Adapting Legacy Callbox System for a 'Smart Home'
This is a draft post.December 2020
This is slightly different from my previous project (a few years back) where I wired up a simple relay circuit to open the front gate remotely.
I have a callbox that calls a registered number for an authentication whether to let someone into the building or not. The authentication flow is simple – the callbox makes the call and waits for a specific DTMF tone on the line, and if it’s received hangs up and sends the ‘open’ signal to the door.
This is a convenient feature, it works for deliveries, and it works for the times I don’t have keys on me, but instead have my phone. Sometimes though, I don’t have my phone on me either – you see where this is going.
TL;DR: I built a wrapper around this legacy callbox system that allows me to define the authentication flow in software.
- Given the problem, identify solutions