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Built-in project · Arduino Uno R3

DS18B20 temperature sensor on pin 2, on an Arduino Uno

A DS18B20 on pin 2, with a 4.7k pull-up on its data line, measures the temperature over one wire; the Dallas library reads it once a second. The whole build, an Arduino Uno and 1 more part, runs here in your browser on the firmware below; open it in the editor to change the wiring or the code and run it again.

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The parts retail for about $32. On Mokxi they're free.

DS18B20 temperature sensor on pin 2 · Arduino Uno R3live0.000 s 0.00x
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The circuit itself, running here on the simulator. Press what can be pressed; click anything else to open it in the editor.

The code

The firmware exactly as the editor opens it. Change a line there and press Run: it compiles in the browser.

sketch.ino · Arduino Uno R3
// A DS18B20 on one wire: pin 2.
//
//   DS18B20 DQ -> pin 2 (4.7k from DQ to 5V)   VDD -> 5V   GND -> GND
//
// The sensor sends its reading as a string of time slots on a single wire.
// OneWire times them; DallasTemperature asks for a conversion and reads the
// answer back in degrees.
//
// Drag the sensor's temperature.

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

OneWire bus(2);
DallasTemperature sensors(&bus);

void setup() {
  Serial.begin(9600);
  sensors.begin();
  Serial.println("Mokxi Uno: DS18B20 on pin 2");
}

void loop() {
  sensors.requestTemperatures();
  Serial.print(sensors.getTempCByIndex(0));
  Serial.println(" C");
  delay(1000);
}

Parts list

3 parts, plus the jumper wires. They retail for about $32; on Mokxi they're free.

How it is wired

3 connections, pin by pin, read from the circuit itself. Each line is one set of pins joined together, by a jumper wire or a breadboard strip.

  • Ground: Arduino Uno R3 pin GND; Temperature sensor, DS18B20 pin GND
  • Arduino Uno R3 pin 2; Temperature sensor, DS18B20 pin DQ
  • Arduino Uno R3 pin 5V; Temperature sensor, DS18B20 pin VDD

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