API-Based Fingerprint Attendance System
From Hand-Soldered Dot PCB to Custom KiCad Fabrication & Cloud Edge Deployment
Dot-Matrix Perfboard Prototyping
Hand-soldered point-to-point jumper wiring to validate the electrical pinouts, UART timing with the optical fingerprint scanner, I2C OLED communications, and Wi-Fi cloud connectivity.
Custom KiCad Routed Board & Enclosure
Designed custom schematics in KiCad 9.0.0, routed high-speed traces with solid ground return planes, added filtering capacitors, and manufactured a clean industrial-grade board.
Final Hardware Complete Assembled Product Prototype
Fully integrated attendance station featuring ESP32 core, optical fingerprint scanner, 0.96" OLED display, 3 tactile menu buttons, and status indicators.
Final Hardware Complete Assembled Product Prototype
Fully integrated attendance station featuring ESP32 core, optical fingerprint scanner, 0.96" OLED display, 3 tactile menu buttons, and status indicators.
The custom hardware is built around the ESP32-DEVKITC-32E, combining high-speed 240MHz dual-core processing with integrated Wi-Fi and Bluetooth connectivity.
Biometric Sensor
UART CommunicationConnected via Hardware Serial (IO16/IO17) with dedicated Touch/Wake interrupt pin.
0.96" OLED Display
I2C ProtocolSDA on IO21, SCL on IO22 with onboard 4.7kΩ pull-up resistors for glitch-free frame rendering.
Feedback & Alert
Active Buzzer + 3 LEDsAudible confirmation on IO27, with discrete status LEDs (D1, D2, D3) on IO13, IO12, and IO14.
Dual Power Subsystem
DC Jack + USB Type-CCON-SOCJ-2155 barrel jack and Type-C connector with reverse-polarity protection and clean 3.3V LDO step-down.
Embedded Device & Cloud Relay Simulation
Test how the embedded firmware handles optical fingerprint scanning, user verification, OLED frame rendering, and Cloudflare D1 edge database sync:
PLACE FINGER
Waiting for optical sensor...
Simulate mechanical switches for local firmware navigation:
ESP32 Dual Core 240MHz
High-speed processing handling concurrent UART biometric acquisition, Wi-Fi networking, and OLED rendering.
UART Optical Fingerprint Scanner
Hardware serial on IO16/IO17 with onboard DSP matching and dedicated capacitive wake interrupt.
0.96" I2C OLED Display
Glitch-free I2C frame buffer running on IO21 (SDA) and IO22 (SCL) with onboard 4.7kΩ pull-up resistors.
KiCad E.D.A. 9.0.0
Full schematic hierarchy, customized component library, differential trace routing, and certified Gerber packages.
2-Layer FR-4 with Ground Pour
Continuous bottom ground return plane minimizing high-frequency Wi-Fi RF noise and switching ripple.
Active Buzzer + 3 Status LEDs
Discrete audible tones on IO27 and visual indicators: D1 (Power), D2 (Biometric Match), and D3 (Cloud Sync).
3x Tactile Push Buttons
Tactile switches for intuitive local user navigation: Menu navigation, Item increment/Up, and Enter/Confirm.
Dual Power: DC Jack + Type-C
CON-SOCJ-2155 barrel jack and modern USB Type-C connector with reverse-polarity protection and decoupled rails.
Cloudflare Workers (Edge APIs)
Serverless REST microservices deployed across 300+ edge locations for sub-50ms attendance logging.
Cloudflare D1 (Serverless SQL)
Zero-cold-start serverless database providing real-time ACID-compliant attendance audit trails.
SvelteKit Progressive Web App
Responsive real-time dashboard delivering instant daily attendance exports, employee audits, and shift analytics.
SPIFFS Flash Storage Cache
Caches punch transactions locally in ESP32 onboard flash if Wi-Fi network drops, automatically syncing upon reconnect.
Edge-to-Cloud Integration
Unlike standalone offline attendance devices, this hardware seamlessly transmits encrypted punch records via Wi-Fi to a serverless Cloudflare Workers REST API.
Cloudflare D1
Cloudflare D1 serverless SQL stores live audit trails with sub-millisecond edge transactions.
SvelteKit PWA
SvelteKit PWA enables instant admin reporting on mobile devices with live presence metrics.
Offline Fallback
Offline Fallback caches scans in ESP32 SPIFFS memory if Wi-Fi drops, automatically replaying once restored.