diff --git a/Power_Pico/Core/Src/tim.c b/Power_Pico/Core/Src/tim.c
index e811e7e..8b1e6e6 100644
--- a/Power_Pico/Core/Src/tim.c
+++ b/Power_Pico/Core/Src/tim.c
@@ -146,7 +146,7 @@ void MX_TIM4_Init(void)
   htim4.Instance = TIM4;
   htim4.Init.Prescaler = 99;
   htim4.Init.CounterMode = TIM_COUNTERMODE_UP;
-  htim4.Init.Period = 250;
+  htim4.Init.Period = 500;
   htim4.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
   htim4.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
   if (HAL_TIM_PWM_Init(&htim4) != HAL_OK)
@@ -160,7 +160,7 @@ void MX_TIM4_Init(void)
     Error_Handler();
   }
   sConfigOC.OCMode = TIM_OCMODE_PWM1;
-  sConfigOC.Pulse = 0;
+  sConfigOC.Pulse = 250;
   sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
   sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
   if (HAL_TIM_PWM_ConfigChannel(&htim4, &sConfigOC, TIM_CHANNEL_4) != HAL_OK)
diff --git a/Power_Pico/User/GUI/screens/ui_SetPage.c b/Power_Pico/User/GUI/screens/ui_SetPage.c
index cd72114..be4f9a7 100644
--- a/Power_Pico/User/GUI/screens/ui_SetPage.c
+++ b/Power_Pico/User/GUI/screens/ui_SetPage.c
@@ -6,15 +6,19 @@
 #include "../ui.h"
 
 lv_obj_t * ui_SetPage = NULL;
+// backlight
 static lv_obj_t * ui_PanelBL = NULL;
 static lv_obj_t * ui_SliderBL = NULL;
 static lv_obj_t * ui_LabelBL = NULL;
+// key sound
 static lv_obj_t * ui_PanelKS = NULL;
 static lv_obj_t * ui_SwitchKS = NULL;
 static lv_obj_t * ui_LabelKS = NULL;
+// language
 static lv_obj_t * ui_PanelLang = NULL;
 static lv_obj_t * ui_SwitchLang = NULL;
 static lv_obj_t * ui_LabelLang = NULL;
+// about
 static lv_obj_t * ui_PanelAbout = NULL;
 static lv_obj_t * ui_LabelAbout = NULL;
 
@@ -177,7 +181,7 @@ void ui_SetPage_screen_init(void)
     lv_label_set_text(ui_LabelAbout, "About\nPower-Pico\nA uA current meter\nV 1.0.0");
     lv_obj_set_style_text_font(ui_LabelAbout, &lv_font_montserrat_16, LV_PART_MAIN | LV_STATE_DEFAULT);
 
-    //
+    // store panels in array
     panels[0] = ui_PanelBL;
     panels[1] = ui_PanelKS;
     panels[2] = ui_PanelLang;
diff --git a/Power_Pico/User/Tasks/Src/user_KeyTask.c b/Power_Pico/User/Tasks/Src/user_KeyTask.c
index 747f4a1..696fdb9 100644
--- a/Power_Pico/User/Tasks/Src/user_KeyTask.c
+++ b/Power_Pico/User/Tasks/Src/user_KeyTask.c
@@ -3,6 +3,7 @@
 #include "user_TasksInit.h"
 #include "main.h"
 #include "key.h"
+#include "beep.h"
 
 /* Private typedef -----------------------------------------------------------*/
 
@@ -27,6 +28,13 @@ void KeyTask(void *argument)
 		if(keystr != 0)
 		{
 			osMessageQueuePut(Key_MessageQueue, &keystr, 0, 1);
+			// beep
+			if(1)
+			{
+				beep_open();
+				osDelay(50);
+				beep_close();
+			}
 		}
 		osDelay(10);
 	}