MQTT Network Control
As the topic that received the most votes in my recent survey, this video describes how to setup a network in which various puzzle controllers - Arduinos, Raspberry Pis, ESP8266s, and more - can communicate with each other by publishing and subscribing to messages on an MQTT broker. This allows you to monitor the status of puzzles from a central server, or to remotely reset or force-solve them, for example.

You can access the wiring diagram, additional documentation, and code downloads used in this video at

It's quite a long video, and depending on what hardware you're using not all of it might be relevant to you, so here's a guide to jump to the relevant bits!

00:00 - 05:55 Introduction and Demonstration

05:56 - 07:34 Android client demonstration

07:35 - 13:03 Arduino, Wemos, and Raspberry Pi Wiring

13:04 - 20:01 Installing and testing the Mosquitto MQTT server

20:02 - 37:24 Code for Arduino Ethernet and MQTT client

37:25 - 43:05 Code for Wemos WiFi and MQTT client

43:06 - 48:33 Code for Raspberry Pi MQTT client

48:34 - 50:10 Android client (MQTT Dash)

50:11 - 51:12 Wrapup

As ever, please ask any questions or comments below!