Invert Timer and Full Speed tutorials?

[jhillyerd]

As someone new to embedded development, I found the Run at Full Speed chapter overly dense -- it's likely to scare off folks before they even start. The code contains too many unexplained concepts for someone not well versed in STM32 development. Example: hserdyc and hserdyf are not commented, it's just assumed we understand what they mean.

A more compelling example (if feasible) might be to get the LED blinking slowly at a modulus of the clock speed first, then add the code to run at 72MHz, so that the LED blinks faster.

On a related note, it would be nice if the book included links to the drone-os rustdoc when referencing existing traits and structs.