DS18B20

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Demo with arduino

DS18S20-arduino.png
#include <OneWire.h> 
 
int DS18S20_Pin = 2; //DS18S20 Signal pin on digital 2
 
//Temperature chip i/o
OneWire ds(DS18S20_Pin); // on digital pin 2
 
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;
 
}

Multiple Sensor

Ds18b20 mutiple-sensing.png
#include <OneWire.h>
#include <DallasTemperature.h>
 
#define ONE_WIRE_BUS 2    //define one wire bus port
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
 
void setup(void)
{
  Serial.begin(9600);
  Serial.println("Dallas Temperature IC Control Library Demo");
  sensors.begin();   //start the one wire bus line
}
 
void loop(void)
{
  Serial.print("Requesting temperatures...");
  sensors.requestTemperatures();   // send temperature read request
  Serial.println("DONE");
  Serial.print("Temperature for the device 1 (index 0) is: ");
  Serial.println(sensors.getTempCByIndex(0));  //request number 0 sensor data and send
Serial.print("Temperature for the device 2 (index 0) is: ");
  Serial.println(sensors.getTempCByIndex(1));  //request number 1 sensor data and send
}

Datasheet

DS18B20 Datasheet