UNIVERSITY OF FRONTIER TECHNOLOGY, BANGLADESH

Course Code and Name: IRE 460, Mobile Platform for IoT Devices Sessional

Submitted by:

MD Naimur Rashid (2101042)
Sourav Chakraborty (2101031)

Submitted to:

Md. Rafiqul Islam
Lecturer, IRE

TapIn — Smart Attendance System

A full-stack IoT and Flutter ecosystem for seamless university attendance.

System Architecture

Macro Ecosystem Workflow

IoT Hardware

NodeMCU ESP8266
+ RC522 RFID Reader

Scans 13.56 MHz physical
cards. Sends HTTP POST
to Supabase.

Backend Cloud

Supabase Postgres
+ Edge Functions

Validates user, checks
schedule, inserts
attendance records.

Client Application

Flutter cross-platform
mobile app.

Real-time UI for Students
& Admins via
Supabase streams.

IoT Layer Deep-Dive

Hardware Node: Internal Logic

RC522 → NodeMCU Pins

RC522	GPIO	Board
SDA (SS)	GPIO 15	D8
RST	GPIO 0	D3
MOSI	GPIO 13	D7
MISO	GPIO 12	D6
SCK	GPIO 14	D5
GND	GND	GND
3.3V	3.3V	3V3

Reads 13.56 MHz RFID card UID
e.g., EBACC836
via SPI protocol.

3-Second Cooldown!
Prevents double-tap entries on the
same card.

Sends HTTP POST to Supabase Edge
Function with the
scanned UID.

Wait for Card

Read 13.56 MHz UID
(e.g., EBACC836)

HTTP POST
to Supabase

3-Second
Cooldown

Backend Layer

Backend Cloud: Database & Logic

Database Schema

users
(Core Profiles)

subjects
(Academic Courses)

class_schedules
(Timetables)

attendance_logs
(Core Records)

leave_applications
(Requests)

The Edge Function

                    {"rfid_uid": "<CARD_UID>"}
                 

↳ Looks up student
↳ Checks schedule
↳ Inserts log securely

Edge Function

Receives RFID UID
via HTTP POST:
{"rfid_uid":"EBACC836"}

Validates UID →
checks active schedule
→ inserts into
'attendance_logs'

Row Level Security
Students only see
their own records.
Admins see all.

Summary

Key Design Decisions

90% Threshold

Minimum attendance
per subject = full
30/30 marks.
Approved leave = Present.

3-Second Cooldown

NodeMCU ignores same
card within 3 seconds
to prevent duplicate
DB inserts.

Intelligent Grouping

Last 3 digits of
University ID auto-assigns
to Lab G1 (≤25)
or G2 (>25).

Dark / Light Mode

Theme persisted via
shared_preferences
as single source
of truth.

Row Level Security

Supabase RLS ensures
students only view
their own
attendance records.

RFID Required

Admin must link
physical RFID UID
to student profile
before taps work.

Thank You!

MD Naimur Rashid

🌐 naimurrashid.dev github/naimurhamim