Tablet terminal waiting for the employee to select an action.
RFID via USB OTGCard input as a HID device
Offline modeLocal storage and later synchronization
Context
Time registration without complex and expensive hardware
The system was created as an alternative to closed time-attendance terminals whose functionality, appearance and integrations are difficult to adapt to real business processes.
The project includes both a simple interface used daily by employees and an administration layer for reviewing events, corrections and reporting.
Problem
What should a good time and attendance system solve?
The terminal must be fast and unambiguous for employees while remaining resilient to network issues and invalid event sequences.
01
Too many steps
Registering a basic event should not require logging in, typing an identifier or completing forms.
02
No network
A temporary Wi-Fi or server outage must not prevent an employee from registering the start of work.
03
Inconsistent events
The system has to detect repeated starts, endings without a start, and incorrectly closed breaks.
04
Difficult reporting
Data should be available both as a clear daily summary and as a monthly report ready for further processing.
Solution
One coherent ecosystem from employee card to monthly report
Each layer was designed for a different task: the terminal for speed, the API for consistency, and the administration panel for control and reporting.
Fast registration
An employee registers a work start, end or break using an RFID card and a single tap.
Data consistency
The backend validates event order and reduces the possibility of storing an invalid sequence.
Offline operation
Losing server connectivity does not block registration. Events are stored locally and synchronized later.
Clear reporting
Administrators receive daily and monthly summaries of working time, breaks and absences.
Employee terminal
An interface limited to essential decisions
The application runs in landscape mode and is designed for a fixed tablet station operated from a short distance.
01
RFID card reading
The USB OTG reader works as a HID keyboard, so the card number is captured without manual input.
02
Three primary actions
After reading a card, the employee chooses work start, work end or break start.
03
Frozen event time
The displayed time is tied to the moment the action is selected and does not change while communicating with the API.
04
Automatic reset
After completing an operation or after inactivity, the interface returns to the card waiting screen.
05
Local event queue
Unsent entries are stored in SQLite and retried after connectivity returns.
06
Employee confirmation
After successful registration the system displays the employee name and the stored event type.
07
Hour balance
The terminal can retrieve and present the current working-time balance for an employee.
08
Error handling
The interface distinguishes connectivity errors, unknown cards, invalid event order and synchronization problems.
Architecture
A modular design that allows the terminal to be replaced
A tablet or any other terminal uses the same server-side business logic. The device layer can evolve independently from the backend.
IdentificationRFID cardA unique number assigned to the employee
Device layerTabletAction selection and event timestamp capture
Application layerSymfony APIValidation, persistence and employee handling
Data and reportsAdministration panelAnalysis, corrections and monthly export
Failure resilience
Losing connectivity does not stop registration
The terminal stores unsent events in a local SQLite database. Once connectivity is restored, the queue is processed again and confirmed entries are removed from device storage.
01
Local registration
Card, event type and timestamp are written to terminal storage.
02
Synchronization attempt
The application retries sending data when the server becomes available.
03
Write confirmation
After the API confirms the event, the local copy is removed.
TerminalSQLite
Synchronization
Symfony APICentral database
Central management
Administration panel based on Symfony and EasyAdmin
The panel manages events, employees, absences and reports without requiring changes to the terminal application.
Symfony + EasyAdmin
One place to control the entire system
An administrator can review the full event history, filter it by employee and date, correct invalid entries and generate summaries used for time settlement.
Event registration through a REST API
Validation of starts, endings and breaks
Leave, absence and administrative events
Filtering by employee, date and event type
Daily start/end and break summaries
Monthly XLSX reports
RCP panel
Administration view for working-time events and employee data.
Reporting
From a single event to a monthly settlement
Data is aggregated into daily summaries and monthly reports including working time, breaks and absence events.
Monthly report
Monthly summary of employee working hours.
Daily summary
First start, last end, working time and total break duration.
XLSX export
A monthly summary ready for further analysis or payroll processing.
Multiple event types
Work, breaks, paid and unpaid leave, childcare, doctor visits and other absences.
Project layers
One system developed as a coherent ecosystem
1
Layer 1
Tablet terminal
A React Native application for a landscape tablet with an external RFID reader connected through USB OTG.
Operational version
2
Layer 2
Backend and admin panel
Symfony stores and validates events, manages employees and generates working-time reports.
Central management
3
Layer 3
Embedded terminal
An alternative reader based on ESP32-PoE, a touch display, RFID and local RTC, designed as a standalone device.
Hardware development
Result
A custom time and attendance system without lock-in to a closed platform
The modular architecture lets the terminal UI, embedded devices, business rules and reporting evolve independently while sharing one central source of data.
