Do you want to program microcontrollers down at their no-frills level, where you can get a deeper understanding of how they actually work? This guide written for developers will help you get started using just the GCC compiler and a reference manual. The fundamentals learned here will help you understand better how frameworks such as Cube, Keil, and Arduino do their job. In this two-part-guide, we will use the STM32F429 controller on a Nucleo-F429ZI board, but, what you learn here can easily be adapted to other microcontrollers.