esp32s2

　　一、esp32-nvs常用接口介绍
　　NVS  将每个键值对分配给一个命名空间。主要接口如下：
　　打开一个命名空间：  esp_err_t nvs_open(const char *name, nvs_open_mode_topen_mode, nvs_handle_t *out_handle)
　　设置获取数字型键值对：  esp_err_t nvs_get_i32(nvs_handle_thandle, const char *key, int32_t *out_value) esp_err_t nvs_set_i32(nvs_handle_thandle, const char *key, int32_t value)
　　设置获取字符型键值对：  esp_err_t nvs_get_str(nvs_handle_thandle, const char *key, char *out_value, size_t *length) esp_err_t nvs_set_str(nvs_handle_thandle, const char *key, const char *value)
　　删除键值对的key：  esp_err_t nvs_erase_key(nvs_handle_thandle, const char *key)
　　提交修改：  esp_err_t nvs_commit(nvs_handle_thandle)
　　关闭命名空间：  void nvs_close(nvs_handle_thandle)二、应用实例：2.1. 保存键值对：char *ssid = ＂xxx＂; char *password = ＂1234＂; /* 将得到的WiFi名称和密码存入NVS*/ nvs_handle wificfg_nvs_handler; ESP_ERROR_CHECK( nvs_open(＂WiFi_cfg＂, NVS_READWRITE, &wificfg_nvs_handler) ); ESP_ERROR_CHECK( nvs_set_str(wificfg_nvs_handler,＂wifi_ssid＂,ssid) ); ESP_ERROR_CHECK( nvs_set_str(wificfg_nvs_handler,＂wifi_passwd＂,password) ); ESP_ERROR_CHECK( nvs_commit(wificfg_nvs_handler) ); /* 提交 */ nvs_close(wificfg_nvs_handler); /* 关闭 */2.2. 读取键值对：nvs_handle wificfg_nvs_handler; /* 定义一个NVS操作句柄 */ char wifi_ssid[33] = { 0 }; /* 定义一个数组用来存储ssid*/ char wifi_passwd[65] = { 0 }; /* 定义一个数组用来存储passwd */ size_t len;  /* 打开一个NVS命名空间WiFi_cfg获取ssid/passwd */ if(ESP_OK != nvs_open(＂WiFi_cfg＂, NVS_READWRITE, &wificfg_nvs_handler) ){ 	ESP_LOGI(WIFI_TAG, ＂nvs_open error!＂); }else{   len = sizeof(wifi_ssid); /* 从NVS中获取ssid */ 	if(ESP_OK != nvs_get_str(wificfg_nvs_handler,＂wifi_ssid＂,wifi_ssid,&len) ){ 		ESP_LOGI(WIFI_TAG, ＂nvs_get_str wifi_ssid error!＂); 	}  	len = sizeof(wifi_passwd); /* 从NVS中获取passwd */ 	if(ESP_OK != nvs_get_str(wificfg_nvs_handler,＂wifi_passwd＂,wifi_passwd,&len) ){ 		ESP_LOGI(WIFI_TAG, ＂nvs_get_str wifi_passwd error!＂); 	} 	ESP_ERROR_CHECK( nvs_commit(wificfg_nvs_handler) ); /* 提交 */ 	nvs_close(wificfg_nvs_handler); /* 关闭 */  	if((0 == strcmp(wifi_ssid,＂＂)) | (0 == strcmp(wifi_passwd,＂＂))){ 		ESP_LOGI(WIFI_TAG, ＂nvs_get_str wifi_ssid or wifi_passwd is empty,start smartconfig!＂); 	} }2.3. 清除键值对：// clear WiFi_cfg space nvs_handle wificfg_nvs_handler; ESP_ERROR_CHECK( nvs_open(＂WiFi_cfg＂, NVS_READWRITE, &wificfg_nvs_handler) ); ESP_ERROR_CHECK( nvs_erase_key(wificfg_nvs_handler,＂wifi_ssid＂) ); ESP_ERROR_CHECK( nvs_erase_key(wificfg_nvs_handler,＂wifi_passwd＂) ); ESP_ERROR_CHECK( nvs_commit(wificfg_nvs_handler) ); /* 提交 */ nvs_close(wificfg_nvs_handler); /* 关闭 */