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55 lines
2.7 KiB
Markdown
55 lines
2.7 KiB
Markdown
| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-C6 | ESP32-H2 | ESP32-P4 | ESP32-S2 | ESP32-S3 |
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| ----------------- | ----- | -------- | -------- | -------- | -------- | -------- | -------- | -------- |
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# NVS Partition Image Generation on Build 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 how to use the NVS image generation tool [nvs_partition_gen.py](../../../components/nvs_flash/nvs_partition_generator/nvs_partition_gen.py) to automatically create a NVS partition image from the contents of a CSV file during build, with an option of automatically flashing the created image on invocation of `idf.py -p PORT flash`. For more information, see description of `nvs_partition_gen.py` on the ESP-IDF Programming Guide under API Reference > Storage API > NVS Partition Generator Utility.
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The following gives an overview of the example:
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1. There is a file `nvs_data.csv` from which the NVS partition image will be created.
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2. The function `nvs_create_partition_image` is used to specify that a NVS image should be created during build for the `nvs` partition. It is called from [the main component's CMakeLists.txt](./main/CMakeLists.txt). `FLASH_IN_PROJECT` specifies that the created image should be flashed on invocation of `idf.py -p PORT flash` together with app, bootloader, partition table, etc. For both build systems, the image is created on the example's build directory with the output filename `nvs.bin`.
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3. Upon invocation of `idf.py -p PORT flash monitor`, application loads and finds there is already a valid and pre-filled NVS partition in the `nvs` partition with values same as those in `nvs_data.csv` file. The application is then able to read those values.
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## How to use example
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### Build and flash
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To run the example, type the following command:
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```CMake
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idf.py -p PORT flash monitor
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```
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## Example output
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Here is the example's console output:
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```
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...
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I (357) example: Opening Non-Volatile Storage (NVS) handle
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I (357) example: Done
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I (357) example: Reading values from NVS
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255
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-128
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65535
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4294967295
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-2147483648
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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
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Fusce quis risus justo.
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Suspendisse egestas in nisi sit amet auctor.
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Pellentesque rhoncus dictum sodales.
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In justo erat, viverra at interdum eget, interdum vel dui.
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I (387) example: Reading values from NVS done - all OK
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```
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The logic of the example is contained in a [single source file](./main/nvsgen_example_main.c), and it should be relatively simple to match points in its execution with the log outputs above.
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