Excellent… driving the inputs and looking at the data is one part I skipped in my testing 
And yes, slowing that ADC clock way down is the way to go once you’re trying to make real measurements… better to tune later from a low setting, than puzzle why readings don’t make sense from a fast setting.
Yes, I was a bit slack documenting some of the more mundane stuff. In my main.h I’d added the following, but didn’t mention it in the tutorial:
/* USER CODE BEGIN Includes */
#include <stdbool.h>
#include <inttypes.h>
/* USER CODE END Includes */
I think you’re correct, there’s no mention of ADC self calibration in the reference manual for your processor (RM0368). When I copied some of my old F091 ADC code to kickstart this F303 demo, I noticed there was a second parameter to that function on the F303. I just had a look at your stm Arduino pointer above and they’ve ifdef’d that call based on CPU type to 3 variants… 1 argument, 2 arguments, and no call at all.
And if you want to avoid the walking-across-the-screen syndrome without the \r on the end of all your strings, minicom has a ‘U’ option to automatically add a CR:
