-void usb_enable();\r
-bool usb_check();\r
-bool usb_poll();\r
-uint32_t usb_read(byte_t* data, size_t len);\r
-uint32_t usb_write(const byte_t* data, const size_t len);\r
-\r
-#endif // _USB_CDC_H_\r
+extern void usb_disable();\r
+extern void usb_enable();\r
+extern bool usb_check();\r
+extern bool usb_poll();\r
+extern bool usb_poll_validate_length();\r
+extern uint32_t usb_read(uint8_t* data, size_t len);\r
+extern uint32_t usb_write(const uint8_t* data, const size_t len);\r