I just made a alarm that sends a twitter message to your Phone/Tablet when someone enters a room.
The electronics are simple: just a NodeMCU with a control led and a PIR.
Basic program is just 16 lines of code !!!!
That is right 16 lines of code is enough to detect a movement with a PIR and send a message to twitter !!!!
Well.... the message is send to IFTTT which send a message to twitter. Nevertheless amazing.
Find the project here:
http://lucstechblog.blogspot.nl/2017/05 ... ifttt.html
Complete with source code, breadboard layout, schematics and STL file for printing your own casing.