By: Robert Kurkowski 

Brief Description:    This project is used to test the temperature, altitude, and pressure of an area. These variables are taken in by a Thermometer that tests for the temperature of a surface, and a barometer that measures the altitude and the pressure.  This data is then stred on a memory card.

Detailed Description:  This project takes in the information of the barometer and the infrared thermometer and stored it on a memory card which is located in a log shield.  The temperature, pressure, date, time, and altitude are taken and calculated by the arduino using an I2C master library(calculates the pressure, altitude, and temperature) and a RTClip library(calculated date and time). Once the variables have been calculated and stored the memory card is taken out of the shield and placed into a computer where we can view the files as a spreadsheet.

My Code:

Text Box

#include <i2cmaster.h>

//Arduino 1.0+ Only
//Arduino 1.0+ Only

/*Based largely on code by  Jim Lindblom
//Made by Robert Kurkowski 

 Get pressure, altitude, and temperature from the BMP085.
 Serial.print it out at 9600 baud to serial monitor.

#include <Wire.h>
#include <SD.h>
#include "RTClib.h"

// A simple data logger for the Arduino analog pins

// how many milliseconds between grabbing data and logging it. 1000 ms is once a second
#define LOG_INTERVAL  1000 // mills between entries (reduce to take more/faster data)

// how many milliseconds before writing the logged data permanently to disk
// set it to the LOG_INTERVAL to write each time (safest)
// set it to 10*LOG_INTERVAL to write all data every 10 datareads, you could lose up to 
// the last 10 reads if power is lost but it uses less power and is much faster!
#define SYNC_INTERVAL 1000 // mills between calls to flush() - to write data to the card
uint32_t syncTime = 0; // time of last sync()

#define ECHO_TO_SERIAL   1 // echo data to serial port
#define WAIT_TO_START    0 // Wait for serial input in setup()

// the digital pins that connect to the LEDs
#define redLEDpin 2
#define greenLEDpin 3

// The analog pins that connect to the sensors

#define BMP085_ADDRESS 0x77  // I2C address of BMP085

const unsigned char OSS = 0;  // Oversampling Setting
#define IRthermometer
#define BANDGAPREF 14            // special indicator that we want to measure the bandgap
#define aref_voltage 3.3         // we tie 3.3V to ARef and measure it with a multimeter!
#define bandgap_voltage 1.1      // this is not super guaranteed but its not -too- off

RTC_DS1307 RTC; // define the Real Time Clock object

// for the data logging shield, we use digital pin 10 for the SD cs line
const int chipSelect = 10;
float celcius;
float pressure;
// the logging file
File logfile;

void error(char *str)
  Serial.print("error: ");
  // red LED indicates error
  digitalWrite(redLEDpin, HIGH);


// Calibration values
int ac1;
int ac2;
int ac3;
unsigned int ac4;
unsigned int ac5;
unsigned int ac6;
int b1;
int b2;
int mb;
int mc;
int md;

// b5 is calculated in bmp085GetTemperature(...), this variable is also used in bmp085GetPressure(...)
// so ...Temperature(...) must be called before ...Pressure(...).
long b5; 

void setup(){
  // use debugging LEDs
  pinMode(redLEDpin, OUTPUT);
  pinMode(greenLEDpin, OUTPUT);
  Serial.println("Type any character to start");
  while (!Serial.available());
#endif //WAIT_TO_START

  // initialize the SD card
  Serial.print("Initializing SD card...");
  // make sure that the default chip select pin is set to
  // output, even if you don't use it:
  pinMode(10, OUTPUT);
  // see if the card is present and can be initialized:
  if (!SD.begin(chipSelect)) {
    error("Card failed, or not present");
  Serial.println("card initialized.");
  // create a new file
  char filename[] = "LOGGER00.CSV";
  for (uint8_t i = 0; i < 100; i++) {
    filename[6] = i/10 + '0';
    filename[7] = i%10 + '0';
    if (! SD.exists(filename)) {
      // only open a new file if it doesn't exist
      logfile = SD.open(filename, FILE_WRITE); 
      break;  // leave the loop!
  if (! logfile) {
    error("couldnt create file");
  Serial.print("Logging to: ");

  // connect to RTC
  if (!RTC.begin()) {
    logfile.println("RTC failed");
    Serial.println("RTC failed");
#endif  //ECHO_TO_SERIAL

  // If you want to set the aref to something other than 5v

  i2c_init(); //Initialise the i2c bus
PORTC = (1 << PORTC4) | (1 << PORTC5);//enable pullups


void loop()
  DateTime now;

  // delay for the amount of time we want between readings
  delay((LOG_INTERVAL -1) - (millis() % LOG_INTERVAL));
  digitalWrite(greenLEDpin, HIGH);
  // log milliseconds since starting
  uint32_t m = millis();
  logfile.print(m);           // milliseconds since start
  logfile.print(", ");    
  Serial.print(m);         // milliseconds since start
  Serial.print(", ");  

  // fetch the time
  now = RTC.now();
  // log time
  logfile.print(now.unixtime()); // seconds since 1/1/1970
  logfile.print(", ");
  logfile.print(now.year(), DEC);
  logfile.print(now.month(), DEC);
  logfile.print(now.day(), DEC);
  logfile.print(" ");
  logfile.print(now.hour(), DEC);
  logfile.print(now.minute(), DEC);
  logfile.print(now.second(), DEC);
  logfile.print(", ");
  Serial.print(now.unixtime()); // seconds since 1/1/1970
  Serial.print(", ");
  Serial.print(now.year(), DEC);
  Serial.print(now.month(), DEC);
  Serial.print(now.day(), DEC);
  Serial.print(" ");
  Serial.print(now.hour(), DEC);
  Serial.print(now.minute(), DEC);
  Serial.print(now.second(), DEC);
  float temperature = bmp085GetTemperature(bmp085ReadUT()); //MUST be called first
   pressure = bmp085GetPressure(bmp085ReadUP());
  float atm = pressure / 101325; // "standard atmosphere"
  float altitude = calcAltitude(pressure); //Uncompensated caculation - in Meters 

  Serial.print("Temperature: ");
  Serial.print(temperature, 2); //display 2 decimal places
  Serial.println("deg C");

  Serial.print("Pressure: ");
  Serial.print(pressure, 0); //whole number only.
  Serial.println(" Pa");

  Serial.print("Standard Atmosphere: ");
  Serial.println(atm, 4); //display 4 decimal places

  Serial.print("Altitude: ");
  Serial.print(altitude, 2); //display 2 decimal places
  Serial.println(" M");

//logfile.print();//line break
   logfile.print(altitude,2); //display 2 decimal places
   logfile.print(" ,");
 //  delay(1000); //wait a second and get values again.    
   logfile.print(pressure, 0); //whole number only.
  Serial.print(", ");   

  // Log the estimated 'VCC' voltage by measuring the internal 1.1v ref
  int refReading = analogRead(BANDGAPREF); 
  float supplyvoltage = (bandgap_voltage * 1024) / refReading; 
  Serial.print(", ");   
#endif // ECHO_TO_SERIAL

#endif // ECHO_TO_SERIAL

  digitalWrite(greenLEDpin, LOW);

  // Now we write data to disk! Don't sync too often - requires 2048 bytes of I/O to SD card
  // which uses a bunch of power and takes time
  if ((millis() - syncTime) < SYNC_INTERVAL) return;
  syncTime = millis();
  // blink LED to show we are syncing data to the card & updating FAT!
  digitalWrite(redLEDpin, HIGH);
  digitalWrite(redLEDpin, LOW);

// Stores all of the bmp085's calibration values into global variables
// Calibration values are required to calculate temp and pressure
// This function should be called at the beginning of the program
void bmp085Calibration()
  ac1 = bmp085ReadInt(0xAA);
  ac2 = bmp085ReadInt(0xAC);
  ac3 = bmp085ReadInt(0xAE);
  ac4 = bmp085ReadInt(0xB0);
  ac5 = bmp085ReadInt(0xB2);
  ac6 = bmp085ReadInt(0xB4);
  b1 = bmp085ReadInt(0xB6);
  b2 = bmp085ReadInt(0xB8);
  mb = bmp085ReadInt(0xBA);
  mc = bmp085ReadInt(0xBC);
  md = bmp085ReadInt(0xBE);

// Calculate temperature in deg C
float bmp085GetTemperature(unsigned int ut){
  long x1, x2;

  x1 = (((long)ut - (long)ac6)*(long)ac5) >> 15;
  x2 = ((long)mc << 11)/(x1 + md);
  b5 = x1 + x2;

  float temp = ((b5 + 8)>>4);
  temp = temp /10;

  return temp;

// Calculate pressure given up
// calibration values must be known
// b5 is also required so bmp085GetTemperature(...) must be called first.
// Value returned will be pressure in units of Pa.
long bmp085GetPressure(unsigned long up){
  long x1, x2, x3, b3, b6, p;
  unsigned long b4, b7;

  b6 = b5 - 4000;
  // Calculate B3
  x1 = (b2 * (b6 * b6)>>12)>>11;
  x2 = (ac2 * b6)>>11;
  x3 = x1 + x2;
  b3 = (((((long)ac1)*4 + x3)<<OSS) + 2)>>2;

  // Calculate B4
  x1 = (ac3 * b6)>>13;
  x2 = (b1 * ((b6 * b6)>>12))>>16;
  x3 = ((x1 + x2) + 2)>>2;
  b4 = (ac4 * (unsigned long)(x3 + 32768))>>15;

  b7 = ((unsigned long)(up - b3) * (50000>>OSS));
  if (b7 < 0x80000000)
    p = (b7<<1)/b4;
    p = (b7/b4)<<1;

  x1 = (p>>8) * (p>>8);
  x1 = (x1 * 3038)>>16;
  x2 = (-7357 * p)>>16;
  p += (x1 + x2 + 3791)>>4;

  long temp = p;
  return temp;

// Read 1 byte from the BMP085 at 'address'
char bmp085Read(unsigned char address)
  unsigned char data;


  Wire.requestFrom(BMP085_ADDRESS, 1);

  return Wire.read();

// Read 2 bytes from the BMP085
// First byte will be from 'address'
// Second byte will be from 'address'+1
int bmp085ReadInt(unsigned char address)
  unsigned char msb, lsb;


  Wire.requestFrom(BMP085_ADDRESS, 2);
  msb = Wire.read();
  lsb = Wire.read();

  return (int) msb<<8 | lsb;

// Read the uncompensated temperature value
unsigned int bmp085ReadUT(){
  unsigned int ut;

  // Write 0x2E into Register 0xF4
  // This requests a temperature reading

  // Wait at least 4.5ms

  // Read two bytes from registers 0xF6 and 0xF7
  ut = bmp085ReadInt(0xF6);
  return ut;

// Read the uncompensated pressure value
unsigned long bmp085ReadUP(){

  unsigned char msb, lsb, xlsb;
  unsigned long up = 0;

  // Write 0x34+(OSS<<6) into register 0xF4
  // Request a pressure reading w/ oversampling setting
  Wire.write(0x34 + (OSS<<6));

  // Wait for conversion, delay time dependent on OSS
  delay(2 + (3<<OSS));

  // Read register 0xF6 (MSB), 0xF7 (LSB), and 0xF8 (XLSB)
  msb = bmp085Read(0xF6);
  lsb = bmp085Read(0xF7);
  xlsb = bmp085Read(0xF8);

  up = (((unsigned long) msb << 16) | ((unsigned long) lsb << 8) | (unsigned long) xlsb) >> (8-OSS);

  return up;

void writeRegister(int deviceAddress, byte address, byte val) {
  Wire.beginTransmission(deviceAddress); // start transmission to device 
  Wire.write(address);       // send register address
  Wire.write(val);         // send value to write
  Wire.endTransmission();     // end transmission

int readRegister(int deviceAddress, byte address){

  int v;
  Wire.write(address); // register to read

  Wire.requestFrom(deviceAddress, 1); // read a byte

  while(!Wire.available()) {
    // waiting

  v = Wire.read();
  return v;

float calcAltitude(float pressureA){

  float A = pressureA/101388;
  float B = 1/5.25588;
  float C = pow(A,B);
  C = 1 - C;
  C = C /0.0000225577;

  return C;

void bob()
  int dev = 0x5A<<1;
int data_low = 0;
int data_high = 0;
int pec = 0;


// read
data_low = i2c_readAck(); //Read 1 byte and then send ack
data_high = i2c_readAck(); //Read 1 byte and then send ack
pec = i2c_readNak();

//This converts high and low bytes together and processes temperature, MSB is a error bit and is ignored for temps
double tempFactor = 0.02; // 0.02 degrees per LSB (measurement resolution of the MLX90614)
double tempData = 0x0000; // zero out the data
int frac; // data past the decimal point

// This masks off the error bit of the high byte, then moves it left 8 bits and adds the low byte.
tempData = (double)(((data_high & 0x007F) << 8) + data_low);
tempData = (tempData * tempFactor)-0.01;

 celcius = tempData - 273.15;
float fahrenheit = (celcius*1.8) + 32;

Serial.print("Celcius: ");

Serial.print("Fahrenheit: ");

delay(1000); // wait a second before printing again

Problems Encountered:    The problems encountered while making this project where combining the different code codes especially the I2C master libraries. In order to make this project work i had to pull together three different codes to make one. In order to do this I had to combine different codes and change variables that would then mess up another part of the code.