RFID Access Indicator Kit

Classes 9-10, typical ages 14–16. Age ranges vary by learner. Guided low-voltage electronics.

Activity engagement

90–120 minutes. Explore 15–20 min · Build 30–40 min · Test and discuss 45–60 min. Estimated time for building, testing and discussion.

What you need

A computer with a USB port and Arduino IDE is required and is not included.

Included components

• Small Breadboard / Mini Solderless Board - 400 points — 1 breadboard
• Jumper Wire Combo - Male to Male, Male to Female and Female to Female Breadboard Connecting Wires (10 Qty Each) — 1 set
• Illustrated Activity Guide and Observation Sheets — 1 set
• Fitted Headers and Labelled Connection Leads — 1 set
• Arduino Uno R3 CH340G version compatible Arduino Development Board — 1 controller board
• USB A to B Programming Cable for Arduino Uno/ Arduino Mega — 1 data cable
• RC522 13.56 MHz RFID Reader Writer Module with Card and Tag — 1 reader set
• 4-Channel 5 V to 3.3 V SPI Level Shifter (74LVC125) — 1 level-shifter module
• 5mm LED - Red Color — 1 LED
• 5mm LED - Green Color — 1 LED
• 330 Ω 1/4 Watts (10 PCS) — 2 resistor (individual units)

What you learn

• An RFID reader returns a tag identifier.
• A comparison rule can control separate accepted/rejected indicators.
• UID matching alone is not secure access control.

Connection guide

• RC522 VCC → 3.3 V, GND → GND. Never connect its supply or signal inputs directly to 5 V.
• 74LVC125 shifter VCC → 3.3 V, GND → GND; its enabled outputs lower Uno D13/SCK, D11/MOSI, D10/SS and D9/RST to RC522 SCK, MOSI, SDA/SS and RST respectively.
• RC522 MISO → Uno D12 directly; IRQ remains unconnected. Green LED D6 and red LED D7 each use their own 330 Ohm resistor to GND.

Steps to make it

1. Disconnect all power and identify the supplied part labels and pinouts before wiring.
2. Connect the reader through the supplied SPI-capable level shifter.
3. Install MFRC522 and upload; scan the supplied card and write down its UID bytes from Serial Monitor.
4. Replace the demonstration UID array and its length with that card UID, then upload again.
5. Compare the enrolled card and a different supplied tag; treat the LEDs as a classroom decision model.
6. Change only the named parameter for the extension, repeat the controlled trials, save observations and disconnect power afterward.

Programming resources

Arduino IDE: select Arduino Uno and the USB port. Use the supplied USB data cable. Serial Monitor/Plotter: 115200 baud.

Libraries to install

• MFRC522

Download starter sketch

Test challenge

Test enrolled and different tags five times each, including removing the tag between reads.

Observation task

Tag label, UID length, expected decision and observed LED.

Expected result

The configured UID lights green; a different UID lights red. No real lock or security guarantee is provided.

If it does not work

Verify 3.3 V reader power, SPI pin order, shifter direction and UID length. A 125 kHz card does not work with this 13.56 MHz reader.

Try next

Explain why copying or changing a UID defeats a UID-only rule and list stronger authentication requirements.

Use and supervision

Use only the supplied low-voltage DC parts. Disconnect power before rewiring; check polarity and labelled pinouts. No soldering or exposed mains connections. Adult guidance is recommended.

How this experiment works

Download class activity guide

Cover illustrations show component types. Functional animations explain principles and are not recorded prototype tests. Follow the supplied connection labels and pinouts.