“Hey! Don’t Lock the Door, I’m in Here!”

Those that work in front of a computer for a living spend most of the time making very little sound. Unless you’re a member of the clicky mechanical keyboard club, your working time is a low-observables time during which people can forget about you. You can make sure you’re not overlooked with this smartphone hotspot presence detector.

[Emilio Ficara]’s quiet work habits resulted in his housemates locking him in sometimes, to his inconvenience. PIR or microwave occupancy sensors might have worked to fix the problem, except that a few flexing fingers aren’t always enough to trigger them. Luckily, [Emilio] is also wisely distrustful of free WiFi, so his phone is always set up as a mobile hotspot, giving him the means to reliably detect his presence. An ATtiny2313 and an ESP-01 do the business of polling for the SSID of his phone and blinking a bright blue LED by his door for his housemates. It’s not perfect, of course; it could easily be spoofed by anyone else who knows his SSID. But simple works for now.

With almost everyone carrying one now, smartphone detection is a good proxy for the presence of a person. But it doesn’t work in every case, so you may want to familiarize yourself with the aforementioned PIR and microwave methods.

24 thoughts on ““Hey! Don’t Lock the Door, I’m in Here!”

    1. Probably in Europe then. US building codes have dictated no key to open on interior locks for safety for pretty much forever at this point. (American forever is shorter, mostly going back as far as the post-war housing and building boom, maybe the 20’s or 30’s at the most)

      1. Yet insurance gives discounts or requirements for having double locked dead bolt locks on all exterior doors. It keeps a window entry from becoming a quick door exit with the big screen TV.

    2. We’ve had it happen at work… boss was leaving and went into auto-pilot mode, locked the front door and put the bolt through without thinking. Locked an employee in the building in the process.

      The bolt is not accessible from inside, nor are there any windows that can be opened to drop a key down to someone.

        1. In my state, wage law violations are both a civil and criminal matter – the executives of the company can be criminally charged, and employees can also independently seek civil court action.

          Check into your area’s wage laws…

    3. Why hasn’t he got his own key? What sort of house is this? If I paid rent I’d want a damn key! This needs a less-technical, more getting-shirty-based solution for his housemates.

  1. How does that solve the problem of your roommates being assholes though? If they’re gonna be too inconsiderate to really check, then all the indicators in the world won’t fix it.

  2. Seems to me that this would be better for stalking people.
    On a more serious note, one could build this into a home automation machine to detect the presence of its users a la startrek 2nd gen com badge style!

    1. My home automation does just the reverse. My router gives my and my wife’s phones fixed IP addresses. The home automation then pings the phones periodically to decide if we’re present or not. Used to work great, but the newer Android on our new phones is very aggressive about shutting off WiFi when the phone is idle (and not on charge), even if I check the box to stay connected. This also makes WiFi calling almost useless for incoming calls. :-(

  3. What a genius idea ! Now I understand better that Michelangelo reference as a front picture of the original italian blog ! :D ESP8266 and blinking a LED to solve real-life hipsters problems (locked in an AirBNB) earns it a well-deserved Hackaday article.

    The guy not only has soldering skills up to this bold task, he even provides a full schematic, and ready-to-use software too : a pre-compiled binary firmware for the ATTINY (thats sends two AT commands over serial and read the response to turn on a LED) and a 400KB Windows-executable just to edit the SSID inside the former file. No source code and tedious compilation required ! Kudos, and thank you ever so much for reporting such great stuff here ! :D

  4. I fail to understand the meaning of these microcontroller + ESP8266 combinations… Compared to a 20 MHz 8-bit AVR, ESP is a powerful 80 MHz 32-bit architecture. So why not just do everything on an ESP?
    What’s the point that this is so polular? Can someone enlighten me?

    1. People use what they know how to use.

      I just made a network-attached IR blaster for controlling my TV, FireTV, Xbox One, and Roomba (via Alexa and/or SmartThings). I built it using a Raspberry Pi, but very nearly put an atmega on a shield just to handle the IR send/receive. Setting this up on the RPi was way harder than it needed to be, while the arduino library was just so easy to setup. In the end, I got it working with LIRC, but honestly, any changes I make are going forward are going to take more effort to implement than if I had just slapped an atmega on top (or arduino via USB even).

      1. You can program the ESP using the exact same IDE as arduino. Literally just about the exact same code to do the same job as you would do on the arduino, then connect to the corresponding GPIO pin on the ESP. Every time i see a project where an ESP is connected to an arduino or some other microcontroller I just have to shake my head in shame. It probably takes more code and more complication to make the arduino poll the ESP with AT commands than it would have to just put everything on the ESP to begin with.

    2. Every approach is good to get a working solution. Believe me, I often read someone that writes the same question; I also often read some people saying: “he doesn’t know any other way to do it”. Well, in my opinion, using multiple processors that cooperates to achieve a result, is the only way to realize a true “parallel computing”. I like very much to put together many different small processors, as they were bricks of a game. The result is often bigger than the sum of the single parts. Anyway, I perfectly know that this (and many many others) simple task can be programmed directly into the ESP8266 itself. I’m used to work with different languages and systems, but I create such small projects in my free time, just for fun. I like to play and this is a game :)

  5. I was wondering about using just the ESP8288-esp01. Not looking at the code, yet, I don’t know if it will fit within the ESP01. I’ve done enough with them that I think it should. Also, being on dial-up I haven’t read all of the information about this yet. I have to go to rehearsal tonight. I hope to have time tomorrow.
    I do have a question though, does Noisy Keyboard mean one like the one my daughter and her boyfriend gave me as a gift? IBM Model M. Clickety Clack! And my wife thinks the keyboard on my laptop is noisy. :-D

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