Connects to a MQTT server, subscribes to a topic, and sends anything sent to that topic over a serial port (with optional header/trailer added).
Control of projectors and other RS232 commandable devices from something like HomeAssistant.
Written using the ESP8266 Arduino core, and uses PubSubClient for MQTT.
Copy config.example.h to config.h and edit.
For more information, take a look at my blog post on this project