You have an ESP8266 board like the Wemos D1, a Li-Ion battery, you want to build a small battery-powered sensor that wakes up every few minutes to do something, and you don’t want to delve into ...

Which is how this ESP8266 sensor gadget from [Josef Adamčík ... Currently [Josef] has an SHT21 humidity/temperature sensor and a BH1750 light sensor slotted into the headers on the top side ...