diff --git a/.github/workflows/compile-sketch.yml b/.github/workflows/compile-sketch.yml
index c23a834..74e2476 100644
--- a/.github/workflows/compile-sketch.yml
+++ b/.github/workflows/compile-sketch.yml
@@ -1,4 +1,4 @@
-name: Compile Sketch
+name: Compile Firmware
 
 on:
   - push
@@ -12,19 +12,17 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
-      # See: https://github.com/arduino/compile-sketches#readme
-      - name: Compile sketches
-        uses: arduino/compile-sketches@v1
+      - uses: actions/cache@v4
         with:
-          platforms: |
-            - name: "rp2040:rp2040"
-              source-url: https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
-          fqbn: rp2040:rp2040:rpipico
-          sketch-paths: |
-            - firmware/
-          cli-compile-flags: |
-            - --board-options
-            - "usbstack=tinyusb"
-          libraries: |
-            - name: Adafruit NeoPixel
-            - name: Adafruit MPU6050
+          path: |
+            ~/.cache/pip
+            ~/.platformio/.cache
+          key: ${{ runner.os }}-pio
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+      - name: Install PlatformIO Core
+        run: pip install --upgrade platformio
+
+      - name: Build PlatformIO Project
+        run: cd firmware && pio run
\ No newline at end of file
diff --git a/firmware/.gitignore b/firmware/.gitignore
new file mode 100644
index 0000000..759fbd4
--- /dev/null
+++ b/firmware/.gitignore
@@ -0,0 +1,10 @@
+.pio
+.vscode/.browse.c_cpp.db*
+.vscode/c_cpp_properties.json
+.vscode/launch.json
+.vscode/ipch
+.pioenvs
+.piolibdeps
+.clang_complete
+.gcc-flags.json
+.pio
\ No newline at end of file
diff --git a/firmware/include/README b/firmware/include/README
new file mode 100644
index 0000000..194dcd4
--- /dev/null
+++ b/firmware/include/README
@@ -0,0 +1,39 @@
+
+This directory is intended for project header files.
+
+A header file is a file containing C declarations and macro definitions
+to be shared between several project source files. You request the use of a
+header file in your project source file (C, C++, etc) located in `src` folder
+by including it, with the C preprocessing directive `#include'.
+
+```src/main.c
+
+#include "header.h"
+
+int main (void)
+{
+ ...
+}
+```
+
+Including a header file produces the same results as copying the header file
+into each source file that needs it. Such copying would be time-consuming
+and error-prone. With a header file, the related declarations appear
+in only one place. If they need to be changed, they can be changed in one
+place, and programs that include the header file will automatically use the
+new version when next recompiled. The header file eliminates the labor of
+finding and changing all the copies as well as the risk that a failure to
+find one copy will result in inconsistencies within a program.
+
+In C, the usual convention is to give header files names that end with `.h'.
+It is most portable to use only letters, digits, dashes, and underscores in
+header file names, and at most one dot.
+
+Read more about using header files in official GCC documentation:
+
+* Include Syntax
+* Include Operation
+* Once-Only Headers
+* Computed Includes
+
+https://gcc.gnu.org/onlinedocs/cpp/Header-Files.html
diff --git a/firmware/lib/README b/firmware/lib/README
new file mode 100644
index 0000000..2593a33
--- /dev/null
+++ b/firmware/lib/README
@@ -0,0 +1,46 @@
+
+This directory is intended for project specific (private) libraries.
+PlatformIO will compile them to static libraries and link into executable file.
+
+The source code of each library should be placed in an own separate directory
+("lib/your_library_name/[here are source files]").
+
+For example, see a structure of the following two libraries `Foo` and `Bar`:
+
+|--lib
+|  |
+|  |--Bar
+|  |  |--docs
+|  |  |--examples
+|  |  |--src
+|  |     |- Bar.c
+|  |     |- Bar.h
+|  |  |- library.json (optional, custom build options, etc) https://docs.platformio.org/page/librarymanager/config.html
+|  |
+|  |--Foo
+|  |  |- Foo.c
+|  |  |- Foo.h
+|  |
+|  |- README --> THIS FILE
+|
+|- platformio.ini
+|--src
+   |- main.c
+
+and a contents of `src/main.c`:
+```
+#include <Foo.h>
+#include <Bar.h>
+
+int main (void)
+{
+  ...
+}
+
+```
+
+PlatformIO Library Dependency Finder will find automatically dependent
+libraries scanning project source files.
+
+More information about PlatformIO Library Dependency Finder
+- https://docs.platformio.org/page/librarymanager/ldf.html
diff --git a/firmware/platformio.ini b/firmware/platformio.ini
new file mode 100644
index 0000000..23cdedd
--- /dev/null
+++ b/firmware/platformio.ini
@@ -0,0 +1,19 @@
+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:pico]
+platform = https://github.com/maxgerhardt/platform-raspberrypi.git
+board = pico
+framework = arduino
+board_build.core = earlephilhower
+build_flags = -DUSE_TINYUSB
+lib_deps = 
+	adafruit/Adafruit NeoPixel @ ^1.12.4
+	adafruit/Adafruit MPU6050 @ ^2.2.6
diff --git a/firmware/MonomeSerialDevice.cpp b/firmware/src/MonomeSerialDevice.cpp
similarity index 100%
rename from firmware/MonomeSerialDevice.cpp
rename to firmware/src/MonomeSerialDevice.cpp
diff --git a/firmware/MonomeSerialDevice.h b/firmware/src/MonomeSerialDevice.h
similarity index 100%
rename from firmware/MonomeSerialDevice.h
rename to firmware/src/MonomeSerialDevice.h
diff --git a/firmware/debug.cpp b/firmware/src/debug.cpp
similarity index 100%
rename from firmware/debug.cpp
rename to firmware/src/debug.cpp
diff --git a/firmware/debug.h b/firmware/src/debug.h
similarity index 100%
rename from firmware/debug.h
rename to firmware/src/debug.h
diff --git a/firmware/firmware.ino b/firmware/src/firmware.ino
similarity index 100%
rename from firmware/firmware.ino
rename to firmware/src/firmware.ino
diff --git a/firmware/test/README b/firmware/test/README
new file mode 100644
index 0000000..9b1e87b
--- /dev/null
+++ b/firmware/test/README
@@ -0,0 +1,11 @@
+
+This directory is intended for PlatformIO Test Runner and project tests.
+
+Unit Testing is a software testing method by which individual units of
+source code, sets of one or more MCU program modules together with associated
+control data, usage procedures, and operating procedures, are tested to
+determine whether they are fit for use. Unit testing finds problems early
+in the development cycle.
+
+More information about PlatformIO Unit Testing:
+- https://docs.platformio.org/en/latest/advanced/unit-testing/index.html