esp_storage

Slot-based storage component for ESP-IDF.

Features

• Slots from 0 to 255
• NVS slots:
  • integer (int64_t)
  • number (double)
  • string
• LittleFS slots:
  • raw binary (blob)
  • string
  • JSON text
• Optional AT commands for read/write and listing
• Optional internal logs

Storage model

• NVS namespace: storage
• LittleFS mount point: /littlefs
• LittleFS file per slot: /littlefs/slot_XXX.bin

Prerequisites

• nvs_flash_init() called before esp_storage_init(...)
• esp_at_init(false) called before esp_storage_init(..., true) when AT commands are desired
• Partition table containing a LittleFS partition labeled storage

Init policy

esp_storage_init(log_enabled, at_enabled) controls optional behavior.

• log_enabled
  • enables storage logs
• at_enabled
  • registers AT+NVS, AT+LFS and AT+SLOTS?

Usage

#include <inttypes.h>
#include "nvs_flash.h"
#include "esp_err.h"
#include "esp_at.h"
#include "esp_storage.h"

void app_main(void)
{
    ESP_ERROR_CHECK(nvs_flash_init());
    ESP_ERROR_CHECK(esp_at_init(false));
    ESP_ERROR_CHECK(esp_storage_init(false, true));

    ESP_ERROR_CHECK(esp_storage_nvs_set_int(1, 25));
    ESP_ERROR_CHECK(esp_storage_lfs_write_json(10, "{\"setpoint\":25,\"mode\":\"auto\"}"));
}

AT commands

When esp_storage_init(log_enabled, true) is used:

• AT+NVS=<slot>
• AT+NVS=<slot>,<int>
• AT+NVS=<slot>,<number>
• AT+NVS=<slot>,"<text>"
• AT+NVS=<slot>,NULL
• AT+LFS=<slot>
• AT+LFS=<slot>,<text_or_json>
• AT+LFS=<slot>,NULL
• AT+SLOTS?
• AT+SLOTS?=NVS
• AT+SLOTS?=LFS

Notes

• Public API is non-blocking apart from storage and filesystem operations themselves.
• Slot range is 0..255.
• Slot exists independently of the payload value.