This project connects an number of inexpensive sensors (light, motion, temperature/humidy so far) to an MQTT broker via an ESP8266 based board. It leverages PlatformIO, and some Arduino libraries.
When starting up for the first time the module will open an access point that you can connect to. Depending the the device that you connect with, it should prompt you to "sign in", which directs your browser to an HTTP server running on the device which exposes a form that you can configure the unit with, including WIFI and MQTT credentials, as well as a poll frequency in milliseconds.
To reset your config, hold the flash button. All settings will be cleared and a new access point will be started, ready for re-configuration.
The MQTT base topic is also configured in this way. Periodic status updates will be sent on this topic for the light and climate sensors. The topic <you-base-topic>/motion will recieve motion updates as they happen, independent of the periodic updates.
pio run -t upload; pio device monitor