diff --git a/CMakeLists.txt b/CMakeLists.txt
index 65fc184..745ba70 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -309,6 +309,7 @@ install(FILES
   ${CMAKE_CURRENT_SOURCE_DIR}/include/mynteye/device/callbacks.h
   ${CMAKE_CURRENT_SOURCE_DIR}/include/mynteye/device/context.h
   ${CMAKE_CURRENT_SOURCE_DIR}/include/mynteye/device/device.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/include/mynteye/device/types.h
   ${CMAKE_CURRENT_SOURCE_DIR}/include/mynteye/device/utils.h
   DESTINATION ${MYNTEYE_CMAKE_INCLUDE_DIR}/device
 )
diff --git a/include/mynteye/device/device.h b/include/mynteye/device/device.h
index 6dded7a..30634b9 100644
--- a/include/mynteye/device/device.h
+++ b/include/mynteye/device/device.h
@@ -22,8 +22,8 @@
 #include <vector>
 
 #include "mynteye/mynteye.h"
-#include "mynteye/types.h"
 #include "mynteye/device/callbacks.h"
+#include "mynteye/device/types.h"
 
 MYNTEYE_BEGIN_NAMESPACE
 
@@ -51,26 +51,6 @@ class StreamsAdapter;
 template <class Data>
 class AsyncCallback;
 
-namespace device {
-
-typedef struct ImgParams {
-  bool ok;
-  std::string version;
-  std::shared_ptr<IntrinsicsBase> in_left;
-  std::shared_ptr<IntrinsicsBase> in_right;
-  Extrinsics ex_right_to_left;
-} img_params_t;
-
-typedef struct ImuParams {
-  bool ok;
-  std::string version;
-  ImuIntrinsics in_accel;
-  ImuIntrinsics in_gyro;
-  Extrinsics ex_left_to_imu;
-} imu_params_t;
-
-}  // namespace device
-
 /**
  * The Device class to communicate with MYNT® EYE device.
  */
@@ -89,6 +69,7 @@ class MYNTEYE_API Device {
   using motion_async_callback_ptr_t = std::shared_ptr<motion_async_callback_t>;
 
   using img_params_t = device::img_params_t;
+  using img_params_map_t = std::map<Resolution, img_params_t>;
   using imu_params_t = device::imu_params_t;
 
  protected:
@@ -337,10 +318,10 @@ class MYNTEYE_API Device {
 
   virtual Capabilities GetKeyStreamCapability() const = 0;
 
-  std::map<Resolution, device::img_params_t> GetImgParams() const {
+  img_params_map_t GetImgParams() const {
     return all_img_params_;
   }
-  device::imu_params_t GetImuParams() const {
+  imu_params_t GetImuParams() const {
     return imu_params_;
   }
 
@@ -352,8 +333,8 @@ class MYNTEYE_API Device {
   std::shared_ptr<uvc::device> device_;
   std::shared_ptr<DeviceInfo> device_info_;
 
-  std::map<Resolution, device::img_params_t> all_img_params_;
-  device::imu_params_t imu_params_;
+  img_params_map_t all_img_params_;
+  imu_params_t imu_params_;
 
   std::map<Stream, std::shared_ptr<IntrinsicsBase>> stream_intrinsics_;
   std::map<Stream, std::map<Stream, Extrinsics>> stream_from_extrinsics_;
@@ -384,6 +365,11 @@ class MYNTEYE_API Device {
   void CallbackPushedStreamData(const Stream &stream);
   void CallbackMotionData(const device::MotionData &data);
 
+  bool GetFiles(
+      DeviceInfo *info, img_params_map_t *img_params, imu_params_t *imu_params);
+  bool SetFiles(
+      DeviceInfo *info, img_params_map_t *img_params, imu_params_t *imu_params);
+
   friend API;
   friend tools::DeviceWriter;
 };
diff --git a/src/mynteye/device/types.h b/include/mynteye/device/types.h
similarity index 73%
rename from src/mynteye/device/types.h
rename to include/mynteye/device/types.h
index 41b372a..7ad1b75 100644
--- a/src/mynteye/device/types.h
+++ b/include/mynteye/device/types.h
@@ -18,13 +18,35 @@
 #include <cstdint>
 #include <array>
 #include <bitset>
+#include <memory>
 #include <string>
 #include <vector>
 
 #include "mynteye/mynteye.h"
+#include "mynteye/types.h"
 
 MYNTEYE_BEGIN_NAMESPACE
 
+namespace device {
+
+typedef struct ImgParams {
+  bool ok;
+  std::string version;
+  std::shared_ptr<IntrinsicsBase> in_left;
+  std::shared_ptr<IntrinsicsBase> in_right;
+  Extrinsics ex_right_to_left;
+} img_params_t;
+
+typedef struct ImuParams {
+  bool ok;
+  std::string version;
+  ImuIntrinsics in_accel;
+  ImuIntrinsics in_gyro;
+  Extrinsics ex_left_to_imu;
+} imu_params_t;
+
+}  // namespace device
+
 #define MYNTEYE_PROPERTY(TYPE, NAME) \
  public:                             \
   void set_##NAME(TYPE NAME) {       \
@@ -142,73 +164,6 @@ struct MYNTEYE_API DeviceInfo {
   std::uint16_t nominal_baseline;
 };
 
-/**
- * @ingroup datatypes
- * Imu request packet.
- */
-#pragma pack(push, 1)
-struct ImuReqPacket {
-  std::uint8_t header;
-  std::uint32_t serial_number;
-
-  ImuReqPacket() = default;
-  explicit ImuReqPacket(std::uint32_t serial_number)
-      : ImuReqPacket(0x5A, serial_number) {}
-  ImuReqPacket(std::uint8_t header, std::uint32_t serial_number)
-      : header(header), serial_number(serial_number) {}
-
-  std::array<std::uint8_t, 5> to_data() const {
-    return {{header, static_cast<std::uint8_t>((serial_number >> 24) & 0xFF),
-             static_cast<std::uint8_t>((serial_number >> 16) & 0xFF),
-             static_cast<std::uint8_t>((serial_number >> 8) & 0xFF),
-             static_cast<std::uint8_t>(serial_number & 0xFF)}};
-  }
-};
-#pragma pack(pop)
-
-/**
- * @ingroup datatypes
- * Imu segment.
- */
-#pragma pack(push, 1)
-struct ImuSegment {
-  std::uint32_t frame_id;
-  std::uint64_t timestamp;
-  std::uint8_t flag;
-  std::int16_t temperature;
-  std::int16_t accel[3];
-  std::int16_t gyro[3];
-};
-#pragma pack(pop)
-
-/**
- * @ingroup datatypes
- * Imu packet.
- */
-#pragma pack(push, 1)
-struct ImuPacket {
-  std::uint8_t version;
-  std::uint8_t count;
-  std::uint32_t serial_number;
-  std::vector<ImuSegment> segments;
-};
-#pragma pack(pop)
-
-/**
- * @ingroup datatypes
- * Imu response packet.
- */
-#pragma pack(push, 1)
-struct ImuResPacket {
-  std::uint8_t version;
-  std::uint8_t header;
-  std::uint8_t state;
-  std::uint16_t size;
-  std::vector<ImuPacket> packets;
-  std::uint8_t checksum;
-};
-#pragma pack(pop)
-
 #undef MYNTEYE_PROPERTY
 
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/channel/def.h b/src/mynteye/device/channel/def.h
index 7e5d39e..a903854 100644
--- a/src/mynteye/device/channel/def.h
+++ b/src/mynteye/device/channel/def.h
@@ -15,6 +15,10 @@
 #define MYNTEYE_DEVICE_CHANNEL_DEF_H_
 #pragma once
 
+#include <array>
+#include <cstdint>
+#include <vector>
+
 #include "mynteye/mynteye.h"
 
 MYNTEYE_BEGIN_NAMESPACE
@@ -35,6 +39,73 @@ typedef enum FileId {
   FID_LAST,
 } file_id_t;
 
+/**
+ * @ingroup datatypes
+ * Imu request packet.
+ */
+#pragma pack(push, 1)
+struct ImuReqPacket {
+  std::uint8_t header;
+  std::uint32_t serial_number;
+
+  ImuReqPacket() = default;
+  explicit ImuReqPacket(std::uint32_t serial_number)
+      : ImuReqPacket(0x5A, serial_number) {}
+  ImuReqPacket(std::uint8_t header, std::uint32_t serial_number)
+      : header(header), serial_number(serial_number) {}
+
+  std::array<std::uint8_t, 5> to_data() const {
+    return {{header, static_cast<std::uint8_t>((serial_number >> 24) & 0xFF),
+             static_cast<std::uint8_t>((serial_number >> 16) & 0xFF),
+             static_cast<std::uint8_t>((serial_number >> 8) & 0xFF),
+             static_cast<std::uint8_t>(serial_number & 0xFF)}};
+  }
+};
+#pragma pack(pop)
+
+/**
+ * @ingroup datatypes
+ * Imu segment.
+ */
+#pragma pack(push, 1)
+struct ImuSegment {
+  std::uint32_t frame_id;
+  std::uint64_t timestamp;
+  std::uint8_t flag;
+  std::int16_t temperature;
+  std::int16_t accel[3];
+  std::int16_t gyro[3];
+};
+#pragma pack(pop)
+
+/**
+ * @ingroup datatypes
+ * Imu packet.
+ */
+#pragma pack(push, 1)
+struct ImuPacket {
+  std::uint8_t version;
+  std::uint8_t count;
+  std::uint32_t serial_number;
+  std::vector<ImuSegment> segments;
+};
+#pragma pack(pop)
+
+/**
+ * @ingroup datatypes
+ * Imu response packet.
+ */
+#pragma pack(push, 1)
+struct ImuResPacket {
+  std::uint8_t version;
+  std::uint8_t header;
+  std::uint8_t state;
+  std::uint16_t size;
+  std::vector<ImuPacket> packets;
+  std::uint8_t checksum;
+};
+#pragma pack(pop)
+
 MYNTEYE_END_NAMESPACE
 
 #endif  // MYNTEYE_DEVICE_CHANNEL_DEF_H_
diff --git a/src/mynteye/device/device.cc b/src/mynteye/device/device.cc
index a539a2f..372d62e 100644
--- a/src/mynteye/device/device.cc
+++ b/src/mynteye/device/device.cc
@@ -676,4 +676,14 @@ void Device::CallbackMotionData(const device::MotionData &data) {
   }
 }
 
+bool Device::GetFiles(
+    DeviceInfo *info, img_params_map_t *img_params, imu_params_t *imu_params) {
+  return channels_->GetFiles(info, img_params, imu_params);
+}
+
+bool Device::SetFiles(
+    DeviceInfo *info, img_params_map_t *img_params, imu_params_t *imu_params) {
+  return channels_->SetFiles(info, img_params, imu_params);
+}
+
 MYNTEYE_END_NAMESPACE
diff --git a/tools/writer/CMakeLists.txt b/tools/writer/CMakeLists.txt
index f62cf3e..93b2a10 100644
--- a/tools/writer/CMakeLists.txt
+++ b/tools/writer/CMakeLists.txt
@@ -20,10 +20,6 @@ set_outdir(
   "${OUT_DIR}/bin/${DIR_NAME}"
 )
 
-include_directories(
-  ${PRO_DIR}/src
-)
-
 ## device_writer
 
 add_library(device_writer STATIC device_writer.cc)
diff --git a/tools/writer/device_writer.cc b/tools/writer/device_writer.cc
index a164dc0..cb57712 100644
--- a/tools/writer/device_writer.cc
+++ b/tools/writer/device_writer.cc
@@ -18,7 +18,6 @@
 #include <opencv2/core/core.hpp>
 
 #include "mynteye/logger.h"
-#include "mynteye/device/device.h"
 #include "mynteye/util/files.h"
 
 #define SAVE_LATEST_VERSION Version(1, 2)
@@ -36,15 +35,13 @@ DeviceWriter::~DeviceWriter() {
 }
 
 bool DeviceWriter::WriteDeviceInfo(const dev_info_t &info) {
-  auto &&channels = device_->channels();
-
   // Update device info
   auto &&dev_info = device_->GetInfo();
   dev_info->lens_type = Type(info.lens_type);
   dev_info->imu_type = Type(info.imu_type);
   dev_info->nominal_baseline = info.nominal_baseline;
 
-  if (channels->SetFiles(dev_info.get(), nullptr, nullptr)) {
+  if (device_->SetFiles(dev_info.get(), nullptr, nullptr)) {
     LOG(INFO) << "Write device info success";
     LOG(INFO) << "Device info: {name: " << dev_info->name
               << ", serial_number: " << dev_info->serial_number
@@ -68,8 +65,6 @@ bool DeviceWriter::WriteDeviceInfo(const std::string &filepath) {
 }
 
 bool DeviceWriter::WriteImgParams(const img_params_map_t &img_params_map) {
-  auto &&channels = device_->channels();
-
   img_params_map_t *img_params_new =
       const_cast<img_params_map_t *>(&img_params_map);
   // Update image params with raw
@@ -81,7 +76,7 @@ bool DeviceWriter::WriteImgParams(const img_params_map_t &img_params_map) {
     }
   }
 
-  if (channels->SetFiles(nullptr, img_params_new, nullptr)) {
+  if (device_->SetFiles(nullptr, img_params_new, nullptr)) {
     LOG(INFO) << "Write img params success";
     for (auto it = img_params_new->begin(); it != img_params_new->end(); it++) {
       LOG(INFO) << "Resolution: {width: " << (*it).first.width
@@ -103,8 +98,7 @@ bool DeviceWriter::WriteImgParams(const std::string &filepath) {
 }
 
 bool DeviceWriter::WriteImuParams(const imu_params_t &params) {
-  auto &&channels = device_->channels();
-  if (channels->SetFiles(
+  if (device_->SetFiles(
           nullptr, nullptr, const_cast<imu_params_t *>(&params))) {
     LOG(INFO) << "Write imu params success";
     LOG(INFO) << "Imu intrinsics accel: {" << params.in_accel << "}";
diff --git a/tools/writer/device_writer.h b/tools/writer/device_writer.h
index f3a7af2..1e36ed5 100644
--- a/tools/writer/device_writer.h
+++ b/tools/writer/device_writer.h
@@ -19,9 +19,7 @@
 #include <memory>
 #include <string>
 
-#include "mynteye/mynteye.h"
-#include "mynteye/device/channel/channels.h"
-#include "mynteye/device/types.h"
+#include "mynteye/device/device.h"
 
 MYNTEYE_BEGIN_NAMESPACE