RFID Library Book Return Bin with Self Check-in and Librarian Dashboard

College libraries lose staff hours to manual book check-ins: every returned book is scanned one by one at the counter, queues build up at peak hours, and after-hours returns pile up unsorted. RFID self check-in kiosks exist commercially but are priced for large libraries, and they rarely show students how the tag-to-database loop actually works. This project builds a working return bin around an ESP32 and an RC522 reader: a book dropped through the slot passes the reader, its tag UID is matched against the demo catalogue, and the return is logged instantly with a timestamp — no staff touch needed. A servo-driven flap keeps the slot closed between drops, an ultrasonic sensor tracks how full the bin is, and the librarian dashboard shows the live returns feed, fill gauge and overdue flags. Because the catalogue, firmware and dashboard are all built in the open, the student can explain every step from RF field to database row.

1. A student drops a tagged book through the slot; the IR break-beam wakes the reader and opens the servo flap momentarily.
2. The RC522 energizes its RF field and reads the tag UID as the book falls past the antenna zone.
3. The ESP32 matches the UID against the demo catalogue over Wi-Fi and records the return with a timestamp; unmatched tags are logged as unknown.
4. The flap closes, the green LED and buzzer confirm the check-in, and the OLED updates the last-return display.
5. The ultrasonic sensor re-measures the bin fill after each drop; crossing the collection threshold raises a dashboard and LED alert.
6. The dashboard appends every event to the live returns feed, updates the fill gauge and daily counts, and flags returns whose due dates had passed.

Tech stack:

• ESP32 development board (Wi-Fi)
• RC522 RFID reader (13.56 MHz, ISO14443A)
• SG90 servo (slot flap) + IR break-beam sensor
• Ultrasonic fill-level sensor
• 0.96-inch OLED + LEDs + buzzer
• Demo catalogue backend (Wi-Fi API)
• HTML/CSS/JS librarian dashboard
• Arduino IDE (C/C++ firmware)

• [RFID self check-in] An RC522 reader identifies each book's tag as it drops through the slot and the ESP32 logs the return instantly against the demo catalogue.
• [Servo-controlled slot flap] The entry flap opens for each drop and closes after, keeping dust out and preventing books from being fished back out.
• [Bin-fill monitoring] An ultrasonic sensor measures the fill level continuously; the dashboard gauge and a local LED warn staff before the bin overflows.
• [Live librarian dashboard] Returns feed with timestamps, per-book check-in log, fill gauge, daily return counts and overdue flags from the demo catalogue data.
• [Instant user feedback] A green LED and buzzer confirm each successful check-in; a red LED flags an unrecognized tag.
• [On-device display] A 0.96-inch OLED shows the last returned title, today's return count and the fill level at the bin itself.
• [Demo catalogue] A small tagged book set with catalogue records (title, member, due date) ships with the build so the full loop is demonstrable out of the box.

• Working hardware prototype (return bin with reader, flap servo and sensors fitted)
• ESP32 firmware source with RFID, servo and fill-level logic
• Companion dashboard demo (single-file HTML librarian dashboard)
• Demo catalogue with pre-tagged books and due-date records
• Wiring diagram and bin fabrication guide
• Project report PDF (background, RFID principles, architecture, methodology)
• PPT presentation for final review
• Viva Q&A preparation document (RFID, anti-collision, servo control, UID matching)

• RC522 reads one tag at a time at short range — a stack of books dropped together will not all register; single-book drops are the designed workflow.
• Metal covers and foil-lined books detune the 13.56 MHz field; the demo book set avoids these, and the report documents the limitation.
• Tag UIDs are identifiers, not security — UIDs can be cloned, so this is a workflow demo, not an anti-theft system.
• The demo catalogue is a small local dataset, not a full library ILS integration; connecting a real ILS is future scope.
• Bin capacity is demo-scale (25–30 books); a production unit needs a larger, fire-safe enclosure.
• Wi-Fi is required for catalogue matching; the bin queues returns locally if the network drops.