diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp
index db6b149..ee77b45 100644
--- a/cores/arduino/HardwareSerial.cpp
+++ b/cores/arduino/HardwareSerial.cpp
@@ -50,6 +50,10 @@ struct ring_buffer
   volatile int tail;
 };
 
+#if defined(USBCON)
+  ring_buffer rx_buffer = { { 0 }, 0, 0};
+  ring_buffer tx_buffer = { { 0 }, 0, 0};
+#endif
 #if defined(UBRRH) || defined(UBRR0H)
   ring_buffer rx_buffer  =  { { 0 }, 0, 0 };
   ring_buffer tx_buffer  =  { { 0 }, 0, 0 };
@@ -81,6 +85,15 @@ inline void store_char(unsigned char c, ring_buffer *buffer)
   }
 }
 
+#if defined(__AVR_ATmega32U4__)
+  void serialEvent() __attribute__((weak));
+  void serialEvent() {}
+  SIGNAL(USART1_RX_vect) {
+    unsigned char c = UDR1;
+    store_char(c, &rx_buffer);
+	  serialEvent();
+  }
+#else
 #if !defined(USART_RX_vect) && !defined(SIG_USART0_RECV) && \
     !defined(SIG_UART0_RECV) && !defined(USART0_RX_vect) && \
 	!defined(SIG_UART_RECV)
@@ -150,8 +163,19 @@ inline void store_char(unsigned char c, ring_buffer *buffer)
 #elif defined(SIG_USART3_RECV)
   #error SIG_USART3_RECV
 #endif
+#endif
 
-
+#if defined(__AVR_ATmega32U4__)
+ISR(USART1_UDRE_vect) {
+  if (tx_buffer.head == tx_buffer.tail) {
+    cbi(UCSR1B, UDRIE1);  
+  } else {
+	unsigned char c = tx_buffer.buffer[tx_buffer.tail];
+    tx_buffer.tail = (tx_buffer.tail + 1) % SERIAL_BUFFER_SIZE;  
+    UDR1 = c;
+  }
+}
+#else
 #if !defined(UART0_UDRE_vect) && !defined(UART_UDRE_vect) && !defined(USART0_UDRE_vect) && !defined(USART_UDRE_vect)
   #error Don't know what the Data Register Empty vector is called for the first UART
 #else
@@ -205,6 +229,7 @@ ISR(USART1_UDRE_vect)
   }
 }
 #endif
+#endif
 
 #ifdef USART2_UDRE_vect
 ISR(USART2_UDRE_vect)
diff --git a/cores/arduino/HardwareSerial.h b/cores/arduino/HardwareSerial.h
index eefdcbe..a5b1ed3 100644
--- a/cores/arduino/HardwareSerial.h
+++ b/cores/arduino/HardwareSerial.h
@@ -63,6 +63,7 @@ class HardwareSerial : public Stream
   extern HardwareSerial Serial;
 #elif defined(USBCON)
   #include "usb_api.h"
+  extern HardwareSerial Serial_;
 #endif
 #if defined(UBRR1H)
   extern HardwareSerial Serial1;
diff --git a/cores/arduino/usb_api.h b/cores/arduino/usb_api.h
new file mode 100644
index 0000000..4d26d23
--- /dev/null
+++ b/cores/arduino/usb_api.h
@@ -0,0 +1,156 @@
+
+
+#ifndef __USBAPI__
+#define __USBAPI__
+
+//================================================================================
+//================================================================================
+//	USB
+
+class USB_
+{
+public:
+	USB_();
+	bool configured();
+
+	void attach();
+	void detach();	// Serial port goes down too...
+	void poll();
+};
+extern USB_ USB;
+
+//================================================================================
+//================================================================================
+//	Serial over CDC (Serial1 is the physical port)
+
+class Serial_ : public Stream
+{
+public:
+	void begin(uint16_t baud_count);
+	void end(void);
+
+	virtual int available(void);
+	virtual int peek(void);
+	virtual int read(void);
+	virtual void flush(void);
+	virtual void write(uint8_t);
+};
+extern Serial_ Serial;
+
+//================================================================================
+//================================================================================
+//	Mouse
+
+#define MOUSE_LEFT 1
+#define MOUSE_MIDDLE 2
+#define MOUSE_RIGHT 4
+
+class Mouse_
+{
+	uint8_t _buttons;
+public:
+	Mouse_();
+	void click(uint8_t b = MOUSE_LEFT);
+	void move(signed char x, signed char y, signed char wheel = 0);
+	void buttons(uint8_t b);
+};
+extern Mouse_ Mouse;
+
+//================================================================================
+//================================================================================
+//	Keyboard
+
+#define KEY_MODIFIER_LEFT_CTRL		0x01
+#define KEY_MODIFIER_LEFT_SHIFT		0x02
+#define KEY_MODIFIER_LEFT_ALT		0x04
+#define KEY_MODIFIER_LEFT_GUI		0x08
+#define KEY_MODIFIER_RIGHT_CTRL		0x010
+#define KEY_MODIFIER_RIGHT_SHIFT	0x020
+#define KEY_MODIFIER_RIGHT_ALT		0x040
+#define KEY_MODIFIER_RIGHT_GUI		0x080
+
+//	Low level key report: up to 6 keys and shift, ctrl etc at once
+typedef struct
+{
+	uint8_t modifiers;
+	uint8_t reserved;
+	uint8_t keys[6];
+} KeyReport;
+
+//	Map a character into a key report
+//	Called from Print to map text to keycodes
+class KeyMap
+{
+public:
+	virtual void charToKey(int c, KeyReport* keyReport) = 0;
+};
+
+//	
+class Keyboard_ : public Print
+{
+	KeyMap* _keyMap;
+public:
+	Keyboard_();
+	void sendReport(KeyReport* keys);
+	void setKeyMap(KeyMap* keyMap);
+	virtual void write(uint8_t);
+};
+extern Keyboard_ Keyboard;
+
+//================================================================================
+//================================================================================
+//	Low level API
+
+typedef struct
+{
+	uint8_t bmRequestType;
+	uint8_t bRequest;
+	uint8_t wValueL;
+	uint8_t wValueH;
+	uint16_t wIndex;
+	uint16_t wLength;
+} Setup;
+
+//================================================================================
+//================================================================================
+//	HID 'Driver'
+
+int		HID_GetInterface(uint8_t* interfaceNum);
+int		HID_GetDescriptor(int i);
+bool	HID_Setup(Setup& setup);
+void	HID_SendReport(uint8_t id, const void* data, int len);
+
+//================================================================================
+//================================================================================
+//	MSC 'Driver'
+
+int		MSC_GetInterface(uint8_t* interfaceNum);
+int		MSC_GetDescriptor(int i);
+bool	MSC_Setup(Setup& setup);
+bool	MSC_Data(uint8_t rx,uint8_t tx);
+
+//================================================================================
+//================================================================================
+//	CSC 'Driver'
+
+int		CDC_GetInterface(uint8_t* interfaceNum);
+int		CDC_GetDescriptor(int i);
+bool	CDC_Setup(Setup& setup);
+
+//================================================================================
+//================================================================================
+
+#define TRANSFER_PGM		0x80
+#define TRANSFER_RELEASE	0x40
+#define TRANSFER_ZERO		0x20
+
+int USB_SendControl(uint8_t flags, const void* d, int len);
+int USB_RecvControl(void* d, int len);
+
+uint8_t	USB_Available(uint8_t ep);
+int USB_Send(uint8_t ep, const void* data, int len);	// blocking
+int USB_Recv(uint8_t ep, void* data, int len);		// non-blocking
+int USB_Recv(uint8_t ep);							// non-blocking
+void USB_Flush(uint8_t ep);
+
+#endif
\ No newline at end of file