I did this ESP8266 project in aim to make my home smarter.
My IOT is a T/H sensor on battery alimentation which communicate in WiFi (Normal it's an ESP8266).
Like everybody knows, WiFi and consumption is not a good melt but it's so userfriendly. To resolve this problem, I used a TPL5110 from TI.
Thanks to this Timer, the sensor can operate during minimum 1 year with uplink all of 1 hour.
My other goal was to do an end design object which I can put in my home.
Finally my challenge was to spend less than 10$ !

More details on following URL :