Raspberry PI must act as a server and a main controller in the network. Raspberry PI must interrogate every ESP8266 board from the network 3-4 times a day about sensor data. Every ESP8266 board from the network must be in the deep sleep mode until interrogation process begins and to return to that state after reporting. To each ESP8266 board a temperature, a humidity or a barometric sensor can be connected (DHT22, DS18B20, BMP180). I am starting this project from scratch. I am a beginner and I need your help ! Thank You !