esp-idf/examples/08_nvs_rw_blob/main/nvs_rw_blob.c

/* Non-Volatile Storage (NVS) Read and Write a Blob - Example

   For other examples please check:
   https://github.com/espressif/esp-idf/tree/master/examples

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_system.h"
#include "nvs_flash.h"
#include "nvs.h"
#include "driver/gpio.h"

#define STORAGE_NAMESPACE "storage"

/* Save the number of module restarts in NVS
   by first reading and then incrementing
   the number that has been saved previously.
   Return an error if anything goes wrong
   during this process.
 */
esp_err_t save_restart_counter(void)
{
    nvs_handle my_handle;
    esp_err_t err;

    // Open
    err = nvs_open(STORAGE_NAMESPACE, NVS_READWRITE, &my_handle);
    if (err != ESP_OK) return err;

    // Read
    int32_t restart_counter = 0; // value will default to 0, if not set yet in NVS
    err = nvs_get_i32(my_handle, "restart_conter", &restart_counter);
    if (err != ESP_OK && err != ESP_ERR_NVS_NOT_FOUND) return err;

    // Write
    restart_counter++;
    err = nvs_set_i32(my_handle, "restart_conter", restart_counter);
    if (err != ESP_OK) return err;

    // Commit written value.
    // After setting any values, nvs_commit() must be called to ensure changes are written
    // to flash storage. Implementations may write to storage at other times,
    // but this is not guaranteed.
    err = nvs_commit(my_handle);
    if (err != ESP_OK) return err;

    // Close
    nvs_close(my_handle);
    return ESP_OK;
}

/* Save new run time value in NVS
   by first reading a table of previously saved values
   and then adding the new value at the end of the table.
   Return an error if anything goes wrong
   during this process.
 */
esp_err_t save_run_time(void)
{
    nvs_handle my_handle;
    esp_err_t err;

    // Open
    err = nvs_open(STORAGE_NAMESPACE, NVS_READWRITE, &my_handle);
    if (err != ESP_OK) return err;

    // Read the size of memory space required for blob
    size_t required_size = 0;  // value will default to 0, if not set yet in NVS
    err = nvs_get_blob(my_handle, "run_time", NULL, &required_size);
    if (err != ESP_OK && err != ESP_ERR_NVS_NOT_FOUND) return err;

    // Read previously saved blob if available
    uint32_t* run_time = malloc(required_size + sizeof(uint32_t));
    if (required_size > 0) {
        err = nvs_get_blob(my_handle, "run_time", run_time, &required_size);
        if (err != ESP_OK) return err;
    }

    // Write value including previously saved blob if available
    required_size += sizeof(uint32_t);
    run_time[required_size / sizeof(uint32_t) - 1] = xTaskGetTickCount() * portTICK_PERIOD_MS;
    err = nvs_set_blob(my_handle, "run_time", run_time, required_size);
    if (err != ESP_OK) return err;

    free(run_time);

    // Commit
    err = nvs_commit(my_handle);
    if (err != ESP_OK) return err;

    // Close
    nvs_close(my_handle);
    return ESP_OK;
}

/* Read from NVS and print restart counter
   and the table with run times.
   Return an error if anything goes wrong
   during this process.
 */
esp_err_t print_what_saved(void)
{
    nvs_handle my_handle;
    esp_err_t err;

    // Open
    err = nvs_open(STORAGE_NAMESPACE, NVS_READWRITE, &my_handle);
    if (err != ESP_OK) return err;

    // Read restart counter
    int32_t restart_counter = 0; // value will default to 0, if not set yet in NVS
    err = nvs_get_i32(my_handle, "restart_conter", &restart_counter);
    if (err != ESP_OK && err != ESP_ERR_NVS_NOT_FOUND) return err;
    printf("Restart counter = %d\n", restart_counter);

    // Read run time blob
    size_t required_size = 0;  // value will default to 0, if not set yet in NVS
    // obtain required memory space to store blob being read from NVS
    err = nvs_get_blob(my_handle, "run_time", NULL, &required_size);
    if (err != ESP_OK && err != ESP_ERR_NVS_NOT_FOUND) return err;
    printf("Run time:\n");
    if (required_size == 0) {
        printf("Nothing saved yet!\n");
    } else {
        uint32_t* run_time = malloc(required_size);
        err = nvs_get_blob(my_handle, "run_time", run_time, &required_size);
        if (err != ESP_OK) return err;
        for (int i = 0; i < required_size / sizeof(uint32_t); i++) {
            printf("%d: %d\n", i + 1, run_time[i]);
        }
        free(run_time);
    }

    // Close
    nvs_close(my_handle);
    return ESP_OK;
}


void app_main()
{
    nvs_flash_init();

    esp_err_t err;

    err = print_what_saved();
    if (err != ESP_OK) printf("Error (%d) reading data from NVS!\n", err);

    err = save_restart_counter();
    if (err != ESP_OK) printf("Error (%d) saving restart counter to NVS!\n", err);

    gpio_pad_select_gpio(GPIO_NUM_0);
    gpio_set_direction(GPIO_NUM_0, GPIO_MODE_DEF_INPUT);

    /* Read the status of GPIO0. If GPIO0 is LOW for longer than 1000 ms,
       then save module's run time and restart it
     */
    while (1) {
        if (gpio_get_level(GPIO_NUM_0) == 0) {
            vTaskDelay(1000 / portTICK_RATE_MS);
            if(gpio_get_level(GPIO_NUM_0) == 0) {
                err = save_run_time();
                if (err != ESP_OK) printf("Error (%d) saving run time blob to NVS!\n", err);
                printf("Restarting...\n");
                fflush(stdout);
                system_restart();
            }
        }
        vTaskDelay(200 / portTICK_RATE_MS);
    }
}