Demystifying the Boot-Up Sequence in Embedded Systems: From ROM to OS

Excerpt from HWE.DESIGN Platform

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Introduction

Standard System Software includes software components that are commonly used in embedded systems, such as:

Boot ROM (Read-Only Memory): Executes the very initial code to start the hardware and then passes control to the PBL.

• Original Function:
  The Boot ROM contains the initial set of instructions that the processor executes when it is powered up or reset. This code is typically burned onto the ROM and is immutable.
• Technical Details:
  The Boot ROM is a small piece of code, usually stored in a non-volatile memory like flash or an actual ROM chip on the device. The instructions in Boot ROM are hardware-specific and are used to initialize essential hardware components like the CPU and memory controller.
• Boot ROM Execution Sequence: Execute Boot ROM→Initialize Hardware→Load PBL

PBL (Primary Program Loader): Takes over from Boot ROM to initialize minimal hardware and then loads SPL.

• Original Function: The PBL is the first program that runs when a processor powers up. It takes over from the Boot ROM to initialize minimal…