Example-1

Blink an LED in Tinkercad Circuits

Objective

Use Arduino Uno to blink an LED on and off with a fixed delay. Students learn pin mapping, current-limiting resistors, and the basic Arduino program structure.

Learning outcomes

• Identify Arduino digital pins and GND

• Build a simple LED circuit on a breadboard

• Write, upload, and run an Arduino sketch in Tinkercad

• Explain setup() vs loop() and pinMode() vs digitalWrite()

---

Prerequisites

• Tinkercad account and access to Circuits

• Know how to create a New Circuit project

• Basic idea of breadboard rows and power rails

---

Components (Tinkercad palette)

• Arduino Uno R3

• Breadboard (small)

• 1× LED (any color)

• 1× Resistor 220 Ω (or 330 Ω)

• 2× Wires (male-male)

Why the resistor? To limit current through the LED and protect the Arduino pin.

---

Circuit wiring 

You can do this straight on the Uno (using the built-in LED on pin 13) or, better for learning, on a breadboard.

Option A — Recommended (external LED on Pin 8):

1. Place the LED on the breadboard. Long leg = anode (+), short leg = cathode (–).

2. Connect Arduino pin 8 → LED anode row (same row as long leg).

3. Put the 220 Ω resistor from the LED cathode row → GND rail on the breadboard.

4. Wire Arduino GND → breadboard GND rail.

Option B — Quick test (use onboard LED):

• No breadboard. Just code for pin 13 (onboard LED). Good as a fallback.

---

Step-by-step in Tinkercad

1. Create the project: Tinkercad → Circuits → Create new Circuit.

2. Place parts: Drag Arduino Uno and Breadboard into the workspace.

3. Wire: Follow Option A wiring above. Use the color chooser to keep GND wires black for clarity.

4. Start coding: Click Code → choose Text (C/C++).

5. Paste this sketch (for Pin 8):

// EXP-1: Blink LED on Digital Pin 8
const int LED_PIN = 8;

void setup() {
  pinMode(LED_PIN, OUTPUT);     // Set pin as output
}

void loop() {
  digitalWrite(LED_PIN, HIGH);  // LED ON
  delay(1000);                  // wait 1 second (1000 ms)
  digitalWrite(LED_PIN, LOW);   // LED OFF
  delay(1000);                  // wait 1 second
}

(If using onboard LED: set LED_PIN = 13 and you can skip the breadboard.)

6. Simulate: Click Start Simulation. The LED should blink ON/OFF every second.

7. Tweak: Change delay(1000) to delay(200) to blink faster; re-run the simulation.

---

How it works

• setup() runs once when the Arduino starts.

• loop() runs forever.

• pinMode(8, OUTPUT) tells Arduino to drive pin 8.

• digitalWrite(…, HIGH/LOW) sets the voltage to 5V/0V → LED ON/OFF.

• delay(ms) pauses the program.

---

Common mistakes & quick fixes

• LED not lighting: Flip the LED; long leg (anode) must go to the pin, short leg to GND (through resistor).

• No resistor used: Always add 220–330 Ω in series or you can damage real hardware.

• Wrong pin number: Code says 8 but you wired to 7 or 9—match them.

• Floating ground: Ensure Arduino GND is connected to the breadboard GND rail.

---

Viva / check-your-understanding

• Why do we need a resistor with an LED?

• What’s the difference between setup() and loop()?

• What happens if we change the delay to 50 ms?

---

Extensions (mini-tasks)

• Custom pattern: Blink ON 200 ms, OFF 800 ms to simulate a “heartbeat” LED.

• Two LEDs: Add a second LED on pin 9 and alternate them.

• Fade (bonus): Replace blink with PWM on pin 9 using analogWrite(9, value).

---

Lab record (suggested headings)

• Aim

• Circuit diagram (screenshot from Tinkercad)

• Code listing

• Output observation (simulation screenshot)

• Inference/Conclusion

---

Thinkercad Link

https://www.tinkercad.com/things/f8AXWKUrbpl-example-1