.h>

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

// 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)
{
  // call sensors.requestTemperatures() to issue a global temperature
  // request to all devices on the bus
  Serial.print(" Requesting temperatures...");
  sensors.requestTemperatures(); // Send the command to get temperatures
  Serial.println("DONE");

  Serial.print("Temperature is: ");
  Serial.print(sensors.getTempCByIndex(0)); // Why "byIndex"? 
    // You can have more than one IC on the same bus. 
    // 0 refers to the first IC on the wire
    delay(1000);
}

After doing all this I am getting this output on serial monitor.

Result

At which step I am doing wrong?

  • 1
    Could you make a change to a 'schematic' to show your connection? How do you actually connect 2 wires? (Your current schematic has 3 connections between sensor and Arduino, and sensor on your picture has only 2 wires..) Are you aware of the fact that you want to use 'parasite power mode'? In this case you must provide strong pull-up for temperature conversion time. Take a look at datasheets.maximintegrated.com/en/ds/DS18B20.pdf page 11, 'Convert T [44h]' paragraph... – smajli Nov 13 '17 at 8:17
  • 2
    What type or name of the model is your temperature sensor.? It looks like you're trying to connect an analog sensor. But you use the connection schema and code for the digital sensor. – AltAir Nov 13 '17 at 8:26
  • Which model temperature sensor you using? If you using lm35 temperature sensor, Serial.print(sensors.getTempCByIndex(0)/9,31); you need add /9.31 to your code, sensors not directly measure the temperature sensors just have variable resistor inside, resistor value changes by temperature after then voltage changes the arduino just measure the voltage, the voltage value divide the 9.31 this result gives temperature Celcius type. Also you have to unplug 4.7 k resistor it needless. – Buturlin Nov 13 '17 at 8:31
  • Oh, indeed. karanrp: I have assumed you are using DS18B20. Check your sensor first. – smajli Nov 13 '17 at 8:35
  • That looks like a cheap thermocouple from a digital thermometer to me. You need a special chip to run it. – Majenko Nov 13 '17 at 11:09

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