https://youtu.be/ldQG9p2lh38
<  LED  1개  깜박이기 >

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int led1pin=7;

void setup() {
  pinMode(led1pin, OUTPUT);

}

void loop() {
  digitalWrite(led1pin, HIGH);
  delay(500);
  digitalWrite(led1pin,LOW);
  delay(500);
}
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< LED  4개 동작 >
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void setup() {
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
}

void loop() {
  digitalWrite(13, HIGH);
  delay(1000);
  digitalWrite(13, LOW);
  digitalWrite(12, HIGH);
  delay(1000);
  digitalWrite(12, LOW);
  digitalWrite(11, HIGH);
  delay(1000);
  digitalWrite(11, LOW);
  digitalWrite(10, HIGH);
  delay(1000);
  digitalWrite(10, LOW);
  delay(1000);
}