IoT Weighbridge Automation using RFID and Load Cells

At quarries, warehouses and farm collection centers, every truck that enters and leaves must be weighed — and the weighing is still often a manual ritual: the operator reads a display, writes the number in a register, and mistakes, disputes and outright fraud creep in. An automated weighbridge fixes the weak link by tying each weight reading to a vehicle identity automatically: the truck drives on, the barrier-side RFID reader captures its tag, the load cells settle, and the weight is logged against that tag with a timestamp — no handwriting, no transcription error. This project builds that system at demonstrator scale: a steel platform on four button load cells, an HX711 precision amplifier, an ESP32 controller, an RC522 RFID reader and a 16x2 LCD, with firmware that handles tare, calibration and overload alarming and a cloud log of every tagged transaction.

1. The platform is tared empty (or calibrated with a known weight per the included procedure) before the weighing session.
2. A load is placed on the platform and the four load cells' signals are summed by the HX711 24-bit ADC.
3. The ESP32 averages readings and waits for the value to stabilize within the configured tolerance band.
4. The operator presents the RFID tag; the RC522 reader captures the tag ID.
5. Weight, tag ID and timestamp are shown on the LCD and pushed to the cloud log over Wi-Fi.
6. If the load exceeds the overload threshold, the buzzer sounds and the event is flagged in the log.

Tech stack:

• ESP32 development board (Arduino-IDE firmware, C++)
• 4× button load cells with HX711 24-bit ADC amplifier
• RC522 RFID reader module (13.56 MHz) with tags/cards
• 16x2 LCD display, buzzer, regulated 5 V power
• Cloud logging over Wi-Fi (HTTP/MQTT endpoint)
• Steel platform, acrylic base, wiring and mounting hardware

• [Four-cell weigh platform] A steel platform on four button load cells sums corner loads through the HX711 24-bit ADC, demonstrating real multi-cell weighing practice.
• [RFID vehicle tagging] An RC522 reader captures the RFID card/tag presented at weighing time and binds the tag ID to the weight record automatically.
• [Tare and calibration in firmware] One-button tare zeroes the platform, and a known-weight calibration routine sets the scale factor — the standard field procedure, implemented and documented.
• [16x2 LCD readout] Live weight, tag status and system messages on a blue-backlit LCD, so the demo runs standalone without a laptop.
• [Overload alarm] A configurable threshold triggers a buzzer and an LCD warning when the platform load exceeds the set limit.
• [Cloud transaction log] Every weighing — tag ID, weight, timestamp — is pushed over Wi-Fi to a cloud log the student can show, export and analyze.
• [Stable-reading detection] Firmware waits for the reading to settle within a tolerance band before logging, so vibrations don't corrupt the record.

• Assembled weighbridge prototype (platform, load cells, electronics, LCD, RFID reader)
• ESP32 firmware source code with comments
• Wiring diagram and full component list
• Calibration and tare procedure document (known-weight method)
• Cloud-log setup guide (endpoint configuration, log export)
• Project abstract PDF
• Project report (background, load-cell theory, firmware design, calibration results)
• PPT presentation and viva Q&A document (strain gauges, HX711, RFID, IoT logging)

• This is a small demonstrator, not a trade-certified weighbridge: it is not legal-for-trade and cannot certify commercial transactions — the report states this explicitly.
• Accuracy depends on calibration with a known weight, level mounting and a vibration-free table; temperature drift and creep affect readings over time.
• The ~5 kg design capacity is set by the demonstrator's load cells; larger cells and a sturdier platform are possible as a customization.
• Cloud logging needs Wi-Fi; weighing, tare and the LCD readout work fully offline.
• Load cells are sensitive to shock loads and off-center placement — the setup guide covers handling precautions.