Chapter 4. Software framework
in NVS, which does not exceed 100 k. Therefore, such operation is supported even without the eects
of multiple sectors. In actual use, usually there will be multiple sectors given to NVS, and the NVS can
distribute erase cycles to dierent sectors, making the number of erase cycles in each sector necessarily
less than 42 k.
Therefore, the NVS of ESP32 can meet such requirement.
Does NVS have wear levelling function?
Yes, NVS (Non-Volatile Storage) has wear leveling functionality. When storing data in ash memory,
the limited number of writing and erasing operations to the ash will cause some storage blocks to have
shorter service life than others, aecting the overall working life of the memory. To address this issue,
NVS uses an erase-write balancing mechanism implemented internally, rather than the wear_levelling
component in ESP-IDF, to evenly distribute data across the ash memory blocks, ensuring that each
block is used as much as possible to extend the overall working life of the ash memory.
Can NVS sectors be corrupted by accidental power loss during writing?
No, NVS is designed to resist accidental power loss, so it will not be damaged.
Will the congured Wi-Fi SSID and PASSWORD disappear after the ESP series development board is pow-
ered on again and need to be recongured?
• It will be stored in NVS by default and will not disappear due to power failure. You can also set it through
esp_wifi_set_storage(), which can be divided into two situations:
– If you want to save the Wi-Fi SSID and PSAAWORD when powered o, you can store the Wi-Fi infor-
mation in ash by calling esp_wifi_set_storage(WIFI_STORAGE_FLASH).
– If you want to achieve the operation of not saving the Wi-Fi SSID and PASSWORD when powered o,
you can call esp_wifi_set_storage(WIFI_STORAGE_RAM) to store the Wi-Fi information in
RAM.
How to realize that stored user data can be saved after power o, not erased by OTA, and can be re-written
or modied?
• Non-volatile storage can meet the above requirements, and only eFuse and ash can be used to store the data.
Since the data should be modiable, only ash is suitable. It is recommended to use NVS or MFG mechanism.
For details, please refer to
– Manufacturing Utility
– NVS Partition Generator Utility
4.8.3 PSRAM
Espressif Systems 111
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