Smart things, the Internet of Things (IoT) gets a lot of talk these days but connected devices and objects can play a big part in what makes a smart home smart.
I made my first “smart” doorbell in 2004, this used a modified X10 RF keyfob with a standard door bell push button connected to the two traces on the pcb that operated button 2 ‘on’. Pressing the doorbell then sent an X10 signal to Misterhouse which announced through the speakers that there is someone at the door and logged it to a file. When I was out (known from the entry/exit status) it also sent an sms text message to my mobile phone using the now defunct vgsmail.
In 2011 I replaced this system with a Nanode based system that sent a message to Twitter when the doorbell is pressed, I had twitter set up to send me a text message when that account tweeted me @nathanchantrell so that messages were free.
I’ve since changed this to use one of my TinyTX boards which is received by Node-RED running on my Debian server. When the push button is pressed the system will send a message to my phone via Notify My Android and a notification to my Pebble smartwatch in all cases, additionally if I am at home it will speak a message and display a message on the LED matrix sign. I use the Notify My Android priorities so the notification on my phone plays an old fashioned doorbell sound which is a nice addition and the message also includes a link to view my front door camera so it’s only a tap away.
A TinyTX with a magnetic contact sensor on the fridge door sends open and close signals to Node-RED which will alert me if the door has been left ajar, something that seemed to happen all to often so this has been a really useful addition. Additionally it is also used for presence detection as if the fridge door has been opened someone must be there (the cat hasn’t worked that out yet but give him time).
I added a microswitch and a TinyTX to an internal letterbox flap so that I can get alerts when I get mail and can also alert if the letterbox is left open, eg. if something has been left sticking out instead of being pushed all the way through. I wrote a blog post about this here.