Arduino LED Blink Code with Wiring

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Arduino LED Blink Code with Wiring

easyDigital outputArduino (C++)

The Hello World of Arduino — and the first program in almost every PR-4 practical.

The question

Write a sketch that blinks an LED connected to digital pin 10: ON for 200 ms, then OFF for 200 ms, forever.

The sketch

sketch.ino

void setup() {
  pinMode(10, OUTPUT);
}

void loop() {
  digitalWrite(10, HIGH);
  delay(200);
  digitalWrite(10, LOW);
  delay(200);
}

Open the Arduino simulator »

Wiring

LED anode (long leg) → 220Ω resistor → pin 10; cathode → GND.

How it works

1setup() runs once: pinMode(pin, OUTPUT) makes the pin able to drive an LED.
2loop() runs forever: digitalWrite(pin, HIGH) turns the LED on, LOW turns it off.
3delay(ms) waits that many milliseconds; 1000 ms is one second.

Common mistakes

Leaving out the resistor in a real circuit — the LED or the pin can be damaged.
Forgetting the second delay, so the LED turns off and on again instantly and looks always on.

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