The mobile phone seems to be the only thing we need to carry around with it replacing everything from ATM cards to boarding passed to transport tickets….well mobile phone and house keys, and most of us already have the hardware in place to go keyless. Intercoms.
I was able to build a working PoC in a few days using things I had laying around which consists of a ESP266 device connected to Google IoT cloud and a web app containing the pattern lock.
When a pattern is entered in the web app, it’s hash is sent to a cloud function via a REST API.
If the pattern matches a known hash, the function will send a message via Google cloud IoT to the ESP device to set the pin high for 1 second.
The ESP device is wired as per below, setting pin 1 high would switch on the MOSFET which would drive the relay to short the wires of the intercom button.
And finally, video
and code: https://github.com/chris-gunawardena/doorbell-demo