Ency - Smart Power Automation

Ency is a full-stack IoT solution that automates room power using Bluetooth Low Energy (BLE) proximity detection and motion sensing. It consists of a React Native (Expo) mobile app with native Kotlin background services and an Arduino hardware controller.

Features

• Hybrid Sensor Fusion: The system uses an "OR" Logic Gate approach. Lights stay on if any of these are true:

  1. Phone is in the room (BLE Ping).
  2. PIR Sensor detects major movement (Walking).
  3. Radar Sensor detects subtle movement (Breathing/Typing).

• Deep Sleep Resilience: Uses a custom Kotlin Native Module with a partial WakeLock to bypass Android battery optimizations, ensuring the phone keeps pinging even in "Doze Mode."

• Jitter-Free Servo Control: Custom C++ logic attaches the servo only during movement and detaches immediately after to prevent mechanical buzzing and noise.

Hardware Tech Stack

Microcontroller: Arduino Uno R3

Communication: HM-10 BLE Module (CC2541)

Actuator: SG90 Micro Servo (Mechanical Switch Control)

Sensors:

RCWL-0516 (Doppler Microwave Radar - for subtle movement)

PIR Sensor (HC-SR501 - for major movement)

Circuit Diagram

graph TD
    %% --- COMPONENT DEFINITIONS ---
    subgraph Controller [Main Controller]
        Arduino[Arduino Uno R3]
    end

    subgraph PowerGroup1 [Shared Power Line 1]
        Servo[SG90 Servo]
        HM10[HM-10 BLE]
    end

    subgraph PowerGroup2 [Shared Power Line 2]
        PIR[PIR Sensor]
        Radar[RCWL-0516 Radar]
    end

    %% --- LOGIC CONNECTIONS (Blue Wires) ---
    Servo -- "Signal -> D9" --- Arduino
    HM10 -- "TX -> D10" --> Arduino
    Arduino -- "D11 -> RX" --> HM10
    PIR -- "OUT -> D2" --> Arduino
    Radar -- "OUT -> D3" --> Arduino

    %% --- POWER TOPOLOGY (Red/Black Wires) ---

    %% Group 1 Splice (Servo + BLE)
    Arduino == "5V Shared A" ==> Splice1_VCC[Wire Splice A]
    Arduino == "GND Shared A" ==> Splice1_GND[Wire Splice A]
    Splice1_VCC ==> Servo
    Splice1_VCC ==> HM10
    Splice1_GND ==> Servo
    Splice1_GND ==> HM10

    %% Group 2 Splice (Sensors)
    Arduino == "5V Shared B" ==> Splice2_VCC[Wire Splice B]
    Arduino == "GND Shared B" ==> Splice2_GND[Wire Splice B]
    Splice2_VCC ==> PIR
    Splice2_VCC ==> Radar
    Splice2_GND ==> PIR
    Splice2_GND ==> Radar

    %% --- STYLING ---
    %% Logic Lines (Blue)
    linkStyle 0,1,2,3,4 stroke:#2196F3,stroke-width:2px;

    %% Power Lines (Red for VCC, Black for GND)
    linkStyle 5,7,8,11,13,14 stroke:#ef5350,stroke-width:3px;
    linkStyle 6,9,10,12,15,16 stroke:#333,stroke-width:3px;

    style Arduino fill:#00979C,stroke:#333,stroke-width:2px,color:white
    style HM10 fill:#00509d,stroke:#333,color:white
    style Servo fill:#4CAF50,stroke:#333,color:white
    style PIR fill:#ff9800,stroke:#333,color:white
    style Radar fill:#ff9800,stroke:#333,color:white

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Pin Configuration

Component	Pin Label	Arduino Pin	Notes
SG90 Servo	Signal (Orange)	D9	PWM Control
	VCC / GND	5V / GND	Shares wire with HM-10
HM-10 BLE	TX	D10	Connects to Arduino RX
	RX	D11	Connects to Arduino TX
	VCC / GND	5V / GND	Shares wire with Servo
PIR Sensor	OUT	D2	Trigger 1
	VCC / GND	5V / GND	Shares wire with Radar
RCWL-0516	OUT	D3	Trigger 2
	VIN / GND	5V / GND	Shares wire with PIR

Arduino Firmware Logic

The firmware is written in C++. It handles the physical actuation and acts as the central decision maker.

1. Decision Algorithm

The loop runs continuously and checks three inputs. If ANY input is high, the timer resets.

if (phoneStatus || (pirStatus == HIGH) || (radarStatus == HIGH)) {
    // 1. Reset the timer
    lastHeartbeatTime = millis();

    // 2. If the light is OFF, turn it ON
    if (!currentDormState) {
        onSwitch();
    }
}

2. The Timeout (Watchdog)

If the user leaves the room (Phone disconnects) AND no motion is detected for timeout duration, the system saves energy.

// If light is ON... and Time > timeout duration and No Sensors Active...
if (currentDormState) {
    if ((millis() - lastHeartbeatTime > TIMEOUT_DURATION) && (pirStatus == LOW) && (radarStatus == LOW)) {
        closeSwitch(); // Turn OFF
    }
}

3. Noise Reduction (Servo Detach)

Cheap servos (like the SG90) often "jitter" or hum when holding a position. The code fixes this by cutting power to the signal pin once the movement is done.

void onSwitch() {
  switchServo.attach(SERVO_PIN); // Connect
  // ... Move Servo ...
  delay(100);
  switchServo.detach(); // Disconnect immediately to stop noise
}

App Architecture

This project moves beyond standard React Native limitations by implementing a Bare Workflow with native modules.

The Problem Standard Android apps kill background JavaScript tasks after a few minutes to save battery. This caused the lights to turn off unexpectedly when the phone was in the pocket.

The Solution: SmartSwitchService.kt Wrote a custom Native Android Service in Kotlin that handles the connection independently of the JS thread.

Handover Protocol: The React Native UI handles the initial scan and pairing. It then passes the MAC address to the Native Module.

Foreground Service: The app launches a High-Priority Foreground Service (visible via the "Active Apps" menu).

Partial WakeLock: The service acquires a PARTIAL_WAKE_LOCK, forcing the CPU to stay awake for the 15-second heartbeat loop, even if the screen is off.

Auto-Recovery: If the Bluetooth connection hangs (e.g., user walks out of range), a custom withTimeout coroutine forces a reset, ensuring the app reconnects instantly upon return.

Installation & Setup

Prerequisites

Node.js & npm

Android Studio (with SDK 34 installed)

Arduino IDE

Steps

Clone the Repository

git clone https://github.com/pranava-mohan/ency.git
cd ency

First upload arduino/hm10_setup/hm10_setup.ino to the Arduino Uno R3.

Then upload arduino/ency_beacon/ency_beacon.ino to the Arduino Uno R3.

Install Dependencies

React Native app folder is ency-app

npm install

Build the Native Client Note: You cannot use "Expo Go" because this project contains custom Native Code.

npx expo run:android