wip

2024-08-11 17:37:17 +02:00
parent a3c1de878a
commit 2fc8ee4f92
23 changed files with 9613 additions and 839 deletions
--- a/build/final.elf
+++ b/build/final.elf
--- a/build/final.elf.map
+++ b/build/final.elf.map
@@ -36,6 +36,7 @@ Discarded input sections
 .group         0x00000000        0xc build/main.o
 .group         0x00000000        0xc build/main.o
 .group         0x00000000        0xc build/main.o
+ .group         0x00000000        0xc build/main.o
 .text          0x00000000        0x0 build/main.o
 .data          0x00000000        0x0 build/main.o
 .bss           0x00000000        0x0 build/main.o
@@ -52,7 +53,7 @@ Discarded input sections
 .debug_macro   0x00000000       0x89 build/main.o
 .debug_macro   0x00000000      0x4cc build/main.o
 .debug_macro   0x00000000       0x22 build/main.o
- .debug_macro   0x00000000       0x34 build/main.o
+ .debug_macro   0x00000000       0x88 build/main.o
 .group         0x00000000        0xc build/startup.o
 .group         0x00000000        0xc build/startup.o
 .group         0x00000000        0xc build/startup.o
@@ -96,6 +97,42 @@ Discarded input sections
 .debug_macro   0x00000000       0x89 build/timer.o
 .debug_macro   0x00000000      0x4cc build/timer.o
 .debug_macro   0x00000000       0x22 build/timer.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .group         0x00000000        0xc build/usart.o
+ .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
+ .debug_macro   0x00000000       0x5c build/usart.o
+ .debug_macro   0x00000000       0x3c build/usart.o
+ .debug_macro   0x00000000      0x103 build/usart.o
+ .debug_macro   0x00000000       0x3a build/usart.o
+ .debug_macro   0x00000000       0x57 build/usart.o
+ .debug_macro   0x00000000       0x6a build/usart.o
+ .debug_macro   0x00000000      0x1df build/usart.o
+ .debug_macro   0x00000000       0x89 build/usart.o
+ .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

 Memory Configuration

@@ -112,6 +149,7 @@ LOAD build/gpio.o
 LOAD build/main.o
 LOAD build/startup.o
 LOAD build/timer.o
+LOAD build/usart.o
                0x20020000                        stack_start = (ORIGIN (sram) + LENGTH (sram))

 .isr_vector     0x08000000      0x198
@@ -121,7 +159,7 @@ LOAD build/timer.o
                0x08000000                interrupt_vector_table
                0x08000198                        . = ALIGN (0x4)

-.text           0x08000198      0x358
+.text           0x08000198      0x458
                0x08000198                        . = ALIGN (0x4)
 *(.text)
 *(.text.*)
@@ -134,113 +172,116 @@ LOAD build/timer.o
 *fill*         0x08000246        0x2 
 .text.system_clock_init
                0x08000248      0x144 build/main.o
- .text.main     0x0800038c       0x88 build/main.o
+ .text.main     0x0800038c       0x90 build/main.o
                0x0800038c                main
 .text.init_memory
-                0x08000414       0x64 build/startup.o
-                0x08000414                init_memory
- .text.reset    0x08000478       0x10 build/startup.o
-                0x08000478                reset
+                0x0800041c       0x64 build/startup.o
+                0x0800041c                init_memory
+ .text.reset    0x08000480       0x10 build/startup.o
+                0x08000480                reset
 .text.default_handler
-                0x08000488        0x8 build/startup.o
-                0x08000488                exti0
-                0x08000488                debug_monitor
-                0x08000488                rcc
-                0x08000488                x
-                0x08000488                sdio
-                0x08000488                usage_fault
-                0x08000488                tim1_up_tim10
-                0x08000488                usart1
-                0x08000488                i2c3_er
-                0x08000488                spi2
-                0x08000488                dma1_stream1
-                0x08000488                bus_fault
-                0x08000488                spi5
-                0x08000488                exti3
-                0x08000488                dma2_stream5
-                0x08000488                tim2
-                0x08000488                dma1_stream6
-                0x08000488                default_handler
-                0x08000488                i2c1_er
-                0x08000488                hard_fault
-                0x08000488                usart6
-                0x08000488                exti15_10
-                0x08000488                usart2
-                0x08000488                pend_sv
-                0x08000488                i2c1_ev
-                0x08000488                wwdg
-                0x08000488                adc
-                0x08000488                rtc_alarm
-                0x08000488                spi3
-                0x08000488                exti1
-                0x08000488                mem_manage
-                0x08000488                dma2_stream1
-                0x08000488                dma1_stream2
-                0x08000488                dma2_stream3
-                0x08000488                sv_call
-                0x08000488                tim3
-                0x08000488                otg_fs
-                0x08000488                dma1_stream5
-                0x08000488                dma2_stream6
-                0x08000488                flash
-                0x08000488                tamp_stamp
-                0x08000488                i2c3_ev
-                0x08000488                rtc_wkup
-                0x08000488                dma2_stream0
-                0x08000488                pvd
-                0x08000488                fpu
-                0x08000488                exti4
-                0x08000488                exti2
-                0x08000488                spi1
-                0x08000488                dma1_stream0
-                0x08000488                tim1_brk_tim9
-                0x08000488                i2c2_ev
-                0x08000488                otg_fs_wkup
-                0x08000488                spi4
-                0x08000488                dma2_stream2
-                0x08000488                tim1_cc
-                0x08000488                tim1_trg_com_tim11
-                0x08000488                exti9_5
-                0x08000488                dma1_stream3
-                0x08000488                dma2_stream4
-                0x08000488                i2c2_er
-                0x08000488                dma2_stream7
-                0x08000488                dma1_stream7
-                0x08000488                nmi
-                0x08000488                systick
-                0x08000488                tim4
-                0x08000488                tim5
-                0x08000488                dma1_stream4
+                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
 .text.tim4_init
-                0x08000490       0x40 build/timer.o
-                0x08000490                tim4_init
+                0x08000498       0x40 build/timer.o
+                0x08000498                tim4_init
 .text.tim4_start
-                0x080004d0       0x20 build/timer.o
-                0x080004d0                tim4_start
+                0x080004d8       0x20 build/timer.o
+                0x080004d8                tim4_start
+ .text.usart2_init
+                0x080004f8       0xf8 build/usart.o
+                0x080004f8                usart2_init
 *(.rodata)
 *(.rodata.*)
-                0x080004f0                        . = ALIGN (0x4)
-                0x080004f0                        _data_addr = LOADADDR (.data)
+                0x080005f0                        . = ALIGN (0x4)
+                0x080005f0                        _data_addr = LOADADDR (.data)

-.glue_7         0x080004f0        0x0
- .glue_7        0x080004f0        0x0 linker stubs
+.glue_7         0x080005f0        0x0
+ .glue_7        0x080005f0        0x0 linker stubs

-.glue_7t        0x080004f0        0x0
- .glue_7t       0x080004f0        0x0 linker stubs
+.glue_7t        0x080005f0        0x0
+ .glue_7t       0x080005f0        0x0 linker stubs

-.vfp11_veneer   0x080004f0        0x0
- .vfp11_veneer  0x080004f0        0x0 linker stubs
+.vfp11_veneer   0x080005f0        0x0
+ .vfp11_veneer  0x080005f0        0x0 linker stubs

-.v4_bx          0x080004f0        0x0
- .v4_bx         0x080004f0        0x0 linker stubs
+.v4_bx          0x080005f0        0x0
+ .v4_bx         0x080005f0        0x0 linker stubs

-.iplt           0x080004f0        0x0
- .iplt          0x080004f0        0x0 build/main.o
+.iplt           0x080005f0        0x0
+ .iplt          0x080005f0        0x0 build/main.o

-.rel.dyn        0x080004f0        0x0
- .rel.iplt      0x080004f0        0x0 build/main.o
+.rel.dyn        0x080005f0        0x0
+ .rel.iplt      0x080005f0        0x0 build/main.o

-.data           0x20000000        0x0 load address 0x080004f0
+.data           0x20000000        0x0 load address 0x080005f0
                0x20000000                        . = ALIGN (0x4)
                0x20000000                        _data_start = .
 *(.data)
@@ -248,10 +289,10 @@ LOAD build/timer.o
                0x20000000                        . = ALIGN (0x4)
                0x20000000                        _data_end = .

-.igot.plt       0x20000000        0x0 load address 0x080004f0
+.igot.plt       0x20000000        0x0 load address 0x080005f0
 .igot.plt      0x20000000        0x0 build/main.o

-.bss            0x20000000        0x0 load address 0x080004f0
+.bss            0x20000000        0x0 load address 0x080005f0
                0x20000000                        . = ALIGN (0x4)
                0x20000000                        _bss_start = .
 *(.bss)
@@ -261,19 +302,21 @@ LOAD build/timer.o
 OUTPUT(build/final.elf elf32-littlearm)
 LOAD linker stubs

-.debug_info     0x00000000      0xb25
- .debug_info    0x00000000      0x21a build/gpio.o
- .debug_info    0x0000021a      0x44e build/main.o
- .debug_info    0x00000668      0x188 build/startup.o
- .debug_info    0x000007f0      0x335 build/timer.o
+.debug_info     0x00000000      0xe1d
+ .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_abbrev   0x00000000      0x44b
- .debug_abbrev  0x00000000      0x12b build/gpio.o
- .debug_abbrev  0x0000012b      0x144 build/main.o
- .debug_abbrev  0x0000026f      0x127 build/startup.o
- .debug_abbrev  0x00000396       0xb5 build/timer.o
+.debug_abbrev   0x00000000      0x4ee
+ .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_aranges  0x00000000       0xa8
+.debug_aranges  0x00000000       0xd0
 .debug_aranges
                0x00000000       0x28 build/gpio.o
 .debug_aranges
@@ -282,9 +325,11 @@ LOAD linker stubs
                0x00000050       0x30 build/startup.o
 .debug_aranges
                0x00000080       0x28 build/timer.o
+ .debug_aranges
+                0x000000a8       0x28 build/usart.o

 .debug_rnglists
-                0x00000000       0x6c
+                0x00000000       0x86
 .debug_rnglists
                0x00000000       0x19 build/gpio.o
 .debug_rnglists
@@ -293,8 +338,10 @@ LOAD linker stubs
                0x00000034       0x1f build/startup.o
 .debug_rnglists
                0x00000053       0x19 build/timer.o
+ .debug_rnglists
+                0x0000006c       0x1a build/usart.o

-.debug_macro    0x00000000     0x3ba0
+.debug_macro    0x00000000     0x4885
 .debug_macro   0x00000000      0xb56 build/gpio.o
 .debug_macro   0x00000b56       0x22 build/gpio.o
 .debug_macro   0x00000b78       0x75 build/gpio.o
@@ -309,33 +356,39 @@ LOAD linker stubs
 .debug_macro   0x0000108c       0x89 build/gpio.o
 .debug_macro   0x00001115      0x4cc build/gpio.o
 .debug_macro   0x000015e1       0x22 build/gpio.o
- .debug_macro   0x00001603       0x34 build/gpio.o
- .debug_macro   0x00001637      0xb80 build/main.o
- .debug_macro   0x000021b7      0x12a build/main.o
- .debug_macro   0x000022e1       0x46 build/main.o
- .debug_macro   0x00002327       0x2e build/main.o
- .debug_macro   0x00002355       0x22 build/main.o
- .debug_macro   0x00002377      0xb02 build/startup.o
- .debug_macro   0x00002e79       0x56 build/startup.o
- .debug_macro   0x00002ecf       0x51 build/startup.o
- .debug_macro   0x00002f20      0xb5c build/timer.o
- .debug_macro   0x00003a7c      0x124 build/timer.o
+ .debug_macro   0x00001603       0x88 build/gpio.o
+ .debug_macro   0x0000168b      0xb89 build/main.o
+ .debug_macro   0x00002214      0x144 build/main.o
+ .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_line     0x00000000      0x4b9
+.debug_line     0x00000000      0x605
 .debug_line    0x00000000      0x116 build/gpio.o
- .debug_line    0x00000116      0x1da build/main.o
- .debug_line    0x000002f0       0xea build/startup.o
- .debug_line    0x000003da       0xdf build/timer.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_str      0x00000000     0x5eb8
- .debug_str     0x00000000     0x5372 build/gpio.o
-                               0x551a (size before relaxing)
- .debug_str     0x00005372      0xab2 build/main.o
-                               0x5f7c (size before relaxing)
- .debug_str     0x00005e24       0x88 build/startup.o
+.debug_str      0x00000000     0x62fd
+ .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
                               0x3cdf (size before relaxing)
- .debug_str     0x00005eac        0xc build/timer.o
-                               0x5b1a (size before relaxing)
+ .debug_str     0x000062cd        0xc build/timer.o
+                               0x5bc5 (size before relaxing)
+ .debug_str     0x000062d9       0x24 build/usart.o
+                               0x5ffb (size before relaxing)

 .comment        0x00000000       0x45
 .comment       0x00000000       0x45 build/gpio.o
@@ -343,6 +396,7 @@ LOAD linker stubs
 .comment       0x00000045       0x46 build/main.o
 .comment       0x00000045       0x46 build/startup.o
 .comment       0x00000045       0x46 build/timer.o
+ .comment       0x00000045       0x46 build/usart.o

 .ARM.attributes
                0x00000000       0x34
@@ -354,24 +408,30 @@ LOAD linker stubs
                0x00000068       0x34 build/startup.o
 .ARM.attributes
                0x0000009c       0x34 build/timer.o
+ .ARM.attributes
+                0x000000d0       0x34 build/usart.o

 .debug_line_str
-                0x00000000      0x283
+                0x00000000      0x293
 .debug_line_str
                0x00000000      0x24e build/gpio.o
                                0x260 (size before relaxing)
 .debug_line_str
-                0x0000024e       0x23 build/main.o
-                                0x27c (size before relaxing)
+                0x0000024e       0x2b build/main.o
+                                0x284 (size before relaxing)
 .debug_line_str
-                0x00000271        0xa build/startup.o
+                0x00000279        0xa build/startup.o
                                0x21b (size before relaxing)
 .debug_line_str
-                0x0000027b        0x8 build/timer.o
+                0x00000283        0x8 build/timer.o
                                0x25e (size before relaxing)
+ .debug_line_str
+                0x0000028b        0x8 build/usart.o
+                                0x26f (size before relaxing)

-.debug_frame    0x00000000      0x16c
+.debug_frame    0x00000000      0x1bc
 .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
--- a/build/gpio.S
+++ b/build/gpio.S
@@ -182,16 +182,16 @@ gpio_write:
 	.file 4 "src/gpio.h"
 	.section	.debug_info,"",%progbits
 .Ldebug_info0:
-	.4byte	0x216
+	.4byte	0x201
 	.2byte	0x5
 	.byte	0x1
 	.byte	0x4
 	.4byte	.Ldebug_abbrev0
-	.uleb128 0x9
-	.4byte	.LASF894
+	.uleb128 0x8
+	.4byte	.LASF908
 	.byte	0x1d
-	.4byte	.LASF895
-	.4byte	.LASF896
+	.4byte	.LASF909
+	.4byte	.LASF910
 	.4byte	.LLRL0
 	.4byte	0
 	.4byte	.Ldebug_line0
@@ -199,17 +199,17 @@ gpio_write:
 	.uleb128 0x1
 	.byte	0x1
 	.byte	0x6
-	.4byte	.LASF863
+	.4byte	.LASF877
 	.uleb128 0x1
 	.byte	0x1
 	.byte	0x8
-	.4byte	.LASF864
+	.4byte	.LASF878
 	.uleb128 0x1
 	.byte	0x2
 	.byte	0x5
-	.4byte	.LASF865
+	.4byte	.LASF879
 	.uleb128 0x3
-	.4byte	.LASF868
+	.4byte	.LASF882
 	.byte	0x2
 	.byte	0x39
 	.byte	0x1c
@@ -217,13 +217,13 @@ gpio_write:
 	.uleb128 0x1
 	.byte	0x2
 	.byte	0x7
-	.4byte	.LASF866
+	.4byte	.LASF880
 	.uleb128 0x1
 	.byte	0x4
 	.byte	0x5
-	.4byte	.LASF867
+	.4byte	.LASF881
 	.uleb128 0x3
-	.4byte	.LASF869
+	.4byte	.LASF883
 	.byte	0x2
 	.byte	0x4f
 	.byte	0x1b
@@ -231,21 +231,21 @@ gpio_write:
 	.uleb128 0x1
 	.byte	0x4
 	.byte	0x7
-	.4byte	.LASF870
+	.4byte	.LASF884
 	.uleb128 0x1
 	.byte	0x8
 	.byte	0x5
-	.4byte	.LASF871
+	.4byte	.LASF885
 	.uleb128 0x1
 	.byte	0x8
 	.byte	0x7
-	.4byte	.LASF872
-	.uleb128 0xa
+	.4byte	.LASF886
+	.uleb128 0x9
 	.byte	0x4
 	.byte	0x5
 	.ascii	"int\000"
 	.uleb128 0x3
-	.4byte	.LASF873
+	.4byte	.LASF887
 	.byte	0x2
 	.byte	0xe8
 	.byte	0x16
@@ -253,123 +253,114 @@ gpio_write:
 	.uleb128 0x1
 	.byte	0x4
 	.byte	0x7
-	.4byte	.LASF874
+	.4byte	.LASF888
 	.uleb128 0x3
-	.4byte	.LASF875
+	.4byte	.LASF889
 	.byte	0x3
 	.byte	0x24
 	.byte	0x14
 	.4byte	0x3f
 	.uleb128 0x3
-	.4byte	.LASF876
+	.4byte	.LASF890
 	.byte	0x3
 	.byte	0x30
 	.byte	0x14
 	.4byte	0x59
-	.uleb128 0x6
+	.uleb128 0xa
 	.4byte	0xa0
 	.uleb128 0x3
-	.4byte	.LASF877
+	.4byte	.LASF891
 	.byte	0x3
 	.byte	0x52
 	.byte	0x15
 	.4byte	0x81
 	.uleb128 0xb
-	.4byte	.LASF893
-	.byte	0x30
+	.4byte	.LASF907
+	.byte	0x28
 	.byte	0x4
 	.byte	0x7
 	.byte	0x8
 	.4byte	0x139
 	.uleb128 0x2
-	.4byte	.LASF878
+	.4byte	.LASF892
 	.byte	0x8
 	.4byte	0xac
 	.byte	0
 	.uleb128 0x2
-	.4byte	.LASF879
+	.4byte	.LASF893
 	.byte	0x9
 	.4byte	0xac
 	.byte	0x4
 	.uleb128 0x2
-	.4byte	.LASF880
+	.4byte	.LASF894
 	.byte	0xa
 	.4byte	0xac
 	.byte	0x8
 	.uleb128 0x2
-	.4byte	.LASF881
+	.4byte	.LASF895
 	.byte	0xb
 	.4byte	0xac
 	.byte	0xc
-	.uleb128 0x7
+	.uleb128 0x6
 	.ascii	"IDR\000"
 	.byte	0xc
 	.4byte	0xac
 	.byte	0x10
-	.uleb128 0x7
+	.uleb128 0x6
 	.ascii	"ODR\000"
 	.byte	0xd
 	.4byte	0xac
 	.byte	0x14
 	.uleb128 0x2
-	.4byte	.LASF882
+	.4byte	.LASF896
 	.byte	0xe
 	.4byte	0xac
 	.byte	0x18
 	.uleb128 0x2
-	.4byte	.LASF883
+	.4byte	.LASF897
 	.byte	0xf
 	.4byte	0xac
 	.byte	0x1c
 	.uleb128 0x2
-	.4byte	.LASF884
+	.4byte	.LASF898
 	.byte	0x10
-	.4byte	0x149
+	.4byte	0xac
 	.byte	0x20
 	.uleb128 0x2
-	.4byte	.LASF885
+	.4byte	.LASF899
 	.byte	0x11
-	.4byte	0x149
-	.byte	0x28
+	.4byte	0xac
+	.byte	0x24
 	.byte	0
 	.uleb128 0xc
-	.4byte	0xac
-	.4byte	0x149
-	.uleb128 0xd
-	.4byte	0x8d
-	.byte	0x1
-	.byte	0
-	.uleb128 0x6
-	.4byte	0x139
-	.uleb128 0xe
 	.byte	0x7
 	.byte	0x1
 	.4byte	0x31
 	.byte	0x4
-	.byte	0x20
+	.byte	0x3a
 	.byte	0xe
-	.4byte	0x175
+	.4byte	0x160
 	.uleb128 0x4
-	.4byte	.LASF886
+	.4byte	.LASF900
 	.byte	0
 	.uleb128 0x4
-	.4byte	.LASF887
+	.4byte	.LASF901
 	.byte	0x1
 	.uleb128 0x4
-	.4byte	.LASF888
+	.4byte	.LASF902
 	.byte	0x2
 	.uleb128 0x4
-	.4byte	.LASF889
+	.4byte	.LASF903
 	.byte	0x3
 	.byte	0
 	.uleb128 0x3
-	.4byte	.LASF890
+	.4byte	.LASF904
 	.byte	0x4
-	.byte	0x25
+	.byte	0x3f
 	.byte	0x3
-	.4byte	0x14e
-	.uleb128 0xf
-	.4byte	.LASF897
+	.4byte	0x139
+	.uleb128 0xd
+	.4byte	.LASF911
 	.byte	0x1
 	.byte	0xd
 	.byte	0x6
@@ -377,7 +368,7 @@ gpio_write:
 	.4byte	.LFE1-.LFB1
 	.uleb128 0x1
 	.byte	0x9c
-	.4byte	0x1c1
+	.4byte	0x1ac
 	.uleb128 0x5
 	.ascii	"pin\000"
 	.byte	0xd
@@ -390,14 +381,14 @@ gpio_write:
 	.ascii	"val\000"
 	.byte	0xd
 	.byte	0x23
-	.4byte	0x1c1
+	.4byte	0x1ac
 	.uleb128 0x2
 	.byte	0x91
 	.sleb128 -19
-	.uleb128 0x8
-	.4byte	.LASF893
+	.uleb128 0x7
+	.4byte	.LASF907
 	.byte	0xe
-	.4byte	0x1c8
+	.4byte	0x1b3
 	.uleb128 0x2
 	.byte	0x91
 	.sleb128 -12
@@ -405,12 +396,12 @@ gpio_write:
 	.uleb128 0x1
 	.byte	0x1
 	.byte	0x2
-	.4byte	.LASF891
-	.uleb128 0x10
+	.4byte	.LASF905
+	.uleb128 0xe
 	.byte	0x4
 	.4byte	0xbd
-	.uleb128 0x11
-	.4byte	.LASF898
+	.uleb128 0xf
+	.4byte	.LASF912
 	.byte	0x1
 	.byte	0x6
 	.byte	0x6
@@ -426,23 +417,23 @@ gpio_write:
 	.uleb128 0x2
 	.byte	0x91
 	.sleb128 -18
-	.uleb128 0x12
-	.4byte	.LASF892
+	.uleb128 0x10
+	.4byte	.LASF906
 	.byte	0x1
 	.byte	0x6
 	.byte	0x2c
-	.4byte	0x175
+	.4byte	0x160
 	.uleb128 0x2
 	.byte	0x91
 	.sleb128 -19
-	.uleb128 0x8
-	.4byte	.LASF893
+	.uleb128 0x7
+	.4byte	.LASF907
 	.byte	0x7
-	.4byte	0x1c8
+	.4byte	0x1b3
 	.uleb128 0x2
 	.byte	0x91
 	.sleb128 -12
-	.uleb128 0x13
+	.uleb128 0x11
 	.ascii	"pn\000"
 	.byte	0x1
 	.byte	0x8
@@ -528,13 +519,6 @@ gpio_write:
 	.byte	0
 	.byte	0
 	.uleb128 0x6
-	.uleb128 0x35
-	.byte	0
-	.uleb128 0x49
-	.uleb128 0x13
-	.byte	0
-	.byte	0
-	.uleb128 0x7
 	.uleb128 0xd
 	.byte	0
 	.uleb128 0x3
@@ -553,7 +537,7 @@ gpio_write:
 	.uleb128 0xb
 	.byte	0
 	.byte	0
-	.uleb128 0x8
+	.uleb128 0x7
 	.uleb128 0x34
 	.byte	0
 	.uleb128 0x3
@@ -572,7 +556,7 @@ gpio_write:
 	.uleb128 0x18
 	.byte	0
 	.byte	0
-	.uleb128 0x9
+	.uleb128 0x8
 	.uleb128 0x11
 	.byte	0x1
 	.uleb128 0x25
@@ -593,7 +577,7 @@ gpio_write:
 	.uleb128 0x17
 	.byte	0
 	.byte	0
-	.uleb128 0xa
+	.uleb128 0x9
 	.uleb128 0x24
 	.byte	0
 	.uleb128 0xb
@@ -604,6 +588,13 @@ gpio_write:
 	.uleb128 0x8
 	.byte	0
 	.byte	0
+	.uleb128 0xa
+	.uleb128 0x35
+	.byte	0
+	.uleb128 0x49
+	.uleb128 0x13
+	.byte	0
+	.byte	0
 	.uleb128 0xb
 	.uleb128 0x13
 	.byte	0x1
@@ -622,24 +613,6 @@ gpio_write:
 	.byte	0
 	.byte	0
 	.uleb128 0xc
-	.uleb128 0x1
-	.byte	0x1
-	.uleb128 0x49
-	.uleb128 0x13
-	.uleb128 0x1
-	.uleb128 0x13
-	.byte	0
-	.byte	0
-	.uleb128 0xd
-	.uleb128 0x21
-	.byte	0
-	.uleb128 0x49
-	.uleb128 0x13
-	.uleb128 0x2f
-	.uleb128 0xb
-	.byte	0
-	.byte	0
-	.uleb128 0xe
 	.uleb128 0x4
 	.byte	0x1
 	.uleb128 0x3e
@@ -658,7 +631,7 @@ gpio_write:
 	.uleb128 0x13
 	.byte	0
 	.byte	0
-	.uleb128 0xf
+	.uleb128 0xd
 	.uleb128 0x2e
 	.byte	0x1
 	.uleb128 0x3f
@@ -685,7 +658,7 @@ gpio_write:
 	.uleb128 0x13
 	.byte	0
 	.byte	0
-	.uleb128 0x10
+	.uleb128 0xe
 	.uleb128 0xf
 	.byte	0
 	.uleb128 0xb
@@ -694,7 +667,7 @@ gpio_write:
 	.uleb128 0x13
 	.byte	0
 	.byte	0
-	.uleb128 0x11
+	.uleb128 0xf
 	.uleb128 0x2e
 	.byte	0x1
 	.uleb128 0x3f
@@ -719,7 +692,7 @@ gpio_write:
 	.uleb128 0x19
 	.byte	0
 	.byte	0
-	.uleb128 0x12
+	.uleb128 0x10
 	.uleb128 0x5
 	.byte	0
 	.uleb128 0x3
@@ -736,7 +709,7 @@ gpio_write:
 	.uleb128 0x18
 	.byte	0
 	.byte	0
-	.uleb128 0x13
+	.uleb128 0x11
 	.uleb128 0x34
 	.byte	0
 	.uleb128 0x3
@@ -3552,7 +3525,7 @@ gpio_write:
 	.uleb128 0x32
 	.4byte	.LASF854
 	.byte	0
-	.section	.debug_macro,"G",%progbits,wm4.gpio.h.2.d78c96d470f4347bf35ed0e3d72ef81e,comdat
+	.section	.debug_macro,"G",%progbits,wm4.gpio.h.2.618f9f202e3921ef232a09b28d15fb8b,comdat
 .Ldebug_macro15:
 	.2byte	0x5
 	.byte	0
@@ -3566,10 +3539,10 @@ gpio_write:
 	.uleb128 0x15
 	.4byte	.LASF857
 	.byte	0x5
-	.uleb128 0x16
+	.uleb128 0x18
 	.4byte	.LASF858
 	.byte	0x5
-	.uleb128 0x18
+	.uleb128 0x19
 	.4byte	.LASF859
 	.byte	0x5
 	.uleb128 0x1a
@@ -3578,8 +3551,50 @@ gpio_write:
 	.uleb128 0x1c
 	.4byte	.LASF861
 	.byte	0x5
-	.uleb128 0x1e
+	.uleb128 0x1d
 	.4byte	.LASF862
+	.byte	0x5
+	.uleb128 0x1e
+	.4byte	.LASF863
+	.byte	0x5
+	.uleb128 0x21
+	.4byte	.LASF864
+	.byte	0x5
+	.uleb128 0x22
+	.4byte	.LASF865
+	.byte	0x5
+	.uleb128 0x23
+	.4byte	.LASF866
+	.byte	0x5
+	.uleb128 0x25
+	.4byte	.LASF867
+	.byte	0x5
+	.uleb128 0x26
+	.4byte	.LASF868
+	.byte	0x5
+	.uleb128 0x27
+	.4byte	.LASF869
+	.byte	0x5
+	.uleb128 0x2e
+	.4byte	.LASF870
+	.byte	0x5
+	.uleb128 0x2f
+	.4byte	.LASF871
+	.byte	0x5
+	.uleb128 0x30
+	.4byte	.LASF872
+	.byte	0x5
+	.uleb128 0x32
+	.4byte	.LASF873
+	.byte	0x5
+	.uleb128 0x34
+	.4byte	.LASF874
+	.byte	0x5
+	.uleb128 0x36
+	.4byte	.LASF875
+	.byte	0x5
+	.uleb128 0x38
+	.4byte	.LASF876
 	.byte	0
 	.section	.debug_line,"",%progbits
 .Ldebug_line0:
@@ -3624,7 +3639,7 @@ gpio_write:
 	.ascii	"__PTRDIFF_MAX__ 0x7fffffff\000"
 .LASF541:
 	.ascii	"_LONG_DOUBLE long double\000"
-.LASF893:
+.LASF907:
 	.ascii	"gpio\000"
 .LASF591:
 	.ascii	"INT_LEAST8_MIN (-__INT_LEAST8_MAX__ - 1)\000"
@@ -3632,7 +3647,7 @@ gpio_write:
 	.ascii	"_UINT32_T_DECLARED \000"
 .LASF90:
 	.ascii	"__INTMAX_MAX__ 0x7fffffffffffffffLL\000"
-.LASF888:
+.LASF902:
 	.ascii	"GPIO_MODE_AF\000"
 .LASF335:
 	.ascii	"__TQ_IBIT__ 0\000"
@@ -3696,6 +3711,8 @@ gpio_write:
 	.ascii	"PRIXFAST32 __PRI32FAST(X)\000"
 .LASF525:
 	.ascii	"__INT8 \"hh\"\000"
+.LASF860:
+	.ascii	"GPIO_MODER_MODER3_AF (0b10)\000"
 .LASF47:
 	.ascii	"__UINT8_TYPE__ unsigned char\000"
 .LASF368:
@@ -3704,6 +3721,8 @@ gpio_write:
 	.ascii	"INT_LEAST16_MAX (__INT_LEAST16_MAX__)\000"
 .LASF703:
 	.ascii	"SCNiFAST8 __SCN8FAST(i)\000"
+.LASF856:
+	.ascii	"GPIOA_BASE_ADDR (0x40020000U)\000"
 .LASF120:
 	.ascii	"__UINT_LEAST16_MAX__ 0xffff\000"
 .LASF616:
@@ -3746,11 +3765,13 @@ gpio_write:
 	.ascii	"__need_wchar_t\000"
 .LASF199:
 	.ascii	"__FLT32_MIN_EXP__ (-125)\000"
-.LASF894:
+.LASF908:
 	.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"
 	.ascii	"ections -fno-builtin -fno-common\000"
+.LASF864:
+	.ascii	"GPIO_AFRL_AFRL3_BIT 12\000"
 .LASF595:
 	.ascii	"INT16_MAX (__INT16_MAX__)\000"
 .LASF502:
@@ -3831,7 +3852,7 @@ gpio_write:
 	.ascii	"__INT64 \"ll\"\000"
 .LASF138:
 	.ascii	"__INTPTR_MAX__ 0x7fffffff\000"
-.LASF858:
+.LASF872:
 	.ascii	"GPIO(port) ((struct gpio*)(uintptr_t)(GPIO_BASE_ADD"
 	.ascii	"R + (GPIO_PORT_OFFSET * port)))\000"
 .LASF499:
@@ -3867,7 +3888,7 @@ gpio_write:
 	.ascii	"PRId64 __PRI64(d)\000"
 .LASF302:
 	.ascii	"__UACCUM_IBIT__ 16\000"
-.LASF867:
+.LASF881:
 	.ascii	"long int\000"
 .LASF818:
 	.ascii	"PRIXFAST64 __PRI64FAST(X)\000"
@@ -3903,6 +3924,8 @@ gpio_write:
 	.ascii	"__GCC_ATOMIC_BOOL_LOCK_FREE 2\000"
 .LASF554:
 	.ascii	"___int64_t_defined 1\000"
+.LASF863:
+	.ascii	"GPIO_MODER_MODER2_AF (0b10)\000"
 .LASF432:
 	.ascii	"__ARM_NEON__\000"
 .LASF587:
@@ -3963,7 +3986,7 @@ gpio_write:
 	.ascii	"PRIoLEAST16 __PRI16LEAST(o)\000"
 .LASF458:
 	.ascii	"__NEWLIB__ 4\000"
-.LASF886:
+.LASF900:
 	.ascii	"GPIO_MODE_INPUT\000"
 .LASF720:
 	.ascii	"SCNi16 __SCN16(i)\000"
@@ -3973,7 +3996,7 @@ gpio_write:
 	.ascii	"__FLT_DECIMAL_DIG__ 9\000"
 .LASF562:
 	.ascii	"_UINT8_T_DECLARED \000"
-.LASF863:
+.LASF877:
 	.ascii	"signed char\000"
 .LASF805:
 	.ascii	"PRIuLEAST64 __PRI64LEAST(u)\000"
@@ -3985,7 +4008,7 @@ gpio_write:
 	.ascii	"__ARM_FEATURE_FMA 1\000"
 .LASF364:
 	.ascii	"__GNUC_STDC_INLINE__ 1\000"
-.LASF890:
+.LASF904:
 	.ascii	"GPIO_MODE\000"
 .LASF256:
 	.ascii	"__FRACT_FBIT__ 15\000"
@@ -4007,9 +4030,11 @@ gpio_write:
 	.ascii	"__SACCUM_MAX__ 0X7FFFP-7HK\000"
 .LASF219:
 	.ascii	"__FLT64_MAX_10_EXP__ 308\000"
+.LASF868:
+	.ascii	"GPIO_AFRL_AFRL2_MASK (0b1111)\000"
 .LASF65:
 	.ascii	"__UINT_FAST32_TYPE__ unsigned int\000"
-.LASF864:
+.LASF878:
 	.ascii	"unsigned char\000"
 .LASF3:
 	.ascii	"__STDC_UTF_32__ 1\000"
@@ -4057,13 +4082,13 @@ gpio_write:
 	.ascii	"__int_fast64_t_defined 1\000"
 .LASF837:
 	.ascii	"__PRIPTR(x) __STRINGIFY(x)\000"
-.LASF875:
+.LASF889:
 	.ascii	"uint16_t\000"
 .LASF417:
 	.ascii	"__thumb2__ 1\000"
 .LASF321:
 	.ascii	"__ULLACCUM_FBIT__ 32\000"
-.LASF891:
+.LASF905:
 	.ascii	"_Bool\000"
 .LASF366:
 	.ascii	"__STRICT_ANSI__ 1\000"
@@ -4081,7 +4106,7 @@ gpio_write:
 	.ascii	"__PRAGMA_REDEFINE_EXTNAME 1\000"
 .LASF36:
 	.ascii	"__WCHAR_TYPE__ unsigned int\000"
-.LASF887:
+.LASF901:
 	.ascii	"GPIO_MODE_OUTPUT\000"
 .LASF357:
 	.ascii	"__USA_IBIT__ 16\000"
@@ -4119,7 +4144,7 @@ gpio_write:
 	.ascii	"__SCN64(x) __INT64 __STRINGIFY(x)\000"
 .LASF646:
 	.ascii	"_GCC_WRAP_STDINT_H \000"
-.LASF868:
+.LASF882:
 	.ascii	"__uint16_t\000"
 .LASF224:
 	.ascii	"__FLT64_EPSILON__ 2.2204460492503131e-16F64\000"
@@ -4147,7 +4172,7 @@ gpio_write:
 	.ascii	"INTMAX_MAX (__INTMAX_MAX__)\000"
 .LASF601:
 	.ascii	"INT32_MAX (__INT32_MAX__)\000"
-.LASF859:
+.LASF873:
 	.ascii	"BIT(x) (1 << x)\000"
 .LASF469:
 	.ascii	"_MB_LEN_MAX 8\000"
@@ -4165,6 +4190,8 @@ gpio_write:
 	.ascii	"_END_STD_C \000"
 .LASF852:
 	.ascii	"true ((_Bool)+1u)\000"
+.LASF865:
+	.ascii	"GPIO_AFRL_AFRL3_MASK (0b1111)\000"
 .LASF599:
 	.ascii	"UINT_LEAST16_MAX (__UINT_LEAST16_MAX__)\000"
 .LASF123:
@@ -4177,7 +4204,7 @@ gpio_write:
 	.ascii	"__FLT_EPSILON__ 1.1920928955078125e-7F\000"
 .LASF376:
 	.ascii	"__GCC_ATOMIC_SHORT_LOCK_FREE 2\000"
-.LASF860:
+.LASF874:
 	.ascii	"PIN(port,num) ((((port) - 'A') << 8) | num)\000"
 .LASF806:
 	.ascii	"PRIxLEAST64 __PRI64LEAST(x)\000"
@@ -4243,6 +4270,8 @@ gpio_write:
 	.ascii	"__FP_FAST_FMAF 1\000"
 .LASF628:
 	.ascii	"SIG_ATOMIC_MIN (-__STDINT_EXP(INT_MAX) - 1)\000"
+.LASF869:
+	.ascii	"GPIO_AFRL_AFRL2_USART2_TX (0b0111)\000"
 .LASF564:
 	.ascii	"_INT16_T_DECLARED \000"
 .LASF245:
@@ -4285,6 +4314,8 @@ gpio_write:
 	.ascii	"INT64_C(x) __INT64_C(x)\000"
 .LASF615:
 	.ascii	"INT_FAST16_MIN (-__INT_FAST16_MAX__ - 1)\000"
+.LASF862:
+	.ascii	"GPIO_MODER_MODER2_MASK (0b11)\000"
 .LASF106:
 	.ascii	"__INT_LEAST8_MAX__ 0x7f\000"
 .LASF383:
@@ -4333,7 +4364,7 @@ gpio_write:
 	.ascii	"___int8_t_defined 1\000"
 .LASF248:
 	.ascii	"__SFRACT_MIN__ (-0.5HR-0.5HR)\000"
-.LASF870:
+.LASF884:
 	.ascii	"long unsigned int\000"
 .LASF349:
 	.ascii	"__SA_IBIT__ 16\000"
@@ -4349,7 +4380,7 @@ gpio_write:
 	.ascii	"__ARM_FP16_FORMAT_IEEE\000"
 .LASF48:
 	.ascii	"__UINT16_TYPE__ short unsigned int\000"
-.LASF897:
+.LASF911:
 	.ascii	"gpio_write\000"
 .LASF569:
 	.ascii	"__int32_t_defined 1\000"
@@ -4361,7 +4392,7 @@ gpio_write:
 	.ascii	"__FLT_EVAL_METHOD_TS_18661_3__ 0\000"
 .LASF521:
 	.ascii	"int +2\000"
-.LASF896:
+.LASF910:
 	.ascii	"/home/alex/code/own/c-compile-experiments\000"
 .LASF636:
 	.ascii	"INT8_C(x) __INT8_C(x)\000"
@@ -4395,7 +4426,7 @@ gpio_write:
 	.ascii	"SCNx8 __SCN8(x)\000"
 .LASF208:
 	.ascii	"__FLT32_DENORM_MIN__ 1.4012984643248171e-45F32\000"
-.LASF898:
+.LASF912:
 	.ascii	"gpio_set_mode\000"
 .LASF125:
 	.ascii	"__UINT64_C(c) c ## ULL\000"
@@ -4407,6 +4438,8 @@ gpio_write:
 	.ascii	"__USFRACT_FBIT__ 8\000"
 .LASF191:
 	.ascii	"__LDBL_EPSILON__ 2.2204460492503131e-16L\000"
+.LASF857:
+	.ascii	"GPIOA ((struct gpio *) GPIOA_BASE_ADDR)\000"
 .LASF729:
 	.ascii	"PRIXLEAST16 __PRI16LEAST(X)\000"
 .LASF622:
@@ -4415,7 +4448,7 @@ gpio_write:
 	.ascii	"__GCC_ATOMIC_CHAR16_T_LOCK_FREE 2\000"
 .LASF789:
 	.ascii	"__PRI64FAST(x) __FAST64 __STRINGIFY(x)\000"
-.LASF877:
+.LASF891:
 	.ascii	"uintptr_t\000"
 .LASF168:
 	.ascii	"__DBL_MAX_EXP__ 1024\000"
@@ -4463,7 +4496,7 @@ gpio_write:
 	.ascii	"PRIX32 __PRI32(X)\000"
 .LASF773:
 	.ascii	"SCNxLEAST32 __SCN32LEAST(x)\000"
-.LASF880:
+.LASF894:
 	.ascii	"OSPEEDR\000"
 .LASF711:
 	.ascii	"__SCN16LEAST(x) __LEAST16 __STRINGIFY(x)\000"
@@ -4493,7 +4526,7 @@ gpio_write:
 	.ascii	"__ULACCUM_MIN__ 0.0ULK\000"
 .LASF461:
 	.ascii	"_ATEXIT_DYNAMIC_ALLOC 1\000"
-.LASF869:
+.LASF883:
 	.ascii	"__uint32_t\000"
 .LASF188:
 	.ascii	"__LDBL_MAX__ 1.7976931348623157e+308L\000"
@@ -4503,7 +4536,7 @@ gpio_write:
 	.ascii	"__FLT_RADIX__ 2\000"
 .LASF454:
 	.ascii	"_INTTYPES_H \000"
-.LASF871:
+.LASF885:
 	.ascii	"long long int\000"
 .LASF401:
 	.ascii	"__ARM_FEATURE_CMSE\000"
@@ -4539,6 +4572,8 @@ gpio_write:
 	.ascii	"__WCHAR_T \000"
 .LASF223:
 	.ascii	"__FLT64_MIN__ 2.2250738585072014e-308F64\000"
+.LASF866:
+	.ascii	"GPIO_AFRL_AFRL3_USART2_RX (0b0111)\000"
 .LASF553:
 	.ascii	"___int32_t_defined 1\000"
 .LASF83:
@@ -4608,7 +4643,7 @@ gpio_write:
 	.ascii	"\000"
 .LASF582:
 	.ascii	"__int_fast16_t_defined 1\000"
-.LASF878:
+.LASF892:
 	.ascii	"MODER\000"
 .LASF482:
 	.ascii	"__FLOAT_TYPE float\000"
@@ -4619,9 +4654,9 @@ gpio_write:
 	.ascii	"L)\000"
 .LASF607:
 	.ascii	"INT64_MAX (__INT64_MAX__)\000"
-.LASF874:
+.LASF888:
 	.ascii	"unsigned int\000"
-.LASF873:
+.LASF887:
 	.ascii	"__uintptr_t\000"
 .LASF459:
 	.ascii	"__NEWLIB_MINOR__ 3\000"
@@ -4653,7 +4688,7 @@ gpio_write:
 	.ascii	"__CHAR_BIT__ 8\000"
 .LASF143:
 	.ascii	"__FLT_EVAL_METHOD__ 0\000"
-.LASF865:
+.LASF879:
 	.ascii	"short int\000"
 .LASF685:
 	.ascii	"PRIdLEAST8 __PRI8LEAST(d)\000"
@@ -4779,6 +4814,8 @@ gpio_write:
 	.ascii	"__UFRACT_IBIT__ 0\000"
 .LASF399:
 	.ascii	"__ARM_32BIT_STATE 1\000"
+.LASF861:
+	.ascii	"GPIO_MODER_MODER2_BIT 4\000"
 .LASF107:
 	.ascii	"__INT8_C(c) c\000"
 .LASF267:
@@ -4791,12 +4828,14 @@ gpio_write:
 	.ascii	"SCNuFAST16 __SCN16FAST(u)\000"
 .LASF801:
 	.ascii	"SCNx64 __SCN64(x)\000"
-.LASF862:
+.LASF876:
 	.ascii	"PINPORT(pin) (pin >> 8)\000"
 .LASF198:
 	.ascii	"__FLT32_DIG__ 6\000"
 .LASF645:
 	.ascii	"UINTMAX_C(x) __UINTMAX_C(x)\000"
+.LASF859:
+	.ascii	"GPIO_MODER_MODER3_MASK (0b11)\000"
 .LASF623:
 	.ascii	"UINT_FAST64_MAX (__UINT_FAST64_MAX__)\000"
 .LASF515:
@@ -4839,7 +4878,7 @@ gpio_write:
 	.ascii	"__ORDER_LITTLE_ENDIAN__ 1234\000"
 .LASF155:
 	.ascii	"__FLT_NORM_MAX__ 3.4028234663852886e+38F\000"
-.LASF872:
+.LASF886:
 	.ascii	"long long unsigned int\000"
 .LASF611:
 	.ascii	"UINT_LEAST64_MAX (__UINT_LEAST64_MAX__)\000"
@@ -4869,6 +4908,8 @@ gpio_write:
 	.ascii	"SCNdFAST32 __SCN32FAST(d)\000"
 .LASF339:
 	.ascii	"__UHQ_IBIT__ 0\000"
+.LASF858:
+	.ascii	"GPIO_MODER_MODER3_BIT 7\000"
 .LASF60:
 	.ascii	"__INT_FAST16_TYPE__ int\000"
 .LASF631:
@@ -4917,11 +4958,11 @@ gpio_write:
 	.ascii	"SCNdFAST8 __SCN8FAST(d)\000"
 .LASF576:
 	.ascii	"_UINTPTR_T_DECLARED \000"
-.LASF885:
+.LASF899:
 	.ascii	"AFRH\000"
 .LASF314:
 	.ascii	"__ULACCUM_MAX__ 0XFFFFFFFFFFFFFFFFP-32ULK\000"
-.LASF884:
+.LASF898:
 	.ascii	"AFRL\000"
 .LASF273:
 	.ascii	"__ULFRACT_MIN__ 0.0ULR\000"
@@ -4935,7 +4976,7 @@ gpio_write:
 	.ascii	"__INT32_TYPE__ long int\000"
 .LASF118:
 	.ascii	"__UINT_LEAST8_MAX__ 0xff\000"
-.LASF883:
+.LASF897:
 	.ascii	"LCKR\000"
 .LASF520:
 	.ascii	"__int20__ +2\000"
@@ -4981,7 +5022,7 @@ gpio_write:
 	.ascii	"__QQ_IBIT__ 0\000"
 .LASF763:
 	.ascii	"PRIdLEAST32 __PRI32LEAST(d)\000"
-.LASF879:
+.LASF893:
 	.ascii	"OTYPER\000"
 .LASF811:
 	.ascii	"SCNuLEAST64 __SCN64LEAST(u)\000"
@@ -5001,11 +5042,11 @@ gpio_write:
 	.ascii	"__GNUC_MINOR__ 3\000"
 .LASF57:
 	.ascii	"__UINT_LEAST32_TYPE__ long unsigned int\000"
-.LASF895:
+.LASF909:
 	.ascii	"src/gpio.c\000"
 .LASF405:
 	.ascii	"__ARM_FEATURE_NUMERIC_MAXMIN\000"
-.LASF856:
+.LASF870:
 	.ascii	"GPIO_BASE_ADDR (0x40020000U)\000"
 .LASF38:
 	.ascii	"__INTMAX_TYPE__ long long int\000"
@@ -5057,7 +5098,7 @@ gpio_write:
 	.ascii	"__SCN8(x) __INT8 __STRINGIFY(x)\000"
 .LASF23:
 	.ascii	"__SIZEOF_SIZE_T__ 4\000"
-.LASF857:
+.LASF871:
 	.ascii	"GPIO_PORT_OFFSET (0x400U)\000"
 .LASF50:
 	.ascii	"__UINT64_TYPE__ long long unsigned int\000"
@@ -5067,6 +5108,8 @@ gpio_write:
 	.ascii	"__INT64_C(c) c ## LL\000"
 .LASF699:
 	.ascii	"PRIuFAST8 __PRI8FAST(u)\000"
+.LASF867:
+	.ascii	"GPIO_AFRL_AFRL2_BIT 8\000"
 .LASF190:
 	.ascii	"__LDBL_MIN__ 2.2250738585072014e-308L\000"
 .LASF445:
@@ -5075,7 +5118,7 @@ gpio_write:
 	.ascii	"__ACCUM_IBIT__ 16\000"
 .LASF509:
 	.ascii	"unsigned\000"
-.LASF881:
+.LASF895:
 	.ascii	"PUPDR\000"
 .LASF835:
 	.ascii	"SCNuMAX __SCNMAX(u)\000"
@@ -5085,7 +5128,7 @@ gpio_write:
 	.ascii	"_ATTRIBUTE(attrs) __attribute__ (attrs)\000"
 .LASF359:
 	.ascii	"__UDA_IBIT__ 32\000"
-.LASF892:
+.LASF906:
 	.ascii	"mode\000"
 .LASF586:
 	.ascii	"INTPTR_MAX (__INTPTR_MAX__)\000"
@@ -5099,7 +5142,7 @@ gpio_write:
 	.ascii	"__UHQ_FBIT__ 16\000"
 .LASF443:
 	.ascii	"__ARM_FEATURE_COPROC\000"
-.LASF889:
+.LASF903:
 	.ascii	"GPIO_MODE_ANALOG\000"
 .LASF177:
 	.ascii	"__DBL_HAS_INFINITY__ 1\000"
@@ -5137,7 +5180,7 @@ gpio_write:
 	.ascii	"__FAST8 \000"
 .LASF496:
 	.ascii	"__XSI_VISIBLE 0\000"
-.LASF882:
+.LASF896:
 	.ascii	"BSRR\000"
 .LASF794:
 	.ascii	"PRIu64 __PRI64(u)\000"
@@ -5225,7 +5268,7 @@ gpio_write:
 	.ascii	"PRIx32 __PRI32(x)\000"
 .LASF278:
 	.ascii	"__LLFRACT_MIN__ (-0.5LLR-0.5LLR)\000"
-.LASF876:
+.LASF890:
 	.ascii	"uint32_t\000"
 .LASF689:
 	.ascii	"PRIxLEAST8 __PRI8LEAST(x)\000"
@@ -5273,13 +5316,13 @@ gpio_write:
 	.ascii	"__INT_LEAST16_TYPE__ short int\000"
 .LASF326:
 	.ascii	"__QQ_FBIT__ 7\000"
-.LASF861:
+.LASF875:
 	.ascii	"PINNUM(pin) (pin & 0b1111)\000"
 .LASF768:
 	.ascii	"PRIXLEAST32 __PRI32LEAST(X)\000"
 .LASF171:
 	.ascii	"__DBL_MAX__ ((double)1.7976931348623157e+308L)\000"
-.LASF866:
+.LASF880:
 	.ascii	"short unsigned int\000"
 .LASF276:
 	.ascii	"__LLFRACT_FBIT__ 63\000"
--- a/build/gpio.i
+++ b/build/gpio.i
@@ -1995,10 +1995,36 @@ struct gpio {
  volatile uint32_t ODR;
  volatile uint32_t BSRR;
  volatile uint32_t LCKR;
-  volatile uint32_t AFRL[2];
-  volatile uint32_t AFRH[2];
+  volatile uint32_t AFRL;
+  volatile uint32_t AFRH;
 };

+#define GPIOA_BASE_ADDR (0x40020000U)
+#define GPIOA ((struct gpio *) GPIOA_BASE_ADDR)
+
+
+#define GPIO_MODER_MODER3_BIT 7
+#define GPIO_MODER_MODER3_MASK (0b11)
+#define GPIO_MODER_MODER3_AF (0b10)
+
+#define GPIO_MODER_MODER2_BIT 4
+#define GPIO_MODER_MODER2_MASK (0b11)
+#define GPIO_MODER_MODER2_AF (0b10)
+
+
+#define GPIO_AFRL_AFRL3_BIT 12
+#define GPIO_AFRL_AFRL3_MASK (0b1111)
+#define GPIO_AFRL_AFRL3_USART2_RX (0b0111)
+
+#define GPIO_AFRL_AFRL2_BIT 8
+#define GPIO_AFRL_AFRL2_MASK (0b1111)
+#define GPIO_AFRL_AFRL2_USART2_TX (0b0111)
+
+
+
+
+
+
 #define GPIO_BASE_ADDR (0x40020000U)
 #define GPIO_PORT_OFFSET (0x400U)
 #define GPIO(port) ((struct gpio*)(uintptr_t)(GPIO_BASE_ADDR + (GPIO_PORT_OFFSET * port)))
@@ -2020,9 +2046,9 @@ typedef enum {

 void gpio_set_mode(uint16_t pin, GPIO_MODE mode);
 void gpio_write(uint16_t pin, 
-# 40 "src/gpio.h" 3 4
+# 66 "src/gpio.h" 3 4
                             _Bool 
-# 40 "src/gpio.h"
+# 66 "src/gpio.h"
                                  val);
 # 5 "src/gpio.c" 2

--- a/build/gpio.o
+++ b/build/gpio.o
--- a/build/main.S
+++ b/build/main.S
--- a/build/main.i
+++ b/build/main.i
@@ -2097,9 +2097,17 @@ struct rcc {
 #define RCC_CFGR_SW(clock) ((clock & RCC_CFGR_SW_MASK) << RCC_CFGR_SW_BIT)


+
+#define RCC_AHB1ENR_GPIOAEN_BIT 0
+#define RCC_AHB1ENR_GPIOAEN_ENABLE (1 << RCC_AHB1ENR_GPIOAEN_BIT)
+
+
 #define RCC_APB1ENR_PWREN_BIT 28
 #define RCC_APB1ENR_PWREN_CLOCK_ENABLE (1 << RCC_APB1ENR_PWREN_BIT)

+#define RCC_APB1ENR_USART2EN_BIT 17
+#define RCC_APB1ENR_USART2EN_ENABLE (1 << RCC_APB1ENR_USART2EN_BIT)
+
 #define RCC_APB1ENR_TIM4_BIT 2
 #define RCC_APB1ENR_TIM4_ENABLE (1 << RCC_APB1ENR_TIM4_BIT)
 # 5 "src/main.c" 2
@@ -2119,10 +2127,36 @@ struct gpio {
  volatile uint32_t ODR;
  volatile uint32_t BSRR;
  volatile uint32_t LCKR;
-  volatile uint32_t AFRL[2];
-  volatile uint32_t AFRH[2];
+  volatile uint32_t AFRL;
+  volatile uint32_t AFRH;
 };

+#define GPIOA_BASE_ADDR (0x40020000U)
+#define GPIOA ((struct gpio *) GPIOA_BASE_ADDR)
+
+
+#define GPIO_MODER_MODER3_BIT 7
+#define GPIO_MODER_MODER3_MASK (0b11)
+#define GPIO_MODER_MODER3_AF (0b10)
+
+#define GPIO_MODER_MODER2_BIT 4
+#define GPIO_MODER_MODER2_MASK (0b11)
+#define GPIO_MODER_MODER2_AF (0b10)
+
+
+#define GPIO_AFRL_AFRL3_BIT 12
+#define GPIO_AFRL_AFRL3_MASK (0b1111)
+#define GPIO_AFRL_AFRL3_USART2_RX (0b0111)
+
+#define GPIO_AFRL_AFRL2_BIT 8
+#define GPIO_AFRL_AFRL2_MASK (0b1111)
+#define GPIO_AFRL_AFRL2_USART2_TX (0b0111)
+
+
+
+
+
+
 #define GPIO_BASE_ADDR (0x40020000U)
 #define GPIO_PORT_OFFSET (0x400U)
 #define GPIO(port) ((struct gpio*)(uintptr_t)(GPIO_BASE_ADDR + (GPIO_PORT_OFFSET * port)))
@@ -2144,9 +2178,9 @@ typedef enum {

 void gpio_set_mode(uint16_t pin, GPIO_MODE mode);
 void gpio_write(uint16_t pin, 
-# 40 "src/gpio.h" 3 4
+# 66 "src/gpio.h" 3 4
                             _Bool 
-# 40 "src/gpio.h"
+# 66 "src/gpio.h"
                                  val);
 # 6 "src/main.c" 2
 # 1 "src/flash.h" 1
@@ -2237,12 +2271,58 @@ struct timer {
 #define TIM4_BASE_ADDR (0x40000800U)
 #define TIM4 ((struct timer *) TIM4_BASE_ADDR)

-#define TIM4_CR_CEN_BIT 0
-#define TIM4_ENABLE (1 << TIM4_CR_CEN_BIT)
+#define TIM_CR1_CEN_BIT 0
+#define TIM_ENABLE (1 << TIM_CR1_CEN_BIT)

 void tim4_init(void);
 void tim4_start(void);
 # 9 "src/main.c" 2
+# 1 "src/usart.h" 1
+
+#define USART_H_ 
+
+
+
+struct usart {
+  volatile uint32_t SR;
+  volatile uint32_t DR;
+  volatile uint32_t BRR;
+  volatile uint32_t CR1;
+  volatile uint32_t CR2;
+  volatile uint32_t CR3;
+  volatile uint32_t GTPR;
+};
+
+#define USART2_BASE_ADDR (0x40004400U)
+#define USART2 ((struct usart *) USART2_BASE_ADDR)
+
+
+
+#define USART_CR1_OVER8_BIT 15
+#define USART_CR1_OVER8_8 (1 << USART_CR1_OVER8_BIT)
+
+
+#define USART_CR1_UE_BIT 13
+#define USART_CR1_UE_ENABLE (1 << USART_CR1_UE_BIT)
+
+
+#define USART_CR1_TE_BIT 3
+#define USART_CR1_TE_ENABLE (1 << USART_CR1_TE_BIT)
+
+
+#define USART_CR1_RE_BIT 2
+#define USART_CR1_RE_ENABLE (1 << USART_CR1_RE_BIT)
+
+
+#define USART_BRR_MANTISSA_BIT 4
+#define USART_BRR_MANTISSA_MASK (0b111111111111)
+
+#define USART_BRR_FRACTION_BIT 0
+#define USART_BRR_FRACTION_MASK (0b111)
+
+void usart2_init(void);
+void usart2_start(void);
+# 10 "src/main.c" 2

 #define exit 42

@@ -2313,7 +2393,9 @@ static void system_clock_init(void) {
 int main(void) {
  (void) system_clock_init();
  (void) tim4_init();
+  (void) usart2_init();

+  (void) tim4_start();
  (void) tim4_start();

  uint16_t led = (((('C') - 'A') << 8) | 13);
@@ -2322,13 +2404,13 @@ int main(void) {

  uint16_t counter = ((struct timer *) (0x40000800U))->CNT;
  
-# 87 "src/main.c" 3 4
+# 90 "src/main.c" 3 4
 _Bool 
-# 87 "src/main.c"
+# 90 "src/main.c"
      led_on = 
-# 87 "src/main.c" 3 4
+# 90 "src/main.c" 3 4
               ((_Bool)+0u)
-# 87 "src/main.c"
+# 90 "src/main.c"
                    ;
  while(1) {
 if ((((struct timer *) (0x40000800U))->CNT - counter) >= 250) {
--- a/build/main.o
+++ b/build/main.o
--- a/build/timer.S
+++ b/build/timer.S
@@ -136,10 +136,10 @@ tim4_start:
 	.byte	0x4
 	.4byte	.Ldebug_abbrev0
 	.uleb128 0x7
-	.4byte	.LASF956
+	.4byte	.LASF960
 	.byte	0x1d
-	.4byte	.LASF957
-	.4byte	.LASF958
+	.4byte	.LASF961
+	.4byte	.LASF962
 	.4byte	.LLRL0
 	.4byte	0
 	.4byte	.Ldebug_line0
@@ -147,17 +147,17 @@ tim4_start:
 	.uleb128 0x3
 	.byte	0x1
 	.byte	0x6
-	.4byte	.LASF904
+	.4byte	.LASF908
 	.uleb128 0x3
 	.byte	0x1
 	.byte	0x8
-	.4byte	.LASF905
+	.4byte	.LASF909
 	.uleb128 0x3
 	.byte	0x2
 	.byte	0x5
-	.4byte	.LASF906
+	.4byte	.LASF910
 	.uleb128 0x4
-	.4byte	.LASF909
+	.4byte	.LASF913
 	.byte	0x2
 	.byte	0x39
 	.byte	0x1c
@@ -165,13 +165,13 @@ tim4_start:
 	.uleb128 0x3
 	.byte	0x2
 	.byte	0x7
-	.4byte	.LASF907
+	.4byte	.LASF911
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x5
-	.4byte	.LASF908
+	.4byte	.LASF912
 	.uleb128 0x4
-	.4byte	.LASF910
+	.4byte	.LASF914
 	.byte	0x2
 	.byte	0x4f
 	.byte	0x1b
@@ -179,15 +179,15 @@ tim4_start:
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x7
-	.4byte	.LASF911
+	.4byte	.LASF915
 	.uleb128 0x3
 	.byte	0x8
 	.byte	0x5
-	.4byte	.LASF912
+	.4byte	.LASF916
 	.uleb128 0x3
 	.byte	0x8
 	.byte	0x7
-	.4byte	.LASF913
+	.4byte	.LASF917
 	.uleb128 0x8
 	.byte	0x4
 	.byte	0x5
@@ -195,15 +195,15 @@ tim4_start:
 	.uleb128 0x3
 	.byte	0x4
 	.byte	0x7
-	.4byte	.LASF914
+	.4byte	.LASF918
 	.uleb128 0x4
-	.4byte	.LASF915
+	.4byte	.LASF919
 	.byte	0x3
 	.byte	0x24
 	.byte	0x14
 	.4byte	0x3f
 	.uleb128 0x4
-	.4byte	.LASF916
+	.4byte	.LASF920
 	.byte	0x3
 	.byte	0x30
 	.byte	0x14
@@ -224,13 +224,13 @@ tim4_start:
 	.4byte	0xa0
 	.byte	0
 	.uleb128 0x1
-	.4byte	.LASF917
+	.4byte	.LASF921
 	.byte	0x4
 	.byte	0x8
 	.4byte	0xa0
 	.byte	0x4
 	.uleb128 0x1
-	.4byte	.LASF918
+	.4byte	.LASF922
 	.byte	0x4
 	.byte	0x9
 	.4byte	0xa0
@@ -242,115 +242,115 @@ tim4_start:
 	.4byte	0xa0
 	.byte	0xc
 	.uleb128 0x1
-	.4byte	.LASF919
+	.4byte	.LASF923
 	.byte	0x4
 	.byte	0xb
 	.4byte	0xa0
 	.byte	0x10
 	.uleb128 0x1
-	.4byte	.LASF920
+	.4byte	.LASF924
 	.byte	0x4
 	.byte	0xc
 	.4byte	0xa0
 	.byte	0x14
 	.uleb128 0x1
-	.4byte	.LASF921
+	.4byte	.LASF925
 	.byte	0x4
 	.byte	0xd
 	.4byte	0x212
 	.byte	0x18
 	.uleb128 0x1
-	.4byte	.LASF922
+	.4byte	.LASF926
 	.byte	0x4
 	.byte	0xe
 	.4byte	0xa0
 	.byte	0x20
 	.uleb128 0x1
-	.4byte	.LASF923
+	.4byte	.LASF927
 	.byte	0x4
 	.byte	0xf
 	.4byte	0xa0
 	.byte	0x24
 	.uleb128 0x1
-	.4byte	.LASF924
+	.4byte	.LASF928
 	.byte	0x4
 	.byte	0x10
 	.4byte	0x212
 	.byte	0x28
 	.uleb128 0x1
-	.4byte	.LASF925
+	.4byte	.LASF929
 	.byte	0x4
 	.byte	0x11
 	.4byte	0xa0
 	.byte	0x30
 	.uleb128 0x1
-	.4byte	.LASF926
+	.4byte	.LASF930
 	.byte	0x4
 	.byte	0x12
 	.4byte	0xa0
 	.byte	0x34
 	.uleb128 0x1
-	.4byte	.LASF927
+	.4byte	.LASF931
 	.byte	0x4
 	.byte	0x13
 	.4byte	0x212
 	.byte	0x38
 	.uleb128 0x1
-	.4byte	.LASF928
+	.4byte	.LASF932
 	.byte	0x4
 	.byte	0x14
 	.4byte	0xa0
 	.byte	0x40
 	.uleb128 0x1
-	.4byte	.LASF929
+	.4byte	.LASF933
 	.byte	0x4
 	.byte	0x15
 	.4byte	0xa0
 	.byte	0x44
 	.uleb128 0x1
-	.4byte	.LASF930
+	.4byte	.LASF934
 	.byte	0x4
 	.byte	0x16
 	.4byte	0x212
 	.byte	0x48
 	.uleb128 0x1
-	.4byte	.LASF931
+	.4byte	.LASF935
 	.byte	0x4
 	.byte	0x17
 	.4byte	0xa0
 	.byte	0x50
 	.uleb128 0x1
-	.4byte	.LASF932
+	.4byte	.LASF936
 	.byte	0x4
 	.byte	0x18
 	.4byte	0xa0
 	.byte	0x54
 	.uleb128 0x1
-	.4byte	.LASF933
+	.4byte	.LASF937
 	.byte	0x4
 	.byte	0x19
 	.4byte	0x212
 	.byte	0x58
 	.uleb128 0x1
-	.4byte	.LASF934
+	.4byte	.LASF938
 	.byte	0x4
 	.byte	0x1a
 	.4byte	0xa0
 	.byte	0x60
 	.uleb128 0x1
-	.4byte	.LASF935
+	.4byte	.LASF939
 	.byte	0x4
 	.byte	0x1b
 	.4byte	0xa0
 	.byte	0x64
 	.uleb128 0x1
-	.4byte	.LASF936
+	.4byte	.LASF940
 	.byte	0x4
 	.byte	0x1c
 	.4byte	0x212
 	.byte	0x68
 	.uleb128 0x1
-	.4byte	.LASF937
+	.4byte	.LASF941
 	.byte	0x4
 	.byte	0x1d
 	.4byte	0xa0
@@ -362,25 +362,25 @@ tim4_start:
 	.4byte	0xa0
 	.byte	0x74
 	.uleb128 0x1
-	.4byte	.LASF938
+	.4byte	.LASF942
 	.byte	0x4
 	.byte	0x1f
 	.4byte	0x212
 	.byte	0x78
 	.uleb128 0x1
-	.4byte	.LASF939
+	.4byte	.LASF943
 	.byte	0x4
 	.byte	0x20
 	.4byte	0xa0
 	.byte	0x80
 	.uleb128 0x1
-	.4byte	.LASF940
+	.4byte	.LASF944
 	.byte	0x4
 	.byte	0x21
 	.4byte	0xa0
 	.byte	0x84
 	.uleb128 0x1
-	.4byte	.LASF941
+	.4byte	.LASF945
 	.byte	0x4
 	.byte	0x22
 	.4byte	0xa0
@@ -396,7 +396,7 @@ tim4_start:
 	.uleb128 0x5
 	.4byte	0x202
 	.uleb128 0xc
-	.4byte	.LASF942
+	.4byte	.LASF946
 	.byte	0x50
 	.byte	0x5
 	.byte	0x6
@@ -415,13 +415,13 @@ tim4_start:
 	.4byte	0xa0
 	.byte	0x4
 	.uleb128 0x1
-	.4byte	.LASF943
+	.4byte	.LASF947
 	.byte	0x5
 	.byte	0x9
 	.4byte	0xa0
 	.byte	0x8
 	.uleb128 0x1
-	.4byte	.LASF944
+	.4byte	.LASF948
 	.byte	0x5
 	.byte	0xa
 	.4byte	0xa0
@@ -439,19 +439,19 @@ tim4_start:
 	.4byte	0xa0
 	.byte	0x14
 	.uleb128 0x1
-	.4byte	.LASF945
+	.4byte	.LASF949
 	.byte	0x5
 	.byte	0xd
 	.4byte	0xa0
 	.byte	0x18
 	.uleb128 0x1
-	.4byte	.LASF946
+	.4byte	.LASF950
 	.byte	0x5
 	.byte	0xe
 	.4byte	0xa0
 	.byte	0x1c
 	.uleb128 0x1
-	.4byte	.LASF947
+	.4byte	.LASF951
 	.byte	0x5
 	.byte	0xf
 	.4byte	0xa0
@@ -481,31 +481,31 @@ tim4_start:
 	.4byte	0xa0
 	.byte	0x30
 	.uleb128 0x1
-	.4byte	.LASF948
+	.4byte	.LASF952
 	.byte	0x5
 	.byte	0x14
 	.4byte	0xa0
 	.byte	0x34
 	.uleb128 0x1
-	.4byte	.LASF949
+	.4byte	.LASF953
 	.byte	0x5
 	.byte	0x15
 	.4byte	0xa0
 	.byte	0x38
 	.uleb128 0x1
-	.4byte	.LASF950
+	.4byte	.LASF954
 	.byte	0x5
 	.byte	0x16
 	.4byte	0xa0
 	.byte	0x3c
 	.uleb128 0x1
-	.4byte	.LASF951
+	.4byte	.LASF955
 	.byte	0x5
 	.byte	0x17
 	.4byte	0xa0
 	.byte	0x40
 	.uleb128 0x1
-	.4byte	.LASF952
+	.4byte	.LASF956
 	.byte	0x5
 	.byte	0x18
 	.4byte	0xa0
@@ -517,21 +517,21 @@ tim4_start:
 	.4byte	0xa0
 	.byte	0x48
 	.uleb128 0x1
-	.4byte	.LASF953
+	.4byte	.LASF957
 	.byte	0x5
 	.byte	0x1a
 	.4byte	0xa0
 	.byte	0x4c
 	.byte	0
 	.uleb128 0x6
-	.4byte	.LASF954
+	.4byte	.LASF958
 	.byte	0x14
 	.4byte	.LFB1
 	.4byte	.LFE1-.LFB1
 	.uleb128 0x1
 	.byte	0x9c
 	.uleb128 0x6
-	.4byte	.LASF955
+	.4byte	.LASF959
 	.byte	0x4
 	.4byte	.LFB0
 	.4byte	.LFE0-.LFB0
@@ -3501,7 +3501,7 @@ tim4_start:
 	.uleb128 0x135
 	.4byte	.LASF850
 	.byte	0
-	.section	.debug_macro,"G",%progbits,wm4.rcc.h.37.7ab56e8f55874aebd4da18716582113c,comdat
+	.section	.debug_macro,"G",%progbits,wm4.rcc.h.37.a17300cb822ec078eaa06c79bfd3d786,comdat
 .Ldebug_macro14:
 	.2byte	0x5
 	.byte	0
@@ -3638,43 +3638,53 @@ tim4_start:
 	.uleb128 0x73
 	.4byte	.LASF894
 	.byte	0x5
-	.uleb128 0x76
+	.uleb128 0x77
 	.4byte	.LASF895
 	.byte	0x5
-	.uleb128 0x77
+	.uleb128 0x78
 	.4byte	.LASF896
 	.byte	0x5
-	.uleb128 0x79
+	.uleb128 0x7b
 	.4byte	.LASF897
 	.byte	0x5
-	.uleb128 0x7a
+	.uleb128 0x7c
 	.4byte	.LASF898
+	.byte	0x5
+	.uleb128 0x7e
+	.4byte	.LASF899
+	.byte	0x5
+	.uleb128 0x7f
+	.4byte	.LASF900
+	.byte	0x5
+	.uleb128 0x81
+	.4byte	.LASF901
+	.byte	0x5
+	.uleb128 0x82
+	.4byte	.LASF902
 	.byte	0
-	.section	.debug_macro,"G",%progbits,wm4.timer.h.2.a5bec0ee8e2998a7b121820fb4e4e9a6,comdat
+	.section	.debug_macro,"G",%progbits,wm4.timer.h.2.2e929ede818fb0960868f1b0a08a1cbf,comdat
 .Ldebug_macro15:
 	.2byte	0x5
 	.byte	0
 	.byte	0x5
 	.uleb128 0x2
-	.4byte	.LASF899
+	.4byte	.LASF903
 	.byte	0x5
 	.uleb128 0x1d
-	.4byte	.LASF900
+	.4byte	.LASF904
 	.byte	0x5
 	.uleb128 0x1e
-	.4byte	.LASF901
+	.4byte	.LASF905
 	.byte	0x5
 	.uleb128 0x20
-	.4byte	.LASF902
+	.4byte	.LASF906
 	.byte	0x5
 	.uleb128 0x21
-	.4byte	.LASF903
+	.4byte	.LASF907
 	.byte	0
 	.section	.debug_line,"",%progbits
 .Ldebug_line0:
 	.section	.debug_str,"MS",%progbits,1
-.LASF902:
-	.ascii	"TIM4_CR_CEN_BIT 0\000"
 .LASF735:
 	.ascii	"SCNxLEAST16 __SCN16LEAST(x)\000"
 .LASF636:
@@ -3685,7 +3695,7 @@ tim4_start:
 	.ascii	"__UHA_FBIT__ 8\000"
 .LASF815:
 	.ascii	"PRIiFAST64 __PRI64FAST(i)\000"
-.LASF905:
+.LASF909:
 	.ascii	"unsigned char\000"
 .LASF225:
 	.ascii	"__FLT64_DENORM_MIN__ 4.9406564584124654e-324F64\000"
@@ -3731,7 +3741,7 @@ tim4_start:
 	.ascii	"__WCHAR_MAX__ 0xffffffffU\000"
 .LASF514:
 	.ascii	"__int20__\000"
-.LASF897:
+.LASF901:
 	.ascii	"RCC_APB1ENR_TIM4_BIT 2\000"
 .LASF18:
 	.ascii	"__SIZEOF_LONG_LONG__ 8\000"
@@ -3757,7 +3767,7 @@ tim4_start:
 	.ascii	"__ORDER_PDP_ENDIAN__ 3412\000"
 .LASF34:
 	.ascii	"__SIZE_TYPE__ unsigned int\000"
-.LASF898:
+.LASF902:
 	.ascii	"RCC_APB1ENR_TIM4_ENABLE (1 << RCC_APB1ENR_TIM4_BIT)"
 	.ascii	"\000"
 .LASF621:
@@ -3846,7 +3856,7 @@ tim4_start:
 	.ascii	"__need_wchar_t\000"
 .LASF199:
 	.ascii	"__FLT32_MIN_EXP__ (-125)\000"
-.LASF956:
+.LASF960:
 	.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"
@@ -3865,7 +3875,7 @@ tim4_start:
 	.ascii	"__int_fast32_t_defined 1\000"
 .LASF133:
 	.ascii	"__INT_FAST64_WIDTH__ 64\000"
-.LASF953:
+.LASF957:
 	.ascii	"DMAR\000"
 .LASF660:
 	.ascii	"___int_wchar_t_h \000"
@@ -3916,13 +3926,13 @@ tim4_start:
 	.ascii	"SCNo32 __SCN32(o)\000"
 .LASF541:
 	.ascii	"_NOTHROW \000"
-.LASF948:
+.LASF952:
 	.ascii	"CCR1\000"
-.LASF949:
+.LASF953:
 	.ascii	"CCR2\000"
-.LASF950:
+.LASF954:
 	.ascii	"CCR3\000"
-.LASF951:
+.LASF955:
 	.ascii	"CCR4\000"
 .LASF307:
 	.ascii	"__LACCUM_IBIT__ 32\000"
@@ -3946,7 +3956,7 @@ tim4_start:
 	.ascii	"__INT64 \"ll\"\000"
 .LASF138:
 	.ascii	"__INTPTR_MAX__ 0x7fffffff\000"
-.LASF932:
+.LASF936:
 	.ascii	"AHB2LPENR\000"
 .LASF500:
 	.ascii	"__RAND_MAX\000"
@@ -3956,7 +3966,7 @@ tim4_start:
 	.ascii	"INT_LEAST64_MIN (-__INT_LEAST64_MAX__ - 1)\000"
 .LASF614:
 	.ascii	"INT_FAST8_MAX (__INT_FAST8_MAX__)\000"
-.LASF896:
+.LASF898:
 	.ascii	"RCC_APB1ENR_PWREN_CLOCK_ENABLE (1 << RCC_APB1ENR_PW"
 	.ascii	"REN_BIT)\000"
 .LASF487:
@@ -3989,7 +3999,7 @@ tim4_start:
 	.ascii	" RCC_PLLCFGR_PLLP_BIT)\000"
 .LASF302:
 	.ascii	"__UACCUM_IBIT__ 16\000"
-.LASF908:
+.LASF912:
 	.ascii	"long int\000"
 .LASF720:
 	.ascii	"SCNd16 __SCN16(d)\000"
@@ -4066,7 +4076,7 @@ tim4_start:
 	.ascii	"__SIZEOF_LONG__ 4\000"
 .LASF754:
 	.ascii	"PRIi32 __PRI32(i)\000"
-.LASF929:
+.LASF933:
 	.ascii	"APB2ENR\000"
 .LASF822:
 	.ascii	"SCNoFAST64 __SCN64FAST(o)\000"
@@ -4080,7 +4090,7 @@ tim4_start:
 	.ascii	"__FLT32X_MIN_EXP__ (-1021)\000"
 .LASF816:
 	.ascii	"PRIoFAST64 __PRI64FAST(o)\000"
-.LASF931:
+.LASF935:
 	.ascii	"AHB1LPENR\000"
 .LASF406:
 	.ascii	"__ARM_FEATURE_SIMD32 1\000"
@@ -4092,7 +4102,7 @@ tim4_start:
 	.ascii	"PRIoLEAST16 __PRI16LEAST(o)\000"
 .LASF459:
 	.ascii	"__NEWLIB__ 4\000"
-.LASF941:
+.LASF945:
 	.ascii	"DCKCFGR\000"
 .LASF721:
 	.ascii	"SCNi16 __SCN16(i)\000"
@@ -4102,7 +4112,7 @@ tim4_start:
 	.ascii	"__FLT_DECIMAL_DIG__ 9\000"
 .LASF563:
 	.ascii	"_UINT8_T_DECLARED \000"
-.LASF904:
+.LASF908:
 	.ascii	"signed char\000"
 .LASF806:
 	.ascii	"PRIuLEAST64 __PRI64LEAST(u)\000"
@@ -4136,19 +4146,19 @@ tim4_start:
 	.ascii	"__FLT64_MAX_10_EXP__ 308\000"
 .LASF874:
 	.ascii	"RCC_PLLCFGR_PLLN_MASK (0b111111111)\000"
-.LASF957:
+.LASF961:
 	.ascii	"src/timer.c\000"
-.LASF924:
+.LASF928:
 	.ascii	"RESERVED1\000"
-.LASF927:
+.LASF931:
 	.ascii	"RESERVED2\000"
 .LASF3:
 	.ascii	"__STDC_UTF_32__ 1\000"
-.LASF933:
+.LASF937:
 	.ascii	"RESERVED4\000"
 .LASF241:
 	.ascii	"__FLT32X_DENORM_MIN__ 4.9406564584124654e-324F32x\000"
-.LASF938:
+.LASF942:
 	.ascii	"RESERVED6\000"
 .LASF152:
 	.ascii	"__FLT_MAX_10_EXP__ 38\000"
@@ -4168,6 +4178,8 @@ tim4_start:
 	.ascii	"SCNoLEAST32 __SCN32LEAST(o)\000"
 .LASF891:
 	.ascii	"RCC_CFGR_SW_PLL (0b10)\000"
+.LASF906:
+	.ascii	"TIM_CR1_CEN_BIT 0\000"
 .LASF798:
 	.ascii	"SCNd64 __SCN64(d)\000"
 .LASF828:
@@ -4186,33 +4198,36 @@ tim4_start:
 	.ascii	"__int_fast64_t_defined 1\000"
 .LASF838:
 	.ascii	"__PRIPTR(x) __STRINGIFY(x)\000"
-.LASF915:
+.LASF919:
 	.ascii	"uint16_t\000"
 .LASF417:
 	.ascii	"__thumb2__ 1\000"
 .LASF321:
 	.ascii	"__ULLACCUM_FBIT__ 32\000"
-.LASF895:
+.LASF897:
 	.ascii	"RCC_APB1ENR_PWREN_BIT 28\000"
+.LASF900:
+	.ascii	"RCC_APB1ENR_USART2EN_ENABLE (1 << RCC_APB1ENR_USART"
+	.ascii	"2EN_BIT)\000"
 .LASF366:
 	.ascii	"__STRICT_ANSI__ 1\000"
 .LASF486:
 	.ascii	"_SYS_FEATURES_H \000"
 .LASF813:
 	.ascii	"SCNxLEAST64 __SCN64LEAST(x)\000"
-.LASF930:
+.LASF934:
 	.ascii	"RESERVED3\000"
 .LASF22:
 	.ascii	"__SIZEOF_LONG_DOUBLE__ 8\000"
-.LASF936:
+.LASF940:
 	.ascii	"RESERVED5\000"
-.LASF945:
+.LASF949:
 	.ascii	"CCMR1\000"
-.LASF946:
+.LASF950:
 	.ascii	"CCMR2\000"
 .LASF36:
 	.ascii	"__WCHAR_TYPE__ unsigned int\000"
-.LASF899:
+.LASF903:
 	.ascii	"TIMER_H_ \000"
 .LASF470:
 	.ascii	"_MB_LEN_MAX 8\000"
@@ -4256,9 +4271,9 @@ tim4_start:
 	.ascii	"__SCN64(x) __INT64 __STRINGIFY(x)\000"
 .LASF647:
 	.ascii	"_GCC_WRAP_STDINT_H \000"
-.LASF909:
+.LASF913:
 	.ascii	"__uint16_t\000"
-.LASF926:
+.LASF930:
 	.ascii	"AHB2ENR\000"
 .LASF805:
 	.ascii	"PRIoLEAST64 __PRI64LEAST(o)\000"
@@ -4272,7 +4287,7 @@ tim4_start:
 	.ascii	"__UINT8_MAX__ 0xff\000"
 .LASF575:
 	.ascii	"_UINTMAX_T_DECLARED \000"
-.LASF942:
+.LASF946:
 	.ascii	"timer\000"
 .LASF184:
 	.ascii	"__LDBL_MAX_EXP__ 1024\000"
@@ -4316,7 +4331,7 @@ tim4_start:
 	.ascii	"__FLT_EPSILON__ 1.1920928955078125e-7F\000"
 .LASF770:
 	.ascii	"SCNdLEAST32 __SCN32LEAST(d)\000"
-.LASF921:
+.LASF925:
 	.ascii	"RESERVED0\000"
 .LASF807:
 	.ascii	"PRIxLEAST64 __PRI64LEAST(x)\000"
@@ -4352,7 +4367,7 @@ tim4_start:
 	.ascii	"__MISC_VISIBLE 0\000"
 .LASF306:
 	.ascii	"__LACCUM_FBIT__ 31\000"
-.LASF937:
+.LASF941:
 	.ascii	"BDCR\000"
 .LASF211:
 	.ascii	"__FLT32_HAS_QUIET_NAN__ 1\000"
@@ -4414,7 +4429,7 @@ tim4_start:
 	.ascii	"RCC_CR_HSERDY_READY (1 << RCC_CR_HSERDY_BIT)\000"
 .LASF763:
 	.ascii	"SCNx32 __SCN32(x)\000"
-.LASF918:
+.LASF922:
 	.ascii	"CFGR\000"
 .LASF558:
 	.ascii	"___int_least32_t_defined 1\000"
@@ -4484,7 +4499,7 @@ tim4_start:
 	.ascii	"___int8_t_defined 1\000"
 .LASF248:
 	.ascii	"__SFRACT_MIN__ (-0.5HR-0.5HR)\000"
-.LASF911:
+.LASF915:
 	.ascii	"long unsigned int\000"
 .LASF349:
 	.ascii	"__SA_IBIT__ 16\000"
@@ -4502,7 +4517,7 @@ tim4_start:
 	.ascii	"__UINT16_TYPE__ short unsigned int\000"
 .LASF868:
 	.ascii	"RCC_PLLCFGR_PLLSRC_BIT 22\000"
-.LASF944:
+.LASF948:
 	.ascii	"DIER\000"
 .LASF657:
 	.ascii	"_WCHAR_T_DEFINED_ \000"
@@ -4510,7 +4525,7 @@ tim4_start:
 	.ascii	"__FLT_EVAL_METHOD_TS_18661_3__ 0\000"
 .LASF522:
 	.ascii	"int +2\000"
-.LASF958:
+.LASF962:
 	.ascii	"/home/alex/code/own/c-compile-experiments\000"
 .LASF637:
 	.ascii	"INT8_C(x) __INT8_C(x)\000"
@@ -4608,11 +4623,11 @@ tim4_start:
 	.ascii	"PRIX32 __PRI32(X)\000"
 .LASF774:
 	.ascii	"SCNxLEAST32 __SCN32LEAST(x)\000"
-.LASF954:
+.LASF958:
 	.ascii	"tim4_start\000"
 .LASF704:
 	.ascii	"SCNiFAST8 __SCN8FAST(i)\000"
-.LASF917:
+.LASF921:
 	.ascii	"PLLCFGR\000"
 .LASF5:
 	.ascii	"__GNUC__ 12\000"
@@ -4640,7 +4655,7 @@ tim4_start:
 	.ascii	"__ULACCUM_MIN__ 0.0ULK\000"
 .LASF462:
 	.ascii	"_ATEXIT_DYNAMIC_ALLOC 1\000"
-.LASF910:
+.LASF914:
 	.ascii	"__uint32_t\000"
 .LASF188:
 	.ascii	"__LDBL_MAX__ 1.7976931348623157e+308L\000"
@@ -4650,7 +4665,7 @@ tim4_start:
 	.ascii	"__FLT_RADIX__ 2\000"
 .LASF455:
 	.ascii	"_INTTYPES_H \000"
-.LASF912:
+.LASF916:
 	.ascii	"long long int\000"
 .LASF401:
 	.ascii	"__ARM_FEATURE_CMSE\000"
@@ -4670,7 +4685,7 @@ tim4_start:
 	.ascii	"WINT_MAX (__WINT_MAX__)\000"
 .LASF823:
 	.ascii	"SCNuFAST64 __SCN64FAST(u)\000"
-.LASF939:
+.LASF943:
 	.ascii	"SSCGR\000"
 .LASF137:
 	.ascii	"__UINT_FAST64_MAX__ 0xffffffffffffffffULL\000"
@@ -4698,7 +4713,7 @@ tim4_start:
 	.ascii	"___int32_t_defined 1\000"
 .LASF83:
 	.ascii	"__INT_WIDTH__ 32\000"
-.LASF923:
+.LASF927:
 	.ascii	"APB2RSTR\000"
 .LASF409:
 	.ascii	"__ARM_ARCH_PROFILE\000"
@@ -4750,15 +4765,17 @@ tim4_start:
 	.ascii	"__ARM_NEON_FP\000"
 .LASF280:
 	.ascii	"__LLFRACT_EPSILON__ 0x1P-63LLR\000"
-.LASF935:
+.LASF939:
 	.ascii	"APB2LPENR\000"
+.LASF907:
+	.ascii	"TIM_ENABLE (1 << TIM_CR1_CEN_BIT)\000"
 .LASF821:
 	.ascii	"SCNiFAST64 __SCN64FAST(i)\000"
 .LASF538:
 	.ascii	"_ANSIDECL_H_ \000"
 .LASF684:
 	.ascii	"SCNu8 __SCN8(u)\000"
-.LASF900:
+.LASF904:
 	.ascii	"TIM4_BASE_ADDR (0x40000800U)\000"
 .LASF261:
 	.ascii	"__UFRACT_FBIT__ 16\000"
@@ -4778,7 +4795,7 @@ tim4_start:
 	.ascii	"L)\000"
 .LASF608:
 	.ascii	"INT64_MAX (__INT64_MAX__)\000"
-.LASF914:
+.LASF918:
 	.ascii	"unsigned int\000"
 .LASF857:
 	.ascii	"RCC_CR_HSERDY_BIT 17\000"
@@ -4864,7 +4881,7 @@ tim4_start:
 	.ascii	"__STRINGIFY(a) #a\000"
 .LASF356:
 	.ascii	"__USA_FBIT__ 16\000"
-.LASF934:
+.LASF938:
 	.ascii	"APB1LPENR\000"
 .LASF480:
 	.ascii	"__IEEE_LITTLE_ENDIAN \000"
@@ -4972,6 +4989,8 @@ tim4_start:
 	.ascii	"SCNx64 __SCN64(x)\000"
 .LASF198:
 	.ascii	"__FLT32_DIG__ 6\000"
+.LASF899:
+	.ascii	"RCC_APB1ENR_USART2EN_BIT 17\000"
 .LASF884:
 	.ascii	"RCC_CFGR_PPRE1_MASK (0b111)\000"
 .LASF646:
@@ -4990,13 +5009,13 @@ tim4_start:
 	.ascii	"__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 1\000"
 .LASF734:
 	.ascii	"SCNuLEAST16 __SCN16LEAST(u)\000"
-.LASF922:
+.LASF926:
 	.ascii	"APB1RSTR\000"
 .LASF298:
 	.ascii	"__ACCUM_MIN__ (-0X1P15K-0X1P15K)\000"
 .LASF393:
 	.ascii	"__ARM_FEATURE_CRYPTO\000"
-.LASF928:
+.LASF932:
 	.ascii	"APB1ENR\000"
 .LASF742:
 	.ascii	"SCNdFAST16 __SCN16FAST(d)\000"
@@ -5026,7 +5045,7 @@ tim4_start:
 	.ascii	")\000"
 .LASF155:
 	.ascii	"__FLT_NORM_MAX__ 3.4028234663852886e+38F\000"
-.LASF913:
+.LASF917:
 	.ascii	"long long unsigned int\000"
 .LASF612:
 	.ascii	"UINT_LEAST64_MAX (__UINT_LEAST64_MAX__)\000"
@@ -5073,7 +5092,7 @@ tim4_start:
 	.ascii	"__UINT_LEAST16_TYPE__ short unsigned int\000"
 .LASF574:
 	.ascii	"_INTMAX_T_DECLARED \000"
-.LASF947:
+.LASF951:
 	.ascii	"CCER\000"
 .LASF40:
 	.ascii	"__CHAR16_TYPE__ short unsigned int\000"
@@ -5129,7 +5148,7 @@ tim4_start:
 	.ascii	"__int20__ +2\000"
 .LASF655:
 	.ascii	"_WCHAR_T_ \000"
-.LASF943:
+.LASF947:
 	.ascii	"SMCR\000"
 .LASF829:
 	.ascii	"PRIoMAX __PRIMAX(o)\000"
@@ -5137,6 +5156,8 @@ tim4_start:
 	.ascii	"__SCN32(x) __INT32 __STRINGIFY(x)\000"
 .LASF744:
 	.ascii	"SCNoFAST16 __SCN16FAST(o)\000"
+.LASF895:
+	.ascii	"RCC_AHB1ENR_GPIOAEN_BIT 0\000"
 .LASF345:
 	.ascii	"__UTQ_IBIT__ 0\000"
 .LASF348:
@@ -5199,7 +5220,7 @@ tim4_start:
 	.ascii	"__ARM_ARCH_7EM__ 1\000"
 .LASF428:
 	.ascii	"__ARM_FEATURE_FP16_SCALAR_ARITHMETIC\000"
-.LASF925:
+.LASF929:
 	.ascii	"AHB1ENR\000"
 .LASF295:
 	.ascii	"__USACCUM_EPSILON__ 0x1P-8UHK\000"
@@ -5239,7 +5260,7 @@ tim4_start:
 	.ascii	"__DBL_DIG__ 15\000"
 .LASF275:
 	.ascii	"__ULFRACT_EPSILON__ 0x1P-32ULR\000"
-.LASF920:
+.LASF924:
 	.ascii	"AHB2RSTR\000"
 .LASF672:
 	.ascii	"__SCN8(x) __INT8 __STRINGIFY(x)\000"
@@ -5269,14 +5290,12 @@ tim4_start:
 	.ascii	"unsigned\000"
 .LASF381:
 	.ascii	"__GCC_DESTRUCTIVE_SIZE 64\000"
-.LASF906:
+.LASF910:
 	.ascii	"short int\000"
 .LASF836:
 	.ascii	"SCNuMAX __SCNMAX(u)\000"
 .LASF121:
 	.ascii	"__UINT16_C(c) c\000"
-.LASF903:
-	.ascii	"TIM4_ENABLE (1 << TIM4_CR_CEN_BIT)\000"
 .LASF359:
 	.ascii	"__UDA_IBIT__ 32\000"
 .LASF535:
@@ -5297,12 +5316,15 @@ tim4_start:
 	.ascii	"__ARM_FEATURE_COPROC\000"
 .LASF177:
 	.ascii	"__DBL_HAS_INFINITY__ 1\000"
-.LASF901:
+.LASF905:
 	.ascii	"TIM4 ((struct timer *) TIM4_BASE_ADDR)\000"
 .LASF95:
 	.ascii	"__SIG_ATOMIC_MAX__ 0x7fffffff\000"
 .LASF609:
 	.ascii	"UINT64_MAX (__UINT64_MAX__)\000"
+.LASF896:
+	.ascii	"RCC_AHB1ENR_GPIOAEN_ENABLE (1 << RCC_AHB1ENR_GPIOAE"
+	.ascii	"N_BIT)\000"
 .LASF472:
 	.ascii	"_RETARGETABLE_LOCKING 1\000"
 .LASF453:
@@ -5415,13 +5437,13 @@ tim4_start:
 	.ascii	"__ULLFRACT_MIN__ 0.0ULLR\000"
 .LASF652:
 	.ascii	"_T_WCHAR_ \000"
-.LASF952:
+.LASF956:
 	.ascii	"BDTR\000"
 .LASF382:
 	.ascii	"__GCC_CONSTRUCTIVE_SIZE 64\000"
 .LASF665:
 	.ascii	"_BSD_WCHAR_T_\000"
-.LASF940:
+.LASF944:
 	.ascii	"PLLI2SCFGR\000"
 .LASF277:
 	.ascii	"__LLFRACT_IBIT__ 0\000"
@@ -5429,9 +5451,9 @@ tim4_start:
 	.ascii	"UINT16_C(x) __UINT16_C(x)\000"
 .LASF757:
 	.ascii	"PRIx32 __PRI32(x)\000"
-.LASF955:
+.LASF959:
 	.ascii	"tim4_init\000"
-.LASF916:
+.LASF920:
 	.ascii	"uint32_t\000"
 .LASF873:
 	.ascii	"RCC_PLLCFGR_PLLN_BIT 6\000"
@@ -5491,7 +5513,7 @@ tim4_start:
 	.ascii	"PRIXLEAST32 __PRI32LEAST(X)\000"
 .LASF171:
 	.ascii	"__DBL_MAX__ ((double)1.7976931348623157e+308L)\000"
-.LASF907:
+.LASF911:
 	.ascii	"short unsigned int\000"
 .LASF276:
 	.ascii	"__LLFRACT_FBIT__ 63\000"
@@ -5531,7 +5553,7 @@ tim4_start:
 	.ascii	"SCNuFAST32 __SCN32FAST(u)\000"
 .LASF523:
 	.ascii	"long +4\000"
-.LASF919:
+.LASF923:
 	.ascii	"AHB1RSTR\000"
 .LASF724:
 	.ascii	"SCNx16 __SCN16(x)\000"
--- a/build/timer.i
+++ b/build/timer.i
@@ -2082,9 +2082,17 @@ struct rcc {
 #define RCC_CFGR_SW(clock) ((clock & RCC_CFGR_SW_MASK) << RCC_CFGR_SW_BIT)


+
+#define RCC_AHB1ENR_GPIOAEN_BIT 0
+#define RCC_AHB1ENR_GPIOAEN_ENABLE (1 << RCC_AHB1ENR_GPIOAEN_BIT)
+
+
 #define RCC_APB1ENR_PWREN_BIT 28
 #define RCC_APB1ENR_PWREN_CLOCK_ENABLE (1 << RCC_APB1ENR_PWREN_BIT)

+#define RCC_APB1ENR_USART2EN_BIT 17
+#define RCC_APB1ENR_USART2EN_ENABLE (1 << RCC_APB1ENR_USART2EN_BIT)
+
 #define RCC_APB1ENR_TIM4_BIT 2
 #define RCC_APB1ENR_TIM4_ENABLE (1 << RCC_APB1ENR_TIM4_BIT)
 # 2 "src/timer.c" 2
@@ -2120,8 +2128,8 @@ struct timer {
 #define TIM4_BASE_ADDR (0x40000800U)
 #define TIM4 ((struct timer *) TIM4_BASE_ADDR)

-#define TIM4_CR_CEN_BIT 0
-#define TIM4_ENABLE (1 << TIM4_CR_CEN_BIT)
+#define TIM_CR1_CEN_BIT 0
+#define TIM_ENABLE (1 << TIM_CR1_CEN_BIT)

 void tim4_init(void);
 void tim4_start(void);
--- a/build/timer.o
+++ b/build/timer.o
--- a/build/usart.S
+++ b/build/usart.S
--- a/build/usart.i
+++ b/build/usart.i
--- a/build/usart.o
+++ b/build/usart.o
--- a/flake.nix
+++ b/flake.nix
@@ -16,7 +16,11 @@

        devShells = nixpkgs.lib.genAttrs systems (system:
          let
-            pkgs = nixpkgs.legacyPackages.${system};
+            # pkgs = nixpkgs.legacyPackages.${system};
+            pkgs = import nixpkgs {
+              inherit system;
+              config.allowUnfree = true;
+            };
          in
            {
              default = pkgs.mkShell {
@@ -26,6 +30,7 @@
                  pkgs.stlink
                  pkgs.gdb
                  pkgs.openocd
+                  pkgs.stm32cubemx
                  pkgs.gdbgui
                ];
              };
--- a/src/gpio.h
+++ b/src/gpio.h
@@ -13,10 +13,36 @@ struct gpio {
  volatile uint32_t ODR;      // Port output data register
  volatile uint32_t BSRR;     // Port bit set/reset register
  volatile uint32_t LCKR;     // Port configuration lock register
-  volatile uint32_t AFRL[2];  // Alternative function low register
-  volatile uint32_t AFRH[2];  // Alternative function high register
+  volatile uint32_t AFRL;     // Alternative function low register
+  volatile uint32_t AFRH;     // Alternative function high register
 };

+#define GPIOA_BASE_ADDR (0x40020000U)
+#define GPIOA ((struct gpio *) GPIOA_BASE_ADDR)
+
+// MODER register
+#define GPIO_MODER_MODER3_BIT 7 // Bits [7:6]
+#define GPIO_MODER_MODER3_MASK (0b11)
+#define GPIO_MODER_MODER3_AF (0b10)
+
+#define GPIO_MODER_MODER2_BIT 4 // Bits [5:4]
+#define GPIO_MODER_MODER2_MASK (0b11)
+#define GPIO_MODER_MODER2_AF (0b10)
+
+// AFRL register
+#define GPIO_AFRL_AFRL3_BIT 12 // Bits [15:12]
+#define GPIO_AFRL_AFRL3_MASK (0b1111)
+#define GPIO_AFRL_AFRL3_USART2_RX (0b0111) // Alternative function 7
+
+#define GPIO_AFRL_AFRL2_BIT 8 // Bits [11:8]
+#define GPIO_AFRL_AFRL2_MASK (0b1111)
+#define GPIO_AFRL_AFRL2_USART2_TX (0b0111) // Alternative function 7
+
+
+
+
+
+
 #define GPIO_BASE_ADDR (0x40020000U)
 #define GPIO_PORT_OFFSET (0x400U)
 #define GPIO(port) ((struct gpio*)(uintptr_t)(GPIO_BASE_ADDR + (GPIO_PORT_OFFSET * port)))
--- a/src/main.c
+++ b/src/main.c
@@ -6,6 +6,7 @@
 #include "flash.h"
 #include "pwr.h"
 #include "timer.h"
+#include "usart.h"

 #define exit 42

@@ -76,7 +77,9 @@ static void system_clock_init(void) {
 int main(void) {
  (void) system_clock_init();
  (void) tim4_init();
+  (void) usart2_init();

+  (void) tim4_start();
  (void) tim4_start();

  uint16_t led = PIN('C', 13);           // Blue LED
@@ -90,6 +93,9 @@ int main(void) {
 	 led_on = !led_on;
 	 gpio_write(led, led_on);

+while ((USART2->ISR & USART_ISR_TC) != USART_ISR_TC);
+				USART2->TDR = '#';
+
 	 counter = TIM4->CNT;
 	}
  };
--- a/src/rcc.h
+++ b/src/rcc.h
@@ -114,10 +114,18 @@ struct rcc {
 #define RCC_CFGR_SW_MASK (0b11)
 #define RCC_CFGR_SW(clock) ((clock & RCC_CFGR_SW_MASK) << RCC_CFGR_SW_BIT)

+// AHB1ENR Register
+// GPIOA AHB1ENR
+#define RCC_AHB1ENR_GPIOAEN_BIT 0
+#define RCC_AHB1ENR_GPIOAEN_ENABLE (1 << RCC_AHB1ENR_GPIOAEN_BIT)
+
 // APB1ENR Register
 #define RCC_APB1ENR_PWREN_BIT 28
 #define RCC_APB1ENR_PWREN_CLOCK_ENABLE (1 << RCC_APB1ENR_PWREN_BIT)

+#define RCC_APB1ENR_USART2EN_BIT 17
+#define RCC_APB1ENR_USART2EN_ENABLE (1 << RCC_APB1ENR_USART2EN_BIT)
+
 #define RCC_APB1ENR_TIM4_BIT 2
 #define RCC_APB1ENR_TIM4_ENABLE (1 << RCC_APB1ENR_TIM4_BIT)

--- a/src/timer.c
+++ b/src/timer.c
@@ -18,5 +18,5 @@ void tim4_init(void) {
 }

 void tim4_start(void) {
-  TIM4->CR1 |= TIM4_ENABLE;
+  TIM4->CR1 |= TIM_ENABLE;
 }
--- a/src/timer.h
+++ b/src/timer.h
@@ -29,8 +29,8 @@ struct timer {
 #define TIM4_BASE_ADDR (0x40000800U)
 #define TIM4 ((struct timer *) TIM4_BASE_ADDR)

-#define TIM4_CR_CEN_BIT 0
-#define TIM4_ENABLE (1 << TIM4_CR_CEN_BIT)
+#define TIM_CR1_CEN_BIT 0
+#define TIM_ENABLE (1 << TIM_CR1_CEN_BIT)

 void tim4_init(void);
 void tim4_start(void);
--- a/src/usart.c
+++ b/src/usart.c
@@ -0,0 +1,63 @@
+#include "rcc.h"
+#include "gpio.h"
+#include "usart.h"
+
+void usart2_init(void) {
+  // Enable clock for GPIOA
+  RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN_ENABLE;
+
+  // Configure PA2 and PA3 (USART2 pins) to use alternative functions
+  GPIOA->MODER &= ~(GPIO_MODER_MODER2_MASK << GPIO_MODER_MODER2_BIT);
+  GPIOA->MODER |= (GPIO_MODER_MODER2_AF << GPIO_MODER_MODER2_BIT);
+  GPIOA->MODER &= ~(GPIO_MODER_MODER3_MASK << GPIO_MODER_MODER3_BIT);
+  GPIOA->MODER |= (GPIO_MODER_MODER3_AF << GPIO_MODER_MODER3_BIT);
+
+  // Set pin alternative modes to use USART
+  GPIOA->AFRL &= ~(GPIO_AFRL_AFRL2_MASK << GPIO_AFRL_AFRL2_BIT);
+  GPIOA->AFRL |= (GPIO_AFRL_AFRL2_USART2_TX << GPIO_AFRL_AFRL2_BIT);
+  GPIOA->AFRL &= ~(GPIO_AFRL_AFRL3_MASK << GPIO_AFRL_AFRL3_BIT);
+  GPIOA->AFRL |= (GPIO_AFRL_AFRL3_USART2_RX << GPIO_AFRL_AFRL3_BIT);
+
+  // Enable USART
+  RCC->AHB1ENR |= RCC_APB1ENR_USART2EN_ENABLE;
+
+  // Clear control registers
+  USART2->CR1 = 0;
+  USART2->CR2 = 0;
+  USART2->CR3 = 0;
+
+  // Calculate Baud rate:
+  // baud = f_clock / (8 * (2 - OVER8) * USARTDIV); =>
+  // (8 * (2 - OVER8) * USARTDIV) = f_clock / baud; =>
+  // USARTDIV = (f_clock / (baud * (8 * (2 - OVER8))); =>
+
+  // Target Baud rate = 115200, f_clock = 48MHz
+
+  // With OVER8 = 1 (oversampling by 8)
+  // USARTDIV = (48E6 / (115200 * (8 * (2 - 1))) = 52.083
+  // mantissa = 52
+  // fraction = 0.083 * 8 = 0.664 ~= 1
+
+  // rounding fraction up: USARTDIV = 53
+  // baud = 48E6 / (8 * (52 + 1)) = 113207.54716981133
+  // error of 0.1% (115200 / 113207.54716981133)
+
+  // rounding fraction down: USARTDIV = 52
+  // baud = 48E6 / (8 * 52) = 115384.61538461539
+  // error of 0.001% (115384.61538461539 / 115200)
+
+  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 &= ~(USART_BRR_FRACTION_MASK << USART_BRR_FRACTION_BIT);
+  USART2->BRR |= (0 << USART_BRR_FRACTION_BIT);
+
+  // Enable transmitter and receiver
+  USART2->CR1 |= USART_CR1_TE_ENABLE;
+  USART2->CR1 |= USART_CR1_RE_ENABLE;
+}
+
+void usart2_start(void) {
+  USART2->CR1 |= USART_CR1_UE_ENABLE;
+}
--- a/src/usart.h
+++ b/src/usart.h
@@ -0,0 +1,46 @@
+#ifndef USART_H_
+#define USART_H_
+
+#include <inttypes.h>
+
+struct usart {
+  volatile uint32_t SR;   // Status register
+  volatile uint32_t DR;   // Data register
+  volatile uint32_t BRR;  // Baud rate register
+  volatile uint32_t CR1;  // Control register 1
+  volatile uint32_t CR2;  // Control register 2
+  volatile uint32_t CR3;  // Control register 3
+  volatile uint32_t GTPR; // Guard time and prescaler registe
+};
+
+#define USART2_BASE_ADDR (0x40004400U)
+#define USART2 ((struct usart *) USART2_BASE_ADDR)
+
+// CR Register
+// Oversampling mode
+#define USART_CR1_OVER8_BIT 15
+#define USART_CR1_OVER8_8 (1 << USART_CR1_OVER8_BIT)
+
+// USART enable
+#define USART_CR1_UE_BIT 13
+#define USART_CR1_UE_ENABLE (1 << USART_CR1_UE_BIT)
+
+// Trasmitter enable
+#define USART_CR1_TE_BIT 3
+#define USART_CR1_TE_ENABLE (1 << USART_CR1_TE_BIT)
+
+// Receiver enable
+#define USART_CR1_RE_BIT 2
+#define USART_CR1_RE_ENABLE (1 << USART_CR1_RE_BIT)
+
+// BRR Register
+#define USART_BRR_MANTISSA_BIT 4 // Bits [15:4]
+#define USART_BRR_MANTISSA_MASK (0b111111111111) // Bits [15:4]
+
+#define USART_BRR_FRACTION_BIT 0 // Bits [3:0]
+#define USART_BRR_FRACTION_MASK (0b111) // Bits [3:0]
+
+void usart2_init(void);
+void usart2_start(void);
+
+#endif
--- a/todo.txt
+++ b/todo.txt
@@ -0,0 +1,2 @@
+- implement UART
+- implement tim4 interrupt