diff --git a/main/inc/user/led.h b/main/inc/user/led.h
index 44659f5..39a6d38 100644
--- a/main/inc/user/led.h
+++ b/main/inc/user/led.h
@@ -8,8 +8,6 @@
 #ifndef INC_USER_LED_H_
 #define INC_USER_LED_H_
 
-#include <stdint.h>
-
 typedef enum {
     LED_MODE_IDX_BLINK_S1 = 0x00,
     LED_MODE_IDX_BLINK_S0 = 0x01,
diff --git a/main/src/chip/i2s.c b/main/src/chip/i2s.c
index 31a38ad..d52f8e9 100644
--- a/main/src/chip/i2s.c
+++ b/main/src/chip/i2s.c
@@ -19,9 +19,8 @@ static i2s_config_t i2s_output_config = {
     .use_apll = 1,                                                          // use APLL
     .sample_rate = 44100,
     .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
-    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL3,
     .tx_desc_auto_clear = true,                                             // auto clear tx descriptor on underflow
-    .dma_buf_count = 8,
+    .dma_buf_count = 2,
     .dma_buf_len = 128,
     .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT                            // 2-channels
 };
diff --git a/main/src/core/app.c b/main/src/core/app.c
index 18d8ecb..846afcb 100644
--- a/main/src/core/app.c
+++ b/main/src/core/app.c
@@ -31,19 +31,19 @@ esp_err_t app_getenv(const char *key, void *out_value, size_t *length)
 {
     nvs_handle_t handle;
 
-    esp_err_t err = nvs_open("storage", NVS_READONLY, &handle);
+    esp_err_t err = nvs_open("storage", NVS_READWRITE, &handle);
     if (err != ESP_OK) {
-        ESP_LOGE(TAG, "open nvs failed");
+        ESP_LOGE(TAG, "failed to open nvs");
         return err;
     }
 
     err = nvs_get_blob(handle, key, out_value, length);
     if (err == ESP_ERR_NVS_NOT_FOUND) {
-        ESP_LOGW(TAG, "env \"%s\" not found", key);
+        ESP_LOGW(TAG, "env not found: %s", key);
         nvs_close(handle);
         return err;
     } else if (err != ESP_OK) {
-        ESP_LOGE(TAG, "read env \"%s\" failed", key);
+        ESP_LOGE(TAG, "failed to read env: %s", key);
         nvs_close(handle);
         return err;
     }
@@ -59,20 +59,20 @@ esp_err_t app_setenv(const char *key, const void *value, size_t length)
 
     esp_err_t err = nvs_open("storage", NVS_READWRITE, &handle);
     if (err != ESP_OK) {
-        ESP_LOGE(TAG, "open nvs failed");
+        ESP_LOGE(TAG, "failed to open nvs");
         return err;
     }
 
     err = nvs_set_blob(handle, key, value, length);
     if (err != ESP_OK) {
-        ESP_LOGE(TAG, "set nvs blob failed");
+        ESP_LOGE(TAG, "failed to set nvs blob");
         nvs_close(handle);
         return err;
     }
 
     err = nvs_commit(handle);
     if (err != ESP_OK) {
-        ESP_LOGE(TAG, "write env \"%s\" failed", key);
+        ESP_LOGE(TAG, "failed to write env: %s", key);
         nvs_close(handle);
         return err;
     }
diff --git a/main/src/core/os.c b/main/src/core/os.c
index 00fb375..7101a4d 100644
--- a/main/src/core/os.c
+++ b/main/src/core/os.c
@@ -18,10 +18,10 @@
 #include "core/os.h"
 #include "chip/wifi.h"
 
-#include "user/gui.h"
-#include "user/led.h"
 #include "user/ntp.h"
 #include "user/key.h"
+#include "user/led.h"
+#include "user/gui.h"
 #include "user/nfc_app.h"
 #include "user/http_app_ota.h"
 
@@ -58,11 +58,14 @@ static void wifi_event_handler(void* arg, esp_event_base_t event_base,
                 vTaskDelay(2000 / portTICK_RATE_MS);
 #endif
                 os_pwr_reset_wait(OS_PWR_DUMMY_BIT);
+                break;
             }
+
+            xEventGroupClearBits(wifi_event_group, WIFI_RDY_BIT);
+
             if (!(uxBits & WIFI_CFG_BIT)) {
                 esp_wifi_connect();
             }
-            xEventGroupClearBits(wifi_event_group, WIFI_RDY_BIT);
             break;
         }
         default:
@@ -74,11 +77,11 @@ static void ip_event_handler(void* arg, esp_event_base_t event_base,
                              int32_t event_id, void* event_data)
 {
     switch (event_id) {
-        case IP_EVENT_STA_GOT_IP: {
+        case IP_EVENT_STA_GOT_IP:
             xEventGroupSetBits(wifi_event_group, WIFI_RDY_BIT);
-
+#ifdef CONFIG_ENABLE_SC_KEY
             key_set_scan_mode(KEY_SCAN_MODE_IDX_OFF);
-
+#endif
             ntp_sync_time();
 #ifdef CONFIG_ENABLE_OTA
             http_app_check_for_updates();
@@ -92,7 +95,6 @@ static void ip_event_handler(void* arg, esp_event_base_t event_base,
             nfc_app_set_mode(NFC_APP_MODE_IDX_ON);
 
             break;
-        }
         default:
             break;
     }
@@ -121,7 +123,6 @@ static void sc_event_handler(void* arg, esp_event_base_t event_base,
 #ifdef CONFIG_ENABLE_LED
             led_set_mode(LED_MODE_IDX_PULSE_D1);
 #endif
-
             smartconfig_event_got_ssid_pswd_t *evt = (smartconfig_event_got_ssid_pswd_t *)event_data;
             memcpy(wifi_config.sta.ssid, evt->ssid, sizeof(wifi_config.sta.ssid));
             memcpy(wifi_config.sta.password, evt->password, sizeof(wifi_config.sta.password));
diff --git a/main/src/user/http_app.c b/main/src/user/http_app.c
index 18b4e52..6579aeb 100644
--- a/main/src/user/http_app.c
+++ b/main/src/user/http_app.c
@@ -11,8 +11,8 @@
 #include "esp_http_client.h"
 
 #include "core/os.h"
-#include "user/gui.h"
 #include "user/led.h"
+#include "user/gui.h"
 #include "user/http_app.h"
 #include "user/audio_player.h"
 #include "user/http_app_ota.h"
diff --git a/main/src/user/http_app_ota.c b/main/src/user/http_app_ota.c
index e56d6f8..664056f 100644
--- a/main/src/user/http_app_ota.c
+++ b/main/src/user/http_app_ota.c
@@ -24,8 +24,8 @@
 
 static uint32_t data_length = 0;
 
-static const esp_partition_t *update_partition = NULL;
 static esp_ota_handle_t update_handle = 0;
+static const esp_partition_t *update_partition = NULL;
 
 esp_err_t http_app_ota_event_handler(esp_http_client_event_t *evt)
 {
diff --git a/main/src/user/nfc_app.c b/main/src/user/nfc_app.c
index e1d5b16..0761d79 100644
--- a/main/src/user/nfc_app.c
+++ b/main/src/user/nfc_app.c
@@ -118,8 +118,10 @@ static void nfc_app_task_handle(void *pvParameter)
         if (res > 0) {
             if (strstr((char *)rx_data, RX_FRAME_PRFX) != NULL &&
                 strlen((char *)rx_data + RX_FRAME_PRFX_LEN) == RX_FRAME_DATA_LEN) {
-                ESP_LOGW(TAG, "token is %32s", (char *)rx_data + RX_FRAME_PRFX_LEN);
+                ESP_LOGW(TAG, "token: %32s", (char *)rx_data + RX_FRAME_PRFX_LEN);
+#ifdef CONFIG_ENABLE_AUDIO_PROMPT
                 audio_player_play_file(MP3_FILE_IDX_NOTIFY);
+#endif
                 http_app_verify_token((char *)rx_data + RX_FRAME_PRFX_LEN);
             } else {
                 ESP_LOGW(TAG, "unexpected frame");
diff --git a/main/src/user/ntp.c b/main/src/user/ntp.c
index 02d0584..b5822ef 100644
--- a/main/src/user/ntp.c
+++ b/main/src/user/ntp.c
@@ -12,8 +12,8 @@
 
 #include "core/os.h"
 
-#include "user/gui.h"
 #include "user/led.h"
+#include "user/gui.h"
 #include "user/nfc_app.h"
 #include "user/http_app_ota.h"