Arduino project · Smart doors and home · Easy
RFID Access Lights (Green or Red)
A known card turns the green LED on. An unknown tag turns the red LED on.
What you will learn
- How RFID reads a card number
- How a list of allowed cards works
- How access control gives yes or no
How it works
Card A and card B are in the allowed list, so they light the green LED. Any other tag lights the red LED. The reader forgets a card after 2 seconds. Use the drop-down as the card in your hand.
Try this next
- Add a buzzer for unknown tags.
- Add a third card to the list.
- Store the allowed cards in EEPROM.
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 door that opens for the right key
Show the right card (or press the right pattern) in the simulator. The green lamp lights and the real door swings open. Anything else keeps the red lamp on and the door locked.
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.
- Input (card / buttons) = the key or code used at the door
- Green LED = access granted, door opens
- Red LED = access denied, door stays locked