| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-C5 | ESP32-C6 | ESP32-C61 | ESP32-H2 | ESP32-H21 | ESP32-H4 | ESP32-P4 | ESP32-S2 | ESP32-S3 | ESP32-S31 |
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Bootloader extra component
(See the README.md file in the upper level for more information about bootloader examples.)
The purpose of this example is to show how to add bootloader components that are not placed in the conventional bootloader_components directory.
The bootloader always uses the bootloader_components folder name as the project-local search path for bootloader components. Use this folder for bootloader-specific code that belongs to the project, such as hooks or overrides.
Use the BOOTLOADER_EXTRA_COMPONENT_DIRS property when bootloader components already live somewhere else, for example in a shared components directory or in a component reused by several projects. Each path can point either to a directory containing multiple components or directly to a single component. If the extra location contains components that are not needed in a particular bootloader build, list them by component name in BOOTLOADER_IGNORE_EXTRA_COMPONENT.
Usage of this example:
Simply compile it:
idf.py build
Then flash it and open the monitor with the following command:
idf.py flash monitor
If everything went well, the bootloader should output the following message:
I (60) EXTRA: This function is called from an extra component
And finally the application will start and show the message:
User application is loaded and running.
Organization of this example
This project contains a main directory that represents an application. It also has a bootloader_components directory with my_boot_hooks, a bootloader-specific hook component that belongs to this project.
The extra_bootloader_components/ directory demonstrates an extra path that contains several components. extra_component1 is required by my_boot_hooks, while extra_component2 is included directly from BOOTLOADER_EXTRA_COMPONENT_DIRS without being required by another component. extra_component3 is present in the same directory but is excluded from this bootloader build with BOOTLOADER_IGNORE_EXTRA_COMPONENT.
The extra_component4/ and extra_component5/ directories demonstrate extra paths that point directly to individual components. extra_component4 is included directly, while extra_component5 is excluded with BOOTLOADER_IGNORE_EXTRA_COMPONENT.
Below is a short explanation of files in the project folder.
├── CMakeLists.txt Defines the `BOOTLOADER_EXTRA_COMPONENT_DIRS` property
├── main
│ ├── CMakeLists.txt
│ └── main.c User application
├── bootloader_components
│ └── my_boot_hooks
│ ├── CMakeLists.txt
│ └── hooks.c Implementation of the hooks to execute on boot
├── extra_bootloader_components
│ ├── extra_component1
│ │ ├── CMakeLists.txt
│ │ └── extra_component1.c Implementation of the extra component
│ ├── extra_component2
│ │ ├── CMakeLists.txt
│ │ └── extra_component2.c Implementation of the 2nd extra component
│ └── extra_component3
│ ├── CMakeLists.txt
│ └── extra_component3.c Extra component excluded from this bootloader build
├── extra_component4
│ ├── CMakeLists.txt
│ └── extra_component4.c Extra component included directly
├── extra_component5
│ ├── CMakeLists.txt
│ └── extra_component5.c Extra component excluded directly
└── README.md This is the file you are currently reading