A field-deployed residential deep-well pump and water-tank controller I designed, built, and installed in Iloilo, Philippines. It is an operating prototype, not a commercially certified controller.

• Two-node controller — An ESP32 master and ESP8266 tank node exchange framed telemetry over an approximately 40 m RS-485 link with CRC validation and freshness checks.
• Local safety gates — Hardware protection, firmware lockouts, dry-run detection, emergency stop, and maximum-runtime controls keep shutdown decisions local when cloud connectivity is unavailable.
• Native Android client — Kotlin and Jetpack Compose provide BLE provisioning, real-time telemetry, AUTO/MANUAL/COUNTDOWN control, diagnostics, and activity history through Firebase services.

Repository · Live demo

A personal coursework prototype for boarding houses and shared residences, designed around bed-level occupancy, contract lifecycles, metered utilities, and database-level auditability.

• Bed-level occupancy engine — Atomic reservation states and prorated utility rollover calculation across shared meter configurations.
• 45 forensic database triggers — Tamper-resistant, immutable before/after JSON state diffs that run independently of application code — zero-trust at the database layer.
• Read/write database topology — MySQL 8.4 primary-replica replication, idempotency protection for mutations, and Docker Compose-based local orchestration.

Repository · Live demo

A personal coursework prototype that models a real laundry workflow with order automation, reporting, and customer-facing tracking.

• Custom dynamic pricing engine — Computes laundry loads by weight, applies configurable service rates, and price-snapshots each order at creation for historical integrity.
• QR-code customer portal — Customers scan the QR on their thermal receipt and see live order status on a public Vercel portal. No login required.
• Offline-first Windows installer — Inno Setup provisions PostgreSQL, configures a WinSW background service, and writes application configuration without requiring developer tools on the target machine.

_Languages

_Frontend

_Backend

_{Database & DevOps}

_{Tools & Platforms}