2024-02-15 21:47:46 +08:00
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.. zephyr:code-sample:: esp32-flash-memory-mapped
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:name: ESP32 Flash Memory-Mapped
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:relevant-api: flash_interface
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2023-10-19 20:06:53 +08:00
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2024-02-15 21:47:46 +08:00
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Write data into scratch area and read it using flash API and memory-mapped pointer.
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2023-10-19 20:06:53 +08:00
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Overview
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********
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ESP32 features memory hardware which allows regions of flash memory to be mapped into instruction
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and data address spaces. This mapping works only for read operations. It is not possible to modify
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contents of flash memory by writing to a mapped memory region.
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Mapping happens in 64 KB pages. Memory mapping hardware can map flash into the data address space
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and the instruction address space. See the technical reference manual for more details and
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limitations about memory mapping hardware. For more information, check `_ESP32 Flash Memory-Mapping`.
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Supported SoCs
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**************
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All ESP32 SoCs support flash memory-mapped feature.
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Building and Running
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********************
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Make sure you have your board connected over USB port.
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.. code-block:: console
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west build -b esp32s3_devkitm samples/boards/esp32/flash_memory_mapped
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west flash
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Sample Output
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=============
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To check the output of this sample, run ``west espressif monitor`` or any other serial
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console program (e.g., minicom, putty, screen, etc).
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This example uses ``west espressif monitor``, which automatically detects the serial
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port at ``/dev/ttyUSB0``:
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.. code-block:: console
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$ west espressif monitor
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The sample code erases the scratch area defined in DTS file and writes a 32-bytes data buffer in it.
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Next, it prints that region content using flash API read and also using memory-mapped pointer.
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Both readings should return the same value. Important to notice that writing using memory-mapped pointer
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is not allowed.
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.. code-block:: console
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*** Booting Zephyr OS build v3.5.0-rc3-10-g3118724fa268 ***
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[00:00:00.255,000] <inf> flash_memory_mapped: memory-mapped pointer address: 0x3c040000
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[00:00:01.122,000] <inf> flash_memory_mapped: flash read using memory-mapped pointer
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ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |........ ........
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ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |........ ........
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[00:00:01.122,000] <inf> flash_memory_mapped: writing 32-bytes data using flash API
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[00:00:01.122,000] <inf> flash_memory_mapped: flash read using flash API
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00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |........ ........
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10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f |........ ........
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[00:00:01.122,000] <inf> flash_memory_mapped: flash read using memory-mapped pointer
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00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |........ ........
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10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f |........ ........
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.. _ESP32 Flash Memory-Mapping:
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https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/spi_flash/index.html#memory-mapping-api
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