BahayShield ULTRA

Offline flood and typhoon preparedness controller for a tabletop home-safety demo.
Arduino Mega 2560 Pro · HC-SR04 · BME280 · TRI scoring · low-voltage relay cut

Overview  ·  Features  ·  Gallery  ·  Quick Start  ·  Structure  ·  License

Contents

• Overview
• Features
• System architecture
• Hardware
• Firmware
• Gallery
• Quick Start
• Project Structure
• Safety
• License
• Course Note

Overview

BahayShield ULTRA is an offline microcontroller system that combines ultrasonic water-level sensing with barometric pressure trend analysis. It computes a Typhoon Risk Index (TRI), stages visual and audible alerts, and can open a low-voltage demo load through a relay when risk stays high long enough.

The demo unit pairs a control enclosure with a house diorama and clear flood tray. It is a tabletop simulation, not a field-installed household electrical product, and it does not switch AC mains.

Controller: final build uses an Arduino Mega 2560 Pro compact module (ATmega2560, CH340 USB, dual-row 100-mil headers). Early breadboard work may use a full-size Mega 2560 form factor; the MCU and IDE board target stay the same (Arduino Mega or Mega 2560).

Features

Feature	Description
Water level	HC-SR04 over a fixed mast; mapped to dry / ankle / knee / waist / critical
Barometric trend	BME280 pressure feeds rolling slope and baseline into TRI
Storm profiles	Habagat, Bagyo, and Flash Flood reweight water vs pressure
Staged alerts	LED bar, alert LED, buzzer cadence, 20x4 LCD
Relay cut	Relay 1 COM-NC on a 5 V demo load; active-LOW coil drive
Operator inputs	PCF8574 4x4 keypad, A1 button ladder, serial commands
Event log	DS3231 timebase + AT24C32 EEPROM with checksummed records
Mechanical stack	KiCad motherboard project, 3D-printed enclosure, HC-SR04 mast

System architecture

flowchart LR
  subgraph Inputs
    US[HC-SR04]
    BME[BME280]
    POT[A0 pressure pot]
    BTN[Buttons]
    KEY[Keypad]
  end

  subgraph Controller
    MCU[Mega 2560 Pro<br/>ATmega2560<br/>TRI + FSM]
    RTC[DS3231 RTC]
    PWR[XL4015 5 V rail]
  end

  subgraph Outputs
    LED[TRI LEDs + alert]
    BUZ[Active buzzer]
    REL[Relay 1 COM-NC<br/>5 V load]
    LCD[20x4 I2C LCD]
    LOG[AT24C32 event log]
  end

  US --> MCU
  BME --> MCU
  POT --> MCU
  BTN --> MCU
  KEY --> MCU
  RTC --> MCU
  PWR --> MCU
  MCU --> LED
  MCU --> BUZ
  MCU --> REL
  MCU --> LCD
  MCU --> LOG

Editable diagrams: docs/diagrams/.
Deeper write-up: docs/overview.md.

Hardware

Block	Part	Role
MCU	Arduino Mega 2560 Pro (ATmega2560)	Final controller; 5 V on 5V pin (VIN unused)
Water	HC-SR04	Distance over diorama tray
Environment	BME280 (I2C, typically 0x76)	Pressure for TRI; temp/humidity for display only
RTC + log	DS3231 + AT24C32	Timekeeping and event log
Display	20x4 I2C LCD (primary 0x27)	TRI, profile, water, pressure, state
Keypad	4x4 via PCF8574 (0x20)	Profile, mute, cut, ack, page
Buttons	3x tactile on A1 ladder	Yellow cut, Blue view, Green ack
Indicators	5 TRI LEDs + alert LED + buzzer	Staged alert UI
Actuator	2-ch 5 V relay module	Relay 1 demo-load cut; Relay 2 spare
Power	USB-C PD source → XL4015 buck → 5.00 V	Fuse + reverse protection on the design
Load	5 V LED strip on Relay 1 COM-NC	Stand-in for a ground-floor branch
PCB	KiCad Rev A motherboard	Headers for Mega 2560 Pro and modules
Enclosure	Printed base, top panel, BME280 cage, mast	Control unit + sensor geometry

• Pin map: hardware/pinout.md
• Power path: hardware/power-tree.md
• BOM: hardware/bom.md
• Wiring: hardware/wiring-overview.md
• PCB project: pcb/
• Enclosure STLs: enclosure/

Firmware

Production sketch: firmware/bahayshield-ultra/

• Non-blocking millis() scheduler
• Fixed-point TRI suited to Mega-class SRAM
• Non-blocking HC-SR04 echo state machine
• Active-LOW relay with confirm window before power-cut latch
• Serial at 115200 baud

Bring-up suite: firmware/bring-up/ (I2C, LCD, keypad, RTC, BME280, relay, ultrasonic, full breadboard integration).

Libraries for production:

Wire
Adafruit BME280
Adafruit Unified Sensor
Adafruit BusIO

LCD and PCF8574 keypad use direct Wire access.

Gallery

Mega 2560 Pro (front)	Mega 2560 Pro (back)

BME280	DS3231 + AT24C32	XL4015 buck

Serial: upload OK	Serial: HC-SR04

Serial: keypad	Serial: LCD I2C

Full set: docs/photos/.

Quick Start

git clone https://github.com/cikeyz/bahayshield-ultra.git
cd bahayshield-ultra

1. Install Arduino IDE or Arduino CLI.
2. Select board Arduino Mega or Mega 2560 (ATmega2560 on the Mega 2560 Pro module).
3. Install Adafruit BME280 and its dependencies.
4. Open firmware/bahayshield-ultra/bahayshield-ultra.ino.
5. Upload with the external load disconnected.
6. Open Serial Monitor at 115200. Confirm I2C devices, LCD, and inactive relay before connecting the LED-strip load path.

Cmd	Action
c	Manual relay cut
a	Acknowledge / reset when safe
v	Cycle LCD page
m	Mute buzzer
1 / 2 / 3	Habagat / Bagyo / Flash Flood
?	Help

Demo script: docs/demo-procedure.md.

Project Structure

bahayshield-ultra/
├── README.md
├── LICENSE
├── .gitignore
├── firmware/
│   ├── bahayshield-ultra/     # production sketch
│   └── bring-up/              # M00-M16 driver tests
├── hardware/
│   ├── pinout.md
│   ├── power-tree.md
│   ├── bom.md
│   └── wiring-overview.md
├── pcb/
│   ├── README.md
│   ├── rev-a/                 # KiCad Rev A + local libraries
│   └── archive/prototype-1/   # early routing baseline
├── enclosure/
│   ├── README.md
│   ├── scad/
│   └── stl/
└── docs/
    ├── overview.md
    ├── demo-procedure.md
    ├── diagrams/
    └── photos/

Safety

• Relay contacts switch a 5 V demo load only. No AC, outlets, extension cords, or household branch wiring.
• Humidity and temperature are display/log context. Pressure is the barometric input to TRI and cutoff logic.
• Storm demos can use the A0 potentiometer for a repeatable pressure curve while BME280 still reports real ambient pressure.
• Verify buck output at 5.00 V, relay active level, and COM-NC continuity before a live demo.

License

MIT. See LICENSE.

Course Note

Built for CMPE 311 (Microprocessor Systems), Polytechnic University of the Philippines, Group 4, A.Y. 2025-2026, under Engr. Rufo I. Marasigan Jr., D.Eng, PCpE. Published here as a standalone project.