Arduino project · LEDs and lights · Beginner
IR Obstacle Sensor with LEDs
Red lights when something is in front of the sensor, green when the way is clear.
What you will learn
- How an IR obstacle sensor works
- How to use both states of an input
- How a robot sees obstacles
How it works
The sensor sends infrared light and checks for a reflection. If an obstacle reflects it, the output goes LOW. The red LED shows obstacle, the green LED shows clear.
Try this next
- Add a buzzer.
- Use two sensors for left and right.
- Control a servo to point away from the obstacle.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
A beam that sees obstacles
When something blocks the beam the red lamp lights; otherwise the green lamp is on.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- IR sensor = the beam
- LEDs = blocked / clear