I have a demo/development setup on a small breadboard which powers an ESP-01 ( the small, cheap, 8-pin breakout board for an ESP8266 chip ). In addition to being a programming board, it has 3v3 voltage regulation, a pot, a temperature sensor, a simple LED, and a WS2812 3-color LED. I have the installed ESP8266 running a program to subscribe to an MQTT broker and light the LEDs according to publications on a certain topic.
I’ve developed another small program which listens to a 115200 baud serial connection and accepts JSON messages which instruct it to connect to a WiFi, to publish values to an MQTT topic, or to subscribe to an MQTT topic. It is intended as a general-purpose glue service for an otherwise dumb microcontroller to communicate with remote telemetry.
I have also a Teensy 3.1, which supports capacitive touch sensing, interprets the values as control signals, and via the text-to-MQTT glue service publishes them, whence they will control the aformentioned LEDs. The program that does this is also on Github.
It all works, sort of. I’m considering it to be at the late-alpha stage of development.