diff --git a/firmware.asm b/firmware.asm
index 1383963..ecfb280 100644
--- a/firmware.asm
+++ b/firmware.asm
@@ -58,6 +58,12 @@
 .equ SW_FLAG_3 = 0xb0
 .equ SW_FLAG_4 = 0x70
 
+; Value that stored in OCR0A for each tone
+; 880Hz = 71
+; 785Hz = 80
+; 590Hz = 105
+; 440Hz = 142
+
 .include "macros.asm"       ; Include macros
 
 .dseg                       ; Data segment
@@ -123,18 +129,24 @@ loop:                       ; Program loop
     cpi mcu_state_r, INIT_STATE
     brne showing
     rcall MCU_Init
-    set_state SHOWING_STATE
+    set_state SHOWING_STATE 
   showing:                  ; Showing state
     cpi mcu_state_r, SHOWING_STATE
     brne polling
-    
+    rcall show_sequence
+    ; set_state POLLING_STATE
+  polling:                  ; Polling state
+    cpi mcu_state_r, POLLING_STATE
+    brne completion
+  
     lds r18, SW_FLAGS_ADDRESS
     led_1:
       cpi r18, SW_FLAG_1
       brne led_off_1
       led_on_1:
         sbi LED_PORT, 0
-        outi OCR0A, 8
+        sbi BUZZ_DIR, BUZZ_PIN
+        outi OCR0A, 142
         rjmp led_2
       led_off_1:
         cbi LED_PORT, 0
@@ -143,7 +155,8 @@ loop:                       ; Program loop
       brne led_off_2
       led_on_2:
         sbi LED_PORT, 1
-        outi OCR0A, 10
+        sbi BUZZ_DIR, BUZZ_PIN
+        outi OCR0A, 71
         rjmp led_3
       led_off_2:
         cbi LED_PORT, 1
@@ -152,7 +165,8 @@ loop:                       ; Program loop
       brne led_off_3
       led_on_3:
         sbi LED_PORT, 2
-        outi OCR0A, 12
+        sbi BUZZ_DIR, BUZZ_PIN
+        outi OCR0A, 105
         rjmp led_4
       led_off_3:
         cbi LED_PORT, 2
@@ -161,19 +175,21 @@ loop:                       ; Program loop
       brne led_off_4
       led_on_4:
         sbi LED_PORT, 3
-        outi OCR0A, 15
+        sbi BUZZ_DIR, BUZZ_PIN
+        outi OCR0A, 80
         rjmp polling
       led_off_4:
         cbi LED_PORT, 3
-  polling:                  ; Polling state
-    cpi mcu_state_r, POLLING_STATE
-    brne completion
   completion:
     cpi mcu_state_r, COMPLETION_STATE ; Completion state
     brne default
   default:                  ; Do nothing
 rjmp loop
 
+show_sequence:              ; Show sequence of led
+  nop
+ret
+
 effect_1:                   ; Shift bits of an leds in port every 50ms
   push r17
   push r18
@@ -221,6 +237,7 @@ ret
 MCU_Init:
   rcall init_ports
   rcall init_interrupts
+  rcall init_buzzer
   rcall delay_before_start  ; Init MCU and delay before start main program
 ret
 
@@ -245,22 +262,26 @@ init_interrupts:
   ldi temp_r, (1<<PCINT4) | (1<<PCINT5)| (1<<PCINT6) | (1<<PCINT7)
   out PCMSK0, temp_r
 
-  ;
-  ; Setup timer
-  ldi temp_r, (1<<WGM01) | (1<<COM0A0)        ; CTC Mode
-  out TCCR0A, temp_r
-
-  ldi temp_r, 4
-  out OCR0A, temp_r
-
-  ldi temp_r, (1<<CS00) | (1<<CS01)           ; Prescale
-  out TCCR0B, temp_r
-
   clr temp_r
 
   sei                       ; Enable Global Interrupts
 ret
 
+init_buzzer:
+  cbi BUZZ_DIR, BUZZ_PIN
+  ;
+  ; Setup timer
+  ldi temp_r, (1<<COM0A0) | (1<<WGM01)        ; Set CTC timer mode and toggle OC0A pin on Compare Match
+  out TCCR0A, temp_r
+
+  ldi temp_r, 14
+  out OCR0A, temp_r
+
+  ldi temp_r, (1<<CS01)                       ; Prescale on 8
+  out TCCR0B, temp_r
+
+ret
+
 init_ports:                 ; Init MCU ports
   ; Setup PORTA 
   ldi temp_r, 0x0f
diff --git a/firmware.hex b/firmware.hex
index 5e30c66..794168b 100644
--- a/firmware.hex
+++ b/firmware.hex
@@ -1,29 +1,31 @@
 :020000020000FC
 :100000001CC018950EC01895189518951895189538
 :100010001895189518951895189518951895189578
-:1000200018951F932F932FB719B3107F8ED010936D
+:1000200018951F932F932FB719B3107F98D0109363
 :1000300062002FBF2F911F9118950FED0DBF1093E8
 :1000400061000F9301E0009360000F911091600038
-:10005000113041F45BD0109361000F9302E00093E4
-:1000600060000F91123031F520916200203E31F492
-:10007000D89A0F9308E006BF0F9101C0D898203D91
-:1000800031F4D99A0F930AE006BF0F9101C0D998B5
-:10009000203B31F4DA9A0F930CE006BF0F9101C0B8
-:1000A000DA98203731F4DB9A0F930FE006BF0F91F7
-:1000B00001C0DB98133001F4143001F4C7CF1F9353
-:1000C0002F933F934F934BB30F9301EF0BBB0F91C4
-:1000D0003CD011E033E020EF110F210F2BBB35D0C6
-:1000E0003A95C9F70F9308EF0BBB0F912ED018E08C
-:1000F00033E020EF1695210F2BBB27D03A95C9F797
-:100100004BBB4F913F912F911F91089517D009D06C
-:1001100001D0089506E0D3DF0A95E9F722D0002741
-:10012000089500E10BBF00EF02BB02E400BF04E052
-:1001300006BF03E003BF0027789408950FE00ABBD1
-:1001400002950BBBBA9AC29808952F933F9321E46E
-:100150003FEE3A95F1F72A95E1F700003F912F9194
-:1001600008958F939F9324E683EC99E00197F1F72C
-:100170002A95D1F724E69F918F9108954D656D6F73
-:100180007279206C65642067616D652E20577269F5
-:100190007474656E206279205365726765792059A1
-:1001A00061726B6F762032372E30392E3230323119
+:10005000113041F462D0109361000F9302E00093DD
+:1000600060000F91123009F42FD0133051F5209118
+:100070006200203E39F4D89ABA9A0F930EE806BF70
+:100080000F9101C0D898203D39F4D99ABA9A0F93AC
+:1000900007E406BF0F9101C0D998203B39F4DA9AE2
+:1000A000BA9A0F9309E606BF0F9101C0DA9820377C
+:1000B00039F4DB9ABA9A0F9300E506BF0F91D5CFBA
+:1000C000DB98143001F4C2CF000008951F932F93E2
+:1000D0003F934F934BB30F9301EF0BBB0F913FD067
+:1000E00011E033E020EF110F210F2BBB38D03A95F0
+:1000F000C9F70F9308EF0BBB0F9131D018E033E035
+:1001000020EF1695210F2BBB2AD03A95C9F74BBB90
+:100110004F913F912F911F9108951AD00AD010D07E
+:1001200001D0089506E0D2DF0A95E9F724D0002730
+:10013000089500E10BBF00EF02BB002778940895FB
+:10014000BA9802E400BF0EE006BF02E003BF0895C4
+:100150000FE00ABB02950BBBBA9AC29808952F9381
+:100160003F9321E43FEE3A95F1F72A95E1F700003D
+:100170003F912F9108958F939F9324E683EC99E00C
+:100180000197F1F72A95D1F724E69F918F91089571
+:100190004D656D6F7279206C65642067616D652EA9
+:1001A000205772697474656E206279205365726796
+:1001B0006579205961726B6F762032372E30392E77
+:0401C0003230323176
 :00000001FF