// Define the pin for the LED
const int ledPin = 7;

void setup() {
  // Initialize the digital pin as an output.
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Turn the LED on (HIGH is the voltage level)
  digitalWrite(ledPin, HIGH);
  // Wait for a second
  delay(1000);
  // Turn the LED off by making the voltage LOW
  digitalWrite(ledPin, LOW);
  // Wait for a second
  delay(1000);
}