Arduino UNO: LED Lights Up with 3.3V and GND 🔋💡
Level: Super Beginner – No code needed!
🧰 Components Required:
- 1 x Arduino UNO
- 1 x LED (any color)
- 1 x 220-ohm Resistor
- Breadboard
- Jumper Wires
🔌 Circuit Connection:
- Big leg (positive) of LED → connect to one side of 220-ohm resistor
- Other side of resistor → connect to Arduino UNO 3.3V pin
- Small leg (negative) of LED → connect to GND pin on Arduino
✅ Important: This circuit works without uploading any code to Arduino. When you plug in power (USB or battery), the LED will turn ON.
📘 Explanation:
In this basic project, you’re using the Arduino UNO’s 3.3V output to power an LED directly. The resistor protects the LED from high current. When you power the Arduino, 3.3V flows through the resistor to the LED’s positive leg, and the negative leg connects to GND — so the LED lights up instantly!