The Right Start

Abstract

The startup code is called by the microcontroller hardware after reset and is the first code to execute before calling the

subroutine. The startup code predominantly consists of initialization code and may include, among other things, CPU-initialization, zero-clear RAM initialization, ROM-to-RAM static initialization and static ctor call initialization. The compiler’s default startup code is often tightly bound to the compiler’s runtime libraries and may not be available as source code. In addition, even if the source of the startup code is available, it can be hard to understand because it may be written in assembly and cluttered with a multitude of options required for supporting a variety of chip derivatives. This chapter describes how to implement a custom startup code and its initializations written predominantly in C++, from reset to

.