58 lines
3.7 KiB
Markdown
58 lines
3.7 KiB
Markdown
# Finding Partitions Example
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This example demonstrates how to use the partition API functions `esp_partition_find` and `esp_partition_find_first` to search the device partition table.
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These functions return the matching partitions given a set of constraints. By constraints we simply mean
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properties that returned results should match - notably partition type, subtype and label/name. In the case of `esp_partition_find_first`, the first matching instance is returned;
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for `esp_partition_find`, an iterator is returned iterating over matching instances.
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# Example Flow
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The example uses a [custom partition table](./partitions_example.csv). The first part uses `esp_partition_find_first` to search for partition instances
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using two constraints - type and subtype. However, the partition table contains partitions with same type/subtype combination. In order to differentiate these partitions,
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a third constraint - the label, is specified.
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The second part shows how to iterate over partitions that match certain constraints, manually checking the properties of each iterated partition.
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The iterator is obtained using `esp_partition_find` and is released after its use to avoid memory leaks.
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### Output
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```
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I (310) example: Printing partition table csv file contents for reference...
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# Name, Type, SubType, Offset, Size, Flags
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# Note: if you change the phy_init or app partition offset, make sure to change the offset in Kconfig.projbuild
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nvs, data, nvs, 0x9000, 0x6000,
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phy_init, data, phy, 0xf000, 0x1000,
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factory, app, factory, 0x10000, 1M,
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storage1, data, fat, , 0x40000,
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storage2, data, fat, , 0x40000,
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I (350) example: ----------------Find partitions---------------
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I (350) example: Find partition with type ESP_PARTITION_TYPE_DATA, subtype ESP_PARTITION_SUBTYPE_DATA_NVS, label NULL (unspecified)...
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I (370) example: found partition 'nvs' at offset 0x9000 with size 0x6000
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I (370) example: Find partition with type ESP_PARTITION_TYPE_DATA, subtype ESP_PARTITION_SUBTYPE_DATA_PHY, label NULL (unspecified)...
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I (390) example: found partition 'phy_init' at offset 0xf000 with size 0x1000
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I (390) example: Find partition with type ESP_PARTITION_TYPE_APP, subtype ESP_PARTITION_SUBTYPE_APP_FACTORY, label NULL (unspecified)...
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I (410) example: found partition 'factory' at offset 0x10000 with size 0x100000
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I (410) example: Find partition with type ESP_PARTITION_TYPE_DATA, subtype ESP_PARTITION_SUBTYPE_DATA_FAT, label NULL (unspecified)...
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I (430) example: found partition 'storage1' at offset 0x110000 with size 0x40000
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I (440) example: Find second FAT partition by specifying the label
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I (440) example: Find partition with type ESP_PARTITION_TYPE_DATA, subtype ESP_PARTITION_SUBTYPE_DATA_FAT, label storage2...
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I (450) example: found partition 'storage2' at offset 0x150000 with size 0x40000
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I (460) example: ----------------Iterate through partitions---------------
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I (470) example: Iterating through app partitions...
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I (480) example: found partition 'factory' at offset 0x10000 with size 0x100000
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I (480) example: Iterating through data partitions...
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I (490) example: found partition 'nvs' at offset 0x9000 with size 0x6000
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I (500) example: found partition 'phy_init' at offset 0xf000 with size 0x1000
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I (500) example: found partition 'storage1' at offset 0x110000 with size 0x40000
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I (510) example: found partition 'storage2' at offset 0x150000 with size 0x40000
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I (520) example: Example end
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```
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# Others
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Detailed functional description of partition API is provided in [documentation](https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/storage/spi_flash.html).
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See the README.md file in the upper level 'examples' directory for more information about examples.
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