Recommended · for beginners
Embedded Systems Programming Lesson 0 Getting Started
Why people recommend it
The opening lesson of Miro Samek's embedded programming course, repeatedly recommended as a solid starting point for learning how microcontroller code really runs.
Watch for: Uses a specific board; low-level concepts reward extra reading
In their words
This Embedded Systems Programming course does not use your exact board and tool chain but it's a good introduction.
kkrambo on electronics.stackexchange.com, Nov 2017. CC BY-SA.