I2C ain't so bad: simple is as simple does. Vendor implementations and programming models? Those are...more of a challenge.

To change I2C bus speeds in Arduino environments, it turns out you have to set the speed before Wire.begin() is called. If you want to change speed, you have to call Wire.end(), change, and call Wire.begin().

I wrote up some other challenges I hit on my blog:

https://daskunkee.blogspot.com/2021/11/technical-ssd1327-oled-driver-on.html