I am working on smart home projects for my house using ESP8266, nRF24L01, Raspberry Pi, Arduino, etc.! So far I have a working MQTT server and an ESP-01 attached to my panfan which gives me local weather stats and will start background audio/music/sea-sounds in adjacent rooms to eliminate embarrassment of the current bathroom user. I have a package due tomorrow from Adafruit to help with this. I also want it to let me know my upcoming appointments from Google Calendar.
My second MQTT device is a Wemos D1 Mini Pro board from Banggood that is (almost) controlling and monitoring my double door steel garage located apart from the house. WiFi is poor inside the garage so I will mount the electronics box on the inside of the steel panelling and use an external elbow rod antenna.
It will be configured to transfer real-time interrupt messages so that vehicles, people or stray animals may be identified. I have this triggered from a IR detector so the beam only activates (using power) when something is near. This saves heaps of 24/7 beam energy (45 mA).