@jimmie In the thread you link to your post the authors use SPI for SSD1306 LCD, if you need code to use your LCD via IIC here you can found informations https://forum.pycom.io/topic/3900/object-with-buffer-protocol-required I sugest you to explain if the both component are on the same IIC bus pin or not, and if you have already selected a tsl2591 python library to use with your project. After these two step done we can help you to modify one or both library to work on the same i2c instance. (if you have different i2c bus it's very simple).