IDF Frontend - idf.py

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The idf.py command-line tool provides a front-end for easily managing your project builds, deployment and debugging, and more. It manages several tools, for example:

  • CMake, which configures the project to be built.

  • Ninja, which builds the project.

  • esptool.py, which flashes the target.

The Step 5. First Steps on ESP-IDF contains a brief introduction on how to set up idf.py to configure, build, and flash projects.

Important

idf.py should be run in an ESP-IDF project directory, i.e., a directory containing a CMakeLists.txt file. Older style projects that contain a Makefile will not work with idf.py.

Commands

Start a New Project: create-project

idf.py create-project <project name>

This command creates a new ESP-IDF project. Additionally, the folder where the project will be created in can be specified by the --path option.

Create a New Component: create-component

idf.py create-component <component name>

This command creates a new component, which will have a minimum set of files necessary for building. The -C option can be used to specify the directory the component will be created in. For more information about components see the Component CMakeLists Files.

Select the Target Chip: set-target

ESP-IDF supports multiple targets (chips). A full list of supported targets in your version of ESP-IDF can be seen by running idf.py --list-targets.

idf.py set-target <target>

This command sets the current project target.

Important

idf.py set-target will clear the build directory and re-generate the sdkconfig file from scratch. The old sdkconfig file will be saved as sdkconfig.old.

Note

The behavior of the idf.py set-target command is equivalent to:

  1. clearing the build directory (idf.py fullclean)

  2. removing the sdkconfig file (mv sdkconfig sdkconfig.old)

  3. configuring the project with the new target (idf.py -DIDF_TARGET=esp32 reconfigure)

It is also possible to pass the desired IDF_TARGET as an environment variable (e.g., export IDF_TARGET=esp32s2) or as a CMake variable (e.g., -DIDF_TARGET=esp32s2 argument to CMake or idf.py ). Setting the environment variable is a convenient method if you mostly work with one type of the chip.

To specify the default value of IDF_TARGET for a given project, please add the CONFIG_IDF_TARGET option to the project's sdkconfig.defaults file, e.g., CONFIG_IDF_TARGET="esp32s2". This value of the option will be used if IDF_TARGET is not specified by other methods, such as using an environment variable, a CMake variable, or the idf.py set-target command.

If the target has not been set by any of these methods, the build system will default to esp32 target.

Start the Graphical Configuration Tool: menuconfig

idf.py menuconfig

Build the Project: build

idf.py build

This command builds the project found in the current directory. This can involve multiple steps:

  • Create the build directory if needed. The sub-directory "build" is used to hold build output, although this can be changed with the -B option.

  • Run CMake as necessary to configure the project and generate build files for the main build tool.

  • Run the main build tool (Ninja or GNU Make). By default, the build tool is automatically detected but it can be explicitly set by passing the -G option to idf.py.

Building is incremental, so if no source files or configuration has changed since the last build, nothing will be done.

Additionally, the command can be run with app, bootloader and partition-table arguments to build only the app, bootloader or partition table as applicable.

Remove the Build Output: clean

idf.py clean

This command removes the project build output files from the build directory, and the project will be fully rebuilt on next build. Using this command does not remove the CMake configuration output inside the build folder.

Delete the Entire Build Contents: fullclean

idf.py fullclean

This command deletes the entire build directory contents, which includes all CMake configuration output. The next time the project is built, CMake will configure it from scratch. Note that this option recursively deletes all files in the build directory, so use with care. Project configuration is not deleted.

Flash the Project: flash

idf.py flash

This command automatically builds the project if necessary, and then flash it to the target. You can use -p and -b options to set serial port name and flasher baud rate, respectively.

Note

The environment variables ESPPORT and ESPBAUD can be used to set default values for the -p and -b options, respectively. Providing these options on the command line overrides the default.

idf.py uses the write_flash command of esptool.py under the hood to flash the target. You can pass additional arguments to configure the flash writing process using the --extra-args option. For example, to write to an external SPI flash chip, use the following command: idf.py flash --extra-args="--spi-connection <CLK>,<Q>,<D>,<HD>,<CS>". To see the full list of available arguments, run esptool.py write_flash --help or see the esptool.py documentation.

Similarly to the build command, the command can be run with app, bootloader and partition-table arguments to flash only the app, bootloader or partition table as applicable.

Merge binaries: merge-bin

idf.py merge-bin [-o output-file] [-f format] [<format-specific-options>]

There are some situations, e.g. transferring the file to another machine and flashing it without ESP-IDF, where it is convenient to have only one file for flashing instead the several file output of idf.py build.

The command idf.py merge-bin will merge the bootloader, partition table, the application itself, and other partitions (if there are any) according to the project configuration and create a single binary file merged-binary.[bin|hex] in the build folder, which can then be flashed later.

It is possible to output merged file in binary (raw), IntelHex (hex) and UF2 (uf2) formats.

The uf2 binary can also be generated by idf.py uf2. The idf.py uf2 is functionally equivalent to idf.py merge-bin -f uf2. However, the idf.py merge-bin command provides more flexibility and options for merging binaries into various formats described above.

Example usage:

idf.py merge-bin -o my-merged-binary.bin -f raw

There are also some format specific options, which are listed below:

  • Only for raw format:

    • --flash-offset: This option will create a merged binary that should be flashed at the specified offset, instead of at the standard offset of 0x0.

    • --fill-flash-size: If set, the final binary file will be padded with FF bytes up to this flash size in order to fill the full flash content with the image and re-write the whole flash chip upon flashing.

  • Only for uf2 format:

    • --md5-disable: This option will disable MD5 checksums at the end of each block. This can be useful for integration with e.g. tinyuf2.

Hints on How to Resolve Errors

idf.py will try to suggest hints on how to resolve errors. It works with a database of hints stored in tools/idf_py_actions/hints.yml and the hints will be printed if a match is found for the given error. The menuconfig target is not supported at the moment by automatic hints on resolving errors.

The --no-hints argument of idf.py can be used to turn the hints off in case they are not desired.

Important Notes

Multiple idf.py commands can be combined into one. For example, idf.py -p COM4 clean flash monitor will clean the source tree, then build the project and flash it to the target before running the serial monitor.

The order of multiple idf.py commands on the same invocation is not important, as they will automatically be executed in the correct order for everything to take effect (e.g., building before flashing, erasing before flashing).

For commands that are not known to idf.py, an attempt to execute them as a build system target will be made.

The command idf.py supports shell autocompletion for bash, zsh and fish shells.

To enable autocompletion for idf.py, use the export command (Step 4. Set up the environment variables). Autocompletion is initiated by pressing the TAB key. Type idf.py - and press the TAB key to autocomplete options.

The autocomplete support for PowerShell is planned in the future.

Advanced Commands

Open the Documentation: docs

idf.py docs

This command opens the documentation for the projects target and ESP-IDF version in the browser.

Show Size: size

idf.py size

This command prints app size information including the occupied RAM and flash and section (i.e., .bss) sizes.

idf.py size-components

Similarly, this command prints the same information for each component used in the project.

idf.py size-files

This command prints size information per source file in the project.

Options

  • --format specifies the output format with available options: text, csv, json, default being text.

  • --output-file optionally specifies the name of the file to print the command output to instead of the standard output.

Reconfigure the Project: reconfigure

idf.py reconfigure

This command forces CMake to be rerun regardless of whether it is necessary. It is unnecessary during normal usage, but can be useful after adding/removing files from the source tree, or when modifying CMake cache variables. For example, idf.py -DNAME='VALUE' reconfigure can be used to set variable NAME in CMake cache to value VALUE.

Clean the Python Byte Code: python-clean

idf.py python-clean

This command deletes generated python byte code from the ESP-IDF directory. The byte code may cause issues when switching between ESP-IDF and Python versions. It is advised to run this target after switching versions of Python.

Generate a UF2 Binary: uf2

idf.py uf2

This command generates a UF2 (USB Flashing Format) binary uf2.bin in the build directory. This file includes all the necessary binaries (bootloader, app, and partition table) for flashing the target.

This UF2 file can be copied to a USB mass storage device exposed by another ESP running the ESP USB Bridge project. The bridge MCU will use it to flash the target MCU. This is as simple as copying (or "drag-and-dropping") the file to the exposed disk accessed by a file explorer in your machine.

To generate a UF2 binary for the application only (not including the bootloader and partition table), use the uf2-app command.

The idf.py uf2 command is functionally equivalent to idf.py merge-bin -f uf2 described above. However, the idf.py merge-bin command provides more flexibility and options for merging binaries into various formats, not only uf2.

idf.py uf2-app

Read Otadata Partition: read-otadata

idf.py read-otadata

This command prints the contents of the otadata partition which stores the information about the currently selected OTA app slot. Refer to Over The Air Updates (OTA) for more about the otadata partition.

Global Options

To list all available root level options, run idf.py --help. To list options that are specific for a subcommand, run idf.py <command> --help, e.g., idf.py monitor --help. Here is a list of some useful options:

  • -C <dir> allows overriding the project directory from the default current working directory.

  • -B <dir> allows overriding the build directory from the default build subdirectory of the project directory.

  • --ccache enables CCache when compiling source files if the CCache tool is installed. This can dramatically reduce the build time.

Important

Note that some older versions of CCache may exhibit bugs on some platforms, so if files are not rebuilt as expected, try disabling CCache and rebuilding the project. To enable CCache by default, set the IDF_CCACHE_ENABLE environment variable to a non-zero value.

  • -v flag causes both idf.py and the build system to produce verbose build output. This can be useful for debugging build problems.

  • --cmake-warn-uninitialized (or -w) causes CMake to print uninitialized variable warnings found in the project directory only. This only controls CMake variable warnings inside CMake itself, not other types of build warnings. This option can also be set permanently by setting the IDF_CMAKE_WARN_UNINITIALIZED environment variable to a non-zero value.

  • --no-hints flag disables hints on resolving errors and disable capturing output.

Passing arguments via a @file

It is possible to pass multiple arguments to idf.py via a file. The file or path to the file must be annotated with @ at the beginning. Arguments in the file can be separated by newlines or spaces and are expanded exactly as if they had appeared in that order on the idf.py command line.

For example, let's have a file custom_flash.txt:

flash --baud 115200

Then the command can be executed as: idf.py @custom_flash.txt monitor

Arguments from a file can be combined with additional command line arguments, and multiple files annotated with @ can be used simultaneously. For instance, if there is a second file another_config.txt, both can be utilized by specifying idf.py @custom_flash.txt @another_config.txt monitor.

A further example of how this argument file can be used, e.g., creating configuration profile files via @filename, is in the Multiple Build Configurations Example .

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