Intrusion & Alerting Flow

The Challenge

Standard motion sensors generate too many false positives (pets, sunlight, shadows F***** moths and spiders). The goal of this project was to create a "Confirmation Logic" in Node-RED that requires input from multiple sources before triggering a high-priority alarm.

System Architecture

• Input: PIR Sensors (HC-SR501), Door/Window Contacts (Wired/Shelly), Router Presence (FritzBox).
• Logic: Node-RED flow running on Docker.
• Output: Telegram Bot (Critical Alerts), Ip Speaker for Alarm sound and Light control (via Node-Red controlling Shellys.

Logic Snapshot

The system uses a "state machine" approach. It doesn't alarm immediately; it enters a "Pre-Alarm" state to check for corroborating evidence and the presence of trusted devices/people in the house.

var devices = context.get("devices") || {};
var deviceName = msg.payload.NewHostName || "Unknown Device";
var isOnline = msg.payload.NewActive === "1" || msg.payload.NewActive === 1;
var wasOnline = devices[deviceName] || false;

// Update device list
if (isOnline) {
    devices[deviceName] = true;
} else {
    delete devices[deviceName];
}
context.set("devices", devices);

// Get current device count
var allDevices = Object.keys(devices);
var armSystem = allDevices.length === 0; // Arm only when all devices leave
var messages = [];

// ✅ Goodbye message only when a device actually leaves
if (!isOnline && wasOnline) {
    var message = `👋 Goodbye *${deviceName}*!`;

    if (!armSystem) {
        var remainingDevice = allDevices.join(", ");
        message += `\n🏠 System will NOT arm because *${remainingDevice}* is still home.`;
    } else {
        message += `\n🔐 *All devices have left! Arming the system in 30 seconds...*`;
        messages.push({ payload: 911 }); // Send arm signal
    }

    messages.push({
        payload: {
            chatId: "Your Telegram Chat ID",
            type: "message",
            content: message,
            parse_mode: "Markdown"
        }
    });
}

// ✅ **NEW: Welcome message when a device connects**
if (isOnline && !wasOnline) {
    messages.push({
        payload: {
            chatId: "Your Telegram Chat ID",
            type: "message",
            content: `👋 Welcome back *${deviceName}*! \n🔓 I disabled the alarm for you.`,
            parse_mode: "Markdown"
        }
    });

    messages.push({ payload: 912 }); // Send disarm signal
}

return messages.length > 0 ? messages : null;
 // Output 1: CRITICAL ALARM
    } else if (pirActive) {
        return [null, msg]; // Output 2: Warning / Record Cam
    }
}
return null;

Visuals

The flow handles arming, disarming, and snapshot capture from the door camera.