diff --git a/application/sim800_testing/Makefile b/application/sim800_testing/Makefile
index b73bed2..f6b77d5 100644
--- a/application/sim800_testing/Makefile
+++ b/application/sim800_testing/Makefile
@@ -13,6 +13,7 @@ DISPLAY_USED	:= blank
 SD_VER          := 6.0.0
 CONFIG_HEADER	:= 0
 SHARED_RESOURCES := 0
+AT_MOD_USED := SIM800
 	
 SDK_DIR         = ../../SDK_components
 DOC_DIR         = ../../doc
@@ -53,11 +54,11 @@ C_SRC += hal_uart.c tinyprintf.c
 else
 endif
 C_SRC += hal_uarte.c tinyprintf.c 
-C_SRC += AT_proc.c sim800_oper.c
+#C_SRC += AT_proc.c sim800_oper.c
 
-ifneq ($(DISPLAY_USED), blank)
-DISPLAY_DIR	= $(CODEBASE_DIR)/display_lib
-include $(DISPLAY_DIR)/Makefile.display
+ifneq ($(AT_MOD_USED), blank)
+AT_DIR	= $(CODEBASE_DIR)/AT_lib
+include $(AT_DIR)/Makefile.AT
 endif
 
 #Gets the name of the application folder
diff --git a/application/sim800_testing/AT_proc.c b/codebase/AT_lib/AT_proc.c
similarity index 99%
rename from application/sim800_testing/AT_proc.c
rename to codebase/AT_lib/AT_proc.c
index c0d3534..6bc6ee2 100644
--- a/application/sim800_testing/AT_proc.c
+++ b/codebase/AT_lib/AT_proc.c
@@ -358,7 +358,7 @@ void AT_proc_add_ticks (uint32_t ticks)
         {
             {
                 g_current_status = CMD_RUNNING;
-                /** uncomment this if UART is being disabled after command execution is done */
+                // uncomment this if UART is being disabled after command execution is done 
                 //hal_uarte_start_rx (collect_rsp);
                 hal_uarte_puts (g_arr_cmd, g_cmd_len);
             }
diff --git a/application/sim800_testing/AT_proc.h b/codebase/AT_lib/AT_proc.h
similarity index 91%
rename from application/sim800_testing/AT_proc.h
rename to codebase/AT_lib/AT_proc.h
index ab1d75e..8794dfd 100644
--- a/application/sim800_testing/AT_proc.h
+++ b/codebase/AT_lib/AT_proc.h
@@ -16,6 +16,17 @@
  *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+/**
+ * @addtogroup group_at_lib
+ * @{
+ *
+ * @defgroup group_at_proc AT Process
+ * @brief Driver to Process AT commands using hal_uarte module
+ *
+ * @warning This module needs the device_tick and to be on and running to be able to work
+ * @note This module uses UARTE peripheral. So developer can't use uart prints for debugging
+ * @{
+ */
 
 #ifndef AT_PROC_H
 #define AT_PROC_H
@@ -138,7 +149,7 @@ void AT_proc_process ();
 /**
  * @brief Function to check if AT command process module is busy
  * @return 1 if module is executing some AT command
- *         0 if module is available
+ * @return 0 if module is available
  */
 uint8_t AT_proc_is_busy ();
 
@@ -157,3 +168,7 @@ void AT_proc_repeat_last_cmd ();
 void AT_proc_send_cmd_no_rsp (uint8_t * cmd, uint32_t len, uint32_t duration);
 
 #endif /* AT_PROC_H */
+/**
+ * @}
+ * @}
+ */
diff --git a/codebase/AT_lib/Makefile.AT b/codebase/AT_lib/Makefile.AT
new file mode 100644
index 0000000..eecc727
--- /dev/null
+++ b/codebase/AT_lib/Makefile.AT
@@ -0,0 +1,7 @@
+INCLUDEDIRS += $(AT_DIR)
+C_SRC_DIRS += $(AT_DIR)
+C_SRC += AT_proc.c
+ifeq ($(AT_MOD_USED), SIM800)
+C_SRC += sim800_oper.c
+endif
+
diff --git a/codebase/AT_lib/defgroup_peripheral_modules.txt b/codebase/AT_lib/defgroup_peripheral_modules.txt
new file mode 100644
index 0000000..c421942
--- /dev/null
+++ b/codebase/AT_lib/defgroup_peripheral_modules.txt
@@ -0,0 +1,9 @@
+/**
+* @addtogroup group_codebase
+* @{
+* @defgroup group_at_lib AT Library
+* @brief Library to handle all the modules which runs in AT commands
+* @{
+*/
+/** @} */
+/** @} */
diff --git a/application/sim800_testing/sim800_cmd_id.h b/codebase/AT_lib/sim800_cmd_id.h
similarity index 100%
rename from application/sim800_testing/sim800_cmd_id.h
rename to codebase/AT_lib/sim800_cmd_id.h
diff --git a/application/sim800_testing/sim800_oper.c b/codebase/AT_lib/sim800_oper.c
similarity index 100%
rename from application/sim800_testing/sim800_oper.c
rename to codebase/AT_lib/sim800_oper.c
diff --git a/application/sim800_testing/sim800_oper.h b/codebase/AT_lib/sim800_oper.h
similarity index 94%
rename from application/sim800_testing/sim800_oper.h
rename to codebase/AT_lib/sim800_oper.h
index 9d63737..62fe631 100644
--- a/application/sim800_testing/sim800_oper.h
+++ b/codebase/AT_lib/sim800_oper.h
@@ -16,6 +16,16 @@
  *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+/**
+ * @addtogroup group_at_lib
+ * @{
+ *
+ * @defgroup group_sim800 SIM800 Operations
+ * @brief Driver to use SIM800 module using the AT Process
+ *
+ * @warning This module needs the device_tick to be on and running to be able to work
+ * @{
+ */
 
 #ifndef SIM800_OPER_H
 #define SIM800_OPER_H
@@ -174,3 +184,7 @@ sim800_conn_status_t sim800_oper_get_server_status (uint32_t server_id);
 
 
 #endif /* SIM800_OPER_H */
+/**
+ * @}
+ * @}
+ */