Wave box

IoT Power & Sensor Control System

📘 Overview

This project is a modular IoT system built on Arduino Mega / STM32 / ESP32, integrating multiple sensors and actuators with a web-based control interface.
It supports Ethernet communication (static or DHCP), relay/device control, and sensor monitoring, with configuration stored in EEPROM.

📂 Project Structure

• Schematics: schematic/schematic.pdf
• PCB Layout: (to be inserted here — export from KiCad)
• Firmware: src/ directory, modularized by peripherals, network, and utilities

📐 Schematics

In schematics folder whole KiCad's project is available. Also the full circuit design is available in PDF format:

📄 View Schematics

(exported from KiCad)

📑 Bill of Materials (BOM)

⚡ Firmware Structure

src/
├── config.h // Pin definitions, constants
├── globals/ // Global structs & variables
│ ├── globals.h
│ ├── globals.cpp
├── peripherals/ // Sensors & actuators
│ ├── sensors.h / .cpp
│ ├── basic_peripheral.h / .cpp
│ ├── poe_device.h / .cpp
├── network/ // Ethernet + HTTP
│ ├── ethernet_server_class.h / .cpp
│ ├── routes.h / .cpp
├── utils/ // Helpers
│ ├── fan_controller.h / .cpp
│ ├── env.h / .cpp // EEPROM config persistence
├── main.cpp // setup() + loop()

Typical Flow

• Global Declarations

  • All peripherals (relays, PoE devices, fan controller, etc.) are declared in globals.cpp.
  • Corresponding extern references are exposed in globals.h.
  • This way, objects are globally accessible across the codebase.

• setup()

  • Initializes the global objects declared in globals.cpp.
  • Configures network stack (DHCP or static IP, based on saved settings).
  • Loads configuration parameters (e.g., password, IP) from EEPROM via env.

• loop()

  • Uses the global objects (no new declarations here).
  • Handles Ethernet server requests and routes.
  • Calls sensor read functions (sensors are already objects provided by their libraries, e.g. DHT, BMP280, DS18B20).
  • Applies control logic for relays, PoE devices, and fan.
  • Updates and persists runtime data (e.g., energy usage) into EEPROM when needed.

🌐 Network & Web Interface

Features

• Supports DHCP or Static IP (configurable).
• Web interface requires a password (?pwd=your_password).
• Wrong password attempts are logged in the Serial Monitor (shows correct one).
• Configurable parameters via web form:
  • DHCP toggle
  • Static IP / Mask / Gateway
  • Password change
• Config changes are saved to EEPROM → requires manual device restart.
• Reset available via web UI (watchdog reset).

Key Routes

Example Access

http://device_ip/?pwd=my_secret

📝 Notes

• After changing network/password settings, you must restart the device.
• To use static IP, set DHCP = false and configure IP, mask, and gateway.
• All updates are persisted in EEPROM.

🌐 HTTP Routes

The project uses a custom HTTP routing system in routes.cpp.

Route Structure

Each route is defined as a Route object with:

• Path – the URL endpoint (e.g., /system_toggle)
• Handler – lambda function (String requestPath, IPAddress clientIP) that returns a string
• Content Type – "text/html" for pages, "application/json" for API

Example: Simple Route

Route("/hello", [](String requestPath, IPAddress clientIP) {
    Serial.println("Hello route called from IP: " + ipToString(clientIP));
    return String("Hello, World!");
}, "text/plain"),

🌐 API Routes

The project has two types of routes:

1. Web pages – return HTML for control/status/configuration.
2. API endpoints – return JSON with sensor/device states.

📝 Notes

• Web pages (/ and /reset) require password via ?pwd=YOUR_PASSWORD and return HTML.
• API endpoints return JSON with the current state, example:

{
  "system": {
    "isOn": true,
    "power": 12.34
  },
  "poe": {
    "device1": {"isOn": true, "power": 1.23},
    "device2": {"isOn": false, "power": 0.00},
    "device3": {"isOn": true, "power": 0.56},
    "device4": {"isOn": false, "power": 0.00}
  },
  "sensors": {
    "tempInside": 24.50,
    "tempOutside": 22.30,
    "humidity": 55.30,
    "pressure": 1013.20
  }
}

💾 EEPROM Management

The project uses an Env class (env.h / env.cpp) to handle persistent configuration and energy logging.
EEPROM is limited in write cycles, so special care is taken to extend its lifetime.

🔹 Configuration Storage

• A magic byte (0xAB) is used to check if EEPROM is initialized.
• Stored parameters include:
  • DHCP flag
  • MAC address
  • Static IP, Gateway, Subnet
  • Password
  • Ping IP
• On startup, Env::load() checks if EEPROM is valid:
  • If not, defaults are applied and then saved.
  • If valid, all values are read and applied.

🔹 Energy Data (Power Slots)

Because power measurements are updated very frequently, saving them directly to EEPROM would wear it out quickly.
To prevent this, the project uses a slot-based circular buffer:

• EEPROM space 100 → 511 is divided into slots.
• Each slot contains:
  • Marker (0xABCD = valid, 0x0000 = empty)
  • Energy value (float, Wh)
• When saving:
  1. The last used slot is cleared.
  2. Data is written into the next slot.
  3. Wraps back to the start if end is reached.
• This way, writes are distributed across many slots, dramatically extending EEPROM lifetime.

🔹 Key Functions

• Env::loadPowerFromEEPROM() → Reads the last valid saved energy value.
• Env::savePowerToEEPROM(float energy) → Stores the latest energy measurement into the next free slot.
• Env::debugEEPROMPower() → Dumps all EEPROM slots to the Serial Monitor for debugging.

✅ Benefits

• Protects EEPROM from early wear-out.
• Ensures configuration and energy data survive restarts.
• Allows debugging of power history in raw EEPROM memory.

⚙️ PlatformIO Configuration

The project is built using PlatformIO.
Below is the configuration from platformio.ini:

[env:megaatmega2560]
platform = atmelavr
board = megaatmega2560
framework = arduino
monitor_speed = 115200
lib_deps = 
    adafruit/Adafruit NeoPixel@^1.15.1
    Wire
    LiquidCrystal_I2C
    adafruit/DHT sensor library@^1.4.6
    adafruit/Adafruit Unified Sensor@^1.1.15
    adafruit/Adafruit BMP280 Library@^2.6.8
    https://github.com/adafruit/Ethernet2.git
    https://github.com/NicksonYap/Arduino-Ping-W5500.git
    bblanchon/ArduinoJson@^7.0.4
    https://github.com/RobTillaart/ACS712.git
    paulstoffregen/OneWire@^2.3.7
    milesburton/DallasTemperature@^3.11.0