diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7d13eb2..4b1a38e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,6 +17,14 @@ find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 
 project(new_kbd)
 
+if(NOT c_std_11 IN_LIST CMAKE_C_COMPILE_FEATURES)
+  list(APPEND CMAKE_C_COMPILE_FEATURES c_std_11)
+endif()
+
+set(PROTOBUF_PROTOC_EXECUTABLE
+    "${CMAKE_CURRENT_SOURCE_DIR}/scripts/protoc_nanopb.bat"
+    CACHE FILEPATH "Project-local protoc wrapper for nanopb" FORCE)
+
 list(APPEND CMAKE_MODULE_PATH ${ZEPHYR_BASE}/modules/nanopb)
 include(nanopb)
 
@@ -40,6 +48,8 @@ zephyr_nanopb_sources(app
     KeyBorad/proto/keyboard.proto
 )
 
+target_link_libraries(app PRIVATE nanopb)
+
 target_sources(app PRIVATE
     src/main.c
     src/events/battery_status_event.c
diff --git a/KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.cpp b/KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.cpp
index 2b0c1ec..b1b6c48 100644
--- a/KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.cpp
+++ b/KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.cpp
@@ -1,10 +1,210 @@
 #include "DRI/GATT/Dri_Gatt.h"
 
+#include <QtBluetooth/QBluetoothAddress>
 #include <QtBluetooth/QBluetoothDeviceDiscoveryAgent>
 #include <QtBluetooth/QBluetoothDeviceInfo>
+#include <QtBluetooth/QBluetoothUuid>
+#include <QtBluetooth/QLowEnergyCharacteristic>
+#include <QtBluetooth/QLowEnergyController>
+#include <QtBluetooth/QLowEnergyDescriptor>
+#include <QtBluetooth/QLowEnergyService>
 #include <QtCore/QEventLoop>
+#include <QtCore/QList>
 #include <QtCore/QTimer>
 
+struct Dri_Gatt_Struct_Context
+{
+    QLowEnergyController* Controller = nullptr;
+    QLowEnergyService* Service = nullptr;
+    QLowEnergyCharacteristic RxCharacteristic;
+    QLowEnergyCharacteristic TxCharacteristic;
+    QList<QByteArray> ReadQueue;
+};
+
+namespace
+{
+
+const QBluetoothUuid kServiceUuid(
+    QStringLiteral("0b7f6000-38d2-4f62-8f6f-36c4fd73a110"));
+const QBluetoothUuid kRxUuid(
+    QStringLiteral("0b7f6001-38d2-4f62-8f6f-36c4fd73a110"));
+const QBluetoothUuid kTxUuid(
+    QStringLiteral("0b7f6002-38d2-4f62-8f6f-36c4fd73a110"));
+
+bool Dri_Gatt_Func_WaitForControllerConnected(QLowEnergyController* p_Controller)
+{
+    QEventLoop EventLoop;
+    QTimer TimeoutTimer;
+    bool IsConnected = false;
+
+    TimeoutTimer.setSingleShot(true);
+
+    QObject::connect(
+        p_Controller,
+        &QLowEnergyController::connected,
+        &EventLoop,
+        [&EventLoop, &IsConnected]()
+        {
+            IsConnected = true;
+            EventLoop.quit();
+        });
+    QObject::connect(
+        p_Controller,
+        static_cast<void (QLowEnergyController::*)(QLowEnergyController::Error)>(
+            &QLowEnergyController::error),
+        &EventLoop,
+        [&EventLoop]()
+        {
+            EventLoop.quit();
+        });
+    QObject::connect(
+        &TimeoutTimer,
+        &QTimer::timeout,
+        &EventLoop,
+        &QEventLoop::quit);
+
+    p_Controller->connectToDevice();
+    TimeoutTimer.start(5000);
+    EventLoop.exec();
+    return IsConnected;
+}
+
+bool Dri_Gatt_Func_WaitForServiceDiscovery(QLowEnergyController* p_Controller)
+{
+    QEventLoop EventLoop;
+    QTimer TimeoutTimer;
+    bool IsFinished = false;
+
+    TimeoutTimer.setSingleShot(true);
+
+    QObject::connect(
+        p_Controller,
+        &QLowEnergyController::discoveryFinished,
+        &EventLoop,
+        [&EventLoop, &IsFinished]()
+        {
+            IsFinished = true;
+            EventLoop.quit();
+        });
+    QObject::connect(
+        p_Controller,
+        static_cast<void (QLowEnergyController::*)(QLowEnergyController::Error)>(
+            &QLowEnergyController::error),
+        &EventLoop,
+        [&EventLoop]()
+        {
+            EventLoop.quit();
+        });
+    QObject::connect(
+        &TimeoutTimer,
+        &QTimer::timeout,
+        &EventLoop,
+        &QEventLoop::quit);
+
+    p_Controller->discoverServices();
+    TimeoutTimer.start(5000);
+    EventLoop.exec();
+    return IsFinished;
+}
+
+bool Dri_Gatt_Func_WaitForServiceDetails(QLowEnergyService* p_Service)
+{
+    QEventLoop EventLoop;
+    QTimer TimeoutTimer;
+    bool IsDiscovered = false;
+
+    TimeoutTimer.setSingleShot(true);
+
+    QObject::connect(
+        p_Service,
+        &QLowEnergyService::stateChanged,
+        &EventLoop,
+        [&EventLoop, &IsDiscovered](QLowEnergyService::ServiceState State)
+        {
+            if (State == QLowEnergyService::ServiceDiscovered)
+            {
+                IsDiscovered = true;
+                EventLoop.quit();
+            }
+        });
+    QObject::connect(
+        p_Service,
+        static_cast<void (QLowEnergyService::*)(QLowEnergyService::ServiceError)>(
+            &QLowEnergyService::error),
+        &EventLoop,
+        [&EventLoop]()
+        {
+            EventLoop.quit();
+        });
+    QObject::connect(
+        &TimeoutTimer,
+        &QTimer::timeout,
+        &EventLoop,
+        &QEventLoop::quit);
+
+    p_Service->discoverDetails();
+    TimeoutTimer.start(5000);
+    EventLoop.exec();
+    return IsDiscovered;
+}
+
+bool Dri_Gatt_Func_EnableNotify(
+    Dri_Gatt_Struct_Context* p_Context,
+    const QLowEnergyCharacteristic& Characteristic)
+{
+    if (!Characteristic.isValid() || (p_Context == nullptr) || (p_Context->Service == nullptr))
+    {
+        return false;
+    }
+
+    const QLowEnergyDescriptor Cccd =
+        Characteristic.descriptor(QBluetoothUuid::ClientCharacteristicConfiguration);
+    if (!Cccd.isValid())
+    {
+        return false;
+    }
+
+    QEventLoop EventLoop;
+    QTimer TimeoutTimer;
+    bool IsWritten = false;
+
+    TimeoutTimer.setSingleShot(true);
+
+    QObject::connect(
+        p_Context->Service,
+        &QLowEnergyService::descriptorWritten,
+        &EventLoop,
+        [&EventLoop, &IsWritten, Cccd](const QLowEnergyDescriptor& Descriptor, const QByteArray&)
+        {
+            if (Descriptor == Cccd)
+            {
+                IsWritten = true;
+                EventLoop.quit();
+            }
+        });
+    QObject::connect(
+        p_Context->Service,
+        static_cast<void (QLowEnergyService::*)(QLowEnergyService::ServiceError)>(
+            &QLowEnergyService::error),
+        &EventLoop,
+        [&EventLoop]()
+        {
+            EventLoop.quit();
+        });
+    QObject::connect(
+        &TimeoutTimer,
+        &QTimer::timeout,
+        &EventLoop,
+        &QEventLoop::quit);
+
+    p_Context->Service->writeDescriptor(Cccd, QByteArray::fromHex("0100"));
+    TimeoutTimer.start(3000);
+    EventLoop.exec();
+    return IsWritten;
+}
+
+} // namespace
+
 QVector<Dri_Gatt_Struct_PortInfo> Dri_Gatt_Enum()
 {
     QVector<Dri_Gatt_Struct_PortInfo> PortList;
@@ -79,6 +279,17 @@ void Dri_Gatt_Close(Dri_Gatt_Struct_Port* p_Port)
         return;
     }
 
+    if (p_Port->p_Context != nullptr)
+    {
+        if (p_Port->p_Context->Controller != nullptr)
+        {
+            p_Port->p_Context->Controller->disconnectFromDevice();
+            delete p_Port->p_Context->Controller;
+        }
+
+        delete p_Port->p_Context;
+    }
+
     *p_Port = Dri_Gatt_Struct_Port();
 }
 
@@ -93,38 +304,183 @@ bool Dri_Gatt_Open(
     }
 
     Dri_Gatt_Close(p_Port);
+
+    Dri_Gatt_Struct_Context* const p_Context = new Dri_Gatt_Struct_Context();
+    p_Context->Controller = new QLowEnergyController(QBluetoothAddress(DeviceAddress.trimmed()));
+
+    if (!Dri_Gatt_Func_WaitForControllerConnected(p_Context->Controller))
+    {
+        Dri_Gatt_Close(p_Port);
+        delete p_Context->Controller;
+        delete p_Context;
+        return false;
+    }
+
+    if (!Dri_Gatt_Func_WaitForServiceDiscovery(p_Context->Controller) ||
+        !p_Context->Controller->services().contains(kServiceUuid))
+    {
+        Dri_Gatt_Close(p_Port);
+        delete p_Context->Controller;
+        delete p_Context;
+        return false;
+    }
+
+    p_Context->Service = p_Context->Controller->createServiceObject(kServiceUuid, p_Context->Controller);
+    if (p_Context->Service == nullptr)
+    {
+        Dri_Gatt_Close(p_Port);
+        delete p_Context->Controller;
+        delete p_Context;
+        return false;
+    }
+
+    if (!Dri_Gatt_Func_WaitForServiceDetails(p_Context->Service))
+    {
+        Dri_Gatt_Close(p_Port);
+        delete p_Context->Controller;
+        delete p_Context;
+        return false;
+    }
+
+    p_Context->RxCharacteristic = p_Context->Service->characteristic(kRxUuid);
+    p_Context->TxCharacteristic = p_Context->Service->characteristic(kTxUuid);
+
+    if (!p_Context->RxCharacteristic.isValid() || !p_Context->TxCharacteristic.isValid())
+    {
+        Dri_Gatt_Close(p_Port);
+        delete p_Context->Controller;
+        delete p_Context;
+        return false;
+    }
+
+    QObject::connect(
+        p_Context->Service,
+        &QLowEnergyService::characteristicChanged,
+        [p_Context](const QLowEnergyCharacteristic& Characteristic, const QByteArray& Value)
+        {
+            if (Characteristic == p_Context->TxCharacteristic)
+            {
+                p_Context->ReadQueue.append(Value);
+            }
+        });
+
+    if (!Dri_Gatt_Func_EnableNotify(p_Context, p_Context->TxCharacteristic))
+    {
+        Dri_Gatt_Close(p_Port);
+        delete p_Context->Controller;
+        delete p_Context;
+        return false;
+    }
+
+    p_Port->p_Context = p_Context;
     p_Port->IsOpened = true;
     p_Port->DeviceAddress = DeviceAddress.trimmed();
-    return false;
+    return true;
 }
 
 bool Dri_Gatt_ReadBytes(
     Dri_Gatt_Struct_Port* p_Port,
     QByteArray* p_ByteArray,
-    int)
+    int TimeoutMs)
 {
     if (p_ByteArray != nullptr)
     {
         p_ByteArray->clear();
     }
 
-    if ((p_Port == nullptr) || (p_ByteArray == nullptr) || !p_Port->IsOpened)
+    if ((p_Port == nullptr) || (p_ByteArray == nullptr) ||
+        !p_Port->IsOpened || (p_Port->p_Context == nullptr))
     {
         return false;
     }
 
-    return false;
+    if (p_Port->p_Context->ReadQueue.isEmpty() && (TimeoutMs > 0))
+    {
+        QEventLoop EventLoop;
+        QTimer TimeoutTimer;
+
+        TimeoutTimer.setSingleShot(true);
+        QObject::connect(
+            p_Port->p_Context->Service,
+            &QLowEnergyService::characteristicChanged,
+            &EventLoop,
+            [&EventLoop](const QLowEnergyCharacteristic&, const QByteArray&)
+            {
+                EventLoop.quit();
+            });
+        QObject::connect(
+            &TimeoutTimer,
+            &QTimer::timeout,
+            &EventLoop,
+            &QEventLoop::quit);
+
+        TimeoutTimer.start(TimeoutMs);
+        EventLoop.exec();
+    }
+
+    if (p_Port->p_Context->ReadQueue.isEmpty())
+    {
+        return false;
+    }
+
+    *p_ByteArray = p_Port->p_Context->ReadQueue.takeFirst();
+    return !p_ByteArray->isEmpty();
 }
 
 bool Dri_Gatt_WriteBytes(
     Dri_Gatt_Struct_Port* p_Port,
     const QByteArray& ByteArray,
-    int)
+    int TimeoutMs)
 {
-    if ((p_Port == nullptr) || !p_Port->IsOpened)
+    if ((p_Port == nullptr) || !p_Port->IsOpened || (p_Port->p_Context == nullptr))
     {
         return false;
     }
 
-    return !ByteArray.isEmpty();
+    if (ByteArray.isEmpty())
+    {
+        return false;
+    }
+
+    QEventLoop EventLoop;
+    QTimer TimeoutTimer;
+    bool IsWritten = false;
+
+    TimeoutTimer.setSingleShot(true);
+
+    QObject::connect(
+        p_Port->p_Context->Service,
+        &QLowEnergyService::characteristicWritten,
+        &EventLoop,
+        [&EventLoop, &IsWritten, p_Port](const QLowEnergyCharacteristic& Characteristic, const QByteArray&)
+        {
+            if (Characteristic == p_Port->p_Context->RxCharacteristic)
+            {
+                IsWritten = true;
+                EventLoop.quit();
+            }
+        });
+    QObject::connect(
+        p_Port->p_Context->Service,
+        static_cast<void (QLowEnergyService::*)(QLowEnergyService::ServiceError)>(
+            &QLowEnergyService::error),
+        &EventLoop,
+        [&EventLoop]()
+        {
+            EventLoop.quit();
+        });
+    QObject::connect(
+        &TimeoutTimer,
+        &QTimer::timeout,
+        &EventLoop,
+        &QEventLoop::quit);
+
+    p_Port->p_Context->Service->writeCharacteristic(
+        p_Port->p_Context->RxCharacteristic,
+        ByteArray,
+        QLowEnergyService::WriteWithResponse);
+    TimeoutTimer.start(TimeoutMs > 0 ? TimeoutMs : 3000);
+    EventLoop.exec();
+
+    return IsWritten;
 }
diff --git a/KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.h b/KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.h
index c33033f..19898cc 100644
--- a/KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.h
+++ b/KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.h
@@ -4,6 +4,8 @@
 #include <QtCore/QString>
 #include <QtCore/QVector>
 
+struct Dri_Gatt_Struct_Context;
+
 struct Dri_Gatt_Struct_PortInfo
 {
     QString DeviceName;
@@ -17,7 +19,9 @@ struct Dri_Gatt_Struct_OpenConfig
 struct Dri_Gatt_Struct_Port
 {
     bool IsOpened = false;
+    QString DeviceName;
     QString DeviceAddress;
+    Dri_Gatt_Struct_Context* p_Context = nullptr;
 };
 
 QVector<Dri_Gatt_Struct_PortInfo> Dri_Gatt_Enum();
diff --git a/KeyBorad/proto/keyboard.options b/KeyBorad/proto/keyboard.options
index 4d42cc9..aa4c5f2 100644
--- a/KeyBorad/proto/keyboard.options
+++ b/KeyBorad/proto/keyboard.options
@@ -1,2 +1,2 @@
-CdcFrame.payload max_size:64
-Bitmap.usage_bitmap max_size:29
+keyboard.cdc.CdcFrame.payload max_size:64
+keyboard.cdc.Bitmap.usage_bitmap max_size:29
diff --git a/app.overlay b/app.overlay
index 5063ee8..3e0b9a2 100644
--- a/app.overlay
+++ b/app.overlay
@@ -36,7 +36,7 @@
     };
 };
 
-&zephyr_udc0 {
+&usbd {
     cdc_acm_uart0: cdc_acm_uart0 {
         compatible = "zephyr,cdc-acm-uart";
         label = "new_kbd CDC ACM";
diff --git a/docs/firmware_proto_transport.md b/docs/firmware_proto_transport.md
index e38af58..65cfc84 100644
--- a/docs/firmware_proto_transport.md
+++ b/docs/firmware_proto_transport.md
@@ -80,6 +80,8 @@ Implemented behavior:
 - enable CDC ACM class in Zephyr USB device-next stack
 - add a CDC ACM UART node in devicetree
 - wire `zephyr_nanopb_sources()` into the build
+- force nanopb generation to use the NCS toolchain Python instead of the
+  broken Windows app alias
 - add protocol helper functions for:
   - body encode/decode
   - CDC frame encode
diff --git a/docs/host_dri_rebuild.md b/docs/host_dri_rebuild.md
index b6dfc06..e4f25c5 100644
--- a/docs/host_dri_rebuild.md
+++ b/docs/host_dri_rebuild.md
@@ -62,7 +62,30 @@ Implemented behavior:
 - collect device name and address
 - filter to `LowEnergyCoreConfiguration`
 - stop after a short timeout
-### Node 3: CDC transport cleanup
+
+### Node 3: GATT open and raw byte transport
+
+Files updated in this step:
+
+- `KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.h`
+- `KeyBorad/KeyBorad/DRI/GATT/Dri_Gatt.cpp`
+
+Design notes:
+
+- keep transport-only responsibility
+- use Qt Bluetooth instead of custom Win32 BLE code
+- connect, discover service, subscribe, then pass raw bytes upward
+
+Implemented behavior:
+
+- connect to a BLE device by address
+- discover the target custom service
+- resolve RX/TX characteristics
+- enable notify on TX
+- queue raw bytes from TX notify
+- write raw bytes to RX characteristic
+
+### Node 4: CDC transport cleanup
 
 Files updated in this step:
 
diff --git a/inc/keyboard_proto.h b/inc/keyboard_proto.h
index b93aaf5..3c6a62a 100644
--- a/inc/keyboard_proto.h
+++ b/inc/keyboard_proto.h
@@ -20,11 +20,11 @@ enum keyboard_proto_transport {
 };
 
 typedef bool (*keyboard_proto_send_body_fn)(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	void *user_data);
 
 bool keyboard_proto_encode_body(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	uint8_t *buffer,
 	size_t buffer_size,
 	size_t *encoded_size);
@@ -32,11 +32,11 @@ bool keyboard_proto_encode_body(
 bool keyboard_proto_decode_body(
 	const uint8_t *buffer,
 	size_t buffer_size,
-	struct keyboard_cdc_CdcPacketBody *body);
+	keyboard_cdc_CdcPacketBody *body);
 
 bool keyboard_proto_encode_cdc_frame(
 	uint32_t packet_type,
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	uint8_t *buffer,
 	size_t buffer_size,
 	size_t *encoded_size);
@@ -44,19 +44,19 @@ bool keyboard_proto_encode_cdc_frame(
 bool keyboard_proto_try_take_cdc_frame(
 	uint8_t *buffer,
 	size_t *buffer_size,
-	struct keyboard_cdc_CdcFrame *frame);
+	keyboard_cdc_CdcFrame *frame);
 
 bool keyboard_proto_build_function_key_event_body(
 	uint16_t usage,
 	bool pressed,
-	struct keyboard_cdc_CdcPacketBody *body);
+	keyboard_cdc_CdcPacketBody *body);
 
 bool keyboard_proto_build_led_state_body(
 	uint8_t led_mask,
-	struct keyboard_cdc_CdcPacketBody *body);
+	keyboard_cdc_CdcPacketBody *body);
 
 bool keyboard_proto_handle_host_body(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	enum keyboard_proto_transport transport,
 	keyboard_proto_send_body_fn send_fn,
 	void *user_data);
diff --git a/scripts/protoc_nanopb.bat b/scripts/protoc_nanopb.bat
new file mode 100644
index 0000000..740d15c
--- /dev/null
+++ b/scripts/protoc_nanopb.bat
@@ -0,0 +1,5 @@
+@echo off
+setlocal
+set PATH=C:\ncs\toolchains\fd21892d0f\opt\bin;%PATH%
+"C:\ncs\toolchains\fd21892d0f\opt\bin\python.exe" "C:\ncs\v3.2.4\modules\lib\nanopb\generator\protoc" %*
+exit /b %ERRORLEVEL%
diff --git a/src/modules/ble_gatt_proto_module.c b/src/modules/ble_gatt_proto_module.c
index 1a6d557..23670d8 100644
--- a/src/modules/ble_gatt_proto_module.c
+++ b/src/modules/ble_gatt_proto_module.c
@@ -32,6 +32,9 @@ struct ble_gatt_proto_ctx {
 };
 
 static struct ble_gatt_proto_ctx g_ble_proto;
+static bool ble_gatt_proto_send_body(
+	const keyboard_cdc_CdcPacketBody *body,
+	void *user_data);
 
 static void ble_gatt_proto_ccc_changed(
 	const struct bt_gatt_attr *attr,
@@ -50,7 +53,7 @@ static ssize_t ble_gatt_proto_rx_write(
 	uint16_t offset,
 	uint8_t flags)
 {
-	struct keyboard_cdc_CdcPacketBody body;
+	keyboard_cdc_CdcPacketBody body;
 
 	ARG_UNUSED(conn);
 	ARG_UNUSED(attr);
@@ -96,7 +99,7 @@ BT_GATT_SERVICE_DEFINE(
 		    BT_GATT_PERM_READ | BT_GATT_PERM_WRITE));
 
 static bool ble_gatt_proto_send_body(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	void *user_data)
 {
 	uint8_t buffer[KEYBOARD_PROTO_MAX_BODY_SIZE];
@@ -128,7 +131,7 @@ static bool handle_module_state_event(const struct module_state_event *event)
 
 static bool handle_function_key_event(const struct function_key_event *event)
 {
-	struct keyboard_cdc_CdcPacketBody body;
+	keyboard_cdc_CdcPacketBody body;
 
 	if (!keyboard_proto_build_function_key_event_body(event->usage,
 							    event->pressed,
@@ -142,7 +145,7 @@ static bool handle_function_key_event(const struct function_key_event *event)
 
 static bool handle_keyboard_led_event(const struct keyboard_led_event *event)
 {
-	struct keyboard_cdc_CdcPacketBody body;
+	keyboard_cdc_CdcPacketBody body;
 
 	if (!keyboard_proto_build_led_state_body(
 		    keyboard_led_event_get_mask(event),
diff --git a/src/modules/keyboard_proto.c b/src/modules/keyboard_proto.c
index 8f98b10..6c489c5 100644
--- a/src/modules/keyboard_proto.c
+++ b/src/modules/keyboard_proto.c
@@ -3,6 +3,7 @@
 #include <string.h>
 
 #include <zephyr/sys/byteorder.h>
+#include <zephyr/sys/util.h>
 
 #include "display_theme_event.h"
 #include "function_bitmap_event.h"
@@ -48,23 +49,8 @@ static uint8_t keyboard_proto_calc_checksum(const uint8_t *data, size_t len)
 	return checksum;
 }
 
-static bool keyboard_proto_fill_payload(
-	pb_bytes_array_t *dest,
-	size_t max_size,
-	const uint8_t *src,
-	size_t src_len)
-{
-	if ((dest == NULL) || (src == NULL) || (src_len > max_size)) {
-		return false;
-	}
-
-	dest->size = src_len;
-	memcpy(dest->bytes, src, src_len);
-	return true;
-}
-
 bool keyboard_proto_encode_body(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	uint8_t *buffer,
 	size_t buffer_size,
 	size_t *encoded_size)
@@ -88,7 +74,7 @@ bool keyboard_proto_encode_body(
 bool keyboard_proto_decode_body(
 	const uint8_t *buffer,
 	size_t buffer_size,
-	struct keyboard_cdc_CdcPacketBody *body)
+	keyboard_cdc_CdcPacketBody *body)
 {
 	pb_istream_t stream;
 
@@ -96,7 +82,10 @@ bool keyboard_proto_decode_body(
 		return false;
 	}
 
-	*body = keyboard_cdc_CdcPacketBody_init_zero;
+	{
+		keyboard_cdc_CdcPacketBody empty = keyboard_cdc_CdcPacketBody_init_zero;
+		*body = empty;
+	}
 	stream = pb_istream_from_buffer(buffer, buffer_size);
 
 	if (!pb_decode(&stream, keyboard_cdc_CdcPacketBody_fields, body)) {
@@ -108,12 +97,12 @@ bool keyboard_proto_decode_body(
 
 bool keyboard_proto_encode_cdc_frame(
 	uint32_t packet_type,
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	uint8_t *buffer,
 	size_t buffer_size,
 	size_t *encoded_size)
 {
-	struct keyboard_cdc_CdcFrame frame = keyboard_cdc_CdcFrame_init_zero;
+	keyboard_cdc_CdcFrame frame = keyboard_cdc_CdcFrame_init_zero;
 	uint8_t payload[KEYBOARD_PROTO_MAX_BODY_SIZE];
 	size_t payload_size = 0U;
 	pb_ostream_t stream;
@@ -131,10 +120,11 @@ bool keyboard_proto_encode_cdc_frame(
 	frame.head2 = 0x55U;
 	frame.payload_length = payload_size;
 	frame.type = (keyboard_cdc_CdcPacketType)packet_type;
-	if (!keyboard_proto_fill_payload(&frame.payload, KEYBOARD_PROTO_MAX_BODY_SIZE,
-					 payload, payload_size)) {
+	if (payload_size > KEYBOARD_PROTO_MAX_BODY_SIZE) {
 		return false;
 	}
+	frame.payload.size = payload_size;
+	memcpy(frame.payload.bytes, payload, payload_size);
 
 	checksum_bytes[0] = (uint8_t)frame.head1;
 	checksum_bytes[1] = (uint8_t)frame.head2;
@@ -154,7 +144,7 @@ bool keyboard_proto_encode_cdc_frame(
 	return true;
 }
 
-static bool keyboard_proto_validate_frame(const struct keyboard_cdc_CdcFrame *frame)
+static bool keyboard_proto_validate_frame(const keyboard_cdc_CdcFrame *frame)
 {
 	uint8_t checksum_bytes[4U + KEYBOARD_PROTO_MAX_BODY_SIZE];
 	uint8_t checksum;
@@ -181,10 +171,10 @@ static bool keyboard_proto_validate_frame(const struct keyboard_cdc_CdcFrame *fr
 bool keyboard_proto_try_take_cdc_frame(
 	uint8_t *buffer,
 	size_t *buffer_size,
-	struct keyboard_cdc_CdcFrame *frame)
+	keyboard_cdc_CdcFrame *frame)
 {
 	for (size_t candidate_len = 1U; candidate_len <= *buffer_size; ++candidate_len) {
-		struct keyboard_cdc_CdcFrame candidate = keyboard_cdc_CdcFrame_init_zero;
+		keyboard_cdc_CdcFrame candidate = keyboard_cdc_CdcFrame_init_zero;
 		pb_istream_t stream = pb_istream_from_buffer(buffer, candidate_len);
 
 		if (!pb_decode(&stream, keyboard_cdc_CdcFrame_fields, &candidate)) {
@@ -206,9 +196,12 @@ bool keyboard_proto_try_take_cdc_frame(
 }
 
 static bool keyboard_proto_build_hello_rsp_body(
-	struct keyboard_cdc_CdcPacketBody *body)
+	keyboard_cdc_CdcPacketBody *body)
 {
-	*body = keyboard_cdc_CdcPacketBody_init_zero;
+	{
+		keyboard_cdc_CdcPacketBody empty = keyboard_cdc_CdcPacketBody_init_zero;
+		*body = empty;
+	}
 	body->which_body = KB_PROTO_BODY_TAG_HELLO_RSP;
 	body->body.hello_rsp.protocol_version = 1U;
 	body->body.hello_rsp.vendor_id = 0x1209U;
@@ -221,9 +214,12 @@ static bool keyboard_proto_build_hello_rsp_body(
 
 static bool keyboard_proto_build_ack_body(
 	uint32_t acked_type,
-	struct keyboard_cdc_CdcPacketBody *body)
+	keyboard_cdc_CdcPacketBody *body)
 {
-	*body = keyboard_cdc_CdcPacketBody_init_zero;
+	{
+		keyboard_cdc_CdcPacketBody empty = keyboard_cdc_CdcPacketBody_init_zero;
+		*body = empty;
+	}
 	body->which_body = KB_PROTO_BODY_TAG_ACK;
 	body->body.ack.acked_type = acked_type;
 	return true;
@@ -232,9 +228,12 @@ static bool keyboard_proto_build_ack_body(
 static bool keyboard_proto_build_error_body(
 	uint32_t error_type,
 	uint32_t error_code,
-	struct keyboard_cdc_CdcPacketBody *body)
+	keyboard_cdc_CdcPacketBody *body)
 {
-	*body = keyboard_cdc_CdcPacketBody_init_zero;
+	{
+		keyboard_cdc_CdcPacketBody empty = keyboard_cdc_CdcPacketBody_init_zero;
+		*body = empty;
+	}
 	body->which_body = KB_PROTO_BODY_TAG_ERROR;
 	body->body.error.error_type = error_type;
 	body->body.error.error_code = (keyboard_cdc_ErrorCode)error_code;
@@ -244,13 +243,16 @@ static bool keyboard_proto_build_error_body(
 bool keyboard_proto_build_function_key_event_body(
 	uint16_t usage,
 	bool pressed,
-	struct keyboard_cdc_CdcPacketBody *body)
+	keyboard_cdc_CdcPacketBody *body)
 {
 	if (body == NULL) {
 		return false;
 	}
 
-	*body = keyboard_cdc_CdcPacketBody_init_zero;
+	{
+		keyboard_cdc_CdcPacketBody empty = keyboard_cdc_CdcPacketBody_init_zero;
+		*body = empty;
+	}
 	body->which_body = KB_PROTO_BODY_TAG_FUNCTION_KEY_EVENT;
 	body->body.function_key_event.usage = usage;
 	body->body.function_key_event.action = pressed ? 1U : 0U;
@@ -259,24 +261,27 @@ bool keyboard_proto_build_function_key_event_body(
 
 bool keyboard_proto_build_led_state_body(
 	uint8_t led_mask,
-	struct keyboard_cdc_CdcPacketBody *body)
+	keyboard_cdc_CdcPacketBody *body)
 {
 	if (body == NULL) {
 		return false;
 	}
 
-	*body = keyboard_cdc_CdcPacketBody_init_zero;
+	{
+		keyboard_cdc_CdcPacketBody empty = keyboard_cdc_CdcPacketBody_init_zero;
+		*body = empty;
+	}
 	body->which_body = KB_PROTO_BODY_TAG_LED_STATE;
 	body->body.led_state.led_mask = led_mask;
 	return true;
 }
 
 static bool keyboard_proto_handle_bitmap(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	keyboard_proto_send_body_fn send_fn,
 	void *user_data)
 {
-	struct keyboard_cdc_CdcPacketBody response;
+	keyboard_cdc_CdcPacketBody response;
 
 	if (body->body.bitmap.usage_bitmap.size != KEYBOARD_PROTO_FUNCTION_BITMAP_SIZE) {
 		keyboard_proto_build_error_body(KB_PROTO_PACKET_BITMAP,
@@ -292,13 +297,13 @@ static bool keyboard_proto_handle_bitmap(
 }
 
 static bool keyboard_proto_handle_time_sync(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	enum keyboard_proto_transport transport,
 	keyboard_proto_send_body_fn send_fn,
 	void *user_data)
 {
 	struct time_sync_update update;
-	struct keyboard_cdc_CdcPacketBody response;
+	keyboard_cdc_CdcPacketBody response;
 
 	if (!time_manager_is_ready()) {
 		keyboard_proto_build_error_body(KB_PROTO_PACKET_TIME_SYNC,
@@ -326,11 +331,11 @@ static bool keyboard_proto_handle_time_sync(
 }
 
 static bool keyboard_proto_handle_theme_rgb(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	keyboard_proto_send_body_fn send_fn,
 	void *user_data)
 {
-	struct keyboard_cdc_CdcPacketBody response;
+	keyboard_cdc_CdcPacketBody response;
 
 	display_theme_event_submit((uint8_t)body->body.theme_rgb.red,
 				   (uint8_t)body->body.theme_rgb.green,
@@ -341,12 +346,12 @@ static bool keyboard_proto_handle_theme_rgb(
 }
 
 bool keyboard_proto_handle_host_body(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	enum keyboard_proto_transport transport,
 	keyboard_proto_send_body_fn send_fn,
 	void *user_data)
 {
-	struct keyboard_cdc_CdcPacketBody response;
+	keyboard_cdc_CdcPacketBody response;
 
 	if ((body == NULL) || (send_fn == NULL)) {
 		return false;
diff --git a/src/modules/usb_cdc_proto_module.c b/src/modules/usb_cdc_proto_module.c
index 4042511..0c99dbc 100644
--- a/src/modules/usb_cdc_proto_module.c
+++ b/src/modules/usb_cdc_proto_module.c
@@ -32,7 +32,7 @@ static struct usb_cdc_proto_ctx g_usb_cdc = {
 };
 
 static uint32_t keyboard_proto_packet_type_from_body(
-	const struct keyboard_cdc_CdcPacketBody *body)
+	const keyboard_cdc_CdcPacketBody *body)
 {
 	switch (body->which_body) {
 	case 1U:
@@ -59,7 +59,7 @@ static uint32_t keyboard_proto_packet_type_from_body(
 }
 
 static bool usb_cdc_proto_send_body(
-	const struct keyboard_cdc_CdcPacketBody *body,
+	const keyboard_cdc_CdcPacketBody *body,
 	void *user_data)
 {
 	struct usb_cdc_proto_ctx *ctx = user_data;
@@ -88,8 +88,8 @@ static bool usb_cdc_proto_send_body(
 
 static void usb_cdc_proto_process_rx_work(struct k_work *work)
 {
-	struct keyboard_cdc_CdcFrame frame;
-	struct keyboard_cdc_CdcPacketBody body;
+	keyboard_cdc_CdcFrame frame;
+	keyboard_cdc_CdcPacketBody body;
 
 	ARG_UNUSED(work);
 
@@ -162,7 +162,7 @@ static bool handle_module_state_event(const struct module_state_event *event)
 
 static bool handle_function_key_event(const struct function_key_event *event)
 {
-	struct keyboard_cdc_CdcPacketBody body;
+	keyboard_cdc_CdcPacketBody body;
 
 	if (!g_usb_cdc.ready) {
 		return false;
@@ -180,7 +180,7 @@ static bool handle_function_key_event(const struct function_key_event *event)
 
 static bool handle_keyboard_led_event(const struct keyboard_led_event *event)
 {
-	struct keyboard_cdc_CdcPacketBody body;
+	keyboard_cdc_CdcPacketBody body;
 
 	if (!g_usb_cdc.ready) {
 		return false;