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Application Startup Process

This document will introduce the steps (i.e., the startup process) that the W800 undergoes from power-on to running the main function.

Macroscopically, the startup process can be divided into the following three steps:

graph TB A(Primary Bootloader)-->B[Bootloader program] B-->C[Application]

The primary bootloader is fixed in the internal ROM. Once the CPU is powered on, it begins executing the program stored in ROM starting from address 0x0 and loads the Bootloader.
The Bootloader is a small program that runs before the operating system, responsible for initializing hardware devices, bringing the system’s software and hardware environment to a suitable state,preparing for the final call to the operating system, and loading the partition table from QFlash to determine the location of the application to be started.
During the application(app) runtime phase, it retrieves the necessary configurations for the application’s operation from the file, such as the starting memory address and memory layout.

Below is a more detailed explanation of the aforementioned processes.

Primary Bootloader Program

Upon powering on, the CPU initiates execution of the program stored in ROM, including QFLASH self-check, QFLASH mode switching, IMAGE verification, vector table redirection, and upgrade procedures.

For detailed ROM functions, please refer to ROM Functionality 。

Bootloader Program

Its main tasks include: switching the QFlash working mode, verifying the integrity of the application, decompressing the code, moving the code, and jumping to the user’s application to run.

For detailed information on the Bootloader, please refer to Bootloader Functionality 。

Application Running

During the application runtime phase, it retrieves the application’s entry function from the chip_layout.ld.h in components/wm_soc/w80x/ld .

It obtains the application’s memory layout from memory_layout.c located in components/wm_soc/w80x/src.

After a series of initializations, it runs the main function, which the user can write as needed.

Automatic Initialization of Components

In addition to manually initializing components before the mian function, we also provide a method for automatic component initialization.

Each component that needs to execute initialization must use WM_COMPONEN_INIT_*(component_init_function) to annotate its component initialization function. The system will automatically call the component initialization function after startup to initialize the component.

The value of * is: 0, 1, 2 , 3, 4, that is:

WM_COMPONEN_INIT_0(component_init_function)

WM_COMPONEN_INIT_1(component_init_function)

WM_COMPONEN_INIT_2(component_init_function)

WM_COMPONEN_INIT_3(component_init_function)

WM_COMPONEN_INIT_4(component_init_function)

The execution order of these four annotated component initialization functions is different, with the execution order being:

graph TB A(WM_COMPONEN_INIT_0)-->B[wm_start] B-->C[Driver AUTO INIT] C-->D[WM_COMPONEN_INIT_1] D-->E[WM_COMPONEN_INIT_2] E-->F[WM_COMPONEN_INIT_3] F-->G[WM_COMPONEN_INIT_4] G-->H[main]

Among them, WM_COMPONEN_INIT_0 is called at the earliest stage, at this stage, the whole system’s only heap memory is initialized, so it is not recommended to use it unless specially needed.

Generally, Basic system components use WM_COMPONEN_INIT_1 , regular system components use WM_COMPONEN_INIT_2 , application components use WM_COMPONEN_INIT_3 , and user components use WM_COMPONEN_INIT_4.

For example, if the initialization function of the CLI application component is wm_component_cli_init , then add
Decorate WM_COMPONEN_INIT_3(wm_component_cli_init).