An ESP8266-based Smart Smoke Detector that REALLY runs on batteries
Channel: Martin Ger
Date: 27/03/2017

In this video a cheap standard smoke detector is upgraded with an ESP8266 WiFi-chip to make it smart. The project integrates the smoke detector device into the IoT for less than 15€/$ overall costs. 

The project is based on a feature of nearly any smoke detector circuit (e.g. the MC145010 or the CS2105G0-M12), namely the I/O pin, that it typically unused in cheap devices. It can be used to power up an ESP only in an alarm situation (or when the test button is pressed). Thus, the whole WiFi circuit doesn't draw any additional current during standby, therefor it runs on batteries for month's and years. 

In addition, the basic safety critical functionallity of a local alarm with the build-in horn remains completely untouched.

See the video for details.

The software is rather basic for the moment: Just a simple MQTT publisher with hardcoded adresses. It is not even worth publishing: just take the basic MQTT publisher sample from the Arduino environment and you are done. A switch that powers up the ESP for configuration (should pull up between the diode and the resistor), a Web interface for setup and OTA-updates would be perfect, but as there are many frameworks for that out there, this was not the main focus here. It is rather a PoC of a really battery power IoT device (for less than 5$ additional costs).