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Configuration

Configuration system

PlatformIO allows you to customize mbed OS compile time configuration parameters using mbed_app.json manifest. It should be placed into the root of your project and located on the same level as :ref:`projectconf`.

Configuration is defined using JSON. Some examples of configuration parameters:

  • The sampling period for a data acquisition application.
  • The default stack size for a newly created OS thread.
  • The receive buffer size of a serial communication library.
  • The flash and RAM memory size of a target board.

See more details in the official ARM Mbed OS Configuration System.

A few PlatformIO-ready projects based on ARM mbed OS which use mbed_app.json;

Mbed lib and Mbed OS 5

PlatformIO allows compiling projects with or without Mbed OS. By default, project is built without the OS feature. Most of the framework functionality requires the OS to be enabled. To add the OS feature you can use a special macro definition that needs be added to :ref:`projectconf_build_flags` of :ref:`projectconf`:

Name Description
PIO_FRAMEWORK_MBED_RTOS_PRESENT Build the project with enabled rtos

An example of :ref:`projectconf` with enabled rtos

[env:wizwiki_w7500p]
platform = wiznet7500
framework = mbed
board = wizwiki_w7500p
build_flags = -D PIO_FRAMEWORK_MBED_RTOS_PRESENT

Build profiles

By default, PlatformIO builds your project using develop profile which provides optimized firmware size with full error information and allows MCU to go to sleep mode. In the case when default build profile is not suitable for your project there two other profiles release and debug that can be enabled using special macro definitions. You can change build profile :ref:`projectconf_build_flags` of :ref:`projectconf`:

Name Description
MBED_BUILD_PROFILE_RELEASE Release profile (smallest firmware, minimal error info)
MBED_BUILD_PROFILE_DEBUG Debug profile (largest firmware, disabled sleep mode)

More information about differences between build profiles can be found on the official page ARM Mbed OS Build Profiles.

Ignoring particular components

In case you don't need all parts of the framework or you want to reduce the compilation time, you can explicitly exclude folders with redundant sources. For example, to remove cellular, mbedtls and nanostack features from the build process, navigate to :ref:`projectconf_pio_packages_dir` and create a new file framework-mbed/features/.mbedignore with the following contents:

cellular/*
mbedtls/*
nanostack/*

If you want to exclude the entire folder, simply create .mbedignore file and add only one symbol * to this file.

Custom Targets

In case when your board is not officially supported by :ref:`framework_mbed` you can manually add custom board definitions to your project. First of all, you need to create a special file custom_targets.json in the root folder of your project where you describe your board, for example here is the configuration for NUCLEO-F401RE board:

{
  "NUCLEO_F401RE": {
        "inherits": ["FAMILY_STM32"],
        "supported_form_factors": ["ARDUINO", "MORPHO"],
        "core": "Cortex-M4F",
        "extra_labels_add": ["STM32F4", "STM32F401xE", "STM32F401RE"],
        "config": {
            "clock_source": {
                "help": "Mask value : USE_PLL_HSE_EXTC | USE_PLL_HSE_XTAL (need HW patch) | USE_PLL_HSI",
                "value": "USE_PLL_HSE_EXTC|USE_PLL_HSI",
                "macro_name": "CLOCK_SOURCE"
            }
        },
        "detect_code": ["0720"],
        "macros_add": ["USB_STM_HAL", "USBHOST_OTHER"],
        "device_has_add": [
            "SERIAL_ASYNCH",
            "FLASH",
            "MPU"
        ],
        "release_versions": ["2", "5"],
        "device_name": "STM32F401RE"
    }
}

Secondly, you need to add code specific to your target to the src folder of your project. Usually, it's a good idea to isolate this code in a separate folder and add the path to this folder to :ref:`projectconf_build_flags` of :ref:`projectconf`:

[env:my_custom_board]
platform = nxplpc
framework = mbed
board = my_custom_board
build_flags = -I$PROJECT_SRC_DIR/MY_CUSTOM_BOARD_TARGET

Next, you need to inform PlatformIO that there is a new custom board. To do this, you can create boards directory in the root folder of your project and add a board manifest file with your board name, e.g. my_custom_board.json as described here :ref:`board_creating`

After these steps, your project structure should look like this:

project_dir
├── include
├── boards
│    └── my_custom_board.json
├── src
│    ├── main.cpp
│    └── MY_CUSTOM_BOARD_TARGET
│         ├── pinNames.h
│         └── pinNames.c
├── custom_targets.json
└── platformio.ini
More information about adding custom targets can be found on the official page
Adding and configuring targets.

See full examples with a custom board: