Arduino: read temperature and write the data in a json object

temp2json

#include <OneWire.h>

//2012-01-12: Jie Bao adapt from below
// read data stream and write to json

// OneWire DS18S20, DS18B20, DS1822 Temperature Example
//
// http://www.pjrc.com/teensy/td_libs_OneWire.html
//
// The DallasTemperature library can do all this work for you!
// http://milesburton.com/Dallas_Temperature_Control_Library

OneWire  ds(10);  // on pin 10

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

void loop(void) {
  byte i;
  byte present = 0;
  byte type_s;
  byte data[12];
  byte addr[8];
  float celsius, fahrenheit;
  
  if ( !ds.search(addr)) {
    //Serial.println("No more addresses.");
    //Serial.println();
    ds.reset_search();
    delay(250);
    return;
  }
   Serial.println('{');

  
/*  
  Serial.print("ROM =");
  for( i = 0; i < 8; i++) {
    Serial.write(' ');
    Serial.print(addr[i], HEX);
  }
*/
  if (OneWire::crc8(addr, 7) != addr[7]) {
      Serial.println("\"error\" : \"CRC is not valid\"");
      return;
  }
  Serial.println();
  
  // the first ROM byte indicates which chip
  switch (addr[0]) {
    case 0x10:
      Serial.println("  \"chip\" : \"DS18S20\"");  // or old DS1820
      type_s = 1;
      break;
    case 0x28:
      Serial.println("  \"chip\" : \"DS18B20\"");
      type_s = 0;
      break;
    case 0x22:
      Serial.println("  \"chip\" : \"DS1822\"");
      type_s = 0;
      break;
    default:
      Serial.println("\"error\" : \"Device is not a DS18x20 family device.\"");
      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("  \"Data\" : \"");
  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.println("\"");
  //Serial.print(" CRC=");
  //Serial.print(OneWire::crc8(data, 8), HEX);
  //Serial.println();

  // convert the data to actual temperature

  unsigned int raw = (data[1] << 8) | data[0];
  if (type_s) {
    raw = raw << 3; // 9 bit resolution default
    if (data[7] == 0x10) {
      // count remain gives full 12 bit resolution
      raw = (raw & 0xFFF0) + 12 - data[6];
    }
  } else {
    byte cfg = (data[4] & 0x60);
    if (cfg == 0x00) raw = raw << 3;  // 9 bit resolution, 93.75 ms
    else if (cfg == 0x20) raw = raw << 2; // 10 bit res, 187.5 ms
    else if (cfg == 0x40) raw = raw << 1; // 11 bit res, 375 ms
    // default is 12 bit resolution, 750 ms conversion time
  }
  celsius = (float)raw / 16.0;
  fahrenheit = celsius * 1.8 + 32.0;
  Serial.print("  \"celsius\" : ");
  Serial.println(celsius);
  Serial.print("  \"fahrenheit\" : ");
  Serial.println(fahrenheit);
  Serial.println("}");
}