NvsManager¶

Gives the application three separate key-value stores in the ESP32's NVS flash partition, so calibration data, configuration and ordinary application data never collide. Source: NvsManager.h.

Accessor	NVS namespace	Use it for
`App()`	`flux`	Counters, last state, anything the application owns
`Calibration()`	`flux_cal`	Factory or bench calibration
`Config()`	`flux_cfg`	User or deployment configuration

Each accessor returns a BaseNvs& (the interface class; on the ESP32-S3 the platform binding backs it with EspNvs).

API¶

Call	Notes
`App()`, `Calibration()`, `Config()`	`BaseNvs&` for the namespace
`BaseNvs::SetU32 / GetU32`, `SetString / GetString`, `SetBlob / GetBlob`	Return `hf_nvs_err_t`; the ESP32 implementation commits each write
`BaseNvs::KeyExists`, `EraseKey`, `GetSize`, `Commit`
`EnsureInitialized()`, `IsInitialized()`, `Deinitialize()`	Opens / closes all three namespaces
`GetLastError()`, `DumpStatistics()`	`DumpStatistics()` logs each namespace and whether it is open

Example: a boot counter¶

#include "api/Flux.h"
#include "managers/NvsManager.h"

auto& flux = Flux::GetInstance();
if (flux.EnsureInitialized()) {
    BaseNvs& app = flux.nvs.App();
    hf_u32_t boots = 0;
    if (app.GetU32("boot_cnt", boots) != hf_nvs_err_t::NVS_SUCCESS) {
        boots = 0;  // first boot, or the key was erased
    }
    (void)app.SetU32("boot_cnt", boots + 1);
}

The flux_nvs_example app shows strings and blobs in all three namespaces.

Pitfalls¶

Key length. ESP-IDF NVS keys are at most 15 characters (GetMaxKeyLength()).
GetLastError() only reflects initialisation; check each BaseNvs call's return value.
No lock on initialisation. Let Flux::EnsureInitialized() open NVS from one task before others use it.