Partitions API
==============

:link_to_translation:`zh_CN:[中文]`

Overview
--------

The ``esp_partition`` component has higher-level API functions which work with partitions defined in the :doc:`/api-guides/partition-tables`. These APIs are based on lower-level API provided by :doc:`/api-reference/peripherals/spi_flash/index`.

.. _flash-partition-apis:

Partition Table API
-------------------

ESP-IDF projects use a partition table to maintain information about various regions of SPI flash memory (bootloader, various application binaries, data, filesystems). More information can be found in :doc:`/api-guides/partition-tables`.

This component provides API functions to enumerate partitions found in the partition table and perform operations on them. These functions are declared in ``esp_partition.h``:

- :cpp:func:`esp_partition_find` checks a partition table for entries with specific type, returns an opaque iterator.
- :cpp:func:`esp_partition_get` returns a structure describing the partition for a given iterator.
- :cpp:func:`esp_partition_next` shifts the iterator to the next found partition.
- :cpp:func:`esp_partition_iterator_release` releases iterator returned by :cpp:func:`esp_partition_find`.
- :cpp:func:`esp_partition_find_first` is a convenience function which returns the structure describing the first partition found by :cpp:func:`esp_partition_find`.
- :cpp:func:`esp_partition_read`, :cpp:func:`esp_partition_write`, :cpp:func:`esp_partition_erase_range` are equivalent to :cpp:func:`esp_flash_read`, :cpp:func:`esp_flash_write`, :cpp:func:`esp_flash_erase_region`, but operate within partition boundaries.

Application Examples
--------------------

- :example:`storage/partition_api/partition_ops` demonstrates how to perform read, write, and erase operations on a partition table.

- :example:`storage/parttool` demonstrates how to use the partitions tool to perform operations such as reading, writing, erasing partitions, retrieving partition information, and dumping the entire partition table.

- :example:`storage/partition_api/partition_find` demonstrates how to search the partition table and return matching partitions based on set constraints such as partition type, subtype, and label/name.

- :example:`storage/partition_api/partition_mmap` demonstrates how to configure the MMU, map a partition into memory address space for read operations, and verify the data written and read.

Flashing Binaries to Partitions
-------------------------------

The ``esp_partition_register_target`` function allows registering binary files to be flashed to specific partitions. It creates a per-partition flash target (e.g., ``idf.py mypart-flash``, where ``mypart`` is the name of the partition in ``partitions.csv``) and optionally includes the binary in ``idf.py flash``.

This function is defined in :component_file:`esp_partition/project_include.cmake`.

**Basic usage in a project's CMakeLists.txt:**

.. code-block:: cmake

   esp_partition_register_target(my_partition "${CMAKE_BINARY_DIR}/my_data.bin" FLASH_IN_PROJECT)

This creates a ``my_partition-flash`` target and includes the binary when running ``idf.py flash``.

**Arguments:**

- ``partition_name`` — Name of the partition as defined in the partition table.
- ``binary_path`` — Path to the binary file to flash.
- ``FLASH_IN_PROJECT`` (optional) — Also flash this binary when running ``idf.py flash``.
- ``ALWAYS_PLAINTEXT`` (optional) — Flash without encryption even when flash encryption is enabled. Use for filesystems that don't support encryption (e.g., SPIFFS). Must not be used with partitions marked as ``encrypted`` in the partition table.
- ``DEPENDS <targets>`` (optional) — CMake targets that must be built before flashing (e.g., a custom target that generates the binary).
- ``FLASH_IN_PROJECT_DEPENDENCY_TARGETS <targets>`` (optional) — Additional flash targets (e.g., ``encrypted-flash``) that should also depend on the targets specified in ``DEPENDS``. Requires ``FLASH_IN_PROJECT``.

**Component integration examples:**

Several IDF components use ``esp_partition_register_target`` internally:

- :example:`storage/partition_api/partition_ops` uses it to flash a custom partition with predefined content.
- :component_file:`fatfs/project_include.cmake` — ``fatfs_create_spiflash_image`` creates a FATFS image and registers a ``<partition>-flash`` target.
- :component_file:`nvs_flash/project_include.cmake` — ``nvs_create_partition_image`` creates an NVS image and registers a ``<partition>-flash`` target.
- :component_file:`spiffs/project_include.cmake` — ``spiffs_create_partition_image`` creates a SPIFFS image and registers a ``<partition>-flash`` target.

See Also
--------

- :doc:`../../api-guides/partition-tables`
- :doc:`../system/ota` provides high-level API for updating applications stored in flash.
- :doc:`nvs_flash` provides a structured API for storing small pieces of data in SPI flash.


.. _api-reference-partition-table:

API Reference - Partition Table
-------------------------------

.. include-build-file:: inc/esp_partition.inc
