An installation guide for the MQTT API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
All published payload to an from the MQTT bindings is in the JSON format.
If an error occures, the bindings publish a JSON object containing the error message as attribute "_ERROR". It is published on the corresponding response topic: .../response/... for .../request/... and .../callback/... for .../register/....
Sets the r, g and b values for the LED. Each value can be between 0 and 255.
Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.
The position can be 'a', 'b', 'c' or 'd'.
The device identifier numbers can be found here. If symbolic output is not disabled, the device identifier is mapped to the corresponding name in the format used in topics.
The display name contains the RGB LED's name in a human readable form.