diff --git a/README.md b/README.md
index d490f855..31ea23c6 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 # ESP8266_RTOS_SDK #
-
+
 ----------
 
 ESP8266 SDK based on FreeRTOS.
@@ -10,6 +10,20 @@ APIs of "ESP8266_RTOS_SDK" are same as "ESP8266_NONOS_SDK"
 
 More details in "Wiki" !
 
+### about user_rf_cal_sector_set ###
+
+Use this function to set the target flash sector to store RF_CAL parameters. 
+
+The user_rf_cal_sector_set has to be added in application, but need NOT to be called. It will be called inside the SDK.
+The system parameter area (4 flash sectors) has already been used, so the RF_CAL parameters will be stored in the target sector set by user_rf_cal_sector_set. Since we do not know which sector is available in user data area, users need to set an available sector in the user_rf_cal_sector_set for the SDK to store RF_CAL parameter. If the user_rf_cal_sector_set is not added in the application, the compilation will fail in link stage.
+
+For example, refer to user_rf_cal_sector_set in SDK/examples/project_template/user/user_main.c
+
+Note:
+
+1. esp_init_data.bin has to be downloaded into flash at least once.
+2. Download blank.bin to initialize the sector stored RF_CAL parameter (set by user_rf_cal_sector_set), and download esp_init_data.bin into flash, when the system needs to be initialized, or RF needs to be calibrated again.
+
 ## Requrements ##
 
 You can use both xcc and gcc to compile your project, gcc is recommended.
diff --git a/examples/project_template/user/user_main.c b/examples/project_template/user/user_main.c
index d0fabaf9..d9e6132e 100644
--- a/examples/project_template/user/user_main.c
+++ b/examples/project_template/user/user_main.c
@@ -24,6 +24,50 @@
 
 #include "esp_common.h"
 
+/******************************************************************************
+ * FunctionName : user_rf_cal_sector_set
+ * Description  : SDK just reversed 4 sectors, used for rf init data and paramters.
+ *                We add this function to force users to set rf cal sector, since
+ *                we don't know which sector is free in user's application.
+ *                sector map for last several sectors : ABCCC
+ *                A : rf cal
+ *                B : rf init data
+ *                C : sdk parameters
+ * Parameters   : none
+ * Returns      : rf cal sector
+*******************************************************************************/
+uint32 user_rf_cal_sector_set(void)
+{
+    flash_size_map size_map = system_get_flash_size_map();
+    uint32 rf_cal_sec = 0;
+
+    switch (size_map) {
+        case FLASH_SIZE_4M_MAP_256_256:
+            rf_cal_sec = 128 - 5;
+            break;
+
+        case FLASH_SIZE_8M_MAP_512_512:
+            rf_cal_sec = 256 - 5;
+            break;
+
+        case FLASH_SIZE_16M_MAP_512_512:
+        case FLASH_SIZE_16M_MAP_1024_1024:
+            rf_cal_sec = 512 - 5;
+            break;
+
+        case FLASH_SIZE_32M_MAP_512_512:
+        case FLASH_SIZE_32M_MAP_1024_1024:
+            rf_cal_sec = 1024 - 5;
+            break;
+
+        default:
+            rf_cal_sec = 0;
+            break;
+    }
+
+    return rf_cal_sec;
+}
+
 /******************************************************************************
  * FunctionName : user_init
  * Description  : entry of user application, init user function here
diff --git a/examples/smart_config/user/user_main.c b/examples/smart_config/user/user_main.c
index d924e5b7..00ad62c6 100644
--- a/examples/smart_config/user/user_main.c
+++ b/examples/smart_config/user/user_main.c
@@ -204,6 +204,49 @@ smartconfig_task(void *pvParameters)
     vTaskDelete(NULL);
 }
 
+/******************************************************************************
+ * FunctionName : user_rf_cal_sector_set
+ * Description  : SDK just reversed 4 sectors, used for rf init data and paramters.
+ *                We add this function to force users to set rf cal sector, since
+ *                we don't know which sector is free in user's application.
+ *                sector map for last several sectors : ABCCC
+ *                A : rf cal
+ *                B : rf init data
+ *                C : sdk parameters
+ * Parameters   : none
+ * Returns      : rf cal sector
+*******************************************************************************/
+uint32 user_rf_cal_sector_set(void)
+{
+    flash_size_map size_map = system_get_flash_size_map();
+    uint32 rf_cal_sec = 0;
+
+    switch (size_map) {
+        case FLASH_SIZE_4M_MAP_256_256:
+            rf_cal_sec = 128 - 5;
+            break;
+
+        case FLASH_SIZE_8M_MAP_512_512:
+            rf_cal_sec = 256 - 5;
+            break;
+
+        case FLASH_SIZE_16M_MAP_512_512:
+        case FLASH_SIZE_16M_MAP_1024_1024:
+            rf_cal_sec = 512 - 5;
+            break;
+
+        case FLASH_SIZE_32M_MAP_512_512:
+        case FLASH_SIZE_32M_MAP_1024_1024:
+            rf_cal_sec = 1024 - 5;
+            break;
+
+        default:
+            rf_cal_sec = 0;
+            break;
+    }
+
+    return rf_cal_sec;
+}
 
 /******************************************************************************
  * FunctionName : user_init
diff --git a/examples/spiffs_test/user/test_main.c b/examples/spiffs_test/user/test_main.c
index be3bbc85..29b9a924 100644
--- a/examples/spiffs_test/user/test_main.c
+++ b/examples/spiffs_test/user/test_main.c
@@ -49,6 +49,50 @@ void spiffs_fs1_init(void)
     esp_spiffs_init(&config);
 }
 
+/******************************************************************************
+ * FunctionName : user_rf_cal_sector_set
+ * Description  : SDK just reversed 4 sectors, used for rf init data and paramters.
+ *                We add this function to force users to set rf cal sector, since
+ *                we don't know which sector is free in user's application.
+ *                sector map for last several sectors : ABCCC
+ *                A : rf cal
+ *                B : rf init data
+ *                C : sdk parameters
+ * Parameters   : none
+ * Returns      : rf cal sector
+*******************************************************************************/
+uint32 user_rf_cal_sector_set(void)
+{
+    flash_size_map size_map = system_get_flash_size_map();
+    uint32 rf_cal_sec = 0;
+
+    switch (size_map) {
+        case FLASH_SIZE_4M_MAP_256_256:
+            rf_cal_sec = 128 - 5;
+            break;
+
+        case FLASH_SIZE_8M_MAP_512_512:
+            rf_cal_sec = 256 - 5;
+            break;
+
+        case FLASH_SIZE_16M_MAP_512_512:
+        case FLASH_SIZE_16M_MAP_1024_1024:
+            rf_cal_sec = 512 - 5;
+            break;
+
+        case FLASH_SIZE_32M_MAP_512_512:
+        case FLASH_SIZE_32M_MAP_1024_1024:
+            rf_cal_sec = 1024 - 5;
+            break;
+
+        default:
+            rf_cal_sec = 0;
+            break;
+    }
+
+    return rf_cal_sec;
+}
+
 void user_init(void)
 {
     spiffs_fs1_init();
diff --git a/examples/websocket_demo/user/user_main.c b/examples/websocket_demo/user/user_main.c
index ea48b4a0..971ea173 100644
--- a/examples/websocket_demo/user/user_main.c
+++ b/examples/websocket_demo/user/user_main.c
@@ -26,6 +26,50 @@
 
 char test_mode = 4;
 
+/******************************************************************************
+ * FunctionName : user_rf_cal_sector_set
+ * Description  : SDK just reversed 4 sectors, used for rf init data and paramters.
+ *                We add this function to force users to set rf cal sector, since
+ *                we don't know which sector is free in user's application.
+ *                sector map for last several sectors : ABCCC
+ *                A : rf cal
+ *                B : rf init data
+ *                C : sdk parameters
+ * Parameters   : none
+ * Returns      : rf cal sector
+*******************************************************************************/
+uint32 user_rf_cal_sector_set(void)
+{
+    flash_size_map size_map = system_get_flash_size_map();
+    uint32 rf_cal_sec = 0;
+
+    switch (size_map) {
+        case FLASH_SIZE_4M_MAP_256_256:
+            rf_cal_sec = 128 - 5;
+            break;
+
+        case FLASH_SIZE_8M_MAP_512_512:
+            rf_cal_sec = 256 - 5;
+            break;
+
+        case FLASH_SIZE_16M_MAP_512_512:
+        case FLASH_SIZE_16M_MAP_1024_1024:
+            rf_cal_sec = 512 - 5;
+            break;
+
+        case FLASH_SIZE_32M_MAP_512_512:
+        case FLASH_SIZE_32M_MAP_1024_1024:
+            rf_cal_sec = 1024 - 5;
+            break;
+
+        default:
+            rf_cal_sec = 0;
+            break;
+    }
+
+    return rf_cal_sec;
+}
+
 /******************************************************************************
  * FunctionName : user_init
  * Description  : entry of user application, init user function here
diff --git a/lib/libmain.a b/lib/libmain.a
old mode 100644
new mode 100755
index c953a8c0..f6e31582
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diff --git a/lib/libpp.a b/lib/libpp.a
old mode 100644
new mode 100755
index e205dd67..650611dc
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