diff --git a/firmware.asm b/firmware.asm
index aac0c11..14d4029 100644
--- a/firmware.asm
+++ b/firmware.asm
@@ -23,9 +23,9 @@
 ;========================================;
 
 .EQU LED_POWER_PORT   = PD6
-.EQU CLOCK_PIN        = PB0   ; ST_CP on 74HC595
-.EQU DATA_PIN         = PB1   ; DS on 74HC595
-.EQU LATCH_PIN        = PB2   ; SH_CP on 74HC595
+.EQU USI_LATCH_PIN    = PB0   ; ST_CP on 74HC595
+.EQU USI_DO_PIN       = PB6   ; DS on 74HC595
+.EQU USI_CLK_PIN      = PB7   ; SH_CP on 74HC595
 
 ;========================================;
 ;              CODE SEGMENT              ;
@@ -75,63 +75,40 @@ MCU_INIT:
   ;                                                      ;
   ;=======================================================
   rcall     INIT_PORTS
-
-  ;========================================;
-  ;       USI IS USED TO COMMUNICATE       ;
-  ;     WITH SHIFT REGISTER (74HC595N)     ;
-  ;========================================;
-  rcall     INIT_USI
-
   ldi       COUNTER, 0b00000001
   rjmp      LOOP
 
 INIT_PORTS:
   ldi       r16, (1<<LED_POWER_PORT)
   out       DDRD, r16
-  ldi       r16, (1<<CLOCK_PIN) | (1<<LATCH_PIN) | (1<<DATA_PIN)
+  ldi       r16, (1<<USI_CLK_PIN) | (1<<USI_DO_PIN) | (1<<USI_LATCH_PIN)
   out       DDRB, r16
 ret
 
-INIT_USI:
-
-ret
-
 ;========================================;
 ;          SEND BYTE TO 74HC595          ;
 ;========================================;
-TRANSMIT_595:
+
+USI_TRANSMIT_595:
   in        r21, SREG
   mov       r19, COUNTER
-  ldi       TEMP_REG_B, 8
-  _TRANSMIT_595_LOOP:
-    ;
-    ; Shift a bit into the Carry flag and check if it is set to 1 or 0.
-    lsl     r19
-    brcc    _TRANSMIT_595_SEND_LOW
-    brcs    _TRANSMIT_595_SEND_HIGH
-    
-    _TRANSMIT_595_SEND_HIGH:
-      sbi     PORTB, DATA_PIN
-      rjmp    _TRANSMIT_595_COMMIT
+  out       USIDR, r19
+  ldi       r19, (1<<USIOIF)
+  out       USISR, r19
+  ldi       TEMP_REG_A, (1<<USIWM0) | (1<<USICS1) | (1<<USICLK) | (1<<USITC)
+  
+  _USI_TRANSMIT_595_LOOP:
+    out       USICR, TEMP_REG_A
+    sbis      USISR, USIOIF
+    rjmp      _USI_TRANSMIT_595_LOOP
 
-    _TRANSMIT_595_SEND_LOW:
-      cbi     PORTB, DATA_PIN
-
-    _TRANSMIT_595_COMMIT:
-      cbi      PORTB, CLOCK_PIN
-      sbi      PORTB, CLOCK_PIN
-    dec      TEMP_REG_B
-    brne     _TRANSMIT_595_LOOP
-    
-    ;
-    ; Copy data from shift register to storage register
-    sbi      PORTB, LATCH_PIN
-    cbi      PORTB, LATCH_PIN 
-  out        SREG, r21
+  sbi      PORTB, USI_LATCH_PIN
+  cbi      PORTB, USI_LATCH_PIN
+  out       SREG, r21
 ret
 
 SUBPROGRAM_LED_SHIFTING:
-  rcall     TRANSMIT_595
+  rcall     USI_TRANSMIT_595
   rol       COUNTER
 ret
 
diff --git a/firmware.hex b/firmware.hex
index 6814670..996fb2f 100644
--- a/firmware.hex
+++ b/firmware.hex
@@ -1,10 +1,9 @@
 :020000020000FC
-:1000000000C00FED0DBF03D007D041E01AC000E4DF
-:1000100001BB07E007BB089508955FB7342F18E0D0
-:10002000330F18F400F0C19A01C0C198C098C09A6B
-:100030001A95B1F7C29AC2985FBF0895EEDF441FC8
-:10004000089514D0FBDF02D001D0FBCF0F931F9394
-:10005000F8940FEF1FEF1A95000000000000D9F789
-:100060000A95C1F778941F910F91089500E412B397
-:06007000102712BB0895E9
+:1000000000C00FED0DBF02D041E015C000E401BB00
+:1000100001EC07BB08955FB7342F3FB930E43EB918
+:100020000BE10DB9769BFDCFC09AC0985FBF0895D4
+:10003000F2DF441F089514D0FBDF02D001D0FBCFC4
+:100040000F931F93F8940FEF1FEF1A950000000015
+:100050000000D9F70A95C1F778941F910F91089580
+:0A00600000E412B3102712BB08954C
 :00000001FF
diff --git a/firmware.lss b/firmware.lss
index faa39c2..4a80f02 100644
--- a/firmware.lss
+++ b/firmware.lss
@@ -1,5 +1,5 @@
 
-AVRASM ver. 2.2.7  firmware.asm Sun Jan 29 21:32:32 2023
+AVRASM ver. 2.2.7  firmware.asm Sun Jan 29 22:16:18 2023
 
 firmware.asm(14): Including file 'tn2313Adef.inc'
 firmware.asm(14): Including file 'tn2313Adef.inc'
@@ -727,9 +727,9 @@ firmware.asm(14): Including file 'tn2313Adef.inc'
                                  ;========================================;
                                  
                                  .EQU LED_POWER_PORT   = PD6
-                                 .EQU CLOCK_PIN        = PB0   ; ST_CP on 74HC595
-                                 .EQU DATA_PIN         = PB1   ; DS on 74HC595
-                                 .EQU LATCH_PIN        = PB2   ; SH_CP on 74HC595
+                                 .EQU USI_LATCH_PIN    = PB0   ; ST_CP on 74HC595
+                                 .EQU USI_DO_PIN       = PB6   ; DS on 74HC595
+                                 .EQU USI_CLK_PIN      = PB7   ; SH_CP on 74HC595
                                  
                                  ;========================================;
                                  ;              CODE SEGMENT              ;
@@ -778,106 +778,83 @@ firmware.asm(14): Including file 'tn2313Adef.inc'
                                    ;       is working correctly                           ;
                                    ;                                                      ;
                                    ;=======================================================
-000003 d003                        rcall     INIT_PORTS
-                                 
-                                   ;========================================;
-                                   ;       USI IS USED TO COMMUNICATE       ;
-                                   ;     WITH SHIFT REGISTER (74HC595N)     ;
-                                   ;========================================;
-000004 d007                        rcall     INIT_USI
-                                 
-000005 e041                        ldi       COUNTER, 0b00000001
-000006 c01a                        rjmp      LOOP
+000003 d002                        rcall     INIT_PORTS
+000004 e041                        ldi       COUNTER, 0b00000001
+000005 c015                        rjmp      LOOP
                                  
                                  INIT_PORTS:
-000007 e400                        ldi       r16, (1<<LED_POWER_PORT)
-000008 bb01                        out       DDRD, r16
-000009 e007                        ldi       r16, (1<<CLOCK_PIN) | (1<<LATCH_PIN) | (1<<DATA_PIN)
-00000a bb07                        out       DDRB, r16
-00000b 9508                      ret
-                                 
-                                 INIT_USI:
-                                 
-00000c 9508                      ret
+000006 e400                        ldi       r16, (1<<LED_POWER_PORT)
+000007 bb01                        out       DDRD, r16
+000008 ec01                        ldi       r16, (1<<USI_CLK_PIN) | (1<<USI_DO_PIN) | (1<<USI_LATCH_PIN)
+000009 bb07                        out       DDRB, r16
+00000a 9508                      ret
                                  
                                  ;========================================;
                                  ;          SEND BYTE TO 74HC595          ;
                                  ;========================================;
-                                 TRANSMIT_595:
-00000d b75f                        in        r21, SREG
-00000e 2f34                        mov       r19, COUNTER
-00000f e018                        ldi       TEMP_REG_B, 8
-                                   _TRANSMIT_595_LOOP:
-                                     ;
-                                     ; Shift a bit into the Carry flag and check if it is set to 1 or 0.
-000010 0f33                          lsl     r19
-000011 f418                          brcc    _TRANSMIT_595_SEND_LOW
-000012 f000                          brcs    _TRANSMIT_595_SEND_HIGH
-                                     
-                                     _TRANSMIT_595_SEND_HIGH:
-000013 9ac1                            sbi     PORTB, DATA_PIN
-000014 c001                            rjmp    _TRANSMIT_595_COMMIT
                                  
-                                     _TRANSMIT_595_SEND_LOW:
-000015 98c1                            cbi     PORTB, DATA_PIN
+                                 USI_TRANSMIT_595:
+00000b b75f                        in        r21, SREG
+00000c 2f34                        mov       r19, COUNTER
+00000d b93f                        out       USIDR, r19
+00000e e430                        ldi       r19, (1<<USIOIF)
+00000f b93e                        out       USISR, r19
+000010 e10b                        ldi       TEMP_REG_A, (1<<USIWM0) | (1<<USICS1) | (1<<USICLK) | (1<<USITC)
+                                   
+                                   _USI_TRANSMIT_595_LOOP:
+000011 b90d                          out       USICR, TEMP_REG_A
+000012 9b76                          sbis      USISR, USIOIF
+000013 cffd                          rjmp      _USI_TRANSMIT_595_LOOP
                                  
-                                     _TRANSMIT_595_COMMIT:
-000016 98c0                            cbi      PORTB, CLOCK_PIN
-000017 9ac0                            sbi      PORTB, CLOCK_PIN
-000018 951a                          dec      TEMP_REG_B
-000019 f7b1                          brne     _TRANSMIT_595_LOOP
-                                     
-                                     ;
-                                     ; Copy data from shift register to storage register
-00001a 9ac2                          sbi      PORTB, LATCH_PIN
-00001b 98c2                          cbi      PORTB, LATCH_PIN 
-00001c bf5f                        out        SREG, r21
-00001d 9508                      ret
+000014 9ac0                        sbi      PORTB, USI_LATCH_PIN
+000015 98c0                        cbi      PORTB, USI_LATCH_PIN
+000016 bf5f                        out       SREG, r21
+000017 9508                      ret
                                  
                                  SUBPROGRAM_LED_SHIFTING:
-00001e dfee                        rcall     TRANSMIT_595
-00001f 1f44                        rol       COUNTER
-000020 9508                      ret
+000018 dff2                        rcall     USI_TRANSMIT_595
+000019 1f44                        rol       COUNTER
+00001a 9508                      ret
                                  
                                  ;========================================;
                                  ;            MAIN PROGRAM LOOP           ;
                                  ;========================================;
                                  
                                  LOOP:
-000021 d014                        rcall     TOGGLE_POWER_LED
-000022 dffb                        rcall     SUBPROGRAM_LED_SHIFTING
-000023 d002                        rcall     DELAY
-000024 d001                        rcall     DELAY
-000025 cffb                        rjmp      LOOP
+00001b d014                        rcall     TOGGLE_POWER_LED
+00001c dffb                        rcall     SUBPROGRAM_LED_SHIFTING
+00001d d002                        rcall     DELAY
+00001e d001                        rcall     DELAY
+00001f cffb                        rjmp      LOOP
                                  
                                  DELAY:
-000026 930f                        push      r16
-000027 931f                        push      r17
-000028 94f8                        cli
-000029 ef0f                        ldi       r16, 255
+000020 930f                        push      r16
+000021 931f                        push      r17
+000022 94f8                        cli
+000023 ef0f                        ldi       r16, 255
                                    _DELAY_1:
-00002a ef1f                          ldi     r17, 255   
+000024 ef1f                          ldi     r17, 255   
                                    _DELAY_2:
-00002b 951a                          dec     r17         
-00002c 0000                          nop                 
-00002d 0000                          nop                
-00002e 0000                          nop                 
-00002f f7d9                          brne    _DELAY_2    
+000025 951a                          dec     r17         
+000026 0000                          nop                 
+000027 0000                          nop                
+000028 0000                          nop                 
+000029 f7d9                          brne    _DELAY_2    
                                  
-000030 950a                          dec     r16
-000031 f7c1                          brne    _DELAY_1    
-000032 9478                        sei
+00002a 950a                          dec     r16
+00002b f7c1                          brne    _DELAY_1    
+00002c 9478                        sei
                                  
-000033 911f                        pop       r17
-000034 910f                        pop       r16
-000035 9508                      ret                    
+00002d 911f                        pop       r17
+00002e 910f                        pop       r16
+00002f 9508                      ret                    
                                  
                                  TOGGLE_POWER_LED:
-000036 e400                        ldi       r16,  (1<<LED_POWER_PORT)
-000037 b312                        in        r17,  PORTD
-000038 2710                        eor       r17,  r16
-000039 bb12                        out       PORTD, r17
-00003a 9508                      ret
+000030 e400                        ldi       r16,  (1<<LED_POWER_PORT)
+000031 b312                        in        r17,  PORTD
+000032 2710                        eor       r17,  r16
+000033 bb12                        out       PORTD, r17
+000034 9508                      ret
                                  
                                  
                                  ;========================================;
@@ -954,7 +931,7 @@ counted separately from r26..r31 here.
 "ATtiny2313A" register use summary:
 x  :   0 y  :   0 z  :   0 r0 :   0 r1 :   0 r2 :   0 r3 :   0 r4 :   0 
 r5 :   0 r6 :   0 r7 :   0 r8 :   0 r9 :   0 r10:   0 r11:   0 r12:   0 
-r13:   0 r14:   0 r15:   0 r16:  12 r17:   9 r18:   0 r19:   2 r20:   3 
+r13:   0 r14:   0 r15:   0 r16:  14 r17:   7 r18:   0 r19:   4 r20:   3 
 r21:   2 r22:   0 r23:   0 r24:   0 r25:   0 r26:   0 r27:   0 r28:   0 
 r29:   0 r30:   0 r31:   0 
 Registers used: 5 out of 35 (14.3%)
@@ -962,28 +939,28 @@ Registers used: 5 out of 35 (14.3%)
 "ATtiny2313A" instruction use summary:
 .lds  :   0 .sts  :   0 adc   :   0 add   :   0 adiw  :   0 and   :   0 
 andi  :   0 asr   :   0 bclr  :   0 bld   :   0 brbc  :   0 brbs  :   0 
-brcc  :   1 brcs  :   1 break :   0 breq  :   0 brge  :   0 brhc  :   0 
+brcc  :   0 brcs  :   0 break :   0 breq  :   0 brge  :   0 brhc  :   0 
 brhs  :   0 brid  :   0 brie  :   0 brlo  :   0 brlt  :   0 brmi  :   0 
-brne  :   3 brpl  :   0 brsh  :   0 brtc  :   0 brts  :   0 brvc  :   0 
-brvs  :   0 bset  :   0 bst   :   0 cbi   :   3 cbr   :   0 clc   :   0 
+brne  :   2 brpl  :   0 brsh  :   0 brtc  :   0 brts  :   0 brvc  :   0 
+brvs  :   0 bset  :   0 bst   :   0 cbi   :   1 cbr   :   0 clc   :   0 
 clh   :   0 cli   :   1 cln   :   0 clr   :   0 cls   :   0 clt   :   0 
 clv   :   0 clz   :   0 com   :   0 cp    :   0 cpc   :   0 cpi   :   0 
-cpse  :   0 dec   :   3 eor   :   1 icall :   0 ijmp  :   0 in    :   2 
-inc   :   0 ld    :   0 ldd   :   0 ldi   :   8 lds   :   0 lpm   :   0 
-lsl   :   1 lsr   :   0 mov   :   1 movw  :   0 neg   :   0 nop   :   3 
-or    :   0 ori   :   0 out   :   5 pop   :   2 push  :   2 rcall :   7 
-ret   :   6 reti  :   0 rjmp  :   4 rol   :   1 ror   :   0 sbc   :   0 
-sbci  :   0 sbi   :   3 sbic  :   0 sbis  :   0 sbiw  :   0 sbr   :   0 
+cpse  :   0 dec   :   2 eor   :   1 icall :   0 ijmp  :   0 in    :   2 
+inc   :   0 ld    :   0 ldd   :   0 ldi   :   9 lds   :   0 lpm   :   0 
+lsl   :   0 lsr   :   0 mov   :   1 movw  :   0 neg   :   0 nop   :   3 
+or    :   0 ori   :   0 out   :   8 pop   :   2 push  :   2 rcall :   6 
+ret   :   5 reti  :   0 rjmp  :   4 rol   :   1 ror   :   0 sbc   :   0 
+sbci  :   0 sbi   :   1 sbic  :   0 sbis  :   1 sbiw  :   0 sbr   :   0 
 sbrc  :   0 sbrs  :   0 sec   :   0 seh   :   0 sei   :   1 sen   :   0 
 ser   :   0 ses   :   0 set   :   0 sev   :   0 sez   :   0 sleep :   0 
 spm   :   0 st    :   0 std   :   0 sts   :   0 sub   :   0 subi  :   0 
 swap  :   0 tst   :   0 wdr   :   0 
-Instructions used: 21 out of 105 (20.0%)
+Instructions used: 19 out of 105 (18.1%)
 
 "ATtiny2313A" memory use summary [bytes]:
 Segment   Begin    End      Code   Data   Used    Size   Use%
 ---------------------------------------------------------------
-[.cseg] 0x000000 0x000076    118      0    118    2048   5.8%
+[.cseg] 0x000000 0x00006a    106      0    106    2048   5.2%
 [.dseg] 0x000060 0x000060      0      0      0     128   0.0%
 [.eseg] 0x000000 0x000033      0     51     51     128  39.8%