Data Logging with SD Cards - Exploring Arduino: Tools and Techniques for Engineering Wizardry - page 302

//SD card is on standard SPI pins
//RTC is on Standard I2C Pins
const int CS_PIN =10;
const int SD_POW_PIN =8;
const int RTC_POW_PIN =A3;
const int RTC_GND_PIN =A2;
//Default rate of 5 seconds
int refresh_rate = 5000;
//Define an RTC object
RTC_DS1307 RTC;
//Initialize strings
String year, month, day, hour, minute, second, time, date;
void setup()
{
Serial.begin(9600);
Serial.println(F("Initializing Card"));
//CS pin and pwr/gnd pins are outputs
pinMode(CS_PIN, OUTPUT);
pinMode(SD_POW_PIN, OUTPUT);
pinMode(RTC_POW_PIN, OUTPUT);
pinMode(RTC_GND_PIN, OUTPUT);
//Setup power and ground pins for both modules
digitalWrite(SD_POW_PIN, HIGH);
digitalWrite(RTC_POW_PIN, HIGH);
digitalWrite(RTC_GND_PIN, LOW);
//Initiate the I2C bus and the RTC library
Wire.begin();
RTC.begin();
//If RTC is not running, set it to the computer's compile time
if (! RTC.isrunning())
{
Serial.println(F("RTC is NOT running!"));
RTC.adjust(DateTime(__DATE__, __TIME__));
}
//Initialize SD card
if (!SD.begin(CS_PIN))
{
Serial.println(F("Card Failure"));
return;
}
Serial.println(F("Card Ready"));