ESP8266 (NodeMCU 1.0 ESP-12e) firmware that pulls temperature and humidty data from SI7021 then pushes the data via MQTT to an adafruit IOT endpoint.
Expects "Private.h" to define the following macros:
#define AIO_USERNAME //username for https://io.adafruit.com
#define AIO_KEY //Adafruit MQTT API key
#define WIFI_SSID //Wifi SSID
#define WIFI_PW //Wifi Password
Tested on NodeMCU 1.0, probably works on other ESP8266 boards.