Some years ago I had an older analog intercom and added some intelligence for the open button, ignoring the audio part. Doing it with an ESP01 was trivial and I only needed access to my intercom box inside the apartment. The first issue I ran into was that no matter how much I optimized, the power consumption was high and made the thing semi-useless. Then I got smarter and powered it from the 24V lines coming from the intercom system. That worked great until I realized that where I live this counts as stealing electricity so I scratched that, why take the chance that the building administrator notices something and I get burned.
Eventually I got a Nuki Opener which works with all kinds of intercoms and is way less effort. Janky builds are awesome but better for the playground than as a solution you really want to be reliable for the whole family.
P.S. The code from the article should be linked more prominently [0], for anyone who wants to tinker.
> Janky builds are awesome but better for the playground than as a solution you really want to be reliable for the whole family.
I have it configured with a delayed opening so that it's not obvious, it doesn't require an app, and by the time you reach the door, the guest is almost there.
When I'm done with it, I flip the switch. It's hard to have it more reliable than this for me.
I've been considering smarter iterations for myself, but I didn't find enough time to fix something that is working really well.
> It's hard to have it more reliable than this for me.
For me the main point of unreliability was the power consumption of the ESP while connected to WiFi despite my efforts to lower that in idle. I had no good option to have it plugged in and it would go thorough a battery pack in days. And I had no option for Homekit integration at that time, or anything similar, so everything was done locally over WiFi.
I had a fortunate scenario, living on the ground floor and in WiFi range but if you live 10 floor up, when you reach the building door the only way to reach your device is via VPN. Giving access outside your household was off the table. Every component you add comes with potential reliability issues, and every non-transparent component adds usability issues.
For me this wasn't a way for visitors to get in easier, it was for me and the family to do it conveniently without pulling out the keys, or in case you have no key (lost, locked inside).
The Nuki solved that, all-in-one package, always working connectivity, no additional infra for me to maintain except working WiFi, and easy user management. Just an easy app to control everything from anywhere. Downside is that Nuki has to keep their infra up and running. And it's less fun than building my own jank :D.
Most intercoms I've seen don't need any soldering, you'll usually hook into the existing screw terminals of the intercom unit inside your apartment. The Nuki software comes with wiring "recipes" for many popular intercom models and tells you what to hook where. Sometimes your model isn't recognized so you have to get creative, but nothing crazy. Analog intercoms are easy, at worst you hook in just the wires that trigger the "button push", maybe even the one that detects when the intercom rings and gives you a notification.
But it also supports more complicated setups like digital intercoms where it will hook on the bus and learn the various codes that are sent for different operations, or enable the voice function through the phone app.
The biggest benefit is that if your intercom is compatible, it just works. It's the convenience, not that you can't get the same with a janky solution with enough elbow grease. No need to tinker with the firmware, the batteries last forever, and even in the most basic setup you'll have a few more advanced features.
Eventually I got a Nuki Opener which works with all kinds of intercoms and is way less effort. Janky builds are awesome but better for the playground than as a solution you really want to be reliable for the whole family.
P.S. The code from the article should be linked more prominently [0], for anyone who wants to tinker.
[0] https://github.com/ImTheSquid/doorbell2