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Merge branch 'bugfix/fix_psram_size_doc_s3_v4.4' into 'release/v4.4'
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doc: update s3 psram vaddr max range size (v4.4)

See merge request espressif/esp-idf!25504
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suda-morris committed Sep 5, 2023
2 parents 7588771 + 6e465a1 commit 4b46cc0
Showing 1 changed file with 7 additions and 4 deletions.
11 changes: 7 additions & 4 deletions docs/en/api-guides/external-ram.rst
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Expand Up @@ -8,10 +8,13 @@ Support for external RAM

Introduction
============
{IDF_TARGET_PSRAM_SIZE:default="Value not updated", esp32="4 MB", esp32s2="10.5 MB", esp32s3="16 MB"}
{IDF_TARGET_PSRAM_VADDR_SIZE:default="Value not updated", esp32="4 MB", esp32s2="10.5 MB", esp32s3="32 MB"}

{IDF_TARGET_NAME} has a few hundred kilobytes of internal RAM, residing on the same die as the rest of the chip components. It can be insufficient for some purposes, so {IDF_TARGET_NAME} has the ability to also use up to {IDF_TARGET_PSRAM_SIZE} of external SPI RAM memory. The external memory is incorporated in the memory map and, with certain restrictions, is usable in the same way as internal data RAM.
{IDF_TARGET_NAME} has a few hundred kilobytes of internal RAM, residing on the same die as the rest of the chip components. It can be insufficient for some purposes, {IDF_TARGET_NAME} has the ability to use up to {IDF_TARGET_PSRAM_VADDR_SIZE} of virtual addresses for external SPI RAM memory. The external memory is incorporated in the memory map and, with certain restrictions, is usable in the same way as internal data RAM.

.. only:: esp32s3

The {IDF_TARGET_PSRAM_VADDR_SIZE} virtual addresses are shared with flash instructions and rodata.

Hardware
========
Expand Down Expand Up @@ -50,7 +53,7 @@ Select this option by choosing "Integrate RAM into memory map" from :ref:`CONFIG

This is the most basic option for external SPI RAM integration. Most likely, you will need another, more advanced option.

During the ESP-IDF startup, external RAM is mapped into the data address space, starting at address {IDF_TARGET_PSRAM_ADDR_START} (byte-accessible). The length of this region is the same as the SPI RAM size (up to the limit of {IDF_TARGET_PSRAM_SIZE}).
During the ESP-IDF startup, external RAM is mapped into the data address space, starting at address {IDF_TARGET_PSRAM_ADDR_START} (byte-accessible). The length of this region is the same as the SPI RAM size (up to the limit of {IDF_TARGET_PSRAM_VADDR_SIZE}).

Applications can manually place data in external memory by creating pointers to this region. So if an application uses external memory, it is responsible for all management of the external SPI RAM: coordinating buffer usage, preventing corruption, etc.

Expand Down Expand Up @@ -163,4 +166,4 @@ Failure to initialize
.. include:: inc/external-ram-esp32-notes.rst

.. _ESP32 ECO: https://www.espressif.com/sites/default/files/documentation/eco_and_workarounds_for_bugs_in_esp32_en.pdf
.. _ESP32 ECO V3 User Guide: https://www.espressif.com/sites/default/files/documentation/ESP32_ECO_V3_User_Guide__EN.pdf
.. _ESP32 ECO V3 User Guide: https://www.espressif.com/sites/default/files/documentation/ESP32_ECO_V3_User_Guide__EN.pdf

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