wehub-resource-sync
57 lines
2.7 KiB
Markdown
57 lines
2.7 KiB
Markdown
| Supported Targets | ESP32 | ESP32-C5 | ESP32-C61 | ESP32-H4 | ESP32-P4 | ESP32-S2 | ESP32-S3 | ESP32-S31 |
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| ----------------- | ----- | -------- | --------- | -------- | -------- | -------- | -------- | --------- |
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# FreeRTOS PSRAM Stack Example
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(See the README.md file in the upper level `examples` directory for more information about examples.)
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This example demonstrates `CONFIG_FREERTOS_PLACE_TASK_STACKS_IN_EXT_RAM`, which causes `xTaskCreate()` and `xTaskCreatePinnedToCore()` to allocate task stacks from PSRAM by default (with internal RAM as a fallback). TCBs are always kept in internal DRAM.
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It also shows how to use the `esp_flash_dispatcher` component so that flash operations called from PSRAM-stacked tasks remain safe.
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Any code path that disables the cache (flash erase/write, OTA, NVS) must run on a task whose stack is in internal RAM, or must go through `esp_flash_dispatcher`.
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## What is being demonstrated
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1. Three worker tasks are created with `xTaskCreate()`. Each task prints the address of a local variable to confirm its stack resides in PSRAM.
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2. Each worker calls `esp_partition_read()` from its PSRAM stack. The `esp_flash_dispatcher` component intercepts the call and executes it on a dedicated internal-RAM task, avoiding a crash when the cache is temporarily disabled.
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## How to use example
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### Hardware Required
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A board with a PSRAM-capable SoC: ESP32-S2, ESP32-S3, or ESP32-P4.
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### Configure the project
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```
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idf.py menuconfig
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```
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The `sdkconfig.defaults` already enables `CONFIG_SPIRAM`, `CONFIG_FREERTOS_TASK_CREATE_ALLOW_EXT_MEM`, and `CONFIG_FREERTOS_PLACE_TASK_STACKS_IN_EXT_RAM`. No additional configuration is required.
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### Build and Flash
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```
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idf.py build flash monitor
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```
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### Example output
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```
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I (xxx) psram_stack: Initialising flash dispatcher (routes flash ops off PSRAM-stacked tasks)
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I (xxx) psram_stack: worker[0]: stack @ 0x3c0xxxxx -> PSRAM
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I (xxx) psram_stack: worker[0]: flash read OK (first bytes: e9 04 ...)
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I (xxx) psram_stack: worker[1]: stack @ 0x3c0xxxxx -> PSRAM
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I (xxx) psram_stack: worker[1]: flash read OK (first bytes: e9 04 ...)
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I (xxx) psram_stack: worker[2]: stack @ 0x3c0xxxxx -> PSRAM
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I (xxx) psram_stack: worker[2]: flash read OK (first bytes: e9 04 ...)
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I (xxx) psram_stack: Example complete
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```
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## Further reading
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- `CONFIG_FREERTOS_PLACE_TASK_STACKS_IN_EXT_RAM` in `menuconfig → Component config → FreeRTOS → Extra`
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- [External RAM](https://docs.espressif.com/projects/esp-idf/en/latest/esp32s3/api-guides/external-ram.html) — limitations of tasks with PSRAM stacks
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- `espressif/esp_flash_dispatcher` on the [ESP Component Registry](https://components.espressif.com/components/espressif/esp_flash_dispatcher)
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