Low-Cost Resident SOS Alert System
Build a low-cost and self-hosted SOS alert system for residential communities using ESP32, MQTT, Node-RED, Firebase, and Cloudflare.
Send real-time emergency alerts between residents and security personnel without the need for a monthly VPS rental.
A resident selects an emergency message from the Android SOS application.
The application sends the alert to the self-hosted server through an API.
Node-RED processes the incoming message and identifies the appropriate resident topic.
The alert is published to the ESP32 alert box through MQTT over Secure WebSocket.
The alert box displays the emergency message on the LED Matrix and activates the rotary warning light and buzzer.
Firebase Cloud Messaging sends the notification to other residents subscribed to the same topic.
The emergency event is stored in the database as a log.
After the alert has been acknowledged, the security guard can press the reset button to return the alert box to standby mode.
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