Read single DS1820 temperature sensor.

arduino_ds1820.ino

//
//  http://playground.arduino.cc/Learning/OneWire
//

#include <OneWire.h>

#define ONEWIRE_PIN  2

OneWire ds(ONEWIRE_PIN);

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

void loop()
{
  byte data[12];

  ds.reset();
  ds.write(0xCC);  // skip ROM
  ds.write(0x44);  // start conversion

  delay(1000);

  ds.reset();
  ds.write(0xCC);  // skip ROM
  ds.write(0xBE);  // Read Scratchpad

  for(byte i = 0; i < 9; i++) { data[i] = ds.read(); }
  if(OneWire::crc8(data, 8) != data[8]) { return; }
  
  int tr = (data[1] << 8) + data[0];
  Serial.print("t="); Serial.println(tr*0.0625);
  
  delay(1000);
}

//.