diff --git a/.cmake/avr-gcc.cmake b/.cmake/avr-gcc.cmake
new file mode 100644
index 0000000..aacfd9e
--- /dev/null
+++ b/.cmake/avr-gcc.cmake
@@ -0,0 +1,17 @@
+set(CMAKE_SYSTEM_NAME Generic)
+set(CMAKE_SYSTEM_PROCESSOR avr)
+
+find_program(AVR_CC avr-gcc)
+find_program(AVR_CXX avr-g++)
+find_program(AVR_OBJCOPY avr-objcopy)
+find_program(AVR_SIZE_TOOL avr-size)
+find_program(AVR_OBJDUMP avr-objdump)
+find_program(AVR_STRIP avr-strip)
+
+set(CMAKE_C_COMPILER ${AVR_CC})
+set(CMAKE_CXX_COMPILER ${AVR_CXX})
+
+# Umgehen der Standard-Compiler-Checks von CMake, die bei Cross-Compilation oft fehlschlagen
+set(CMAKE_C_COMPILER_WORKS 1)
+set(CMAKE_CXX_COMPILER_WORKS 1)
+set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..3471dc0
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,90 @@
+cmake_minimum_required(VERSION 3.10)
+
+# Set the toolchain file BEFORE the project() call
+set(CMAKE_TOOLCHAIN_FILE ${CMAKE_CURRENT_SOURCE_DIR}/.cmake/avr-gcc.cmake)
+
+project(AVRDxBlink C)
+
+# Configurable variables
+set(MCU "avr128db28" CACHE STRING "Target Microcontroller")
+set(F_CPU "20000000" CACHE STRING "Clock frequency in Hz")
+set(DEVICE_PACK_DIR "/opt/toolchains/microchip/device-packs/AVRDx" CACHE STRING "Path to Device Packs")
+set(PROGRAMMER "pickit4_updi" CACHE STRING "Programmer for avrdude") # often pickit4_updi is the right name for UPDI
+
+# Include Device Pack
+# -B instructs gcc to look for device-specific binaries/specs in this folder
+# -I adds the device-specific headers
+set(AVR_PACK_FLAGS "-B${DEVICE_PACK_DIR}/gcc/dev/${MCU} -I${DEVICE_PACK_DIR}/include")
+
+# Clangd (and therefore eglot/lsp) often does not know about the AVR Device Pack.
+# We define the corresponding macro manually so <avr/io.h> works.
+string(TOUPPER "${MCU}" MCU_UPPER)
+set(AVR_MACRO "-D__AVR_${MCU_UPPER}__ -D__AVR_DEVICE_NAME__=${MCU}")
+
+# If the MCU is a modern AVR (Dx/Ex) or XMEGA, avr-gcc defines __AVR_XMEGA__ internally.
+# Clangd needs this so <avr/fuse.h> uses NVM_FUSES_t instead of the old __fuse_t.
+if(MCU MATCHES "^avr[0-9]+" OR MCU MATCHES "^atxmega")
+    set(AVR_MACRO "${AVR_MACRO} -D__AVR_XMEGA__")
+endif()
+
+# Set Build Type (Default: Release)
+if(NOT CMAKE_BUILD_TYPE)
+    set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Build type: Debug or Release" FORCE)
+endif()
+
+# General Compiler Flags (for all build types)
+# -ffunction-sections and -fdata-sections allow the linker to remove unused code
+set(COMMON_FLAGS "-mmcu=${MCU} ${AVR_MACRO} -DF_CPU=${F_CPU}UL -Wall -Wstrict-prototypes -std=gnu99 ${AVR_PACK_FLAGS} -ffunction-sections -fdata-sections")
+set(CMAKE_C_FLAGS "${COMMON_FLAGS}")
+
+# Specific flags for Debug and Release
+set(CMAKE_C_FLAGS_DEBUG "-O0 -g3 -DDEBUG")
+set(CMAKE_C_FLAGS_RELEASE "-Os -DNDEBUG")
+
+# Linker Flags: -Wl,--gc-sections removes everything that is not needed
+set(CMAKE_EXE_LINKER_FLAGS "-mmcu=${MCU} ${AVR_PACK_FLAGS} -Wl,--gc-sections")
+
+# Generate compile_commands.json for Emacs/clangd (code completion)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# Source and Header files
+file(GLOB_RECURSE SRC_FILES src/*.c)
+list(FILTER SRC_FILES EXCLUDE REGEX "/[.]#") # Ignore Emacs lock files like .#main.c
+include_directories(inc)
+
+# Generate Executable (.elf)
+add_executable(${PROJECT_NAME}.elf ${SRC_FILES})
+
+# Display size after build (Hex file is obsolete thanks to ELF support)
+add_custom_command(TARGET ${PROJECT_NAME}.elf POST_BUILD
+    COMMAND avr-size --format=avr --mcu=${MCU} ${PROJECT_NAME}.elf
+)
+
+# --- Avrdude Programming Targets ---
+
+# F6: Program Flash only
+add_custom_target(flash
+    COMMAND avrdude -c ${PROGRAMMER} -p ${MCU} -U flash:w:${PROJECT_NAME}.elf:e
+    DEPENDS ${PROJECT_NAME}.elf
+    COMMENT "Flashing program code (Flash)..."
+)
+
+# C-F6: Program Flash and EEPROM
+add_custom_target(flash_eeprom
+    COMMAND avrdude -c ${PROGRAMMER} -p ${MCU} -U flash:w:${PROJECT_NAME}.elf:e -U eeprom:w:${PROJECT_NAME}.elf:e
+    DEPENDS ${PROJECT_NAME}.elf
+    COMMENT "Flashing program code and EEPROM..."
+)
+
+# F7: Read Fuses
+add_custom_target(read_fuses
+    COMMAND avrdude -c ${PROGRAMMER} -p ${MCU} -U fuses:r:-:h
+    COMMENT "Reading fuses..."
+)
+
+# C-F7: Program Fuses only
+add_custom_target(flash_fuses
+    COMMAND avrdude -c ${PROGRAMMER} -p ${MCU} -U fuses:w:${PROJECT_NAME}.elf:e
+    DEPENDS ${PROJECT_NAME}.elf
+    COMMENT "Programming fuses from ELF file..."
+)
diff --git a/README-DE.md b/README-DE.md
new file mode 100644
index 0000000..572dffb
--- /dev/null
+++ b/README-DE.md
@@ -0,0 +1,56 @@
+# Emacs AVR IDE Template
+
+Dieses Repository ist ein vollständiges Template, um **Emacs** als leichtgewichtige, aber extrem mächtige IDE für die Entwicklung von **AVR Mikrocontrollern** (speziell moderne AVR Dx/Ex Serien, aber auch voll abwärtskompatibel zu älteren Serien) zu nutzen.
+
+Es verwendet **CMake** als Build-System und verlässt sich auf die Kombination von `avr-gcc`, `avrdude` (ELF-Support) und `clangd` (Language Server), um Code-Vervollständigung, schnelles Kompilieren und direktes Flashen aus dem Editor heraus zu ermöglichen.
+
+## Voraussetzungen auf Betriebssystemebene
+* `avr-gcc` (AVR Toolchain Compiler)
+* `avrdude` (Version 7.0 oder höher zwingend empfohlen für nativen ELF-Support)
+* `clangd` (Für Code-Vervollständigung, Warnungen und Fehleranzeige in Emacs)
+* `cmake` (Build-System)
+* `ripgrep` (Wird für die extrem schnelle Suche in Emacs verwendet)
+* Device Packs für moderne AVRs: [Microchip Packs Repository](http://packs.download.microchip.com/)
+
+## Emacs Packages
+Damit das IDE-Feeling perfekt wird, greift dieses Template auf einige spezifische Emacs-Packages zurück, die sich bewährt haben:
+* **Projectile**: Zur Projektverwaltung (findet den Root-Ordner automatisch anhand der `CMakeLists.txt`).
+* **Eglot**: Als integrierter C/C++ Language Server Client (kommuniziert im Hintergrund mit `clangd`).
+* **Corfu**: Für das moderne Autovervollständigungs-Popup direkt am Cursor.
+* **Vertico, Orderless & Consult**: Für eine smarte, fehlertolerante Suche über das gesamte Projekt (inklusive Ripgrep-Anbindung).
+* **Doom Themes**: Für einen augenschonenden, modernen Dark Mode.
+
+## Installation der Emacs-Konfiguration
+Wenn du Emacs von Grund auf neu einrichtest, kannst du die beiliegende Beispieldatei verwenden:
+1. Kopiere die Datei `init-example.el` in dein Emacs-Konfigurationsverzeichnis (meist `~/.emacs.d/` oder `~/.config/emacs/`).
+2. Benenne sie in `init.el` um.
+   ```bash
+   cp init-example.el ~/.emacs.d/init.el
+   ```
+3. Starte Emacs neu. Beim ersten Start werden alle fehlenden Pakete automatisch von MELPA heruntergeladen und installiert.
+
+## Mikrocontroller (MCU) wechseln
+Dieses Projekt ist standardmäßig für den **AVR128DB28** konfiguriert. Wenn du einen anderen Chip verwenden möchtest:
+1. Öffne die Datei `CMakeLists.txt`.
+2. Ändere den Wert der Variable `MCU` (z.B. auf `atmega328p` oder `avr128da28`).
+3. Ändere bei Bedarf das `DEVICE_PACK_DIR`. (Für moderne AVR Dx/EA Serien wird das Device Pack von Microchip benötigt. Für ältere Modelle wie den ATmega kannst du diesen Pfad oft leer lassen).
+4. Drücke **F5** in Emacs, um das Projekt frisch zu konfigurieren und zu bauen. 
+   *(CMake erzeugt die Datei `compile_commands.json` dabei neu, wodurch `clangd` sofort die Register und Pins des neuen Chips in der Autovervollständigung kennt!)*
+
+## Entwicklungsworkflow & Shortcuts
+
+Sobald du eine `.c` oder `.h` Datei im Projekt öffnest, erkennt Projectile das Projekt automatisch und Eglot startet im Hintergrund den Language Server.
+
+Die wichtigsten Tastenkürzel für die **Projektverwaltung** (via Projectile & Consult):
+* `C-c p f`: Datei im Projekt finden (Fuzzy Search).
+* `C-r`: Projektweit nach Text suchen (Consult Ripgrep - extrem schnell!).
+* `C-c p p`: Zwischen verschiedenen, lokal gespeicherten Projekten wechseln.
+
+Die Tastenkürzel zum **Bauen und Flashen** (eingestellt über F-Tasten in der `init.el`):
+* **`F5`**: **Clean Build**. Löscht den Cache radikal und baut das Projekt komplett neu (Kompiliert inkl. Linker Garbage Collection für minimale Größe).
+* **`F6`**: **Flash Code**. Flasht nur den Programmcode (Flash-Speicher) via Avrdude. *(Standardbefehl während der Entwicklung)*
+* **`Strg + F6`**: **Flash Code & EEPROM**. Flasht den Code und die EEPROM-Daten.
+* **`F7`**: **Read Fuses**. Liest die Fuses vom Mikrocontroller und zeigt sie im Emacs Compile-Fenster an.
+* **`Strg + F7`**: **Flash Fuses**. Schreibt die direkt in der C-Software definierten Fuses (via `<avr/fuse.h>`) auf den Chip.
+
+*Hinweis: Da wir das moderne ELF-Format nutzen, entfällt das manuelle Generieren von alten `.hex`-Dateien vollständig.*
diff --git a/README.md b/README.md
index 426ab6a..3a12435 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,56 @@
-# AVRDxBlink
+# Emacs AVR IDE Template
 
-Template to start devloping for avr8 with emacs
\ No newline at end of file
+This repository is a complete template to use **Emacs** as a lightweight, yet extremely powerful IDE for developing **AVR microcontrollers** (specifically modern AVR Dx/Ex series, but also fully backwards compatible with older series).
+
+It uses **CMake** as the build system and relies on the combination of `avr-gcc`, `avrdude` (with ELF support), and `clangd` (Language Server) to enable code completion, fast compilation, and direct flashing from within the editor.
+
+## System Prerequisites
+* `avr-gcc` (AVR Toolchain Compiler)
+* `avrdude` (Version 7.0 or higher highly recommended for native ELF support)
+* `clangd` (For code completion, warnings, and error display in Emacs)
+* `cmake` (Build System)
+* `ripgrep` (Used for extremely fast searching in Emacs)
+* Device Packs for modern AVRs: [Microchip Packs Repository](http://packs.download.microchip.com/)
+
+## Emacs Packages
+To achieve the perfect IDE feel, this template relies on several proven Emacs packages:
+* **Projectile**: For project management (automatically finds the root folder based on `CMakeLists.txt`).
+* **Eglot**: As an integrated C/C++ Language Server Client (communicates with `clangd` in the background).
+* **Corfu**: For the modern auto-completion popup directly at the cursor.
+* **Vertico, Orderless & Consult**: For smart, fault-tolerant searching across the entire project (including Ripgrep integration).
+* **Doom Themes**: For an eye-friendly, modern dark mode.
+
+## Emacs Configuration Installation
+If you are setting up Emacs from scratch, you can use the provided example file:
+1. Copy the file `init-example.el` to your Emacs configuration directory (usually `~/.emacs.d/` or `~/.config/emacs/`).
+2. Rename it to `init.el`.
+   ```bash
+   cp init-example.el ~/.emacs.d/init.el
+   ```
+3. Restart Emacs. On the first launch, all missing packages will automatically be downloaded and installed from MELPA.
+
+## Changing the Microcontroller (MCU)
+This project is configured for the **AVR128DB28** by default. If you want to use a different chip:
+1. Open the file `CMakeLists.txt`.
+2. Change the value of the `MCU` variable (e.g., to `atmega328p` or `avr128da28`).
+3. If necessary, change the `DEVICE_PACK_DIR`. (For modern AVR Dx/EA series, the Device Pack from Microchip is required. For older models like the ATmega, you can often leave this path empty).
+4. Press **F5** in Emacs to do a fresh configure and build.
+   *(CMake will regenerate the `compile_commands.json` file, allowing `clangd` to immediately know the registers and pins of the new chip for auto-completion!)*
+
+## Development Workflow & Shortcuts
+
+As soon as you open a `.c` or `.h` file in the project, Projectile will automatically detect the project, and Eglot will start the Language Server in the background.
+
+The most important shortcuts for **project management** (via Projectile & Consult):
+* `C-c p f`: Find file in project (Fuzzy Search).
+* `C-r`: Search for text across the project (Consult Ripgrep - extremely fast!).
+* `C-c p p`: Switch between different, locally stored projects.
+
+The shortcuts for **building and flashing** (configured via F-keys in `init.el`):
+* **`F5`**: **Clean Build**. Radically deletes the cache and completely rebuilds the project (Compiles including linker garbage collection for minimal size).
+* **`F6`**: **Flash Code**. Flashes only the program code (Flash memory) via Avrdude. *(Standard command during development)*
+* **`Strg + F6`**: **Flash Code & EEPROM**. Flashes the code and the EEPROM data.
+* **`F7`**: **Read Fuses**. Reads the fuses from the microcontroller and displays them in the Emacs Compile window.
+* **`Strg + F7`**: **Flash Fuses**. Writes the fuses directly defined in the C software (via `<avr/fuse.h>`) to the chip.
+
+*Note: Since we use the modern ELF format, manually generating old `.hex` files is completely obsolete.*
diff --git a/init-example.el b/init-example.el
new file mode 100644
index 0000000..73b9b91
--- /dev/null
+++ b/init-example.el
@@ -0,0 +1,180 @@
+;; ==================================================
+;; AVR Emacs IDE - Minimal Example init.el
+;; ==================================================
+
+;; --- 1. Basic Setup & Package Manager ---
+(setq inhibit-startup-message t)
+(require 'package)
+(setq package-archives '(("melpa" . "https://melpa.org/packages/")
+                         ("elpa" . "https://elpa.gnu.org/packages/")))
+(package-initialize)
+
+;; Install use-package if not present
+(unless (package-installed-p 'use-package)
+  (package-refresh-contents)
+  (package-install 'use-package))
+(require 'use-package)
+(setq use-package-always-ensure t)
+
+;; Mache die Menüleiste, Werkzeugleiste und alte Scroll-Leiste unsichtbar
+(menu-bar-mode -1)
+(tool-bar-mode -1)
+(scroll-bar-mode -1)
+
+;; Erhöhe die Standard-Fensterbreite auf 120 Spalten, damit durch die Minimap (20 Spalten)
+;; immer noch genug Platz (100 Spalten) für den Code bleibt und dieser nicht umbricht.
+(add-to-list 'default-frame-alist '(width . 100))
+(add-to-list 'initial-frame-alist '(width . 100))
+
+;; Unterdrücke nervige Warnungen (z.B. beim Kompilieren von heruntergeladenen Paketen)
+(setq warning-minimum-level :error)
+(setq native-comp-async-report-warnings-errors 'silent)
+
+;; Aktiviere Zeilennummern links
+(global-display-line-numbers-mode 1)
+
+;; Sublime Text ähnliche Minimap (Vorschaubild) auf der rechten Seite
+(use-package minimap
+  :init
+  (setq minimap-window-location 'right)
+  (setq minimap-update-delay 0.2)
+  (setq minimap-width-fraction 0.01)  ; 1% (wird durch Minimum überschrieben)
+  (setq minimap-minimum-width 20)     ; Erzwingt exakt feste 20 Spalten!
+  :config
+  ;; Verhindert, dass das Minimap-Fenster beim Maximieren (Vollbild) des Emacs-Fensters mitwächst
+  (advice-add 'minimap-new-minimap :after
+              (lambda (&rest _)
+                (when-let ((win (minimap-get-window)))
+                  (window-preserve-size win t t))))
+  (minimap-mode 1))
+
+;; Deaktiviere die Erstellung von temporären #Dateien#, .#Lockfiles und Datei~ Backups
+(setq make-backup-files nil)
+(setq auto-save-default nil) ; Deaktiviert die lästigen #Dateien#
+(setq create-lockfiles nil)
+
+;; AKTIVIERE stattdessen modernes "Auto-Save" (speichert direkt in die Originaldatei)
+(auto-save-visited-mode 1)
+(setq auto-save-visited-interval 2) ; Speichert automatisch nach 2 Sekunden Inaktivität
+
+;; --- 2. Theme (Doom Dark Theme) ---
+(use-package doom-themes
+  :config
+  (load-theme 'doom-one t))
+
+;; --- 3. Projectile (Projektverwaltung) ---
+(use-package projectile
+  :demand t
+  :config (projectile-mode +1)
+  :bind-keymap ("C-c p" . projectile-command-map))
+
+;; --- 4. Autocompletion (Corfu & Eglot für clangd) ---
+(use-package corfu
+  :custom
+  (corfu-cycle t)
+  (corfu-auto t)
+  :init
+  (global-corfu-mode))
+
+(use-package eglot
+  :hook ((c-mode . eglot-ensure)
+         (c++-mode . eglot-ensure)
+         (c-ts-mode . eglot-ensure)
+         (c++-ts-mode . eglot-ensure))
+  :config
+  ;; Clangd-spezifische Parameter für C/C++
+  (add-to-list 'eglot-server-programs
+               '(c-mode . ("clangd" "-j=8" "--background-index" "--clang-tidy")))
+  (add-to-list 'eglot-server-programs
+               '(c-ts-mode . ("clangd" "-j=8" "--background-index" "--clang-tidy"))))
+
+;; Modernes Hover-Popup (wie in Eclipse/VS Code) für Dokumentation und Signaturen
+(use-package eldoc-box
+  :hook (eglot-managed-mode . eldoc-box-hover-at-point-mode))
+
+;; --- 5. CMake Syntax Highlighting ---
+(use-package cmake-mode
+  :mode ("CMakeLists\\.txt\\'" "\\.cmake\\'"))
+
+;; --- 5. Suche & Ripgrep (Vertico, Orderless & Consult) ---
+(use-package vertico
+  :init (vertico-mode))
+
+(use-package orderless
+  :custom
+  (completion-styles '(orderless basic)))
+
+(use-package consult
+  :bind (("C-s" . consult-line)
+         ("C-r" . consult-ripgrep)))
+
+;; --- 6. Compilation Window Tweaks ---
+;; Öffne das Compile-Fenster immer unten (nicht rechts) und mache es 30% hoch
+(add-to-list 'display-buffer-alist
+             '("\\*compilation\\*"
+               (display-buffer-reuse-window display-buffer-at-bottom)
+               (window-height . 0.3)))
+
+;; Aktiviere ANSI-Farben im Compile-Fenster (für CMake-Farben)
+(require 'ansi-color)
+(add-hook 'compilation-filter-hook 'ansi-color-compilation-filter)
+
+;; Automatisch nach unten scrollen, um Fehler oder die finale Dateigröße sofort zu sehen
+(setq compilation-scroll-output t)
+
+;; --- 7. Modernes Syntax-Highlighting (Tree-Sitter) ---
+(use-package treesit-auto
+  :custom
+  (treesit-auto-install t) ; Lade fehlende Grammatiken vollautomatisch herunter
+  :config
+  (treesit-auto-add-to-auto-mode-alist 'all)
+  (global-treesit-auto-mode)
+  
+  ;; Workaround für c-ts-mode: Benötigt intern ZWINGEND auch die cpp-Grammatik!
+  ;; Wir prüfen beim Start, ob C, C++ oder CMake fehlen und installieren sie stumm nach.
+  (setq treesit-language-source-alist
+        '((c "https://github.com/tree-sitter/tree-sitter-c")
+          (cpp "https://github.com/tree-sitter/tree-sitter-cpp")
+          (cmake "https://github.com/uyha/tree-sitter-cmake")))
+  
+  (dolist (lang '(c cpp cmake))
+    (unless (treesit-language-available-p lang)
+      (treesit-install-language-grammar lang))))
+
+;; --- 8. AVR Build & Flash Shortcuts ---
+(defun my-avr-clean-build ()
+  "Baut das aktuelle CMake-Projekt komplett neu ohne Rückfrage."
+  (interactive)
+  (let ((default-directory (projectile-project-root)))
+    (compile "cmake --fresh -B build && cmake --build build")))
+
+(defun my-avr-flash-code ()
+  "Flasht nur den Programmcode (Flash)."
+  (interactive)
+  (let ((default-directory (projectile-project-root)))
+    (compile "cmake --build build --target flash")))
+
+(defun my-avr-flash-eeprom ()
+  "Flasht Programmcode und EEPROM."
+  (interactive)
+  (let ((default-directory (projectile-project-root)))
+    (compile "cmake --build build --target flash_eeprom")))
+
+(defun my-avr-read-fuses ()
+  "Liest die Fuses via Avrdude aus."
+  (interactive)
+  (let ((default-directory (projectile-project-root)))
+    (compile "cmake --build build --target read_fuses")))
+
+(defun my-avr-flash-fuses ()
+  "Programmiert die Fuses aus der ELF-Datei."
+  (interactive)
+  (let ((default-directory (projectile-project-root)))
+    (compile "cmake --build build --target flash_fuses")))
+
+;; Tastenbelegungen (F-Tasten)
+(global-set-key (kbd "<f5>") 'my-avr-clean-build)
+(global-set-key (kbd "<f6>") 'my-avr-flash-code)
+(global-set-key (kbd "<C-f6>") 'my-avr-flash-eeprom)
+(global-set-key (kbd "<f7>") 'my-avr-read-fuses)
+(global-set-key (kbd "<C-f7>") 'my-avr-flash-fuses)
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..e29a237
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,35 @@
+#ifndef F_CPU
+#define F_CPU 16000000UL // Set to 16 MHz
+#endif
+
+#include <avr/io.h>
+#include <util/delay.h>
+#include <avr/fuse.h>
+#include <stdbool.h>
+
+/*
+ * Fuses Configuration
+ */
+FUSES = {
+    .WDTCFG = 0x00,  // Watchdog Timer: deactivated
+    .BODCFG = 0x10,  // Brown-out Detector: factory default
+    .OSCCFG = 0x78,  // Oscillator: Internal OSCHF (starting with 4 MHz)
+    .SYSCFG0 = 0xF6, // System Config 0: UPDI activated
+    .SYSCFG1 = 0xE8  // System Config 1: Standard Start-up Time
+};
+
+#define LED_PIN 7
+
+int main(void) {
+    // 1. System clock to 20MHz
+    _PROTECTED_WRITE(CLKCTRL.OSCHFCTRLA, CLKCTRL_FRQSEL_16M_gc);
+
+    // LED Pin as output
+    PORTA.DIRSET = (1 << LED_PIN);
+
+    // main loop
+    while (true) {
+        PORTA.OUTTGL = (1 << LED_PIN);
+        _delay_ms(750);
+    }
+}