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Joined: Tue Apr 09, 2019 6:05 pm

Smart Door Lock, making a Pi act as a smart device?

Tue Apr 09, 2019 6:31 pm

Hi Guys 'n' Gals

New here, I've been using the Pi for years but never registered here before. I'm posting really to ask advice about a project. First let me explain what the project is, what I've already done and finally what I want to do. If anyone can help, I'd be very grateful.

The project is an automated door lock. I purchased a generic electronic door locking system. It's nothing more than a bolt really. A box with two bolts that can extend and retract. The bolt engage with a strike on the door frame to lock to door. The unit comes with 5 fobs with two buttons, lock and unlock, and that's all it does.

I took apart one of the fobs and found that the buttons are basically inputs to a small MC, one side of each button goes to the MC and to ground via a 100k resistor. The other side of the buttons both go to the +ve rail via a 10k resistor. There's other stuff around this too, a tranny, a mosfet some caps and a few diodes. I'm assuming this is a "power-down" circuit. The button press charging a cap and turning on the mosfet which then powers up the microcontroller, the cap charge keeps it on until the MC starts up, pulling up the base of the tranny and keeping itself on, it can then turn itself off, by dropping the pull up to the tranny base. In this state it would use virtually no power during inactivity. Which is understandable for a small device with a CR2032 powering it. Anyway I digress. Since the unit uses a CR2032 It was no problem powering it from 3.3V from the Pi, the extra 0.3V didn't hurt it. And wiring up the buttons to a couple if IO pins via two 10K resistors was trivial since the Pi outputs 3.3V IO, this was ideal.

So now the Pi can lock and unlock the door. I then made a simple web server on a DDNS host (my ISP's IPs are dynamic) and give people I want to give access to the property, the web address and a PIN to unlock the door. This is useful as I can track who has come at what time and I can also remotely give and revoke access at any time, as well as remotely unlock the door in an emergency situation for example.

So you may think what do I need help with, well, it's just a thought really, it's not REALLY something that has to be done, but, it would be cool if I could somehow make the whole thing act as a smart home device. So I could say "OK Google, unlock the door". I am going to give something called Prota OS a look, as from what I've seen already, it looks like this might be able to do this. But this post is basically a feel out to people who have maybe used a Pi as a smart device before and could offer any useful tips and tricks on making this happen.

Anyway, thanks for taking the time in reading this.


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Re: Smart Door Lock, making a Pi act as a smart device?

Fri Apr 12, 2019 10:51 am

I have done something similar.

Google and most Home Auto systems will integrate OOB with IFTTT, and there are libraries and SDK's for Raspbian to IFTTT, plus the IFTTT Webhooks service.

Thats the path I would follow, as its the most 'open', secure and applicable to most HA controllers. ... ktop&hl=en
..the only thing worse than a stupid question is a question not asked.

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