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Bootloader

Introduction

Overview

Terminology Definitions

terminology	definitions
CRC	Cyclic Redundancy Check
IMAGE	Binary File
MAC	Medium Access Control
QFLASH	Quad-SPI Flash
RAM	Read-Write Memory
ROM	Read-Only Memory
SECBOOT	Second Boot
UART	Universal asynchronous receiver-transmitter
MB	Mega Byte
KB	Kilo Byte

Bootloader Flowchart

Bootloader Functionality

Description of Bootloader Functionality

IMAGE Boot Part

QFlash Working Mode Switch

For unknown Flash manufacturers, when switching from ROM to QFlash, it is necessary to switch the QFlash working mode: from single-line mode to quad-line mode.

IMAGE Integrity Check(CRC32)

Perform a CRC check on the IMAGE header;

Perform a CRC check on the contents of the IMAGE.

After this check, subsequent actions are performed on the boot code.

Perform a signature check on the entire IMAGE.

Code Decompression

To save space, customers may compress the code. Based on the compression algorithm used, the code is decompressed. It is necessary to consider which compression and decompression algorithms are used, as well as the compression ratio. Only the GZIP algorithm is supported.

Code Relocation

The decompressed code needs to be placed in the specified running position, determined based on the header information of the IMAGE.

Code Decryption Setup

If the code is encrypted, it is necessary to configure the decryption information for the code.

Code Jump Running

After the code is moved, determine the reset vector address of the code and jump from secboot to the user’s image to run.