LED Blink

September 20, 2025

Solving Approach

How do you plan to solve it?

First, I will build the circuit based on the given diagram. The GPIO pin of the microcontroller will be connected to the positive side (anode) of the LED. A resistor will be added in series to limit the current, and the negative side (cathode) of the LED will be connected to ground.

To find the resistor value, I used Ohm’s Law: V = I × R, which means R = V ÷ I.

The GPIO outputs 5V.

A red LED has a forward voltage drop of about 2V.

So, the resistor will drop the remaining voltage: 5V − 2V = 3V.

I want the LED current to be about 10 mA (0.01 A).

Now, R = 3V ÷ 0.01A = 300 Ω. Since 300 Ω is not always available, I will use the nearest standard value, 330 Ω, which will slightly reduce the current but still allow the LED to light up safely.

Code

/*Paste your code here*/

// Define the pin where the LED is connected
const int ledPin = 13; // Using pin 13, which has a built-in LED on many Arduino boards

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 400 milliseconds
  delay(400);

  // Turn the LED off by making the voltage LOW
  digitalWrite(ledPin, LOW);
  // Wait for 800 milliseconds
  delay(800);
}

Output

Video

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Photo of Output

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