What is Startup Code and What is its Role in Embedded C Programming?

What is Startup Code?

Startup code is the set of code that is executed when an embedded C program is launched. The startup code serves multiple purposes, including setting up the run-time environment, initializing system registers, and performing hardware-specific configuration. It is a crucial element of the embedded development process; it defines how the system will behave in its initial state and is responsible for starting the user-defined code.

Role of Startup Code in Embedded C

1. Reset initialization: The startup code initializes the microcontroller's system registers and sets the default values for the CPU and peripherals. This includes setting up the stack pointer and heap memory, configuring the clock source and frequency, and enabling/disabling interrupts.

2. Copying code and data to memory: The startup code copies the application code and initialized data from non-volatile memory (such as ROM) to volatile memory (such as RAM), where they can be executed by the microcontroller's CPU.

3. Calling main(): Once the initialization tasks are complete, the startup code transfers control to the application's main() function, which is responsible for executing the main logic of the embedded application.

Startup code is typically written in assembly language or a low-level programming language like C, and it is specific to the microcontroller and development environment being used. The startup code is often included in a pre-written library or provided by the microcontroller manufacturer as part of a development kit.

In summary, startup code plays a critical role in Embedded C programming as it initializes the microcontroller's hardware resources and sets up the runtime environment for the embedded application to execute. Without proper startup code, the microcontroller would not be able to function correctly or execute the application code.