You have an ESP8266 board like the Wemos D1 ... and maybe a pushbutton – the Fritzing diagram shows everything you’d like to know. From there, you have examples on using deep sleep, do ...

There was a new WiFi module on the block. It was called the ESP8266, a simple serial device capable of taking care of an 802.11 network and a WiFi stack, giving any project with a microcontroller ...