MySQL for the Internet of Things

ChApTEr 3 ■ how IoT DATA Is sTorED

StOrING Date aND tIMe WIth SaMpLeS

The Arduino does not have a real-time clock (rTC) on board. If you want to store your data locally, you

have to either store the data with an approximate date and time stamp or use an rTC module to read an

accurate date/time value. Fortunately, there are rTC modules for use with an Arduino.

Listing 3-3. Log File Example (Arduino)

/**
Example Arduino SD card log file.

This project demonstrates how to save data to a
microSD card as a log file and read it.
*/
#include <SPI.h>
#include <SD.h>
#include <String.h>

// Pin assignment for Arduino Ethernet shield
#define SD_PIN 4
// Pin assignment for Sparkfun microSD shield
//#define SD_PIN 8
// Pin assignment for Adafruit Data Logging shield
//#define SD_PIN 10

File log_file;

void setup() {
char c = ' ';
char number[4];
int i = 0;
int value = 0;
String text_string;

Serial.begin(115200);
while (!Serial); // wait for serial to load

Serial.print("Initializing SD card...");

if (!SD.begin(SD_PIN)) {
Serial.println("ERROR!");
return;
}
Serial.println("done.");