2023-01-10 00:59:46 -05:00
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| Supported Targets | ESP32 | ESP32-C3 | ESP32-C6 | ESP32-H2 | ESP32-S2 | ESP32-S3 |
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| ----------------- | ----- | -------- | -------- | -------- | -------- | -------- |
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2022-05-20 05:50:08 -04:00
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2019-11-24 22:32:40 -05:00
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# Non-Volatile Storage (NVS) C++ Read and Write 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 read and write a single integer value using NVS.
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It is essentially the same as the nvs_rw_value example. The only difference is that it uses the C++ NVS handle API.
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Please see [nvs_rw_value README](../nvs_rw_value/README.md) for more details about this example.
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## How to use example
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### Hardware required
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This example does not require any special hardware, and can be run on any common development board.
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### Build and flash
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Build the project and flash it to the board, then run monitor tool to view serial output:
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```
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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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First run:
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```
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Opening Non-Volatile Storage (NVS) handle... Done
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Reading restart counter from NVS ... The value is not initialized yet!
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Updating restart counter in NVS ... Done
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Committing updates in NVS ... Done
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Restarting in 10 seconds...
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Restarting in 9 seconds...
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Restarting in 8 seconds...
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Restarting in 7 seconds...
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Restarting in 6 seconds...
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Restarting in 5 seconds...
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Restarting in 4 seconds...
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Restarting in 3 seconds...
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Restarting in 2 seconds...
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Restarting in 1 seconds...
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Restarting in 0 seconds...
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Restarting now.
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```
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Subsequent runs:
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```
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Opening Non-Volatile Storage (NVS) handle... Done
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Reading restart counter from NVS ... Done
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Restart counter = 1
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Updating restart counter in NVS ... Done
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Committing updates in NVS ... Done
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Restarting in 10 seconds...
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Restarting in 9 seconds...
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Restarting in 8 seconds...
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Restarting in 7 seconds...
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Restarting in 6 seconds...
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Restarting in 5 seconds...
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Restarting in 4 seconds...
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Restarting in 3 seconds...
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Restarting in 2 seconds...
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Restarting in 1 seconds...
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Restarting in 0 seconds...
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Restarting now.
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```
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Restart counter will increment on each run.
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2021-08-11 09:24:17 -04:00
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To reset the counter, erase the contents of flash memory using `idf.py erase-flash`, then upload the program again as described above.
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