Integrated QR, RFID, and Temperature Verification Access Control System

This Raspberry Pi-based prototype seamlessly integrates QR code and RFID reading with real‑time temperature checks, authenticating visitors against a remote server to control barrier access.

In the post‑COVID era, many institutions now mandate a temperature check before granting access to secure premises.

The system employs a Raspberry Pi 4, a camera module, an RFID reader, an IR temperature sensor, and a four‑channel relay. A servo motor serves as a demo barrier, but the architecture supports any barrier type.

How does it work?

The prototype uses a Raspberry Pi 4 with a camera module, an RFID reader, an IR temperature sensor, and a four‑channel relay. For the demo, a servo motor acts like a barrier, but in the real world, any barrier type can be integrated.

The software was programmed in Python following this flow:

1. Camera captures a snapshot with a bright LED flash to accommodate printed QR codes.
2. If no QR code is detected, the unit attempts to read an RFID tag.
3. Once decoded, the guest’s QR or RFID code is available.
4. The IR temperature sensor, positioned to the right, measures the guest’s body temperature.
5. The guest code and temperature are transmitted to a remote server via a PHP script.
6. The server returns a response that instructs the relay(s) to unlock the barrier.
7. All access attempts are logged in a database for reporting and audit purposes.

Demo

Technical notes

The choice of Raspberry Pi over Arduino stems from the extensive QR‑code decoding libraries available for Raspbian and Python.

Both the MLX90614 IR temperature sensor and the PN532 RFID reader communicate over I2C and share distinct addresses—verified with sudo i2cdetect -y 1. Simply connect the cables in parallel to resolve address conflicts.

Code snippets

Scan QR Code with Raspberry Pi

camera=picamera.PiCamera()
camera.resolution = (800, 600)
camera.color_effects = (128,128)
camera.capture('qr/'+str(counter)+'.jpg')
camera.close()

Query remote server

url = 'https://IPHere/qr.php'
myobj = {'qr': myData,'temp': str(temp)}
try:
    x = requests.post(url, data = myobj)

Read NFC from Raspberry Pi

for target in n.poll():
    try:
        nfcData=target.uid

Source: Access control with QR, RFID and temperature verification