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This example is for Wiring version 1.0 build 0100+. If you have a previous version, use the examples included with your software. If you see any errors or have comments, please let us know.

Timer by BARRAGAN http://barraganstudio.com
Demonstrates how to create a timer to print a message every 7 seconds

    unsigned long previousTime = 0;

    void setup()
    {
      Serial.begin(9600);
      previousTime = millis(); // mark the initial time
    }

    void loop()
    {
      // if 7 seconds have passed since last mark
      if ((millis() - previousTime) >= 7000)
      {
        Serial.println("seven seconds have passed"); //print message
        previousTime = millis(); // mark again
      }
    }