diff --git a/build/final.elf b/build/final.elf
index 0e569e0..64ba45f 100755
Binary files a/build/final.elf and b/build/final.elf differ
diff --git a/build/final.elf.map b/build/final.elf.map
index b6272e6..ba03548 100644
--- a/build/final.elf.map
+++ b/build/final.elf.map
@@ -116,8 +116,6 @@ Discarded input sections
  .text          0x00000000        0x0 build/usart.o
  .data          0x00000000        0x0 build/usart.o
  .bss           0x00000000        0x0 build/usart.o
- .text.usart2_start
-                0x00000000       0x20 build/usart.o
  .debug_macro   0x00000000       0x22 build/usart.o
  .debug_macro   0x00000000       0x75 build/usart.o
  .debug_macro   0x00000000       0x2a build/usart.o
@@ -132,7 +130,7 @@ Discarded input sections
  .debug_macro   0x00000000      0x4cc build/usart.o
  .debug_macro   0x00000000      0x13e build/usart.o
  .debug_macro   0x00000000       0x22 build/usart.o
- .debug_macro   0x00000000       0x5e build/usart.o
+ .debug_macro   0x00000000       0x76 build/usart.o
 
 Memory Configuration
 
@@ -159,7 +157,7 @@ LOAD build/usart.o
                 0x08000000                interrupt_vector_table
                 0x08000198                        . = ALIGN (0x4)
 
-.text           0x08000198      0x458
+.text           0x08000198      0x4b0
                 0x08000198                        . = ALIGN (0x4)
  *(.text)
  *(.text.*)
@@ -172,116 +170,122 @@ LOAD build/usart.o
  *fill*         0x08000246        0x2 
  .text.system_clock_init
                 0x08000248      0x144 build/main.o
- .text.main     0x0800038c       0x90 build/main.o
+ .text.main     0x0800038c       0x98 build/main.o
                 0x0800038c                main
  .text.init_memory
-                0x0800041c       0x64 build/startup.o
-                0x0800041c                init_memory
- .text.reset    0x08000480       0x10 build/startup.o
-                0x08000480                reset
+                0x08000424       0x64 build/startup.o
+                0x08000424                init_memory
+ .text.reset    0x08000488       0x10 build/startup.o
+                0x08000488                reset
  .text.default_handler
-                0x08000490        0x8 build/startup.o
-                0x08000490                exti0
-                0x08000490                debug_monitor
-                0x08000490                rcc
-                0x08000490                x
-                0x08000490                sdio
-                0x08000490                usage_fault
-                0x08000490                tim1_up_tim10
-                0x08000490                usart1
-                0x08000490                i2c3_er
-                0x08000490                spi2
-                0x08000490                dma1_stream1
-                0x08000490                bus_fault
-                0x08000490                spi5
-                0x08000490                exti3
-                0x08000490                dma2_stream5
-                0x08000490                tim2
-                0x08000490                dma1_stream6
-                0x08000490                default_handler
-                0x08000490                i2c1_er
-                0x08000490                hard_fault
-                0x08000490                usart6
-                0x08000490                exti15_10
-                0x08000490                usart2
-                0x08000490                pend_sv
-                0x08000490                i2c1_ev
-                0x08000490                wwdg
-                0x08000490                adc
-                0x08000490                rtc_alarm
-                0x08000490                spi3
-                0x08000490                exti1
-                0x08000490                mem_manage
-                0x08000490                dma2_stream1
-                0x08000490                dma1_stream2
-                0x08000490                dma2_stream3
-                0x08000490                sv_call
-                0x08000490                tim3
-                0x08000490                otg_fs
-                0x08000490                dma1_stream5
-                0x08000490                dma2_stream6
-                0x08000490                flash
-                0x08000490                tamp_stamp
-                0x08000490                i2c3_ev
-                0x08000490                rtc_wkup
-                0x08000490                dma2_stream0
-                0x08000490                pvd
-                0x08000490                fpu
-                0x08000490                exti4
-                0x08000490                exti2
-                0x08000490                spi1
-                0x08000490                dma1_stream0
-                0x08000490                tim1_brk_tim9
-                0x08000490                i2c2_ev
-                0x08000490                otg_fs_wkup
-                0x08000490                spi4
-                0x08000490                dma2_stream2
-                0x08000490                tim1_cc
-                0x08000490                tim1_trg_com_tim11
-                0x08000490                exti9_5
-                0x08000490                dma1_stream3
-                0x08000490                dma2_stream4
-                0x08000490                i2c2_er
-                0x08000490                dma2_stream7
-                0x08000490                dma1_stream7
-                0x08000490                nmi
-                0x08000490                systick
-                0x08000490                tim4
-                0x08000490                tim5
-                0x08000490                dma1_stream4
+                0x08000498        0x8 build/startup.o
+                0x08000498                exti0
+                0x08000498                debug_monitor
+                0x08000498                rcc
+                0x08000498                x
+                0x08000498                sdio
+                0x08000498                usage_fault
+                0x08000498                tim1_up_tim10
+                0x08000498                usart1
+                0x08000498                i2c3_er
+                0x08000498                spi2
+                0x08000498                dma1_stream1
+                0x08000498                bus_fault
+                0x08000498                spi5
+                0x08000498                exti3
+                0x08000498                dma2_stream5
+                0x08000498                tim2
+                0x08000498                dma1_stream6
+                0x08000498                default_handler
+                0x08000498                i2c1_er
+                0x08000498                hard_fault
+                0x08000498                usart6
+                0x08000498                exti15_10
+                0x08000498                usart2
+                0x08000498                pend_sv
+                0x08000498                i2c1_ev
+                0x08000498                wwdg
+                0x08000498                adc
+                0x08000498                rtc_alarm
+                0x08000498                spi3
+                0x08000498                exti1
+                0x08000498                mem_manage
+                0x08000498                dma2_stream1
+                0x08000498                dma1_stream2
+                0x08000498                dma2_stream3
+                0x08000498                sv_call
+                0x08000498                tim3
+                0x08000498                otg_fs
+                0x08000498                dma1_stream5
+                0x08000498                dma2_stream6
+                0x08000498                flash
+                0x08000498                tamp_stamp
+                0x08000498                i2c3_ev
+                0x08000498                rtc_wkup
+                0x08000498                dma2_stream0
+                0x08000498                pvd
+                0x08000498                fpu
+                0x08000498                exti4
+                0x08000498                exti2
+                0x08000498                spi1
+                0x08000498                dma1_stream0
+                0x08000498                tim1_brk_tim9
+                0x08000498                i2c2_ev
+                0x08000498                otg_fs_wkup
+                0x08000498                spi4
+                0x08000498                dma2_stream2
+                0x08000498                tim1_cc
+                0x08000498                tim1_trg_com_tim11
+                0x08000498                exti9_5
+                0x08000498                dma1_stream3
+                0x08000498                dma2_stream4
+                0x08000498                i2c2_er
+                0x08000498                dma2_stream7
+                0x08000498                dma1_stream7
+                0x08000498                nmi
+                0x08000498                systick
+                0x08000498                tim4
+                0x08000498                tim5
+                0x08000498                dma1_stream4
  .text.tim4_init
-                0x08000498       0x40 build/timer.o
-                0x08000498                tim4_init
+                0x080004a0       0x40 build/timer.o
+                0x080004a0                tim4_init
  .text.tim4_start
-                0x080004d8       0x20 build/timer.o
-                0x080004d8                tim4_start
+                0x080004e0       0x20 build/timer.o
+                0x080004e0                tim4_start
  .text.usart2_init
-                0x080004f8       0xf8 build/usart.o
-                0x080004f8                usart2_init
+                0x08000500       0xf8 build/usart.o
+                0x08000500                usart2_init
+ .text.usart2_start
+                0x080005f8       0x20 build/usart.o
+                0x080005f8                usart2_start
+ .text.usart2_write_byte
+                0x08000618       0x30 build/usart.o
+                0x08000618                usart2_write_byte
  *(.rodata)
  *(.rodata.*)
-                0x080005f0                        . = ALIGN (0x4)
-                0x080005f0                        _data_addr = LOADADDR (.data)
+                0x08000648                        . = ALIGN (0x4)
+                0x08000648                        _data_addr = LOADADDR (.data)
 
-.glue_7         0x080005f0        0x0
- .glue_7        0x080005f0        0x0 linker stubs
+.glue_7         0x08000648        0x0
+ .glue_7        0x08000648        0x0 linker stubs
 
-.glue_7t        0x080005f0        0x0
- .glue_7t       0x080005f0        0x0 linker stubs
+.glue_7t        0x08000648        0x0
+ .glue_7t       0x08000648        0x0 linker stubs
 
-.vfp11_veneer   0x080005f0        0x0
- .vfp11_veneer  0x080005f0        0x0 linker stubs
+.vfp11_veneer   0x08000648        0x0
+ .vfp11_veneer  0x08000648        0x0 linker stubs
 
-.v4_bx          0x080005f0        0x0
- .v4_bx         0x080005f0        0x0 linker stubs
+.v4_bx          0x08000648        0x0
+ .v4_bx         0x08000648        0x0 linker stubs
 
-.iplt           0x080005f0        0x0
- .iplt          0x080005f0        0x0 build/main.o
+.iplt           0x08000648        0x0
+ .iplt          0x08000648        0x0 build/main.o
 
-.rel.dyn        0x080005f0        0x0
- .rel.iplt      0x080005f0        0x0 build/main.o
+.rel.dyn        0x08000648        0x0
+ .rel.iplt      0x08000648        0x0 build/main.o
 
-.data           0x20000000        0x0 load address 0x080005f0
+.data           0x20000000        0x0 load address 0x08000648
                 0x20000000                        . = ALIGN (0x4)
                 0x20000000                        _data_start = .
  *(.data)
@@ -289,10 +293,10 @@ LOAD build/usart.o
                 0x20000000                        . = ALIGN (0x4)
                 0x20000000                        _data_end = .
 
-.igot.plt       0x20000000        0x0 load address 0x080005f0
+.igot.plt       0x20000000        0x0 load address 0x08000648
  .igot.plt      0x20000000        0x0 build/main.o
 
-.bss            0x20000000        0x0 load address 0x080005f0
+.bss            0x20000000        0x0 load address 0x08000648
                 0x20000000                        . = ALIGN (0x4)
                 0x20000000                        _bss_start = .
  *(.bss)
@@ -302,21 +306,21 @@ LOAD build/usart.o
 OUTPUT(build/final.elf elf32-littlearm)
 LOAD linker stubs
 
-.debug_info     0x00000000      0xe1d
+.debug_info     0x00000000      0xe69
  .debug_info    0x00000000      0x205 build/gpio.o
- .debug_info    0x00000205      0x457 build/main.o
- .debug_info    0x0000065c      0x188 build/startup.o
- .debug_info    0x000007e4      0x335 build/timer.o
- .debug_info    0x00000b19      0x304 build/usart.o
+ .debug_info    0x00000205      0x478 build/main.o
+ .debug_info    0x0000067d      0x188 build/startup.o
+ .debug_info    0x00000805      0x335 build/timer.o
+ .debug_info    0x00000b3a      0x32f build/usart.o
 
-.debug_abbrev   0x00000000      0x4ee
+.debug_abbrev   0x00000000      0x519
  .debug_abbrev  0x00000000      0x119 build/gpio.o
- .debug_abbrev  0x00000119      0x143 build/main.o
- .debug_abbrev  0x0000025c      0x127 build/startup.o
- .debug_abbrev  0x00000383       0xb5 build/timer.o
- .debug_abbrev  0x00000438       0xb6 build/usart.o
+ .debug_abbrev  0x00000119      0x142 build/main.o
+ .debug_abbrev  0x0000025b      0x127 build/startup.o
+ .debug_abbrev  0x00000382       0xb5 build/timer.o
+ .debug_abbrev  0x00000437       0xe2 build/usart.o
 
-.debug_aranges  0x00000000       0xd0
+.debug_aranges  0x00000000       0xd8
  .debug_aranges
                 0x00000000       0x28 build/gpio.o
  .debug_aranges
@@ -326,10 +330,10 @@ LOAD linker stubs
  .debug_aranges
                 0x00000080       0x28 build/timer.o
  .debug_aranges
-                0x000000a8       0x28 build/usart.o
+                0x000000a8       0x30 build/usart.o
 
 .debug_rnglists
-                0x00000000       0x86
+                0x00000000       0x8c
  .debug_rnglists
                 0x00000000       0x19 build/gpio.o
  .debug_rnglists
@@ -339,9 +343,9 @@ LOAD linker stubs
  .debug_rnglists
                 0x00000053       0x19 build/timer.o
  .debug_rnglists
-                0x0000006c       0x1a build/usart.o
+                0x0000006c       0x20 build/usart.o
 
-.debug_macro    0x00000000     0x4885
+.debug_macro    0x00000000     0x489d
  .debug_macro   0x00000000      0xb56 build/gpio.o
  .debug_macro   0x00000b56       0x22 build/gpio.o
  .debug_macro   0x00000b78       0x75 build/gpio.o
@@ -362,33 +366,33 @@ LOAD linker stubs
  .debug_macro   0x00002358       0x46 build/main.o
  .debug_macro   0x0000239e       0x2e build/main.o
  .debug_macro   0x000023cc       0x22 build/main.o
- .debug_macro   0x000023ee       0x5e build/main.o
- .debug_macro   0x0000244c      0xb02 build/startup.o
- .debug_macro   0x00002f4e       0x56 build/startup.o
- .debug_macro   0x00002fa4       0x51 build/startup.o
- .debug_macro   0x00002ff5      0xb5c build/timer.o
- .debug_macro   0x00003b51      0x13e build/timer.o
- .debug_macro   0x00003c8f      0xb74 build/usart.o
- .debug_macro   0x00004803       0x82 build/usart.o
+ .debug_macro   0x000023ee       0x76 build/main.o
+ .debug_macro   0x00002464      0xb02 build/startup.o
+ .debug_macro   0x00002f66       0x56 build/startup.o
+ .debug_macro   0x00002fbc       0x51 build/startup.o
+ .debug_macro   0x0000300d      0xb5c build/timer.o
+ .debug_macro   0x00003b69      0x13e build/timer.o
+ .debug_macro   0x00003ca7      0xb74 build/usart.o
+ .debug_macro   0x0000481b       0x82 build/usart.o
 
-.debug_line     0x00000000      0x605
+.debug_line     0x00000000      0x63b
  .debug_line    0x00000000      0x116 build/gpio.o
- .debug_line    0x00000116      0x1e1 build/main.o
- .debug_line    0x000002f7       0xea build/startup.o
- .debug_line    0x000003e1       0xdf build/timer.o
- .debug_line    0x000004c0      0x145 build/usart.o
+ .debug_line    0x00000116      0x1e4 build/main.o
+ .debug_line    0x000002fa       0xea build/startup.o
+ .debug_line    0x000003e4       0xdf build/timer.o
+ .debug_line    0x000004c3      0x178 build/usart.o
 
-.debug_str      0x00000000     0x62fd
+.debug_str      0x00000000     0x6393
  .debug_str     0x00000000     0x550b build/gpio.o
                                0x56b3 (size before relaxing)
- .debug_str     0x0000550b      0xd3a build/main.o
-                               0x639d (size before relaxing)
- .debug_str     0x00006245       0x88 build/startup.o
+ .debug_str     0x0000550b      0xddd build/main.o
+                               0x6440 (size before relaxing)
+ .debug_str     0x000062e8       0x88 build/startup.o
                                0x3cdf (size before relaxing)
- .debug_str     0x000062cd        0xc build/timer.o
+ .debug_str     0x00006370        0xc build/timer.o
                                0x5bc5 (size before relaxing)
- .debug_str     0x000062d9       0x24 build/usart.o
-                               0x5ffb (size before relaxing)
+ .debug_str     0x0000637c       0x17 build/usart.o
+                               0x6091 (size before relaxing)
 
 .comment        0x00000000       0x45
  .comment       0x00000000       0x45 build/gpio.o
@@ -429,9 +433,9 @@ LOAD linker stubs
                 0x0000028b        0x8 build/usart.o
                                 0x26f (size before relaxing)
 
-.debug_frame    0x00000000      0x1bc
+.debug_frame    0x00000000      0x1e4
  .debug_frame   0x00000000       0x60 build/gpio.o
  .debug_frame   0x00000060       0x50 build/main.o
  .debug_frame   0x000000b0       0x6c build/startup.o
  .debug_frame   0x0000011c       0x50 build/timer.o
- .debug_frame   0x0000016c       0x50 build/usart.o
+ .debug_frame   0x0000016c       0x78 build/usart.o
diff --git a/build/main.S b/build/main.S
index 145501f..1f0a81d 100644
--- a/build/main.S
+++ b/build/main.S
@@ -266,7 +266,7 @@ main:
 	.loc 1 82 3
 	bl	tim4_start
 	.loc 1 83 3
-	bl	tim4_start
+	bl	usart2_start
 	.loc 1 85 12
 	movw	r3, #525
 	strh	r3, [r7, #2]	@ movhi
@@ -330,10 +330,13 @@ main:
 	mov	r1, r2
 	mov	r0, r3
 	bl	gpio_write
-	.loc 1 96 45
+	.loc 1 96 3
+	movs	r0, #97
+	bl	usart2_write_byte
+	.loc 1 98 45
 	ldr	r3, .L10+4
 	ldr	r3, [r3, #36]
-	.loc 1 96 11
+	.loc 1 98 11
 	strh	r3, [r7, #6]	@ movhi
 	.loc 1 92 5
 	b	.L9
@@ -357,16 +360,16 @@ main:
 	.file 9 "src/usart.h"
 	.section	.debug_info,"",%progbits
 .Ldebug_info0:
-	.4byte	0x453
+	.4byte	0x474
 	.2byte	0x5
 	.byte	0x1
 	.byte	0x4
 	.4byte	.Ldebug_abbrev0
 	.uleb128 0xd
-	.4byte	.LASF1036
+	.4byte	.LASF1042
 	.byte	0x1d
-	.4byte	.LASF1037
-	.4byte	.LASF1038
+	.4byte	.LASF1043
+	.4byte	.LASF1044
 	.4byte	.LLRL0
 	.4byte	0
 	.4byte	.Ldebug_line0
@@ -374,17 +377,17 @@ main:
 	.uleb128 0x3
 	.byte	0x1
 	.byte	0x6
-	.4byte	.LASF969
+	.4byte	.LASF973
 	.uleb128 0x3
 	.byte	0x1
 	.byte	0x8
-	.4byte	.LASF970
+	.4byte	.LASF974
 	.uleb128 0x3
 	.byte	0x2
 	.byte	0x5
-	.4byte	.LASF971
+	.4byte	.LASF975
 	.uleb128 0x4
-	.4byte	.LASF974
+	.4byte	.LASF978
 	.byte	0x2
 	.byte	0x39
 	.byte	0x1c
@@ -392,13 +395,13 @@ main:
 	.uleb128 0x3
 	.byte	0x2
 	.byte	0x7
-	.4byte	.LASF972
+	.4byte	.LASF976
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x5
-	.4byte	.LASF973
+	.4byte	.LASF977
 	.uleb128 0x4
-	.4byte	.LASF975
+	.4byte	.LASF979
 	.byte	0x2
 	.byte	0x4f
 	.byte	0x1b
@@ -406,15 +409,15 @@ main:
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x7
-	.4byte	.LASF976
+	.4byte	.LASF980
 	.uleb128 0x3
 	.byte	0x8
 	.byte	0x5
-	.4byte	.LASF977
+	.4byte	.LASF981
 	.uleb128 0x3
 	.byte	0x8
 	.byte	0x7
-	.4byte	.LASF978
+	.4byte	.LASF982
 	.uleb128 0xe
 	.byte	0x4
 	.byte	0x5
@@ -422,22 +425,22 @@ main:
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x7
-	.4byte	.LASF979
+	.4byte	.LASF983
 	.uleb128 0x4
-	.4byte	.LASF980
+	.4byte	.LASF984
 	.byte	0x3
 	.byte	0x24
 	.byte	0x14
 	.4byte	0x3f
 	.uleb128 0x4
-	.4byte	.LASF981
+	.4byte	.LASF985
 	.byte	0x3
 	.byte	0x30
 	.byte	0x14
 	.4byte	0x59
-	.uleb128 0x8
-	.4byte	0x94
 	.uleb128 0x9
+	.4byte	0x94
+	.uleb128 0xa
 	.ascii	"rcc\000"
 	.byte	0x8c
 	.byte	0x4
@@ -449,13 +452,13 @@ main:
 	.4byte	0xa0
 	.byte	0
 	.uleb128 0x1
-	.4byte	.LASF982
+	.4byte	.LASF986
 	.byte	0x4
 	.byte	0x8
 	.4byte	0xa0
 	.byte	0x4
 	.uleb128 0x1
-	.4byte	.LASF983
+	.4byte	.LASF987
 	.byte	0x4
 	.byte	0x9
 	.4byte	0xa0
@@ -467,115 +470,115 @@ main:
 	.4byte	0xa0
 	.byte	0xc
 	.uleb128 0x1
-	.4byte	.LASF984
+	.4byte	.LASF988
 	.byte	0x4
 	.byte	0xb
 	.4byte	0xa0
 	.byte	0x10
 	.uleb128 0x1
-	.4byte	.LASF985
+	.4byte	.LASF989
 	.byte	0x4
 	.byte	0xc
 	.4byte	0xa0
 	.byte	0x14
 	.uleb128 0x1
-	.4byte	.LASF986
+	.4byte	.LASF990
 	.byte	0x4
 	.byte	0xd
 	.4byte	0x210
 	.byte	0x18
 	.uleb128 0x1
-	.4byte	.LASF987
+	.4byte	.LASF991
 	.byte	0x4
 	.byte	0xe
 	.4byte	0xa0
 	.byte	0x20
 	.uleb128 0x1
-	.4byte	.LASF988
+	.4byte	.LASF992
 	.byte	0x4
 	.byte	0xf
 	.4byte	0xa0
 	.byte	0x24
 	.uleb128 0x1
-	.4byte	.LASF989
+	.4byte	.LASF993
 	.byte	0x4
 	.byte	0x10
 	.4byte	0x210
 	.byte	0x28
 	.uleb128 0x1
-	.4byte	.LASF990
+	.4byte	.LASF994
 	.byte	0x4
 	.byte	0x11
 	.4byte	0xa0
 	.byte	0x30
 	.uleb128 0x1
-	.4byte	.LASF991
+	.4byte	.LASF995
 	.byte	0x4
 	.byte	0x12
 	.4byte	0xa0
 	.byte	0x34
 	.uleb128 0x1
-	.4byte	.LASF992
+	.4byte	.LASF996
 	.byte	0x4
 	.byte	0x13
 	.4byte	0x210
 	.byte	0x38
 	.uleb128 0x1
-	.4byte	.LASF993
+	.4byte	.LASF997
 	.byte	0x4
 	.byte	0x14
 	.4byte	0xa0
 	.byte	0x40
 	.uleb128 0x1
-	.4byte	.LASF994
+	.4byte	.LASF998
 	.byte	0x4
 	.byte	0x15
 	.4byte	0xa0
 	.byte	0x44
 	.uleb128 0x1
-	.4byte	.LASF995
+	.4byte	.LASF999
 	.byte	0x4
 	.byte	0x16
 	.4byte	0x210
 	.byte	0x48
 	.uleb128 0x1
-	.4byte	.LASF996
+	.4byte	.LASF1000
 	.byte	0x4
 	.byte	0x17
 	.4byte	0xa0
 	.byte	0x50
 	.uleb128 0x1
-	.4byte	.LASF997
+	.4byte	.LASF1001
 	.byte	0x4
 	.byte	0x18
 	.4byte	0xa0
 	.byte	0x54
 	.uleb128 0x1
-	.4byte	.LASF998
+	.4byte	.LASF1002
 	.byte	0x4
 	.byte	0x19
 	.4byte	0x210
 	.byte	0x58
 	.uleb128 0x1
-	.4byte	.LASF999
+	.4byte	.LASF1003
 	.byte	0x4
 	.byte	0x1a
 	.4byte	0xa0
 	.byte	0x60
 	.uleb128 0x1
-	.4byte	.LASF1000
+	.4byte	.LASF1004
 	.byte	0x4
 	.byte	0x1b
 	.4byte	0xa0
 	.byte	0x64
 	.uleb128 0x1
-	.4byte	.LASF1001
+	.4byte	.LASF1005
 	.byte	0x4
 	.byte	0x1c
 	.4byte	0x210
 	.byte	0x68
 	.uleb128 0x1
-	.4byte	.LASF1002
+	.4byte	.LASF1006
 	.byte	0x4
 	.byte	0x1d
 	.4byte	0xa0
@@ -587,25 +590,25 @@ main:
 	.4byte	0xa0
 	.byte	0x74
 	.uleb128 0x1
-	.4byte	.LASF1003
+	.4byte	.LASF1007
 	.byte	0x4
 	.byte	0x1f
 	.4byte	0x210
 	.byte	0x78
 	.uleb128 0x1
-	.4byte	.LASF1004
+	.4byte	.LASF1008
 	.byte	0x4
 	.byte	0x20
 	.4byte	0xa0
 	.byte	0x80
 	.uleb128 0x1
-	.4byte	.LASF1005
+	.4byte	.LASF1009
 	.byte	0x4
 	.byte	0x21
 	.4byte	0xa0
 	.byte	0x84
 	.uleb128 0x1
-	.4byte	.LASF1006
+	.4byte	.LASF1010
 	.byte	0x4
 	.byte	0x22
 	.4byte	0xa0
@@ -618,7 +621,7 @@ main:
 	.4byte	0x81
 	.byte	0x1
 	.byte	0
-	.uleb128 0x8
+	.uleb128 0x9
 	.4byte	0x200
 	.uleb128 0x11
 	.byte	0x7
@@ -628,27 +631,27 @@ main:
 	.byte	0x3a
 	.byte	0xe
 	.4byte	0x23c
-	.uleb128 0x5
-	.4byte	.LASF1007
+	.uleb128 0x6
+	.4byte	.LASF1011
 	.byte	0
-	.uleb128 0x5
-	.4byte	.LASF1008
+	.uleb128 0x6
+	.4byte	.LASF1012
 	.byte	0x1
-	.uleb128 0x5
-	.4byte	.LASF1009
+	.uleb128 0x6
+	.4byte	.LASF1013
 	.byte	0x2
-	.uleb128 0x5
-	.4byte	.LASF1010
+	.uleb128 0x6
+	.4byte	.LASF1014
 	.byte	0x3
 	.byte	0
 	.uleb128 0x4
-	.4byte	.LASF1011
+	.4byte	.LASF1015
 	.byte	0x5
 	.byte	0x3f
 	.byte	0x3
 	.4byte	0x215
-	.uleb128 0xa
-	.4byte	.LASF1012
+	.uleb128 0xb
+	.4byte	.LASF1016
 	.byte	0x18
 	.byte	0x6
 	.4byte	0x29a
@@ -659,13 +662,13 @@ main:
 	.4byte	0xa0
 	.byte	0
 	.uleb128 0x1
-	.4byte	.LASF1013
+	.4byte	.LASF1017
 	.byte	0x6
 	.byte	0x8
 	.4byte	0xa0
 	.byte	0x4
 	.uleb128 0x1
-	.4byte	.LASF1014
+	.4byte	.LASF1018
 	.byte	0x6
 	.byte	0x9
 	.4byte	0xa0
@@ -683,13 +686,13 @@ main:
 	.4byte	0xa0
 	.byte	0x10
 	.uleb128 0x1
-	.4byte	.LASF1015
+	.4byte	.LASF1019
 	.byte	0x6
 	.byte	0xc
 	.4byte	0xa0
 	.byte	0x14
 	.byte	0
-	.uleb128 0x9
+	.uleb128 0xa
 	.ascii	"pwr\000"
 	.byte	0x8
 	.byte	0x7
@@ -707,8 +710,8 @@ main:
 	.4byte	0xa0
 	.byte	0x4
 	.byte	0
-	.uleb128 0xa
-	.4byte	.LASF1016
+	.uleb128 0xb
+	.4byte	.LASF1020
 	.byte	0x50
 	.byte	0x8
 	.4byte	0x3b8
@@ -725,13 +728,13 @@ main:
 	.4byte	0xa0
 	.byte	0x4
 	.uleb128 0x1
-	.4byte	.LASF1017
+	.4byte	.LASF1021
 	.byte	0x8
 	.byte	0x9
 	.4byte	0xa0
 	.byte	0x8
 	.uleb128 0x1
-	.4byte	.LASF1018
+	.4byte	.LASF1022
 	.byte	0x8
 	.byte	0xa
 	.4byte	0xa0
@@ -749,19 +752,19 @@ main:
 	.4byte	0xa0
 	.byte	0x14
 	.uleb128 0x1
-	.4byte	.LASF1019
+	.4byte	.LASF1023
 	.byte	0x8
 	.byte	0xd
 	.4byte	0xa0
 	.byte	0x18
 	.uleb128 0x1
-	.4byte	.LASF1020
+	.4byte	.LASF1024
 	.byte	0x8
 	.byte	0xe
 	.4byte	0xa0
 	.byte	0x1c
 	.uleb128 0x1
-	.4byte	.LASF1021
+	.4byte	.LASF1025
 	.byte	0x8
 	.byte	0xf
 	.4byte	0xa0
@@ -791,31 +794,31 @@ main:
 	.4byte	0xa0
 	.byte	0x30
 	.uleb128 0x1
-	.4byte	.LASF1022
+	.4byte	.LASF1026
 	.byte	0x8
 	.byte	0x14
 	.4byte	0xa0
 	.byte	0x34
 	.uleb128 0x1
-	.4byte	.LASF1023
+	.4byte	.LASF1027
 	.byte	0x8
 	.byte	0x15
 	.4byte	0xa0
 	.byte	0x38
 	.uleb128 0x1
-	.4byte	.LASF1024
+	.4byte	.LASF1028
 	.byte	0x8
 	.byte	0x16
 	.4byte	0xa0
 	.byte	0x3c
 	.uleb128 0x1
-	.4byte	.LASF1025
+	.4byte	.LASF1029
 	.byte	0x8
 	.byte	0x17
 	.4byte	0xa0
 	.byte	0x40
 	.uleb128 0x1
-	.4byte	.LASF1026
+	.4byte	.LASF1030
 	.byte	0x8
 	.byte	0x18
 	.4byte	0xa0
@@ -827,48 +830,66 @@ main:
 	.4byte	0xa0
 	.byte	0x48
 	.uleb128 0x1
-	.4byte	.LASF1027
+	.4byte	.LASF1031
 	.byte	0x8
 	.byte	0x1a
 	.4byte	0xa0
 	.byte	0x4c
 	.byte	0
-	.uleb128 0xb
-	.4byte	.LASF1029
+	.uleb128 0x8
+	.4byte	.LASF1032
+	.byte	0x9
+	.byte	0x37
+	.4byte	0x3c9
+	.uleb128 0x5
+	.4byte	0x3c9
+	.byte	0
+	.uleb128 0x3
+	.byte	0x1
+	.byte	0x8
+	.4byte	.LASF510
+	.uleb128 0x8
+	.4byte	.LASF1033
+	.byte	0x5
 	.byte	0x42
-	.4byte	0x3cd
-	.uleb128 0x6
+	.4byte	0x3e6
+	.uleb128 0x5
 	.4byte	0x88
-	.uleb128 0x6
-	.4byte	0x3cd
+	.uleb128 0x5
+	.4byte	0x3e6
 	.byte	0
 	.uleb128 0x3
 	.byte	0x1
 	.byte	0x2
-	.4byte	.LASF1028
-	.uleb128 0xb
-	.4byte	.LASF1030
+	.4byte	.LASF1034
+	.uleb128 0x8
+	.4byte	.LASF1035
+	.byte	0x5
 	.byte	0x41
-	.4byte	0x3e9
-	.uleb128 0x6
+	.4byte	0x403
+	.uleb128 0x5
 	.4byte	0x88
-	.uleb128 0x6
+	.uleb128 0x5
 	.4byte	0x23c
 	.byte	0
 	.uleb128 0x7
-	.4byte	.LASF1031
+	.4byte	.LASF1036
+	.byte	0x9
+	.byte	0x35
+	.uleb128 0x7
+	.4byte	.LASF1037
 	.byte	0x8
 	.byte	0x24
 	.uleb128 0x7
-	.4byte	.LASF1032
+	.4byte	.LASF1038
 	.byte	0x9
-	.byte	0x2b
+	.byte	0x34
 	.uleb128 0x7
-	.4byte	.LASF1033
+	.4byte	.LASF1039
 	.byte	0x8
 	.byte	0x23
 	.uleb128 0x12
-	.4byte	.LASF1039
+	.4byte	.LASF1045
 	.byte	0x1
 	.byte	0x4d
 	.byte	0x5
@@ -877,7 +898,7 @@ main:
 	.4byte	.LFE1-.LFB1
 	.uleb128 0x1
 	.byte	0x9c
-	.4byte	0x444
+	.4byte	0x465
 	.uleb128 0x13
 	.ascii	"led\000"
 	.byte	0x1
@@ -888,7 +909,7 @@ main:
 	.byte	0x91
 	.sleb128 -14
 	.uleb128 0xc
-	.4byte	.LASF1034
+	.4byte	.LASF1040
 	.byte	0x59
 	.byte	0xc
 	.4byte	0x88
@@ -896,16 +917,16 @@ main:
 	.byte	0x91
 	.sleb128 -10
 	.uleb128 0xc
-	.4byte	.LASF1035
+	.4byte	.LASF1041
 	.byte	0x5a
 	.byte	0x7
-	.4byte	0x3cd
+	.4byte	0x3e6
 	.uleb128 0x2
 	.byte	0x91
 	.sleb128 -11
 	.byte	0
 	.uleb128 0x14
-	.4byte	.LASF1040
+	.4byte	.LASF1046
 	.byte	0x1
 	.byte	0xd
 	.byte	0xd
@@ -979,6 +1000,13 @@ main:
 	.byte	0
 	.byte	0
 	.uleb128 0x5
+	.uleb128 0x5
+	.byte	0
+	.uleb128 0x49
+	.uleb128 0x13
+	.byte	0
+	.byte	0
+	.uleb128 0x6
 	.uleb128 0x28
 	.byte	0
 	.uleb128 0x3
@@ -987,13 +1015,6 @@ main:
 	.uleb128 0xb
 	.byte	0
 	.byte	0
-	.uleb128 0x6
-	.uleb128 0x5
-	.byte	0
-	.uleb128 0x49
-	.uleb128 0x13
-	.byte	0
-	.byte	0
 	.uleb128 0x7
 	.uleb128 0x2e
 	.byte	0
@@ -1015,13 +1036,35 @@ main:
 	.byte	0
 	.byte	0
 	.uleb128 0x8
+	.uleb128 0x2e
+	.byte	0x1
+	.uleb128 0x3f
+	.uleb128 0x19
+	.uleb128 0x3
+	.uleb128 0xe
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x39
+	.uleb128 0x21
+	.sleb128 6
+	.uleb128 0x27
+	.uleb128 0x19
+	.uleb128 0x3c
+	.uleb128 0x19
+	.uleb128 0x1
+	.uleb128 0x13
+	.byte	0
+	.byte	0
+	.uleb128 0x9
 	.uleb128 0x35
 	.byte	0
 	.uleb128 0x49
 	.uleb128 0x13
 	.byte	0
 	.byte	0
-	.uleb128 0x9
+	.uleb128 0xa
 	.uleb128 0x13
 	.byte	0x1
 	.uleb128 0x3
@@ -1040,7 +1083,7 @@ main:
 	.uleb128 0x13
 	.byte	0
 	.byte	0
-	.uleb128 0xa
+	.uleb128 0xb
 	.uleb128 0x13
 	.byte	0x1
 	.uleb128 0x3
@@ -1059,29 +1102,6 @@ main:
 	.uleb128 0x13
 	.byte	0
 	.byte	0
-	.uleb128 0xb
-	.uleb128 0x2e
-	.byte	0x1
-	.uleb128 0x3f
-	.uleb128 0x19
-	.uleb128 0x3
-	.uleb128 0xe
-	.uleb128 0x3a
-	.uleb128 0x21
-	.sleb128 5
-	.uleb128 0x3b
-	.uleb128 0xb
-	.uleb128 0x39
-	.uleb128 0x21
-	.sleb128 6
-	.uleb128 0x27
-	.uleb128 0x19
-	.uleb128 0x3c
-	.uleb128 0x19
-	.uleb128 0x1
-	.uleb128 0x13
-	.byte	0
-	.byte	0
 	.uleb128 0xc
 	.uleb128 0x34
 	.byte	0
@@ -2790,7 +2810,7 @@ main:
 	.byte	0x4
 	.byte	0x5
 	.uleb128 0xb
-	.4byte	.LASF968
+	.4byte	.LASF972
 	.byte	0x4
 	.byte	0
 	.section	.debug_macro,"G",%progbits,wm4._newlib_version.h.4.6d111ab2e95434b664b53815e5c8ccba,comdat
@@ -4389,7 +4409,7 @@ main:
 	.uleb128 0x21
 	.4byte	.LASF952
 	.byte	0
-	.section	.debug_macro,"G",%progbits,wm4.usart.h.2.0debbac628af0f73f2055baa828e03f0,comdat
+	.section	.debug_macro,"G",%progbits,wm4.usart.h.2.499ef099adc8b232d514889834b2ea6a,comdat
 .Ldebug_macro20:
 	.2byte	0x5
 	.byte	0
@@ -4415,29 +4435,41 @@ main:
 	.uleb128 0x1a
 	.4byte	.LASF959
 	.byte	0x5
-	.uleb128 0x1d
+	.uleb128 0x1e
 	.4byte	.LASF960
 	.byte	0x5
-	.uleb128 0x1e
+	.uleb128 0x1f
 	.4byte	.LASF961
 	.byte	0x5
-	.uleb128 0x21
+	.uleb128 0x22
 	.4byte	.LASF962
 	.byte	0x5
-	.uleb128 0x22
+	.uleb128 0x23
 	.4byte	.LASF963
 	.byte	0x5
-	.uleb128 0x25
+	.uleb128 0x26
 	.4byte	.LASF964
 	.byte	0x5
-	.uleb128 0x26
+	.uleb128 0x27
 	.4byte	.LASF965
 	.byte	0x5
-	.uleb128 0x28
+	.uleb128 0x2a
 	.4byte	.LASF966
 	.byte	0x5
-	.uleb128 0x29
+	.uleb128 0x2b
 	.4byte	.LASF967
+	.byte	0x5
+	.uleb128 0x2e
+	.4byte	.LASF968
+	.byte	0x5
+	.uleb128 0x2f
+	.4byte	.LASF969
+	.byte	0x5
+	.uleb128 0x31
+	.4byte	.LASF970
+	.byte	0x5
+	.uleb128 0x32
+	.4byte	.LASF971
 	.byte	0
 	.section	.debug_line,"",%progbits
 .Ldebug_line0:
@@ -4454,7 +4486,7 @@ main:
 	.ascii	"__UHA_FBIT__ 8\000"
 .LASF814:
 	.ascii	"PRIiFAST64 __PRI64FAST(i)\000"
-.LASF970:
+.LASF974:
 	.ascii	"unsigned char\000"
 .LASF225:
 	.ascii	"__FLT64_DENORM_MIN__ 4.9406564584124654e-324F64\000"
@@ -4484,7 +4516,7 @@ main:
 	.ascii	"__WINT_MIN__ 0U\000"
 .LASF90:
 	.ascii	"__INTMAX_MAX__ 0x7fffffffffffffffLL\000"
-.LASF1009:
+.LASF1013:
 	.ascii	"GPIO_MODE_AF\000"
 .LASF335:
 	.ascii	"__TQ_IBIT__ 0\000"
@@ -4500,7 +4532,7 @@ main:
 	.ascii	"__int20__\000"
 .LASF906:
 	.ascii	"RCC_APB1ENR_TIM4_BIT 2\000"
-.LASF967:
+.LASF971:
 	.ascii	"USART_BRR_FRACTION_MASK (0b111)\000"
 .LASF18:
 	.ascii	"__SIZEOF_LONG_LONG__ 8\000"
@@ -4512,7 +4544,7 @@ main:
 	.ascii	"__FRACT_MIN__ (-0.5R-0.5R)\000"
 .LASF324:
 	.ascii	"__ULLACCUM_MAX__ 0XFFFFFFFFFFFFFFFFP-32ULLK\000"
-.LASF1012:
+.LASF1016:
 	.ascii	"flash\000"
 .LASF294:
 	.ascii	"__USACCUM_MAX__ 0XFFFFP-8UHK\000"
@@ -4629,7 +4661,7 @@ main:
 	.ascii	"__need_wchar_t\000"
 .LASF199:
 	.ascii	"__FLT32_MIN_EXP__ (-125)\000"
-.LASF1036:
+.LASF1042:
 	.ascii	"GNU C2X 12.3.1 20230626 -mcpu=cortex-m4 -mthumb -mf"
 	.ascii	"loat-abi=hard -mfpu=fpv4-sp-d16 -march=armv7e-m+fp "
 	.ascii	"-g3 -ggdb -O0 -std=c2x -ffunction-sections -fdata-s"
@@ -4650,7 +4682,7 @@ main:
 	.ascii	"__int_fast32_t_defined 1\000"
 .LASF133:
 	.ascii	"__INT_FAST64_WIDTH__ 64\000"
-.LASF1027:
+.LASF1031:
 	.ascii	"DMAR\000"
 .LASF659:
 	.ascii	"___int_wchar_t_h \000"
@@ -4703,13 +4735,13 @@ main:
 	.ascii	"SCNo32 __SCN32(o)\000"
 .LASF540:
 	.ascii	"_NOTHROW \000"
-.LASF1022:
+.LASF1026:
 	.ascii	"CCR1\000"
 .LASF633:
 	.ascii	"WCHAR_MAX (__WCHAR_MAX__)\000"
-.LASF1024:
+.LASF1028:
 	.ascii	"CCR3\000"
-.LASF1025:
+.LASF1029:
 	.ascii	"CCR4\000"
 .LASF307:
 	.ascii	"__LACCUM_IBIT__ 32\000"
@@ -4733,7 +4765,7 @@ main:
 	.ascii	"__INT64 \"ll\"\000"
 .LASF138:
 	.ascii	"__INTPTR_MAX__ 0x7fffffff\000"
-.LASF997:
+.LASF1001:
 	.ascii	"AHB2LPENR\000"
 .LASF499:
 	.ascii	"__RAND_MAX\000"
@@ -4776,7 +4808,7 @@ main:
 	.ascii	" RCC_PLLCFGR_PLLP_BIT)\000"
 .LASF302:
 	.ascii	"__UACCUM_IBIT__ 16\000"
-.LASF973:
+.LASF977:
 	.ascii	"long int\000"
 .LASF719:
 	.ascii	"SCNd16 __SCN16(d)\000"
@@ -4829,7 +4861,7 @@ main:
 	.ascii	"__FLT32_MAX_EXP__ 128\000"
 .LASF824:
 	.ascii	"__PRIMAX(x) __STRINGIFY(ll ##x)\000"
-.LASF1039:
+.LASF1045:
 	.ascii	"main\000"
 .LASF435:
 	.ascii	"__THUMB_INTERWORK__ 1\000"
@@ -4837,6 +4869,8 @@ main:
 	.ascii	"__ULLFRACT_MAX__ 0XFFFFFFFFFFFFFFFFP-64ULLR\000"
 .LASF697:
 	.ascii	"PRIiFAST8 __PRI8FAST(i)\000"
+.LASF959:
+	.ascii	"USART_SR_RXNE_READY (1 <<USART_SR_RXNE_BIT)\000"
 .LASF33:
 	.ascii	"__GNUC_WIDE_EXECUTION_CHARSET_NAME \"UTF-32LE\"\000"
 .LASF571:
@@ -4857,7 +4891,7 @@ main:
 	.ascii	"__SIZEOF_LONG__ 4\000"
 .LASF753:
 	.ascii	"PRIi32 __PRI32(i)\000"
-.LASF994:
+.LASF998:
 	.ascii	"APB2ENR\000"
 .LASF855:
 	.ascii	"RCC_H_ \000"
@@ -4873,7 +4907,7 @@ main:
 	.ascii	"FLASH_ACR_ICEN_BIT 9\000"
 .LASF815:
 	.ascii	"PRIoFAST64 __PRI64FAST(o)\000"
-.LASF996:
+.LASF1000:
 	.ascii	"AHB1LPENR\000"
 .LASF406:
 	.ascii	"__ARM_FEATURE_SIMD32 1\000"
@@ -4885,7 +4919,7 @@ main:
 	.ascii	"PRIoLEAST16 __PRI16LEAST(o)\000"
 .LASF458:
 	.ascii	"__NEWLIB__ 4\000"
-.LASF1006:
+.LASF1010:
 	.ascii	"DCKCFGR\000"
 .LASF720:
 	.ascii	"SCNi16 __SCN16(i)\000"
@@ -4895,7 +4929,7 @@ main:
 	.ascii	"__FLT_DECIMAL_DIG__ 9\000"
 .LASF562:
 	.ascii	"_UINT8_T_DECLARED \000"
-.LASF969:
+.LASF973:
 	.ascii	"signed char\000"
 .LASF805:
 	.ascii	"PRIuLEAST64 __PRI64LEAST(u)\000"
@@ -4905,7 +4939,7 @@ main:
 	.ascii	"INTMAX_MIN (-INTMAX_MAX - 1)\000"
 .LASF364:
 	.ascii	"__GNUC_STDC_INLINE__ 1\000"
-.LASF1011:
+.LASF1015:
 	.ascii	"GPIO_MODE\000"
 .LASF256:
 	.ascii	"__FRACT_FBIT__ 15\000"
@@ -4933,19 +4967,19 @@ main:
 	.ascii	"GPIO_AFRL_AFRL2_MASK (0b1111)\000"
 .LASF879:
 	.ascii	"RCC_PLLCFGR_PLLN_MASK (0b111111111)\000"
-.LASF986:
+.LASF990:
 	.ascii	"RESERVED0\000"
-.LASF989:
+.LASF993:
 	.ascii	"RESERVED1\000"
-.LASF992:
+.LASF996:
 	.ascii	"RESERVED2\000"
 .LASF3:
 	.ascii	"__STDC_UTF_32__ 1\000"
-.LASF998:
+.LASF1002:
 	.ascii	"RESERVED4\000"
 .LASF241:
 	.ascii	"__FLT32X_DENORM_MIN__ 4.9406564584124654e-324F32x\000"
-.LASF1003:
+.LASF1007:
 	.ascii	"RESERVED6\000"
 .LASF152:
 	.ascii	"__FLT_MAX_10_EXP__ 38\000"
@@ -4957,6 +4991,8 @@ main:
 	.ascii	"__FRACT_MAX__ 0X7FFFP-15R\000"
 .LASF728:
 	.ascii	"PRIxLEAST16 __PRI16LEAST(x)\000"
+.LASF1032:
+	.ascii	"usart2_write_byte\000"
 .LASF947:
 	.ascii	"PWR_CR_VOS(scale) ((scale & PWR_CR_VOS_MASK) << PWR"
 	.ascii	"_CR_VOS_BIT)\000"
@@ -4992,13 +5028,13 @@ main:
 	.ascii	"__int_fast64_t_defined 1\000"
 .LASF837:
 	.ascii	"__PRIPTR(x) __STRINGIFY(x)\000"
-.LASF980:
+.LASF984:
 	.ascii	"uint16_t\000"
 .LASF417:
 	.ascii	"__thumb2__ 1\000"
 .LASF321:
 	.ascii	"__ULLACCUM_FBIT__ 32\000"
-.LASF1028:
+.LASF1034:
 	.ascii	"_Bool\000"
 .LASF902:
 	.ascii	"RCC_APB1ENR_PWREN_BIT 28\000"
@@ -5013,15 +5049,15 @@ main:
 	.ascii	"SCNxLEAST64 __SCN64LEAST(x)\000"
 .LASF769:
 	.ascii	"SCNdLEAST32 __SCN32LEAST(d)\000"
-.LASF995:
+.LASF999:
 	.ascii	"RESERVED3\000"
 .LASF22:
 	.ascii	"__SIZEOF_LONG_DOUBLE__ 8\000"
-.LASF1001:
+.LASF1005:
 	.ascii	"RESERVED5\000"
-.LASF1019:
+.LASF1023:
 	.ascii	"CCMR1\000"
-.LASF1020:
+.LASF1024:
 	.ascii	"CCMR2\000"
 .LASF36:
 	.ascii	"__WCHAR_TYPE__ unsigned int\000"
@@ -5029,7 +5065,7 @@ main:
 	.ascii	"TIMER_H_ \000"
 .LASF469:
 	.ascii	"_MB_LEN_MAX 8\000"
-.LASF1008:
+.LASF1012:
 	.ascii	"GPIO_MODE_OUTPUT\000"
 .LASF357:
 	.ascii	"__USA_IBIT__ 16\000"
@@ -5063,7 +5099,7 @@ main:
 	.ascii	"__FLT32_IS_IEC_60559__ 2\000"
 .LASF629:
 	.ascii	"SIG_ATOMIC_MAX (__STDINT_EXP(INT_MAX))\000"
-.LASF963:
+.LASF967:
 	.ascii	"USART_CR1_RE_ENABLE (1 << USART_CR1_RE_BIT)\000"
 .LASF724:
 	.ascii	"PRIdLEAST16 __PRI16LEAST(d)\000"
@@ -5073,9 +5109,9 @@ main:
 	.ascii	"__SCN64(x) __INT64 __STRINGIFY(x)\000"
 .LASF646:
 	.ascii	"_GCC_WRAP_STDINT_H \000"
-.LASF974:
+.LASF978:
 	.ascii	"__uint16_t\000"
-.LASF991:
+.LASF995:
 	.ascii	"AHB2ENR\000"
 .LASF804:
 	.ascii	"PRIoLEAST64 __PRI64LEAST(o)\000"
@@ -5089,7 +5125,7 @@ main:
 	.ascii	"__UINT8_MAX__ 0xff\000"
 .LASF574:
 	.ascii	"_UINTMAX_T_DECLARED \000"
-.LASF1016:
+.LASF1020:
 	.ascii	"timer\000"
 .LASF184:
 	.ascii	"__LDBL_MAX_EXP__ 1024\000"
@@ -5109,7 +5145,7 @@ main:
 	.ascii	"BIT(x) (1 << x)\000"
 .LASF426:
 	.ascii	"__ARM_FP16_FORMAT_ALTERNATIVE\000"
-.LASF1040:
+.LASF1046:
 	.ascii	"system_clock_init\000"
 .LASF932:
 	.ascii	"FLASH ((struct flash *) FLASH_BASE_ADDR)\000"
@@ -5183,7 +5219,7 @@ main:
 	.ascii	"__MISC_VISIBLE 0\000"
 .LASF452:
 	.ascii	"__ELF__ 1\000"
-.LASF1002:
+.LASF1006:
 	.ascii	"BDCR\000"
 .LASF853:
 	.ascii	"false ((_Bool)+0u)\000"
@@ -5245,7 +5281,7 @@ main:
 	.ascii	"RCC_CR_HSERDY_READY (1 << RCC_CR_HSERDY_BIT)\000"
 .LASF762:
 	.ascii	"SCNx32 __SCN32(x)\000"
-.LASF983:
+.LASF987:
 	.ascii	"CFGR\000"
 .LASF557:
 	.ascii	"___int_least32_t_defined 1\000"
@@ -5253,7 +5289,7 @@ main:
 	.ascii	"__LLACCUM_MAX__ 0X7FFFFFFFFFFFFFFFP-31LLK\000"
 .LASF666:
 	.ascii	"__need_NULL\000"
-.LASF957:
+.LASF961:
 	.ascii	"USART_CR1_OVER8_8 (1 << USART_CR1_OVER8_BIT)\000"
 .LASF363:
 	.ascii	"__USER_LABEL_PREFIX__ \000"
@@ -5297,7 +5333,7 @@ main:
 	.ascii	"__PRI8LEAST(x) __LEAST8 __STRINGIFY(x)\000"
 .LASF174:
 	.ascii	"__DBL_EPSILON__ ((double)2.2204460492503131e-16L)\000"
-.LASF1014:
+.LASF1018:
 	.ascii	"OPTKEYR\000"
 .LASF268:
 	.ascii	"__LFRACT_MIN__ (-0.5LR-0.5LR)\000"
@@ -5321,7 +5357,7 @@ main:
 	.ascii	"___int8_t_defined 1\000"
 .LASF248:
 	.ascii	"__SFRACT_MIN__ (-0.5HR-0.5HR)\000"
-.LASF976:
+.LASF980:
 	.ascii	"long unsigned int\000"
 .LASF349:
 	.ascii	"__SA_IBIT__ 16\000"
@@ -5339,9 +5375,9 @@ main:
 	.ascii	"__UINT16_TYPE__ short unsigned int\000"
 .LASF873:
 	.ascii	"RCC_PLLCFGR_PLLSRC_BIT 22\000"
-.LASF1029:
+.LASF1033:
 	.ascii	"gpio_write\000"
-.LASF1018:
+.LASF1022:
 	.ascii	"DIER\000"
 .LASF656:
 	.ascii	"_WCHAR_T_DEFINED_ \000"
@@ -5349,11 +5385,11 @@ main:
 	.ascii	"__FLT_EVAL_METHOD_TS_18661_3__ 0\000"
 .LASF521:
 	.ascii	"int +2\000"
-.LASF1038:
+.LASF1044:
 	.ascii	"/home/alex/code/own/c-compile-experiments\000"
 .LASF636:
 	.ascii	"INT8_C(x) __INT8_C(x)\000"
-.LASF968:
+.LASF972:
 	.ascii	"exit 42\000"
 .LASF63:
 	.ascii	"__UINT_FAST8_TYPE__ unsigned int\000"
@@ -5385,7 +5421,7 @@ main:
 	.ascii	"SCNx8 __SCN8(x)\000"
 .LASF208:
 	.ascii	"__FLT32_DENORM_MIN__ 1.4012984643248171e-45F32\000"
-.LASF1030:
+.LASF1035:
 	.ascii	"gpio_set_mode\000"
 .LASF125:
 	.ascii	"__UINT64_C(c) c ## ULL\000"
@@ -5403,7 +5439,7 @@ main:
 	.ascii	"PRIXLEAST16 __PRI16LEAST(X)\000"
 .LASF622:
 	.ascii	"INT_FAST64_MAX (__INT_FAST64_MAX__)\000"
-.LASF962:
+.LASF966:
 	.ascii	"USART_CR1_RE_BIT 2\000"
 .LASF373:
 	.ascii	"__GCC_ATOMIC_CHAR16_T_LOCK_FREE 2\000"
@@ -5455,7 +5491,7 @@ main:
 	.ascii	"PRIX32 __PRI32(X)\000"
 .LASF773:
 	.ascii	"SCNxLEAST32 __SCN32LEAST(x)\000"
-.LASF1031:
+.LASF1037:
 	.ascii	"tim4_start\000"
 .LASF711:
 	.ascii	"__SCN16LEAST(x) __LEAST16 __STRINGIFY(x)\000"
@@ -5487,7 +5523,7 @@ main:
 	.ascii	"__ULACCUM_MIN__ 0.0ULK\000"
 .LASF461:
 	.ascii	"_ATEXIT_DYNAMIC_ALLOC 1\000"
-.LASF975:
+.LASF979:
 	.ascii	"__uint32_t\000"
 .LASF188:
 	.ascii	"__LDBL_MAX__ 1.7976931348623157e+308L\000"
@@ -5497,7 +5533,7 @@ main:
 	.ascii	"__FLT_RADIX__ 2\000"
 .LASF454:
 	.ascii	"_INTTYPES_H \000"
-.LASF977:
+.LASF981:
 	.ascii	"long long int\000"
 .LASF784:
 	.ascii	"SCNxFAST32 __SCN32FAST(x)\000"
@@ -5507,7 +5543,7 @@ main:
 	.ascii	"__LONG_WIDTH__ 32\000"
 .LASF602:
 	.ascii	"UINT32_MAX (__UINT32_MAX__)\000"
-.LASF1034:
+.LASF1040:
 	.ascii	"counter\000"
 .LASF648:
 	.ascii	"__wchar_t__ \000"
@@ -5523,7 +5559,7 @@ main:
 	.ascii	"WINT_MAX (__WINT_MAX__)\000"
 .LASF822:
 	.ascii	"SCNuFAST64 __SCN64FAST(u)\000"
-.LASF1004:
+.LASF1008:
 	.ascii	"SSCGR\000"
 .LASF137:
 	.ascii	"__UINT_FAST64_MAX__ 0xffffffffffffffffULL\000"
@@ -5537,7 +5573,9 @@ main:
 	.ascii	"__INTPTR_WIDTH__ 32\000"
 .LASF379:
 	.ascii	"__GCC_ATOMIC_LLONG_LOCK_FREE 1\000"
-.LASF982:
+.LASF956:
+	.ascii	"USART_SR_TXE_BIT 7\000"
+.LASF986:
 	.ascii	"PLLCFGR\000"
 .LASF239:
 	.ascii	"__FLT32X_MIN__ 2.2250738585072014e-308F32x\000"
@@ -5555,7 +5593,7 @@ main:
 	.ascii	"___int32_t_defined 1\000"
 .LASF83:
 	.ascii	"__INT_WIDTH__ 32\000"
-.LASF988:
+.LASF992:
 	.ascii	"APB2RSTR\000"
 .LASF409:
 	.ascii	"__ARM_ARCH_PROFILE\000"
@@ -5605,7 +5643,7 @@ main:
 	.ascii	"__ARM_NEON_FP\000"
 .LASF280:
 	.ascii	"__LLFRACT_EPSILON__ 0x1P-63LLR\000"
-.LASF1000:
+.LASF1004:
 	.ascii	"APB2LPENR\000"
 .LASF952:
 	.ascii	"TIM_ENABLE (1 << TIM_CR1_CEN_BIT)\000"
@@ -5619,7 +5657,7 @@ main:
 	.ascii	"TIM4_BASE_ADDR (0x40000800U)\000"
 .LASF261:
 	.ascii	"__UFRACT_FBIT__ 16\000"
-.LASF956:
+.LASF960:
 	.ascii	"USART_CR1_OVER8_BIT 15\000"
 .LASF342:
 	.ascii	"__UDQ_FBIT__ 64\000"
@@ -5640,7 +5678,7 @@ main:
 	.ascii	"L)\000"
 .LASF607:
 	.ascii	"INT64_MAX (__INT64_MAX__)\000"
-.LASF979:
+.LASF983:
 	.ascii	"unsigned int\000"
 .LASF862:
 	.ascii	"RCC_CR_HSERDY_BIT 17\000"
@@ -5686,6 +5724,8 @@ main:
 	.ascii	"__INT16 \"h\"\000"
 .LASF402:
 	.ascii	"__ARM_FEATURE_LDREX\000"
+.LASF1036:
+	.ascii	"usart2_start\000"
 .LASF336:
 	.ascii	"__UQQ_FBIT__ 8\000"
 .LASF427:
@@ -5732,7 +5772,7 @@ main:
 	.ascii	"PWR_H_ \000"
 .LASF356:
 	.ascii	"__USA_FBIT__ 16\000"
-.LASF999:
+.LASF1003:
 	.ascii	"APB1LPENR\000"
 .LASF479:
 	.ascii	"__IEEE_LITTLE_ENDIAN \000"
@@ -5780,7 +5820,7 @@ main:
 	.ascii	"WCHAR_MIN (__WCHAR_MIN__)\000"
 .LASF594:
 	.ascii	"INT16_MIN (-__INT16_MAX__ - 1)\000"
-.LASF1023:
+.LASF1027:
 	.ascii	"CCR2\000"
 .LASF189:
 	.ascii	"__LDBL_NORM_MAX__ 1.7976931348623157e+308L\000"
@@ -5838,7 +5878,7 @@ main:
 	.ascii	"__LFRACT_IBIT__ 0\000"
 .LASF16:
 	.ascii	"__SIZEOF_INT__ 4\000"
-.LASF961:
+.LASF965:
 	.ascii	"USART_CR1_TE_ENABLE (1 << USART_CR1_TE_BIT)\000"
 .LASF166:
 	.ascii	"__DBL_MIN_EXP__ (-1021)\000"
@@ -5874,19 +5914,21 @@ main:
 	.ascii	"__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 1\000"
 .LASF733:
 	.ascii	"SCNuLEAST16 __SCN16LEAST(u)\000"
-.LASF987:
+.LASF991:
 	.ascii	"APB1RSTR\000"
 .LASF298:
 	.ascii	"__ACCUM_MIN__ (-0X1P15K-0X1P15K)\000"
 .LASF393:
 	.ascii	"__ARM_FEATURE_CRYPTO\000"
-.LASF993:
+.LASF997:
 	.ascii	"APB1ENR\000"
 .LASF741:
 	.ascii	"SCNdFAST16 __SCN16FAST(d)\000"
 .LASF872:
 	.ascii	"RCC_PLLCFGR_PLLQ(q) ((q & RCC_PLLCFGR_PLLQ_MASK) <<"
 	.ascii	" RCC_PLLCFGR_PLLQ_BIT)\000"
+.LASF957:
+	.ascii	"USART_SR_TXE_TRANSMITTED (1 << USART_SR_TXE_BIT)\000"
 .LASF787:
 	.ascii	"__PRI64LEAST(x) __LEAST64 __STRINGIFY(x)\000"
 .LASF677:
@@ -5910,7 +5952,7 @@ main:
 	.ascii	")\000"
 .LASF155:
 	.ascii	"__FLT_NORM_MAX__ 3.4028234663852886e+38F\000"
-.LASF978:
+.LASF982:
 	.ascii	"long long unsigned int\000"
 .LASF611:
 	.ascii	"UINT_LEAST64_MAX (__UINT_LEAST64_MAX__)\000"
@@ -5963,7 +6005,7 @@ main:
 	.ascii	"PWR_SCALE3 (0b11)\000"
 .LASF573:
 	.ascii	"_INTMAX_T_DECLARED \000"
-.LASF1021:
+.LASF1025:
 	.ascii	"CCER\000"
 .LASF40:
 	.ascii	"__CHAR16_TYPE__ short unsigned int\000"
@@ -6021,7 +6063,7 @@ main:
 	.ascii	"__int20__ +2\000"
 .LASF654:
 	.ascii	"_WCHAR_T_ \000"
-.LASF1017:
+.LASF1021:
 	.ascii	"SMCR\000"
 .LASF828:
 	.ascii	"PRIoMAX __PRIMAX(o)\000"
@@ -6029,11 +6071,11 @@ main:
 	.ascii	"__SCN32(x) __INT32 __STRINGIFY(x)\000"
 .LASF939:
 	.ascii	"FLASH_ACR_LATENCY_MASK (0b1111)\000"
-.LASF1007:
+.LASF1011:
 	.ascii	"GPIO_MODE_INPUT\000"
 .LASF743:
 	.ascii	"SCNoFAST16 __SCN16FAST(o)\000"
-.LASF1032:
+.LASF1038:
 	.ascii	"usart2_init\000"
 .LASF345:
 	.ascii	"__UTQ_IBIT__ 0\000"
@@ -6061,7 +6103,7 @@ main:
 	.ascii	"PRIi16 __PRI16(i)\000"
 .LASF390:
 	.ascii	"__ARM_FEATURE_DSP 1\000"
-.LASF959:
+.LASF963:
 	.ascii	"USART_CR1_UE_ENABLE (1 << USART_CR1_UE_BIT)\000"
 .LASF825:
 	.ascii	"__SCNMAX(x) __STRINGIFY(ll ##x)\000"
@@ -6095,15 +6137,17 @@ main:
 	.ascii	"__INTMAX_TYPE__ long long int\000"
 .LASF377:
 	.ascii	"__GCC_ATOMIC_INT_LOCK_FREE 2\000"
-.LASF965:
+.LASF969:
 	.ascii	"USART_BRR_MANTISSA_MASK (0b111111111111)\000"
+.LASF958:
+	.ascii	"USART_SR_RXNE_BIT 5\000"
 .LASF561:
 	.ascii	"_INT8_T_DECLARED \000"
 .LASF436:
 	.ascii	"__ARM_ARCH_7EM__ 1\000"
 .LASF428:
 	.ascii	"__ARM_FEATURE_FP16_SCALAR_ARITHMETIC\000"
-.LASF990:
+.LASF994:
 	.ascii	"AHB1ENR\000"
 .LASF295:
 	.ascii	"__USACCUM_EPSILON__ 0x1P-8UHK\000"
@@ -6143,7 +6187,7 @@ main:
 	.ascii	"__DBL_DIG__ 15\000"
 .LASF275:
 	.ascii	"__ULFRACT_EPSILON__ 0x1P-32ULR\000"
-.LASF985:
+.LASF989:
 	.ascii	"AHB2RSTR\000"
 .LASF671:
 	.ascii	"__SCN8(x) __INT8 __STRINGIFY(x)\000"
@@ -6169,13 +6213,13 @@ main:
 	.ascii	"__LDBL_MIN__ 2.2250738585072014e-308L\000"
 .LASF445:
 	.ascii	"__ARM_FEATURE_CDE\000"
-.LASF1013:
+.LASF1017:
 	.ascii	"KEYR\000"
 .LASF509:
 	.ascii	"unsigned\000"
 .LASF381:
 	.ascii	"__GCC_DESTRUCTIVE_SIZE 64\000"
-.LASF971:
+.LASF975:
 	.ascii	"short int\000"
 .LASF835:
 	.ascii	"SCNuMAX __SCNMAX(u)\000"
@@ -6183,7 +6227,7 @@ main:
 	.ascii	"USART2 ((struct usart *) USART2_BASE_ADDR)\000"
 .LASF121:
 	.ascii	"__UINT16_C(c) c\000"
-.LASF966:
+.LASF970:
 	.ascii	"USART_BRR_FRACTION_BIT 0\000"
 .LASF359:
 	.ascii	"__UDA_IBIT__ 32\000"
@@ -6203,7 +6247,7 @@ main:
 	.ascii	"_ATTRIBUTE(attrs) __attribute__ (attrs)\000"
 .LASF443:
 	.ascii	"__ARM_FEATURE_COPROC\000"
-.LASF1010:
+.LASF1014:
 	.ascii	"GPIO_MODE_ANALOG\000"
 .LASF177:
 	.ascii	"__DBL_HAS_INFINITY__ 1\000"
@@ -6290,11 +6334,11 @@ main:
 	.ascii	"__LDBL_DECIMAL_DIG__ 17\000"
 .LASF701:
 	.ascii	"PRIXFAST8 __PRI8FAST(X)\000"
-.LASF1035:
+.LASF1041:
 	.ascii	"led_on\000"
 .LASF308:
 	.ascii	"__LACCUM_MIN__ (-0X1P31LK-0X1P31LK)\000"
-.LASF1037:
+.LASF1043:
 	.ascii	"src/main.c\000"
 .LASF126:
 	.ascii	"__INT_FAST8_MAX__ 0x7fffffff\000"
@@ -6332,13 +6376,13 @@ main:
 	.ascii	"__ULLFRACT_MIN__ 0.0ULLR\000"
 .LASF651:
 	.ascii	"_T_WCHAR_ \000"
-.LASF1026:
+.LASF1030:
 	.ascii	"BDTR\000"
 .LASF382:
 	.ascii	"__GCC_CONSTRUCTIVE_SIZE 64\000"
 .LASF664:
 	.ascii	"_BSD_WCHAR_T_\000"
-.LASF1005:
+.LASF1009:
 	.ascii	"PLLI2SCFGR\000"
 .LASF277:
 	.ascii	"__LLFRACT_IBIT__ 0\000"
@@ -6346,9 +6390,9 @@ main:
 	.ascii	"UINT16_C(x) __UINT16_C(x)\000"
 .LASF756:
 	.ascii	"PRIx32 __PRI32(x)\000"
-.LASF1033:
+.LASF1039:
 	.ascii	"tim4_init\000"
-.LASF981:
+.LASF985:
 	.ascii	"uint32_t\000"
 .LASF878:
 	.ascii	"RCC_PLLCFGR_PLLN_BIT 6\000"
@@ -6356,7 +6400,7 @@ main:
 	.ascii	"PRIxLEAST8 __PRI8LEAST(x)\000"
 .LASF506:
 	.ascii	"_SYS__INTSUP_H \000"
-.LASF1015:
+.LASF1019:
 	.ascii	"OPTCR\000"
 .LASF290:
 	.ascii	"__SACCUM_EPSILON__ 0x1P-7HK\000"
@@ -6414,7 +6458,7 @@ main:
 	.ascii	"PRIXLEAST32 __PRI32LEAST(X)\000"
 .LASF171:
 	.ascii	"__DBL_MAX__ ((double)1.7976931348623157e+308L)\000"
-.LASF972:
+.LASF976:
 	.ascii	"short unsigned int\000"
 .LASF276:
 	.ascii	"__LLFRACT_FBIT__ 63\000"
@@ -6422,7 +6466,7 @@ main:
 	.ascii	"__FLT32_HAS_INFINITY__ 1\000"
 .LASF416:
 	.ascii	"__thumb__ 1\000"
-.LASF964:
+.LASF968:
 	.ascii	"USART_BRR_MANTISSA_BIT 4\000"
 .LASF421:
 	.ascii	"__ARMEL__ 1\000"
@@ -6432,7 +6476,7 @@ main:
 	.ascii	"__HQ_FBIT__ 15\000"
 .LASF854:
 	.ascii	"__bool_true_false_are_defined 1\000"
-.LASF958:
+.LASF962:
 	.ascii	"USART_CR1_UE_BIT 13\000"
 .LASF925:
 	.ascii	"GPIO(port) ((struct gpio*)(uintptr_t)(GPIO_BASE_ADD"
@@ -6463,7 +6507,7 @@ main:
 	.ascii	"SCNuFAST32 __SCN32FAST(u)\000"
 .LASF522:
 	.ascii	"long +4\000"
-.LASF984:
+.LASF988:
 	.ascii	"AHB1RSTR\000"
 .LASF723:
 	.ascii	"SCNx16 __SCN16(x)\000"
@@ -6509,7 +6553,7 @@ main:
 	.ascii	"__DBL_MIN_10_EXP__ (-307)\000"
 .LASF795:
 	.ascii	"PRIx64 __PRI64(x)\000"
-.LASF960:
+.LASF964:
 	.ascii	"USART_CR1_TE_BIT 3\000"
 .LASF512:
 	.ascii	"__int20\000"
diff --git a/build/main.i b/build/main.i
index 07f7fd2..ef8b24f 100644
--- a/build/main.i
+++ b/build/main.i
@@ -2298,6 +2298,15 @@ struct usart {
 
 
 
+#define USART_SR_TXE_BIT 7
+#define USART_SR_TXE_TRANSMITTED (1 << USART_SR_TXE_BIT)
+
+
+#define USART_SR_RXNE_BIT 5
+#define USART_SR_RXNE_READY (1 <<USART_SR_RXNE_BIT)
+
+
+
 #define USART_CR1_OVER8_BIT 15
 #define USART_CR1_OVER8_8 (1 << USART_CR1_OVER8_BIT)
 
@@ -2322,6 +2331,8 @@ struct usart {
 
 void usart2_init(void);
 void usart2_start(void);
+
+void usart2_write_byte(char byte);
 # 10 "src/main.c" 2
 
 #define exit 42
@@ -2396,7 +2407,7 @@ int main(void) {
   (void) usart2_init();
 
   (void) tim4_start();
-  (void) tim4_start();
+  (void) usart2_start();
 
   uint16_t led = (((('C') - 'A') << 8) | 13);
   ((struct rcc *) (0x40023800U))->AHB1ENR |= (1 << (led >> 8));
@@ -2417,6 +2428,8 @@ int main(void) {
   led_on = !led_on;
   gpio_write(led, led_on);
 
+  usart2_write_byte('a');
+
   counter = ((struct timer *) (0x40000800U))->CNT;
  }
   };
diff --git a/build/main.o b/build/main.o
index 22ca011..7937152 100644
Binary files a/build/main.o and b/build/main.o differ
diff --git a/build/usart.S b/build/usart.S
index 367db15..8f5b9b4 100644
--- a/build/usart.S
+++ b/build/usart.S
@@ -230,6 +230,64 @@ usart2_start:
 	.cfi_endproc
 .LFE1:
 	.size	usart2_start, .-usart2_start
+	.section	.text.usart2_write_byte,"ax",%progbits
+	.align	1
+	.global	usart2_write_byte
+	.syntax unified
+	.thumb
+	.thumb_func
+	.type	usart2_write_byte, %function
+usart2_write_byte:
+.LFB2:
+	.loc 1 65 32
+	.cfi_startproc
+	@ args = 0, pretend = 0, frame = 8
+	@ frame_needed = 1, uses_anonymous_args = 0
+	@ link register save eliminated.
+	push	{r7}
+	.cfi_def_cfa_offset 4
+	.cfi_offset 7, -4
+	sub	sp, sp, #12
+	.cfi_def_cfa_offset 16
+	add	r7, sp, #0
+	.cfi_def_cfa_register 7
+	mov	r3, r0
+	strb	r3, [r7, #7]
+	.loc 1 67 35
+	ldr	r2, .L9
+	.loc 1 67 40
+	ldrb	r3, [r7, #7]	@ zero_extendqisi2
+	str	r3, [r2, #4]
+	.loc 1 70 9
+	nop
+.L8:
+	.loc 1 70 43 discriminator 1
+	ldr	r3, .L9
+	ldr	r3, [r3]
+	.loc 1 70 48 discriminator 1
+	and	r3, r3, #128
+	.loc 1 70 60 discriminator 1
+	cmp	r3, #0
+	beq	.L8
+	.loc 1 71 1
+	nop
+	nop
+	adds	r7, r7, #12
+	.cfi_def_cfa_offset 4
+	mov	sp, r7
+	.cfi_def_cfa_register 13
+	@ sp needed
+	ldr	r7, [sp], #4
+	.cfi_restore 7
+	.cfi_def_cfa_offset 0
+	bx	lr
+.L10:
+	.align	2
+.L9:
+	.word	1073759232
+	.cfi_endproc
+.LFE2:
+	.size	usart2_write_byte, .-usart2_write_byte
 	.text
 .Letext0:
 	.file 2 "/nix/store/yr89i11mszv2az19r26l372zgaiivj1c-gcc-arm-embedded-12.3.rel1/arm-none-eabi/include/machine/_default_types.h"
@@ -239,16 +297,16 @@ usart2_start:
 	.file 6 "src/usart.h"
 	.section	.debug_info,"",%progbits
 .Ldebug_info0:
-	.4byte	0x300
+	.4byte	0x32b
 	.2byte	0x5
 	.byte	0x1
 	.byte	0x4
 	.4byte	.Ldebug_abbrev0
 	.uleb128 0x8
-	.4byte	.LASF994
+	.4byte	.LASF998
 	.byte	0x1d
-	.4byte	.LASF995
-	.4byte	.LASF996
+	.4byte	.LASF999
+	.4byte	.LASF1000
 	.4byte	.LLRL0
 	.4byte	0
 	.4byte	.Ldebug_line0
@@ -256,25 +314,25 @@ usart2_start:
 	.uleb128 0x3
 	.byte	0x1
 	.byte	0x6
-	.4byte	.LASF945
+	.4byte	.LASF949
 	.uleb128 0x3
 	.byte	0x1
 	.byte	0x8
-	.4byte	.LASF946
+	.4byte	.LASF950
 	.uleb128 0x3
 	.byte	0x2
 	.byte	0x5
-	.4byte	.LASF947
+	.4byte	.LASF951
 	.uleb128 0x3
 	.byte	0x2
 	.byte	0x7
-	.4byte	.LASF948
+	.4byte	.LASF952
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x5
-	.4byte	.LASF949
+	.4byte	.LASF953
 	.uleb128 0x4
-	.4byte	.LASF954
+	.4byte	.LASF958
 	.byte	0x2
 	.byte	0x4f
 	.byte	0x1b
@@ -282,15 +340,15 @@ usart2_start:
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x7
-	.4byte	.LASF950
+	.4byte	.LASF954
 	.uleb128 0x3
 	.byte	0x8
 	.byte	0x5
-	.4byte	.LASF951
+	.4byte	.LASF955
 	.uleb128 0x3
 	.byte	0x8
 	.byte	0x7
-	.4byte	.LASF952
+	.4byte	.LASF956
 	.uleb128 0x9
 	.byte	0x4
 	.byte	0x5
@@ -298,9 +356,9 @@ usart2_start:
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x7
-	.4byte	.LASF953
+	.4byte	.LASF957
 	.uleb128 0x4
-	.4byte	.LASF955
+	.4byte	.LASF959
 	.byte	0x3
 	.byte	0x30
 	.byte	0x14
@@ -321,13 +379,13 @@ usart2_start:
 	.4byte	0x88
 	.byte	0
 	.uleb128 0x1
-	.4byte	.LASF956
+	.4byte	.LASF960
 	.byte	0x4
 	.byte	0x8
 	.4byte	0x88
 	.byte	0x4
 	.uleb128 0x1
-	.4byte	.LASF957
+	.4byte	.LASF961
 	.byte	0x4
 	.byte	0x9
 	.4byte	0x88
@@ -339,115 +397,115 @@ usart2_start:
 	.4byte	0x88
 	.byte	0xc
 	.uleb128 0x1
-	.4byte	.LASF958
+	.4byte	.LASF962
 	.byte	0x4
 	.byte	0xb
 	.4byte	0x88
 	.byte	0x10
 	.uleb128 0x1
-	.4byte	.LASF959
+	.4byte	.LASF963
 	.byte	0x4
 	.byte	0xc
 	.4byte	0x88
 	.byte	0x14
 	.uleb128 0x1
-	.4byte	.LASF960
+	.4byte	.LASF964
 	.byte	0x4
 	.byte	0xd
 	.4byte	0x1fa
 	.byte	0x18
 	.uleb128 0x1
-	.4byte	.LASF961
+	.4byte	.LASF965
 	.byte	0x4
 	.byte	0xe
 	.4byte	0x88
 	.byte	0x20
 	.uleb128 0x1
-	.4byte	.LASF962
+	.4byte	.LASF966
 	.byte	0x4
 	.byte	0xf
 	.4byte	0x88
 	.byte	0x24
 	.uleb128 0x1
-	.4byte	.LASF963
+	.4byte	.LASF967
 	.byte	0x4
 	.byte	0x10
 	.4byte	0x1fa
 	.byte	0x28
 	.uleb128 0x1
-	.4byte	.LASF964
+	.4byte	.LASF968
 	.byte	0x4
 	.byte	0x11
 	.4byte	0x88
 	.byte	0x30
 	.uleb128 0x1
-	.4byte	.LASF965
+	.4byte	.LASF969
 	.byte	0x4
 	.byte	0x12
 	.4byte	0x88
 	.byte	0x34
 	.uleb128 0x1
-	.4byte	.LASF966
+	.4byte	.LASF970
 	.byte	0x4
 	.byte	0x13
 	.4byte	0x1fa
 	.byte	0x38
 	.uleb128 0x1
-	.4byte	.LASF967
+	.4byte	.LASF971
 	.byte	0x4
 	.byte	0x14
 	.4byte	0x88
 	.byte	0x40
 	.uleb128 0x1
-	.4byte	.LASF968
+	.4byte	.LASF972
 	.byte	0x4
 	.byte	0x15
 	.4byte	0x88
 	.byte	0x44
 	.uleb128 0x1
-	.4byte	.LASF969
+	.4byte	.LASF973
 	.byte	0x4
 	.byte	0x16
 	.4byte	0x1fa
 	.byte	0x48
 	.uleb128 0x1
-	.4byte	.LASF970
+	.4byte	.LASF974
 	.byte	0x4
 	.byte	0x17
 	.4byte	0x88
 	.byte	0x50
 	.uleb128 0x1
-	.4byte	.LASF971
+	.4byte	.LASF975
 	.byte	0x4
 	.byte	0x18
 	.4byte	0x88
 	.byte	0x54
 	.uleb128 0x1
-	.4byte	.LASF972
+	.4byte	.LASF976
 	.byte	0x4
 	.byte	0x19
 	.4byte	0x1fa
 	.byte	0x58
 	.uleb128 0x1
-	.4byte	.LASF973
+	.4byte	.LASF977
 	.byte	0x4
 	.byte	0x1a
 	.4byte	0x88
 	.byte	0x60
 	.uleb128 0x1
-	.4byte	.LASF974
+	.4byte	.LASF978
 	.byte	0x4
 	.byte	0x1b
 	.4byte	0x88
 	.byte	0x64
 	.uleb128 0x1
-	.4byte	.LASF975
+	.4byte	.LASF979
 	.byte	0x4
 	.byte	0x1c
 	.4byte	0x1fa
 	.byte	0x68
 	.uleb128 0x1
-	.4byte	.LASF976
+	.4byte	.LASF980
 	.byte	0x4
 	.byte	0x1d
 	.4byte	0x88
@@ -459,25 +517,25 @@ usart2_start:
 	.4byte	0x88
 	.byte	0x74
 	.uleb128 0x1
-	.4byte	.LASF977
+	.4byte	.LASF981
 	.byte	0x4
 	.byte	0x1f
 	.4byte	0x1fa
 	.byte	0x78
 	.uleb128 0x1
-	.4byte	.LASF978
+	.4byte	.LASF982
 	.byte	0x4
 	.byte	0x20
 	.4byte	0x88
 	.byte	0x80
 	.uleb128 0x1
-	.4byte	.LASF979
+	.4byte	.LASF983
 	.byte	0x4
 	.byte	0x21
 	.4byte	0x88
 	.byte	0x84
 	.uleb128 0x1
-	.4byte	.LASF980
+	.4byte	.LASF984
 	.byte	0x4
 	.byte	0x22
 	.4byte	0x88
@@ -493,31 +551,31 @@ usart2_start:
 	.uleb128 0x5
 	.4byte	0x1ea
 	.uleb128 0x6
-	.4byte	.LASF981
+	.4byte	.LASF985
 	.byte	0x28
 	.byte	0x5
 	.byte	0x7
 	.4byte	0x284
 	.uleb128 0x1
-	.4byte	.LASF982
+	.4byte	.LASF986
 	.byte	0x5
 	.byte	0x8
 	.4byte	0x88
 	.byte	0
 	.uleb128 0x1
-	.4byte	.LASF983
+	.4byte	.LASF987
 	.byte	0x5
 	.byte	0x9
 	.4byte	0x88
 	.byte	0x4
 	.uleb128 0x1
-	.4byte	.LASF984
+	.4byte	.LASF988
 	.byte	0x5
 	.byte	0xa
 	.4byte	0x88
 	.byte	0x8
 	.uleb128 0x1
-	.4byte	.LASF985
+	.4byte	.LASF989
 	.byte	0x5
 	.byte	0xb
 	.4byte	0x88
@@ -535,32 +593,32 @@ usart2_start:
 	.4byte	0x88
 	.byte	0x14
 	.uleb128 0x1
-	.4byte	.LASF986
+	.4byte	.LASF990
 	.byte	0x5
 	.byte	0xe
 	.4byte	0x88
 	.byte	0x18
 	.uleb128 0x1
-	.4byte	.LASF987
+	.4byte	.LASF991
 	.byte	0x5
 	.byte	0xf
 	.4byte	0x88
 	.byte	0x1c
 	.uleb128 0x1
-	.4byte	.LASF988
+	.4byte	.LASF992
 	.byte	0x5
 	.byte	0x10
 	.4byte	0x88
 	.byte	0x20
 	.uleb128 0x1
-	.4byte	.LASF989
+	.4byte	.LASF993
 	.byte	0x5
 	.byte	0x11
 	.4byte	0x88
 	.byte	0x24
 	.byte	0
 	.uleb128 0x6
-	.4byte	.LASF990
+	.4byte	.LASF994
 	.byte	0x1c
 	.byte	0x6
 	.byte	0x6
@@ -602,21 +660,45 @@ usart2_start:
 	.4byte	0x88
 	.byte	0x14
 	.uleb128 0x1
-	.4byte	.LASF991
+	.4byte	.LASF995
 	.byte	0x6
 	.byte	0xd
 	.4byte	0x88
 	.byte	0x18
 	.byte	0
+	.uleb128 0xd
+	.4byte	.LASF1001
+	.byte	0x1
+	.byte	0x41
+	.byte	0x6
+	.4byte	.LFB2
+	.4byte	.LFE2-.LFB2
+	.uleb128 0x1
+	.byte	0x9c
+	.4byte	0x307
+	.uleb128 0xe
+	.ascii	"c\000"
+	.byte	0x1
+	.byte	0x41
+	.byte	0x1d
+	.4byte	0x307
+	.uleb128 0x2
+	.byte	0x91
+	.sleb128 -9
+	.byte	0
+	.uleb128 0x3
+	.byte	0x1
+	.byte	0x8
+	.4byte	.LASF511
 	.uleb128 0x7
-	.4byte	.LASF992
+	.4byte	.LASF996
 	.byte	0x3d
 	.4byte	.LFB1
 	.4byte	.LFE1-.LFB1
 	.uleb128 0x1
 	.byte	0x9c
 	.uleb128 0x7
-	.4byte	.LASF993
+	.4byte	.LASF997
 	.byte	0x5
 	.4byte	.LFB0
 	.4byte	.LFE0-.LFB0
@@ -806,9 +888,53 @@ usart2_start:
 	.uleb128 0xb
 	.byte	0
 	.byte	0
+	.uleb128 0xd
+	.uleb128 0x2e
+	.byte	0x1
+	.uleb128 0x3f
+	.uleb128 0x19
+	.uleb128 0x3
+	.uleb128 0xe
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x39
+	.uleb128 0xb
+	.uleb128 0x27
+	.uleb128 0x19
+	.uleb128 0x11
+	.uleb128 0x1
+	.uleb128 0x12
+	.uleb128 0x6
+	.uleb128 0x40
+	.uleb128 0x18
+	.uleb128 0x7a
+	.uleb128 0x19
+	.uleb128 0x1
+	.uleb128 0x13
+	.byte	0
+	.byte	0
+	.uleb128 0xe
+	.uleb128 0x5
+	.byte	0
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x39
+	.uleb128 0xb
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0x2
+	.uleb128 0x18
+	.byte	0
+	.byte	0
 	.byte	0
 	.section	.debug_aranges,"",%progbits
-	.4byte	0x24
+	.4byte	0x2c
 	.2byte	0x2
 	.4byte	.Ldebug_info0
 	.byte	0x4
@@ -819,6 +945,8 @@ usart2_start:
 	.4byte	.LFE0-.LFB0
 	.4byte	.LFB1
 	.4byte	.LFE1-.LFB1
+	.4byte	.LFB2
+	.4byte	.LFE2-.LFB2
 	.4byte	0
 	.4byte	0
 	.section	.debug_rnglists,"",%progbits
@@ -836,6 +964,9 @@ usart2_start:
 	.byte	0x7
 	.4byte	.LFB1
 	.uleb128 .LFE1-.LFB1
+	.byte	0x7
+	.4byte	.LFB2
+	.uleb128 .LFE2-.LFB2
 	.byte	0
 .Ldebug_ranges3:
 	.section	.debug_macro,"",%progbits
@@ -3852,7 +3983,7 @@ usart2_start:
 	.uleb128 0x38
 	.4byte	.LASF929
 	.byte	0
-	.section	.debug_macro,"G",%progbits,wm4.usart.h.2.0debbac628af0f73f2055baa828e03f0,comdat
+	.section	.debug_macro,"G",%progbits,wm4.usart.h.2.499ef099adc8b232d514889834b2ea6a,comdat
 .Ldebug_macro17:
 	.2byte	0x5
 	.byte	0
@@ -3878,29 +4009,41 @@ usart2_start:
 	.uleb128 0x1a
 	.4byte	.LASF936
 	.byte	0x5
-	.uleb128 0x1d
+	.uleb128 0x1e
 	.4byte	.LASF937
 	.byte	0x5
-	.uleb128 0x1e
+	.uleb128 0x1f
 	.4byte	.LASF938
 	.byte	0x5
-	.uleb128 0x21
+	.uleb128 0x22
 	.4byte	.LASF939
 	.byte	0x5
-	.uleb128 0x22
+	.uleb128 0x23
 	.4byte	.LASF940
 	.byte	0x5
-	.uleb128 0x25
+	.uleb128 0x26
 	.4byte	.LASF941
 	.byte	0x5
-	.uleb128 0x26
+	.uleb128 0x27
 	.4byte	.LASF942
 	.byte	0x5
-	.uleb128 0x28
+	.uleb128 0x2a
 	.4byte	.LASF943
 	.byte	0x5
-	.uleb128 0x29
+	.uleb128 0x2b
 	.4byte	.LASF944
+	.byte	0x5
+	.uleb128 0x2e
+	.4byte	.LASF945
+	.byte	0x5
+	.uleb128 0x2f
+	.4byte	.LASF946
+	.byte	0x5
+	.uleb128 0x31
+	.4byte	.LASF947
+	.byte	0x5
+	.uleb128 0x32
+	.4byte	.LASF948
 	.byte	0
 	.section	.debug_line,"",%progbits
 .Ldebug_line0:
@@ -3915,7 +4058,7 @@ usart2_start:
 	.ascii	"__UHA_FBIT__ 8\000"
 .LASF815:
 	.ascii	"PRIiFAST64 __PRI64FAST(i)\000"
-.LASF946:
+.LASF950:
 	.ascii	"unsigned char\000"
 .LASF225:
 	.ascii	"__FLT64_DENORM_MIN__ 4.9406564584124654e-324F64\000"
@@ -3943,7 +4086,7 @@ usart2_start:
 	.ascii	"__PTRDIFF_MAX__ 0x7fffffff\000"
 .LASF542:
 	.ascii	"_LONG_DOUBLE long double\000"
-.LASF981:
+.LASF985:
 	.ascii	"gpio\000"
 .LASF592:
 	.ascii	"INT_LEAST8_MIN (-__INT_LEAST8_MAX__ - 1)\000"
@@ -3967,7 +4110,7 @@ usart2_start:
 	.ascii	"__int20__\000"
 .LASF901:
 	.ascii	"RCC_APB1ENR_TIM4_BIT 2\000"
-.LASF944:
+.LASF948:
 	.ascii	"USART_BRR_FRACTION_MASK (0b111)\000"
 .LASF18:
 	.ascii	"__SIZEOF_LONG_LONG__ 8\000"
@@ -4010,6 +4153,8 @@ usart2_start:
 	.ascii	"PRIo16 __PRI16(o)\000"
 .LASF203:
 	.ascii	"__FLT32_DECIMAL_DIG__ 9\000"
+.LASF379:
+	.ascii	"__GCC_ATOMIC_LLONG_LOCK_FREE 1\000"
 .LASF182:
 	.ascii	"__LDBL_MIN_EXP__ (-1021)\000"
 .LASF180:
@@ -4040,8 +4185,8 @@ usart2_start:
 	.ascii	"SCNiFAST8 __SCN8FAST(i)\000"
 .LASF909:
 	.ascii	"GPIOA_BASE_ADDR (0x40020000U)\000"
-.LASF120:
-	.ascii	"__UINT_LEAST16_MAX__ 0xffff\000"
+.LASF791:
+	.ascii	"__SCN64FAST(x) __FAST64 __STRINGIFY(x)\000"
 .LASF617:
 	.ascii	"INT_FAST16_MAX (__INT_FAST16_MAX__)\000"
 .LASF281:
@@ -4082,7 +4227,7 @@ usart2_start:
 	.ascii	"__need_wchar_t\000"
 .LASF199:
 	.ascii	"__FLT32_MIN_EXP__ (-125)\000"
-.LASF994:
+.LASF998:
 	.ascii	"GNU C2X 12.3.1 20230626 -mcpu=cortex-m4 -mthumb -mf"
 	.ascii	"loat-abi=hard -mfpu=fpv4-sp-d16 -march=armv7e-m+fp "
 	.ascii	"-g3 -ggdb -O0 -std=c2x -ffunction-sections -fdata-s"
@@ -4156,7 +4301,7 @@ usart2_start:
 	.ascii	"CC_CFGR_SW_BIT)\000"
 .LASF134:
 	.ascii	"__UINT_FAST8_MAX__ 0xffffffffU\000"
-.LASF943:
+.LASF947:
 	.ascii	"USART_BRR_FRACTION_BIT 0\000"
 .LASF541:
 	.ascii	"_NOTHROW \000"
@@ -4182,7 +4327,7 @@ usart2_start:
 	.ascii	"__INT64 \"ll\"\000"
 .LASF138:
 	.ascii	"__INTPTR_MAX__ 0x7fffffff\000"
-.LASF971:
+.LASF975:
 	.ascii	"AHB2LPENR\000"
 .LASF500:
 	.ascii	"__RAND_MAX\000"
@@ -4225,7 +4370,7 @@ usart2_start:
 	.ascii	" RCC_PLLCFGR_PLLP_BIT)\000"
 .LASF302:
 	.ascii	"__UACCUM_IBIT__ 16\000"
-.LASF949:
+.LASF953:
 	.ascii	"long int\000"
 .LASF720:
 	.ascii	"SCNd16 __SCN16(d)\000"
@@ -4282,6 +4427,8 @@ usart2_start:
 	.ascii	"__ULLFRACT_MAX__ 0XFFFFFFFFFFFFFFFFP-64ULLR\000"
 .LASF698:
 	.ascii	"PRIiFAST8 __PRI8FAST(i)\000"
+.LASF936:
+	.ascii	"USART_SR_RXNE_READY (1 <<USART_SR_RXNE_BIT)\000"
 .LASF33:
 	.ascii	"__GNUC_WIDE_EXECUTION_CHARSET_NAME \"UTF-32LE\"\000"
 .LASF572:
@@ -4302,7 +4449,7 @@ usart2_start:
 	.ascii	"__SIZEOF_LONG__ 4\000"
 .LASF754:
 	.ascii	"PRIi32 __PRI32(i)\000"
-.LASF968:
+.LASF972:
 	.ascii	"APB2ENR\000"
 .LASF822:
 	.ascii	"SCNoFAST64 __SCN64FAST(o)\000"
@@ -4316,7 +4463,7 @@ usart2_start:
 	.ascii	"__FLT32X_MIN_EXP__ (-1021)\000"
 .LASF816:
 	.ascii	"PRIoFAST64 __PRI64FAST(o)\000"
-.LASF970:
+.LASF974:
 	.ascii	"AHB1LPENR\000"
 .LASF406:
 	.ascii	"__ARM_FEATURE_SIMD32 1\000"
@@ -4328,19 +4475,19 @@ usart2_start:
 	.ascii	"PRIoLEAST16 __PRI16LEAST(o)\000"
 .LASF459:
 	.ascii	"__NEWLIB__ 4\000"
-.LASF980:
+.LASF984:
 	.ascii	"DCKCFGR\000"
 .LASF721:
 	.ascii	"SCNi16 __SCN16(i)\000"
 .LASF360:
 	.ascii	"__UTA_FBIT__ 64\000"
-.LASF990:
+.LASF994:
 	.ascii	"usart\000"
 .LASF153:
 	.ascii	"__FLT_DECIMAL_DIG__ 9\000"
 .LASF563:
 	.ascii	"_UINT8_T_DECLARED \000"
-.LASF945:
+.LASF949:
 	.ascii	"signed char\000"
 .LASF806:
 	.ascii	"PRIuLEAST64 __PRI64LEAST(u)\000"
@@ -4364,8 +4511,8 @@ usart2_start:
 	.ascii	"__GCC_ATOMIC_CHAR32_T_LOCK_FREE 2\000"
 .LASF866:
 	.ascii	"RCC_PLLCFGR_PLLQ_MASK (0b1111)\000"
-.LASF649:
-	.ascii	"__wchar_t__ \000"
+.LASF120:
+	.ascii	"__UINT_LEAST16_MAX__ 0xffff\000"
 .LASF410:
 	.ascii	"__ARM_ARCH_PROFILE 77\000"
 .LASF547:
@@ -4378,19 +4525,19 @@ usart2_start:
 	.ascii	"GPIO_AFRL_AFRL2_MASK (0b1111)\000"
 .LASF874:
 	.ascii	"RCC_PLLCFGR_PLLN_MASK (0b111111111)\000"
-.LASF960:
+.LASF964:
 	.ascii	"RESERVED0\000"
-.LASF963:
+.LASF967:
 	.ascii	"RESERVED1\000"
-.LASF966:
+.LASF970:
 	.ascii	"RESERVED2\000"
 .LASF3:
 	.ascii	"__STDC_UTF_32__ 1\000"
-.LASF972:
+.LASF976:
 	.ascii	"RESERVED4\000"
 .LASF241:
 	.ascii	"__FLT32X_DENORM_MIN__ 4.9406564584124654e-324F32x\000"
-.LASF977:
+.LASF981:
 	.ascii	"RESERVED6\000"
 .LASF152:
 	.ascii	"__FLT_MAX_10_EXP__ 38\000"
@@ -4402,7 +4549,9 @@ usart2_start:
 	.ascii	"__FRACT_MAX__ 0X7FFFP-15R\000"
 .LASF729:
 	.ascii	"PRIxLEAST16 __PRI16LEAST(x)\000"
-.LASF995:
+.LASF1001:
+	.ascii	"usart2_write_byte\000"
+.LASF999:
 	.ascii	"src/usart.c\000"
 .LASF130:
 	.ascii	"__INT_FAST32_MAX__ 0x7fffffff\000"
@@ -4453,11 +4602,11 @@ usart2_start:
 	.ascii	"SCNxLEAST64 __SCN64LEAST(x)\000"
 .LASF770:
 	.ascii	"SCNdLEAST32 __SCN32LEAST(d)\000"
-.LASF969:
+.LASF973:
 	.ascii	"RESERVED3\000"
 .LASF22:
 	.ascii	"__SIZEOF_LONG_DOUBLE__ 8\000"
-.LASF975:
+.LASF979:
 	.ascii	"RESERVED5\000"
 .LASF896:
 	.ascii	"RCC_AHB1ENR_GPIOAEN_ENABLE (1 << RCC_AHB1ENR_GPIOAE"
@@ -4502,7 +4651,7 @@ usart2_start:
 	.ascii	"__FLT32_IS_IEC_60559__ 2\000"
 .LASF630:
 	.ascii	"SIG_ATOMIC_MAX (__STDINT_EXP(INT_MAX))\000"
-.LASF940:
+.LASF944:
 	.ascii	"USART_CR1_RE_ENABLE (1 << USART_CR1_RE_BIT)\000"
 .LASF725:
 	.ascii	"PRIdLEAST16 __PRI16LEAST(d)\000"
@@ -4512,7 +4661,7 @@ usart2_start:
 	.ascii	"__SCN64(x) __INT64 __STRINGIFY(x)\000"
 .LASF647:
 	.ascii	"_GCC_WRAP_STDINT_H \000"
-.LASF965:
+.LASF969:
 	.ascii	"AHB2ENR\000"
 .LASF805:
 	.ascii	"PRIoLEAST64 __PRI64LEAST(o)\000"
@@ -4610,7 +4759,7 @@ usart2_start:
 	.ascii	"__ELF__ 1\000"
 .LASF689:
 	.ascii	"PRIuLEAST8 __PRI8LEAST(u)\000"
-.LASF976:
+.LASF980:
 	.ascii	"BDCR\000"
 .LASF211:
 	.ascii	"__FLT32_HAS_QUIET_NAN__ 1\000"
@@ -4672,7 +4821,7 @@ usart2_start:
 	.ascii	"RCC_CR_HSERDY_READY (1 << RCC_CR_HSERDY_BIT)\000"
 .LASF763:
 	.ascii	"SCNx32 __SCN32(x)\000"
-.LASF957:
+.LASF961:
 	.ascii	"CFGR\000"
 .LASF558:
 	.ascii	"___int_least32_t_defined 1\000"
@@ -4680,12 +4829,14 @@ usart2_start:
 	.ascii	"__LLACCUM_MAX__ 0X7FFFFFFFFFFFFFFFP-31LLK\000"
 .LASF667:
 	.ascii	"__need_NULL\000"
-.LASF934:
+.LASF938:
 	.ascii	"USART_CR1_OVER8_8 (1 << USART_CR1_OVER8_BIT)\000"
 .LASF363:
 	.ascii	"__USER_LABEL_PREFIX__ \000"
 .LASF105:
 	.ascii	"__UINT64_MAX__ 0xffffffffffffffffULL\000"
+.LASF699:
+	.ascii	"PRIoFAST8 __PRI8FAST(o)\000"
 .LASF104:
 	.ascii	"__UINT32_MAX__ 0xffffffffUL\000"
 .LASF643:
@@ -4708,8 +4859,8 @@ usart2_start:
 	.ascii	"__ARM_FEATURE_COMPLEX\000"
 .LASF832:
 	.ascii	"PRIXMAX __PRIMAX(X)\000"
-.LASF680:
-	.ascii	"PRIX8 __PRI8(X)\000"
+.LASF852:
+	.ascii	"RCC ((struct rcc *) RCC_BASE_ADDR)\000"
 .LASF524:
 	.ascii	"_INTPTR_EQ_INT \000"
 .LASF408:
@@ -4744,7 +4895,7 @@ usart2_start:
 	.ascii	"___int8_t_defined 1\000"
 .LASF248:
 	.ascii	"__SFRACT_MIN__ (-0.5HR-0.5HR)\000"
-.LASF950:
+.LASF954:
 	.ascii	"long unsigned int\000"
 .LASF349:
 	.ascii	"__SA_IBIT__ 16\000"
@@ -4770,7 +4921,7 @@ usart2_start:
 	.ascii	"__FLT_EVAL_METHOD_TS_18661_3__ 0\000"
 .LASF522:
 	.ascii	"int +2\000"
-.LASF996:
+.LASF1000:
 	.ascii	"/home/alex/code/own/c-compile-experiments\000"
 .LASF637:
 	.ascii	"INT8_C(x) __INT8_C(x)\000"
@@ -4788,8 +4939,6 @@ usart2_start:
 	.ascii	"__INT32_MAX__ 0x7fffffffL\000"
 .LASF506:
 	.ascii	"_USE_GDTOA \000"
-.LASF451:
-	.ascii	"__GXX_TYPEINFO_EQUALITY_INLINE 0\000"
 .LASF692:
 	.ascii	"SCNdLEAST8 __SCN8LEAST(d)\000"
 .LASF115:
@@ -4820,7 +4969,7 @@ usart2_start:
 	.ascii	"PRIXLEAST16 __PRI16LEAST(X)\000"
 .LASF623:
 	.ascii	"INT_FAST64_MAX (__INT_FAST64_MAX__)\000"
-.LASF939:
+.LASF943:
 	.ascii	"USART_CR1_RE_BIT 2\000"
 .LASF373:
 	.ascii	"__GCC_ATOMIC_CHAR16_T_LOCK_FREE 2\000"
@@ -4828,7 +4977,7 @@ usart2_start:
 	.ascii	"__PRI64FAST(x) __FAST64 __STRINGIFY(x)\000"
 .LASF892:
 	.ascii	"RCC_CFGR_SW_BIT 0\000"
-.LASF987:
+.LASF991:
 	.ascii	"LCKR\000"
 .LASF168:
 	.ascii	"__DBL_MAX_EXP__ 1024\000"
@@ -4858,8 +5007,6 @@ usart2_start:
 	.ascii	"_INT32_T_DECLARED \000"
 .LASF1:
 	.ascii	"__STDC_VERSION__ 202000L\000"
-.LASF791:
-	.ascii	"__SCN64FAST(x) __FAST64 __STRINGIFY(x)\000"
 .LASF532:
 	.ascii	"__FAST32 \000"
 .LASF520:
@@ -4878,11 +5025,11 @@ usart2_start:
 	.ascii	"PRIX32 __PRI32(X)\000"
 .LASF774:
 	.ascii	"SCNxLEAST32 __SCN32LEAST(x)\000"
-.LASF984:
+.LASF988:
 	.ascii	"OSPEEDR\000"
 .LASF712:
 	.ascii	"__SCN16LEAST(x) __LEAST16 __STRINGIFY(x)\000"
-.LASF956:
+.LASF960:
 	.ascii	"PLLCFGR\000"
 .LASF5:
 	.ascii	"__GNUC__ 12\000"
@@ -4910,7 +5057,7 @@ usart2_start:
 	.ascii	"__ULACCUM_MIN__ 0.0ULK\000"
 .LASF462:
 	.ascii	"_ATEXIT_DYNAMIC_ALLOC 1\000"
-.LASF954:
+.LASF958:
 	.ascii	"__uint32_t\000"
 .LASF188:
 	.ascii	"__LDBL_MAX__ 1.7976931348623157e+308L\000"
@@ -4920,12 +5067,14 @@ usart2_start:
 	.ascii	"__FLT_RADIX__ 2\000"
 .LASF455:
 	.ascii	"_INTTYPES_H \000"
-.LASF951:
+.LASF955:
 	.ascii	"long long int\000"
 .LASF401:
 	.ascii	"__ARM_FEATURE_CMSE\000"
 .LASF603:
 	.ascii	"UINT32_MAX (__UINT32_MAX__)\000"
+.LASF649:
+	.ascii	"__wchar_t__ \000"
 .LASF195:
 	.ascii	"__LDBL_HAS_QUIET_NAN__ 1\000"
 .LASF85:
@@ -4936,7 +5085,7 @@ usart2_start:
 	.ascii	"WINT_MAX (__WINT_MAX__)\000"
 .LASF823:
 	.ascii	"SCNuFAST64 __SCN64FAST(u)\000"
-.LASF978:
+.LASF982:
 	.ascii	"SSCGR\000"
 .LASF137:
 	.ascii	"__UINT_FAST64_MAX__ 0xffffffffffffffffULL\000"
@@ -4948,8 +5097,10 @@ usart2_start:
 	.ascii	"__HA_IBIT__ 8\000"
 .LASF139:
 	.ascii	"__INTPTR_WIDTH__ 32\000"
-.LASF379:
-	.ascii	"__GCC_ATOMIC_LLONG_LOCK_FREE 1\000"
+.LASF0:
+	.ascii	"__STDC__ 1\000"
+.LASF933:
+	.ascii	"USART_SR_TXE_BIT 7\000"
 .LASF239:
 	.ascii	"__FLT32X_MIN__ 2.2250738585072014e-308F32x\000"
 .LASF218:
@@ -4958,13 +5109,13 @@ usart2_start:
 	.ascii	"__WCHAR_T \000"
 .LASF223:
 	.ascii	"__FLT64_MIN__ 2.2250738585072014e-308F64\000"
-.LASF991:
+.LASF995:
 	.ascii	"GTPR\000"
 .LASF554:
 	.ascii	"___int32_t_defined 1\000"
 .LASF83:
 	.ascii	"__INT_WIDTH__ 32\000"
-.LASF962:
+.LASF966:
 	.ascii	"APB2RSTR\000"
 .LASF409:
 	.ascii	"__ARM_ARCH_PROFILE\000"
@@ -5014,7 +5165,7 @@ usart2_start:
 	.ascii	"__FLT32_EPSILON__ 1.1920928955078125e-7F32\000"
 .LASF434:
 	.ascii	"__ARM_NEON_FP\000"
-.LASF974:
+.LASF978:
 	.ascii	"APB2LPENR\000"
 .LASF821:
 	.ascii	"SCNiFAST64 __SCN64FAST(i)\000"
@@ -5026,7 +5177,7 @@ usart2_start:
 	.ascii	"_STDBOOL_H \000"
 .LASF261:
 	.ascii	"__UFRACT_FBIT__ 16\000"
-.LASF933:
+.LASF937:
 	.ascii	"USART_CR1_OVER8_BIT 15\000"
 .LASF342:
 	.ascii	"__UDQ_FBIT__ 64\000"
@@ -5035,7 +5186,7 @@ usart2_start:
 	.ascii	"\000"
 .LASF583:
 	.ascii	"__int_fast16_t_defined 1\000"
-.LASF982:
+.LASF986:
 	.ascii	"MODER\000"
 .LASF483:
 	.ascii	"__FLOAT_TYPE float\000"
@@ -5046,7 +5197,7 @@ usart2_start:
 	.ascii	"L)\000"
 .LASF608:
 	.ascii	"INT64_MAX (__INT64_MAX__)\000"
-.LASF953:
+.LASF957:
 	.ascii	"unsigned int\000"
 .LASF857:
 	.ascii	"RCC_CR_HSERDY_BIT 17\000"
@@ -5072,8 +5223,6 @@ usart2_start:
 	.ascii	"__FLT_DIG__ 6\000"
 .LASF305:
 	.ascii	"__UACCUM_EPSILON__ 0x1P-16UK\000"
-.LASF464:
-	.ascii	"_FVWRITE_IN_STREAMIO 1\000"
 .LASF663:
 	.ascii	"_WCHAR_T_DECLARED \000"
 .LASF24:
@@ -5082,7 +5231,7 @@ usart2_start:
 	.ascii	"GPIO_AFRL_AFRL3_USART2_RX (0b0111)\000"
 .LASF143:
 	.ascii	"__FLT_EVAL_METHOD__ 0\000"
-.LASF947:
+.LASF951:
 	.ascii	"short int\000"
 .LASF686:
 	.ascii	"PRIdLEAST8 __PRI8LEAST(d)\000"
@@ -5094,7 +5243,7 @@ usart2_start:
 	.ascii	"__STDC_UTF_16__ 1\000"
 .LASF402:
 	.ascii	"__ARM_FEATURE_LDREX\000"
-.LASF992:
+.LASF996:
 	.ascii	"usart2_start\000"
 .LASF336:
 	.ascii	"__UQQ_FBIT__ 8\000"
@@ -5138,7 +5287,7 @@ usart2_start:
 	.ascii	"__STRINGIFY(a) #a\000"
 .LASF356:
 	.ascii	"__USA_FBIT__ 16\000"
-.LASF973:
+.LASF977:
 	.ascii	"APB1LPENR\000"
 .LASF480:
 	.ascii	"__IEEE_LITTLE_ENDIAN \000"
@@ -5242,7 +5391,7 @@ usart2_start:
 	.ascii	"__LFRACT_IBIT__ 0\000"
 .LASF16:
 	.ascii	"__SIZEOF_INT__ 4\000"
-.LASF938:
+.LASF942:
 	.ascii	"USART_CR1_TE_ENABLE (1 << USART_CR1_TE_BIT)\000"
 .LASF166:
 	.ascii	"__DBL_MIN_EXP__ (-1021)\000"
@@ -5274,23 +5423,23 @@ usart2_start:
 	.ascii	"__HAVE_SPECULATION_SAFE_VALUE 1\000"
 .LASF286:
 	.ascii	"__SACCUM_FBIT__ 7\000"
-.LASF370:
-	.ascii	"__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 1\000"
 .LASF734:
 	.ascii	"SCNuLEAST16 __SCN16LEAST(u)\000"
-.LASF961:
+.LASF965:
 	.ascii	"APB1RSTR\000"
 .LASF298:
 	.ascii	"__ACCUM_MIN__ (-0X1P15K-0X1P15K)\000"
 .LASF393:
 	.ascii	"__ARM_FEATURE_CRYPTO\000"
-.LASF967:
+.LASF971:
 	.ascii	"APB1ENR\000"
 .LASF742:
 	.ascii	"SCNdFAST16 __SCN16FAST(d)\000"
 .LASF867:
 	.ascii	"RCC_PLLCFGR_PLLQ(q) ((q & RCC_PLLCFGR_PLLQ_MASK) <<"
 	.ascii	" RCC_PLLCFGR_PLLQ_BIT)\000"
+.LASF934:
+	.ascii	"USART_SR_TXE_TRANSMITTED (1 << USART_SR_TXE_BIT)\000"
 .LASF788:
 	.ascii	"__PRI64LEAST(x) __LEAST64 __STRINGIFY(x)\000"
 .LASF678:
@@ -5314,7 +5463,7 @@ usart2_start:
 	.ascii	")\000"
 .LASF155:
 	.ascii	"__FLT_NORM_MAX__ 3.4028234663852886e+38F\000"
-.LASF952:
+.LASF956:
 	.ascii	"long long unsigned int\000"
 .LASF612:
 	.ascii	"UINT_LEAST64_MAX (__UINT_LEAST64_MAX__)\000"
@@ -5346,12 +5495,12 @@ usart2_start:
 	.ascii	"SCNdFAST32 __SCN32FAST(d)\000"
 .LASF339:
 	.ascii	"__UHQ_IBIT__ 0\000"
-.LASF911:
-	.ascii	"GPIO_MODER_MODER3_BIT 7\000"
+.LASF370:
+	.ascii	"__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 1\000"
 .LASF60:
 	.ascii	"__INT_FAST16_TYPE__ int\000"
-.LASF632:
-	.ascii	"PTRDIFF_MIN (-PTRDIFF_MAX - 1)\000"
+.LASF680:
+	.ascii	"PRIX8 __PRI8(X)\000"
 .LASF61:
 	.ascii	"__INT_FAST32_TYPE__ int\000"
 .LASF288:
@@ -5401,11 +5550,11 @@ usart2_start:
 	.ascii	"SCNdFAST8 __SCN8FAST(d)\000"
 .LASF577:
 	.ascii	"_UINTPTR_T_DECLARED \000"
-.LASF989:
+.LASF993:
 	.ascii	"AFRH\000"
 .LASF314:
 	.ascii	"__ULACCUM_MAX__ 0XFFFFFFFFFFFFFFFFP-32ULK\000"
-.LASF988:
+.LASF992:
 	.ascii	"AFRL\000"
 .LASF273:
 	.ascii	"__ULFRACT_MIN__ 0.0ULR\000"
@@ -5431,10 +5580,13 @@ usart2_start:
 	.ascii	"__SCN32(x) __INT32 __STRINGIFY(x)\000"
 .LASF744:
 	.ascii	"SCNoFAST16 __SCN16FAST(o)\000"
-.LASF993:
+.LASF997:
 	.ascii	"usart2_init\000"
 .LASF345:
 	.ascii	"__UTQ_IBIT__ 0\000"
+.LASF925:
+	.ascii	"GPIO(port) ((struct gpio*)(uintptr_t)(GPIO_BASE_ADD"
+	.ascii	"R + (GPIO_PORT_OFFSET * port)))\000"
 .LASF348:
 	.ascii	"__SA_FBIT__ 15\000"
 .LASF661:
@@ -5459,7 +5611,7 @@ usart2_start:
 	.ascii	"PRIi16 __PRI16(i)\000"
 .LASF390:
 	.ascii	"__ARM_FEATURE_DSP 1\000"
-.LASF936:
+.LASF940:
 	.ascii	"USART_CR1_UE_ENABLE (1 << USART_CR1_UE_BIT)\000"
 .LASF826:
 	.ascii	"__SCNMAX(x) __STRINGIFY(ll ##x)\000"
@@ -5467,7 +5619,7 @@ usart2_start:
 	.ascii	"__QQ_IBIT__ 0\000"
 .LASF764:
 	.ascii	"PRIdLEAST32 __PRI32LEAST(d)\000"
-.LASF983:
+.LASF987:
 	.ascii	"OTYPER\000"
 .LASF812:
 	.ascii	"SCNuLEAST64 __SCN64LEAST(u)\000"
@@ -5495,13 +5647,15 @@ usart2_start:
 	.ascii	"__INTMAX_TYPE__ long long int\000"
 .LASF512:
 	.ascii	"short\000"
-.LASF942:
+.LASF946:
 	.ascii	"USART_BRR_MANTISSA_MASK (0b111111111111)\000"
+.LASF935:
+	.ascii	"USART_SR_RXNE_BIT 5\000"
 .LASF436:
 	.ascii	"__ARM_ARCH_7EM__ 1\000"
 .LASF428:
 	.ascii	"__ARM_FEATURE_FP16_SCALAR_ARITHMETIC\000"
-.LASF964:
+.LASF968:
 	.ascii	"AHB1ENR\000"
 .LASF295:
 	.ascii	"__USACCUM_EPSILON__ 0x1P-8UHK\000"
@@ -5541,7 +5695,7 @@ usart2_start:
 	.ascii	"__DBL_DIG__ 15\000"
 .LASF275:
 	.ascii	"__ULFRACT_EPSILON__ 0x1P-32ULR\000"
-.LASF959:
+.LASF963:
 	.ascii	"AHB2RSTR\000"
 .LASF672:
 	.ascii	"__SCN8(x) __INT8 __STRINGIFY(x)\000"
@@ -5557,8 +5711,8 @@ usart2_start:
 	.ascii	"__int_least32_t_defined 1\000"
 .LASF116:
 	.ascii	"__INT64_C(c) c ## LL\000"
-.LASF700:
-	.ascii	"PRIuFAST8 __PRI8FAST(u)\000"
+.LASF464:
+	.ascii	"_FVWRITE_IN_STREAMIO 1\000"
 .LASF920:
 	.ascii	"GPIO_AFRL_AFRL2_BIT 8\000"
 .LASF190:
@@ -5571,7 +5725,7 @@ usart2_start:
 	.ascii	"unsigned\000"
 .LASF381:
 	.ascii	"__GCC_DESTRUCTIVE_SIZE 64\000"
-.LASF985:
+.LASF989:
 	.ascii	"PUPDR\000"
 .LASF836:
 	.ascii	"SCNuMAX __SCNMAX(u)\000"
@@ -5637,7 +5791,7 @@ usart2_start:
 	.ascii	"__FAST8 \000"
 .LASF497:
 	.ascii	"__XSI_VISIBLE 0\000"
-.LASF986:
+.LASF990:
 	.ascii	"BSRR\000"
 .LASF795:
 	.ascii	"PRIu64 __PRI64(u)\000"
@@ -5669,8 +5823,8 @@ usart2_start:
 	.ascii	"SCNoFAST32 __SCN32FAST(o)\000"
 .LASF394:
 	.ascii	"__ARM_FEATURE_UNALIGNED 1\000"
-.LASF0:
-	.ascii	"__STDC__ 1\000"
+.LASF451:
+	.ascii	"__GXX_TYPEINFO_EQUALITY_INLINE 0\000"
 .LASF187:
 	.ascii	"__LDBL_DECIMAL_DIG__ 17\000"
 .LASF702:
@@ -5709,6 +5863,8 @@ usart2_start:
 	.ascii	"__PRI32(x) __INT32 __STRINGIFY(x)\000"
 .LASF437:
 	.ascii	"__ARM_PCS_VFP 1\000"
+.LASF700:
+	.ascii	"PRIuFAST8 __PRI8FAST(u)\000"
 .LASF283:
 	.ascii	"__ULLFRACT_MIN__ 0.0ULLR\000"
 .LASF652:
@@ -5719,7 +5875,7 @@ usart2_start:
 	.ascii	"__GCC_CONSTRUCTIVE_SIZE 64\000"
 .LASF665:
 	.ascii	"_BSD_WCHAR_T_\000"
-.LASF979:
+.LASF983:
 	.ascii	"PLLI2SCFGR\000"
 .LASF277:
 	.ascii	"__LLFRACT_IBIT__ 0\000"
@@ -5729,7 +5885,7 @@ usart2_start:
 	.ascii	"PRIx32 __PRI32(x)\000"
 .LASF278:
 	.ascii	"__LLFRACT_MIN__ (-0.5LLR-0.5LLR)\000"
-.LASF955:
+.LASF959:
 	.ascii	"uint32_t\000"
 .LASF873:
 	.ascii	"RCC_PLLCFGR_PLLN_BIT 6\000"
@@ -5787,7 +5943,7 @@ usart2_start:
 	.ascii	"PRIXLEAST32 __PRI32LEAST(X)\000"
 .LASF171:
 	.ascii	"__DBL_MAX__ ((double)1.7976931348623157e+308L)\000"
-.LASF948:
+.LASF952:
 	.ascii	"short unsigned int\000"
 .LASF276:
 	.ascii	"__LLFRACT_FBIT__ 63\000"
@@ -5795,7 +5951,7 @@ usart2_start:
 	.ascii	"__FLT32_HAS_INFINITY__ 1\000"
 .LASF416:
 	.ascii	"__thumb__ 1\000"
-.LASF941:
+.LASF945:
 	.ascii	"USART_BRR_MANTISSA_BIT 4\000"
 .LASF421:
 	.ascii	"__ARMEL__ 1\000"
@@ -5805,11 +5961,10 @@ usart2_start:
 	.ascii	"__HQ_FBIT__ 15\000"
 .LASF908:
 	.ascii	"__bool_true_false_are_defined 1\000"
-.LASF935:
+.LASF939:
 	.ascii	"USART_CR1_UE_BIT 13\000"
-.LASF925:
-	.ascii	"GPIO(port) ((struct gpio*)(uintptr_t)(GPIO_BASE_ADD"
-	.ascii	"R + (GPIO_PORT_OFFSET * port)))\000"
+.LASF911:
+	.ascii	"GPIO_MODER_MODER3_BIT 7\000"
 .LASF799:
 	.ascii	"SCNi64 __SCN64(i)\000"
 .LASF861:
@@ -5834,7 +5989,7 @@ usart2_start:
 	.ascii	"SCNuFAST32 __SCN32FAST(u)\000"
 .LASF523:
 	.ascii	"long +4\000"
-.LASF958:
+.LASF962:
 	.ascii	"AHB1RSTR\000"
 .LASF724:
 	.ascii	"SCNx16 __SCN16(x)\000"
@@ -5882,7 +6037,7 @@ usart2_start:
 	.ascii	"__DBL_MIN_10_EXP__ (-307)\000"
 .LASF796:
 	.ascii	"PRIx64 __PRI64(x)\000"
-.LASF937:
+.LASF941:
 	.ascii	"USART_CR1_TE_BIT 3\000"
 .LASF513:
 	.ascii	"__int20\000"
@@ -5892,16 +6047,14 @@ usart2_start:
 	.ascii	"__FLT32_NORM_MAX__ 3.4028234663852886e+38F32\000"
 .LASF905:
 	.ascii	"bool _Bool\000"
-.LASF699:
-	.ascii	"PRIoFAST8 __PRI8FAST(o)\000"
+.LASF632:
+	.ascii	"PTRDIFF_MIN (-PTRDIFF_MAX - 1)\000"
 .LASF92:
 	.ascii	"__UINTMAX_MAX__ 0xffffffffffffffffULL\000"
 .LASF164:
 	.ascii	"__DBL_MANT_DIG__ 53\000"
 .LASF272:
 	.ascii	"__ULFRACT_IBIT__ 0\000"
-.LASF852:
-	.ascii	"RCC ((struct rcc *) RCC_BASE_ADDR)\000"
 .LASF887:
 	.ascii	"RCC_CFGR_HPRE_MASK (0b1111)\000"
 .LASF72:
diff --git a/build/usart.i b/build/usart.i
index b8850b7..8e1f4ff 100644
--- a/build/usart.i
+++ b/build/usart.i
@@ -2201,6 +2201,15 @@ struct usart {
 
 
 
+#define USART_SR_TXE_BIT 7
+#define USART_SR_TXE_TRANSMITTED (1 << USART_SR_TXE_BIT)
+
+
+#define USART_SR_RXNE_BIT 5
+#define USART_SR_RXNE_READY (1 <<USART_SR_RXNE_BIT)
+
+
+
 #define USART_CR1_OVER8_BIT 15
 #define USART_CR1_OVER8_8 (1 << USART_CR1_OVER8_BIT)
 
@@ -2225,6 +2234,8 @@ struct usart {
 
 void usart2_init(void);
 void usart2_start(void);
+
+void usart2_write_byte(char byte);
 # 4 "src/usart.c" 2
 
 void usart2_init(void) {
@@ -2254,9 +2265,9 @@ void usart2_init(void) {
   ((struct usart *) (0x40004400U))->CR1 |= (1 << 15);
 
   ((struct usart *) (0x40004400U))->BRR &= ~((0b111111111111) << 4);
-  ((struct usart *) (0x40004400U))->BRR |= (52 << 4);
+  ((struct usart *) (0x40004400U))->BRR |= (0x34 << 4);
   ((struct usart *) (0x40004400U))->BRR &= ~((0b111) << 0);
-  ((struct usart *) (0x40004400U))->BRR |= (0 << 0);
+  ((struct usart *) (0x40004400U))->BRR |= (0x0 << 0);
 
 
   ((struct usart *) (0x40004400U))->CR1 |= (1 << 3);
@@ -2266,3 +2277,11 @@ void usart2_init(void) {
 void usart2_start(void) {
   ((struct usart *) (0x40004400U))->CR1 |= (1 << 13);
 }
+
+void usart2_write_byte(char c) {
+
+  ((struct usart *) (0x40004400U))->DR = c;
+
+
+  while ((((struct usart *) (0x40004400U))->SR & (1 << 7)) == 0);
+}
diff --git a/build/usart.o b/build/usart.o
index be35d2b..d9bad2b 100644
Binary files a/build/usart.o and b/build/usart.o differ
diff --git a/src/main.c b/src/main.c
index ec063ee..329baf3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -80,7 +80,7 @@ int main(void) {
   (void) usart2_init();
 
   (void) tim4_start();
-  (void) tim4_start();
+  (void) usart2_start();
 
   uint16_t led = PIN('C', 13);           // Blue LED
   RCC->AHB1ENR |= BIT(PINPORT(led));     // Enable GPIO clock for LED
@@ -93,8 +93,7 @@ int main(void) {
 	 led_on = !led_on;
 	 gpio_write(led, led_on);
 
-while ((USART2->ISR & USART_ISR_TC) != USART_ISR_TC);
-				USART2->TDR = '#';
+	 usart2_write_byte('a');
 
 	 counter = TIM4->CNT;
 	}
diff --git a/src/usart.c b/src/usart.c
index ba79f7f..846bc5a 100644
--- a/src/usart.c
+++ b/src/usart.c
@@ -49,9 +49,9 @@ void usart2_init(void) {
   USART2->CR1 |= USART_CR1_OVER8_8;
 
   USART2->BRR &= ~(USART_BRR_MANTISSA_MASK << USART_BRR_MANTISSA_BIT);
-  USART2->BRR |= (52 << USART_BRR_MANTISSA_BIT);
+  USART2->BRR |= (0x34 << USART_BRR_MANTISSA_BIT);
   USART2->BRR &= ~(USART_BRR_FRACTION_MASK << USART_BRR_FRACTION_BIT);
-  USART2->BRR |= (0 << USART_BRR_FRACTION_BIT);
+  USART2->BRR |= (0x0 << USART_BRR_FRACTION_BIT);
 
   // Enable transmitter and receiver
   USART2->CR1 |= USART_CR1_TE_ENABLE;
@@ -61,3 +61,11 @@ void usart2_init(void) {
 void usart2_start(void) {
   USART2->CR1 |= USART_CR1_UE_ENABLE;
 }
+
+void usart2_write_byte(char c) {
+  // Send data
+  USART2->DR = c;
+
+  // Wait indefinitely for transmission to be ready for data
+  while ((USART2->SR & USART_SR_TXE_TRANSMITTED) == 0);
+}
diff --git a/src/usart.h b/src/usart.h
index 27f3408..873df4e 100644
--- a/src/usart.h
+++ b/src/usart.h
@@ -16,6 +16,15 @@ struct usart {
 #define USART2_BASE_ADDR (0x40004400U)
 #define USART2 ((struct usart *) USART2_BASE_ADDR)
 
+// SR Register
+// Transmission data register empty
+#define USART_SR_TXE_BIT 7
+#define USART_SR_TXE_TRANSMITTED (1 << USART_SR_TXE_BIT)
+
+// Read data register not empty
+#define USART_SR_RXNE_BIT 5
+#define USART_SR_RXNE_READY (1 <<USART_SR_RXNE_BIT)
+
 // CR Register
 // Oversampling mode
 #define USART_CR1_OVER8_BIT 15
@@ -43,4 +52,6 @@ struct usart {
 void usart2_init(void);
 void usart2_start(void);
 
+void usart2_write_byte(char byte);
+
 #endif