Moisture and temperature sensors data logging on an SD card

Moisture and Temperature sensor data logger (temperature sensor TMP36)  on an SD card ( Using SPI protocol)

/*  A simple data logger for the Arduino analog pins  */
/*  After some studying of both codes, i came up with this.
 These example code is in the public domain.
 http://dubworks.blogspot.co.uk/2012/11/moisture-and-temperature-sensors-data.html
 https://github.com/adafruit/Light-and-Temp-logger
 http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay
 */
#include <SD.h>
// constants won't change. Used here to 
// set pin numbers:
const int ledPin =  13;      // the number of the LED pin
// the digital pins that connect to the LEDs
#define redLEDpin 2
#define greenLEDpin 3
int seconds = 0;
int minutes = 0;
int hour = 0;
int day = 0;
int week=0;
// Variables will change:
int ledState = LOW;             // ledState used to set the LED
int logState = LOW;
long previousMillis = 0;        // will store last time time increment was updated
// the follow variables is a long because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long interval = 1000;// interval at which to increment a second (milliseconds)
int Hours_interval = 0;         // Hours interval 
int Minutes_interval = 0;       // Hours interval 
int log_Minutes_interval = 1;          // interval in mnts at which to log
int log_Hours_interval =4;            // interval in hours at which to log
#define ECHO_TO_SERIAL   1 // echo data to serial port
#define WAIT_TO_START    0 // Wait for serial input in setup()

// The analog pins that connect to the sensors
#define Moisture_sensor_Pin 0           // analog 0
#define tempPin 1                // analog 1
#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


// for the data logging shield, we use digital pin 10 for the SD cs line
const int chipSelect = 10;

// the logging file
File logfile;

void error(char *str)
{
  Serial.print("error: ");
  Serial.println(str);

  // red LED indicates error
  digitalWrite(redLEDpin, HIGH);

  while(1);
}


void setup() {
  // set the digital pin as output:
  pinMode(ledPin, OUTPUT);

  Serial.begin(9600);
  Serial.println();

  // use debugging LEDs
  pinMode(redLEDpin, OUTPUT);
  pinMode(greenLEDpin, OUTPUT);

#if WAIT_TO_START
  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:
  // 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: ");
    Serial.println(filename);
  }
  logfile.println("time,moisture,temp,vcc");    
#if ECHO_TO_SERIAL
  Serial.println("time,moisture,temp,vcc");
#endif //ECHO_TO_SERIAL

  // If you want to set the aref to something other than 5v
  analogReference(EXTERNAL);  
}

void loop()
{
  // here is where you'd put code that needs to be running all the time.

 
  unsigned long currentMillis = millis();


  if (seconds==60){
    seconds=0;
    minutes = minutes += 1;
    // hour= hour += 1;
    Minutes_interval = Minutes_interval += 1;
  }
  if (minutes==60){
    minutes = 0;
    hour= hour += 1;

    Minutes_interval =0;
Hours_interval = Hours_interval += 1;
  }
  if (hour == 24){
    day = day += 1;
    hour= 0;
    minutes = 0;
  }
  if (day == 7 && hour== 23 && minutes == 59 && seconds==59){
    day = 0;
    week = week +=1;
  }
  if(currentMillis - previousMillis > interval) {
    // save the last time you incremented
    previousMillis = currentMillis;   
    seconds= seconds += 1;

    // if the LED is off turn it on and vice-versa:
    if (ledState == LOW)
      ledState = HIGH;
    else
      ledState = LOW;

    // set the LED with the ledState of the variable:
    digitalWrite(ledPin, ledState);
  }
  //log_Hours_interval if hours prefered
  if ( Hours_interval ==log_Hours_interval ){
    Minutes_interval =0;//reset the last interval
    Hours_interval = 0; //reset the last interval
    logState = HIGH; // if the LOG is off turn it on and vice-versa:
  }
  if (logState == HIGH){
    logState = LOW;
    //Log code to sd card 
    logfile.print(minutes);           // mnts since start
    logfile.print("mnts, "); 
    logfile.print(hour);           // hours since start
    logfile.print("hrs, ");  
    logfile.print(day);           // days since start
    logfile.print("dd, "); 
    logfile.print(week);           // weeks since start
    logfile.print("Week, ");  
#if ECHO_TO_SERIAL
    Serial.print(minutes);         // mnts since start
    Serial.print("mnts, ");  
    Serial.print(hour);         // hours since start
    Serial.print("hrs, "); 
    Serial.print(day);         // days since start
    Serial.print("dd, "); 
    Serial.print(week);         // weeks since start
    Serial.print("Week, "); 
#endif 
    analogRead(Moisture_sensor_Pin);
    delay(10); 
    int Moisture_sensor_PinReading = analogRead(Moisture_sensor_Pin);  

    analogRead(tempPin); 
    delay(10);
    int tempReading = analogRead(tempPin);    

    // converting that reading to voltage, for 3.3v arduino use 3.3, for 5.0, use 5.0
    float voltage = tempReading * aref_voltage / 1024;  
    float temperatureC = (voltage - 0.5) * 100 ;
    //float temperatureF = (temperatureC * 9 / 5) + 32; // uncomment the beggining of this line for F

    logfile.print("Moisture, ");    
    logfile.print(Moisture_sensor_PinReading);
    logfile.print("Temp, ");    
    logfile.print(temperatureC);
#if ECHO_TO_SERIAL
    Serial.print("Moisture, ");   
    Serial.print(Moisture_sensor_PinReading);
    Serial.print("Temp, ");    
    Serial.print(temperatureC);
#endif //ECHO_TO_SERIAL

    // Log the estimated 'VCC' voltage by measuring the internal 1.1v ref
    analogRead(BANDGAPREF); 
    delay(10);
    int refReading = analogRead(BANDGAPREF); 
    float supplyvoltage = (bandgap_voltage * 1024) / refReading; 

    logfile.print("Supply_V, ");
    logfile.print(supplyvoltage);
#if ECHO_TO_SERIAL
    Serial.print("Supply_V, ");   
    Serial.print(supplyvoltage);
#endif // ECHO_TO_SERIAL

    logfile.println();
#if ECHO_TO_SERIAL
    Serial.println();
#endif // ECHO_TO_SERIAL

    digitalWrite(greenLEDpin, LOW);

    // blink LED to show we are syncing data to the card & updating FAT!
    digitalWrite(redLEDpin, HIGH);
    logfile.flush();
    digitalWrite(redLEDpin, LOW);

  }
}