thermometer3.c

// Include the libraries we need
#include <OneWire.h>
#include <DallasTemperature.h>
#include <Ticker.h>

Ticker temperatureTicker;

// Data wire is plugged into port 2 on the Arduino
#define ONE_WIRE_BUS D2

// Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
OneWire oneWire(ONE_WIRE_BUS);

// Pass our oneWire reference to Dallas Temperature. 
DallasTemperature sensors(&oneWire);

// arrays to hold device address
DeviceAddress insideThermometer;

//parameters
#define SAMPLES 30
//arrays to hold temperature time series
float data[2][SAMPLES];
int dataSetBeingWritten = 0;
int dataWriteIndex = 0;

void getTemp()
{
  sensors.requestTemperatures();
  data[dataSetBeingWritten][dataWriteIndex] = sensors.getTempF(insideThermometer);
  dataWriteIndex++;
  if (dataWriteIndex == SAMPLES) {
    dataWriteIndex = 0; dataSetBeingWritten = 1 - dataSetBeingWritten;
    float sum_x = 0;
    float sum_x2 = 0;
    float sum_y = 0;
    float sum_xy = 0;
    for (int i=0; i<SAMPLES; i++) {
      sum_x += i;
      sum_x2 += i * i;
      sum_y += data[1-dataSetBeingWritten][i];
      sum_xy += i * data[1-dataSetBeingWritten][i];
    }
    float mean_x = sum_x/SAMPLES;
    float mean_x2 = sum_x2/SAMPLES;
    float mean_y = sum_y/SAMPLES;
    float mean_xy = sum_xy/SAMPLES;
    float m = (mean_x * mean_y - mean_xy) / (mean_x * mean_x - mean_x2);
    
    Serial.print("Slope = ");
    Serial.print(m, 3);
    Serial.print("    C = ");
    Serial.print(data[1-dataSetBeingWritten][0], 3);
    Serial.print("    CurrentTemp = ");
    Serial.println(data[1-dataSetBeingWritten][SAMPLES - 1], 3);
  }
}

void setup(void)
{
  // start serial port
  Serial.begin(9600);

  // locate devices on the bus
  Serial.print("Locating devices...");
  sensors.begin();
  Serial.print("Found ");
  Serial.print(sensors.getDeviceCount(), DEC);
  Serial.println(" devices.");

  // report parasite power requirements
  Serial.print("Parasite power is: "); 
  if (sensors.isParasitePowerMode()) Serial.println("ON");
  else Serial.println("OFF");
  
  // Assign address manually. The addresses below will beed to be changed
  // to valid device addresses on your bus. Device address can be retrieved
  // by using either oneWire.search(deviceAddress) or individually via
  // sensors.getAddress(deviceAddress, index)
  // Note that you will need to use your specific address here
  //insideThermometer = { 0x28, 0x1D, 0x39, 0x31, 0x2, 0x0, 0x0, 0xF0 };

  // Method 1:
  // Search for devices on the bus and assign based on an index. Ideally,
  // you would do this to initially discover addresses on the bus and then 
  // use those addresses and manually assign them (see above) once you know 
  // the devices on your bus (and assuming they don't change).
  if (!sensors.getAddress(insideThermometer, 0)) Serial.println("Unable to find address for Device 0"); 
  
  // method 2: search()
  // search() looks for the next device. Returns 1 if a new address has been
  // returned. A zero might mean that the bus is shorted, there are no devices, 
  // or you have already retrieved all of them. It might be a good idea to 
  // check the CRC to make sure you didn't get garbage. The order is 
  // deterministic. You will always get the same devices in the same order
  //
  // Must be called before search()
  //oneWire.reset_search();
  // assigns the first address found to insideThermometer
  //if (!oneWire.search(insideThermometer)) Serial.println("Unable to find address for insideThermometer");

  // show the addresses we found on the bus
  Serial.print("Device 0 Address: ");
  printAddress(insideThermometer);
  Serial.println();

  // set the resolution to 9 bit (Each Dallas/Maxim device is capable of several different resolutions)
  sensors.setResolution(insideThermometer, 12);
 
  Serial.print("Device 0 Resolution: ");
  Serial.print(sensors.getResolution(insideThermometer), DEC); 
  Serial.println();

  temperatureTicker.attach(1, getTemp);  
}

void loop(void)
{ 
}

// function to print a device address
void printAddress(DeviceAddress deviceAddress)
{
  for (uint8_t i = 0; i < 8; i++)
  {
    if (deviceAddress[i] < 16) Serial.print("0");
    Serial.print(deviceAddress[i], HEX);
  }
}