DS18b20 Temperature Sensor Module

Introduction:

These 3-wire digital temperature sensors are fairly precise (±0.5°C over much of the range) and can give up to 12 bits of precision from the onboard digital-to-analog converter. They work great with any microcontroller using a single digital pin, and you can even connect multiple ones to the same pin, each one has a unique 64-bit ID burned in at the factory to differentiate them. Usable with 3.0-5.0V systems.

Technical Details:

Technical specs:

• Usable temperature range: -5° to 90°C (-23°F to +194°F)
• 9 to 12 bit selectable resolution
• Uses 1-Wire interface- requires only one digital pin for communication
• Unique 64 bit ID burned into chip
• Multiple sensors can share one pin
• ±0.5°C Accuracy from -10°C to +85°C
• Temperature-limit alarm system
• Query time is less than 750ms
• Usable with 3.0V to 5.5V power/data

Example of Use:

Materials:

• DS18b20 Temperature Sensor Module
• 3 - Jumper Wire

Wiring Instructions:

    Wire the pin labeled "S" to pin 11, "--" to pin GROUND, and the middle pin to the 5V pin.

Sketch Instructions:

    After copying and uploading this code your DS18b20 module should display the temperature in Celsius and Fahrenheit . You can check your temperature valor in the serial monitor.

        

Sketch Code

#include <OneWire.h>

/* DS18S20 Temperature chip i/o

 */

OneWire  ds(10);  // on pin 10

void setup(void) {
  // initialize inputs/outputs
  // start serial port
  Serial.begin(9600);
}



void loop(void) {
  byte i;
  byte present = 0;
  byte data[12];
  byte addr[8];
  
  if ( !ds.search(addr)) {
      //Serial.print("No more addresses.\n");
      ds.reset_search();
      return;
  }
  
  Serial.print("R=");  //R=28 Not sure what this is
  for( i = 0; i < 8; i++) {
    Serial.print(addr[i], HEX);
    Serial.print(" ");
  }

  if ( OneWire::crc8( addr, 7) != addr[7]) {
      Serial.print("CRC is not valid!\n");
      return;
  }
  
  if ( addr[0] != 0x28) {
      Serial.print("Device is not a DS18S20 family device.\n");
      return;
  }

  ds.reset();
  ds.select(addr);
  ds.write(0x44,1);         // start conversion, with parasite power on at the end
  
  delay(1000);     // maybe 750ms is enough, maybe not
  // we might do a ds.depower() here, but the reset will take care of it.
  
  present = ds.reset();
  ds.select(addr);    
  ds.write(0xBE);         // Read Scratchpad

  Serial.print("P=");  
  Serial.print(present,HEX);
  Serial.print(" ");
  for ( i = 0; i < 9; i++) {           // we need 9 bytes
    data[i] = ds.read();
    Serial.print(data[i], HEX);
    Serial.print(" ");
  }

  Serial.print(" CRC=");
  Serial.print( OneWire::crc8( data, 8), HEX);
  Serial.println();
}