Day 21

//data logging pressure and temperature data to SD card with time

#include <Wire.h>
#include <SD.h>
#define BMP180_ADDRESS 0x77 // I2C address of BMP180
const int CS_PIN = 10;
const int POW_PIN = 8;
int refresh_rate = 5000;
const unsigned char OSS = 0; // Oversampling Setting
unsigned long t;
double temp;
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;
long b5;
short temperature;
long pressure;
const float p0 = 101325; // Pressure at sea level (Pa)
float altitude;
//-------------------------------------------------------------------------------//
void setup()
{
 Serial.begin(9600);
 Wire.begin();
 Serial.println("Initializing Card");
 pinMode(CS_PIN, OUTPUT);
 if(!SD.begin(CS_PIN))
 {
  Serial.println("Card Failure");
  return;
 }
 Serial.println("Card Ready");
  File commandFile = SD.open("speed.txt");
  if (commandFile)
  {
    Serial.println("Reading Command FIle");
    while (commandFile.available())
    {
      refresh_rate = commandFile.parseInt();
    }
    Serial.print("Refresh Rate = ");
    Serial.print(refresh_rate);
    Serial.println("ms");
    commandFile.close();
  }
  else
  {
    Serial.println("Could not read command file");
//    return;
  }
 bmp180Calibration();
}


// Stores all of the bmp180'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 bmp180Calibration()
{
 ac1 = bmp180ReadInt(0xAA);
 ac2 = bmp180ReadInt(0xAC);
 ac3 = bmp180ReadInt(0xAE);
 ac4 = bmp180ReadInt(0xB0);
 ac5 = bmp180ReadInt(0xB2);
 ac6 = bmp180ReadInt(0xB4);
 b1 = bmp180ReadInt(0xB6);
 b2 = bmp180ReadInt(0xB8);
 mb = bmp180ReadInt(0xBA);
 mc = bmp180ReadInt(0xBC);
 md = bmp180ReadInt(0xBE);
}

char bmp180Read(unsigned char address)
{
 unsigned char data;
 Wire.beginTransmission(BMP180_ADDRESS);
 Wire.write(address);
 Wire.endTransmission();
 Wire.requestFrom(BMP180_ADDRESS, 1);
 while(!Wire.available())
 ;
 return Wire.read();
}
// Read 2 bytes from the BMP180
// First byte will be from 'address'
// Second byte will be from 'address'+1
int bmp180ReadInt(unsigned char address)
{
 unsigned char msb, lsb;
 Wire.beginTransmission(BMP180_ADDRESS);
 Wire.write(address);
 Wire.endTransmission();

 Wire.requestFrom(BMP180_ADDRESS, 2);
 while(Wire.available()<2)
 ;
 msb = Wire.read();
 lsb = Wire.read();

 return (int) msb<<8 | lsb;
}
long bmp180GetPressure(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;
 else
 p = (b7/b4)<<1;
 x1 = (p>>8) * (p>>8);
 x1 = (x1 * 3038)>>16;
 x2 = (-7357 * p)>>16;
 p += (x1 + x2 + 3791)>>4;
 return p;
}
unsigned long bmp180ReadUP()
{
 unsigned char msb, lsb, xlsb;
 unsigned long up = 0;
 // Write 0x34+(OSS<<6) into register 0xF4
 // Request a pressure reading w/ oversampling setting
 Wire.beginTransmission(BMP180_ADDRESS);
 Wire.write(0xF4);
 Wire.write(0x34 + (OSS<<6));
 Wire.endTransmission();
 // Wait for conversion, delay time dependent on OSS
 delay(2 + (3<<OSS));
 // Read register 0xF6 (MSB), 0xF7 (LSB), and 0xF8 (XLSB)
 Wire.beginTransmission(BMP180_ADDRESS);
 Wire.write(0xF6);
 Wire.endTransmission();
 Wire.requestFrom(BMP180_ADDRESS, 3);
 // Wait for data to become available
 while(Wire.available() < 3)
 ;
 msb = Wire.read();
 lsb = Wire.read();
 xlsb = Wire.read();
 up = (((unsigned long) msb << 16) | ((unsigned long) lsb << 8) | (unsigned long) xlsb) >> (8-OSS);
 return up;
}
unsigned int bmp180ReadUT()
{
 unsigned int ut;
 // Write 0x2E into Register 0xF4
 // This requests a temperature reading
 Wire.beginTransmission(BMP180_ADDRESS);
 Wire.write(0xF4);
 Wire.write(0x2E);
 Wire.endTransmission();
 // Wait at least 4.5ms
 delay(5);
 // Read two bytes from registers 0xF6 and 0xF7
 ut = bmp180ReadInt(0xF6);
 return ut;
}
short bmp180GetTemperature(unsigned int ut)
{
 long x1, x2;

 x1 = (((long)ut - (long)ac6)*(long)ac5) >> 15;
 x2 = ((long)mc << 11)/(x1 + md);
 b5 = x1 + x2;
 return ((b5 + 8)>>4);
}


void loop()
{
  t = millis();
  Serial.print(t);
  Serial.print(",");


 
 
 temperature = bmp180GetTemperature(bmp180ReadUT());
 pressure = bmp180GetPressure(bmp180ReadUP());
 temp = temperature *.1;
 const float p0 = 101325; // Pressure at sea level (Pa)
 float altitude;
 altitude = (float)44330 * (1 - pow(((float) pressure/p0), 1/5.255));
// Serial.print("Altitude: ");
// Serial.print(altitude, 2);
// Serial.println(" m");
// Serial.print("Temperature: ");
// Serial.println(temp, DEC);
// Serial.print("Pressure: ");
// Serial.print(pressure, DEC);
// Serial.println(" Pa");
// Serial.println();

File dataFile = SD.open("LOG.csv", FILE_WRITE);
  if (dataFile)
  {
    Serial.print(altitude);
    Serial.print(",");
    Serial.print(temp);
    Serial.println(" ");
    dataFile.print(t);
    dataFile.print(",");
    dataFile.print(altitude);
    dataFile.print(",");
    dataFile.print(temp);
    dataFile.println();
    dataFile.close();
    delay(1000);
  }
 
}