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Documentation/esp32s3: Add ESP32-S3's PSRAM entry

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Add entry for the external PSRAM support on ESP32-S3 and document
how to move data to the external PSRAM to free the internal memory.
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Tiago Medicci Serrano 2025-02-13 10:43:19 -03:00 • committed by Alan C. Assis
parent 97aa90570c
commit 436dbe3f0b
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Documentation/platforms/xtensa/esp32s3/index.rst
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@ -430,6 +430,30 @@ using WPA2.
The ``dhcpd_start`` is necessary to let your board to associate an IP to your smartphone.
PSRAM
-----
The external PSRAM is supported in ESP32-S3. The PSRAM is mapped to the data bus during
the boot process. The PSRAM is used as a heap memory and is available for the application.
Please check the following examples for more information:
* :ref:`esp32s3-devkit:psram_octal <platforms/xtensa/esp32s3/boards/esp32s3-devkit/index:psram_octal>`
* :ref:`esp32s3-devkit:psram_quad <platforms/xtensa/esp32s3/boards/esp32s3-devkit/index:psram_quad>`
Moving not initialized data to the external PSRAM
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Static or global not-initialized data can be moved to the external PSRAM. Usually allocated at the
``.bss`` memory segment, this data can be set to another section in the external PSRAM.
Set the attribute ``__attribute__ ((section (".ext_ram.bss")))`` to the variable. For example::
__attribute__ ((section (".ext_ram.bss"))) static uint8_t my_data[1024];
``my_data`` will be allocated in the external PSRAM and can be explicitly initialized on runtime.
This is particularly useful when the internal RAM is not enough to hold all the data.
Supported Boards
================