diff --git a/CDC.cpp b/CDC.cpp
index c4e4d1a..79a790b 100644
--- a/CDC.cpp
+++ b/CDC.cpp
@@ -50,8 +50,9 @@ const CDCDescriptor _cdcInterface =
 
 	//	CDC data interface
 	D_INTERFACE(CDC_DATA_INTERFACE, 2, CDC_DATA_INTERFACE_CLASS, 0, 0),
-	D_ENDPOINT(USB_ENDPOINT_OUT(CDC_ENDPOINT_OUT), USB_ENDPOINT_TYPE_BULK, 0x40, 0),
-	D_ENDPOINT(USB_ENDPOINT_IN(CDC_ENDPOINT_IN), USB_ENDPOINT_TYPE_BULK, 0x40, 0)
+	// edit by NicoHood
+	D_ENDPOINT(USB_ENDPOINT_OUT(CDC_ENDPOINT_OUT), USB_ENDPOINT_TYPE_BULK, USB_EP_SIZE, 0),
+	D_ENDPOINT(USB_ENDPOINT_IN(CDC_ENDPOINT_IN), USB_ENDPOINT_TYPE_BULK, USB_EP_SIZE, 0)
 };
 
 int WEAK CDC_GetInterface(u8* interfaceNum)
@@ -96,8 +97,28 @@ bool WEAK CDC_Setup(Setup& setup)
 			// We check DTR state to determine if host port is open (bit 0 of lineState).
 			if (1200 == _usbLineInfo.dwDTERate && (_usbLineInfo.lineState & 0x01) == 0)
 			{
+				// edit by NicoHood
+				// change ram pointer to fit the 16u2's ram size and only use an 8bit value
+#if defined(__AVR_ATmega32U4__)
 				*(uint16_t *)0x0800 = 0x7777;
 				wdt_enable(WDTO_120MS);
+#else
+				// workaround for this issue:
+				// https://github.com/arduino/Arduino/issues/2474
+				// I didn't change this for the 32u4 to simply not touch their code
+				// the correct way would be to add a compiler flag like this:
+				// -Wl,--section-start=.blkey=0x280
+				//volatile uint8_t MagicBootKey __attribute__((section(".blkey")));
+				cli();
+
+				//MagicBootKey = 0x77;
+				*(uint8_t *)0x0280 = 0x77;
+
+				wdt_enable(WDTO_120MS);
+
+				// wait for reset
+				for (;;);
+#endif
 			}
 			else
 			{
@@ -106,9 +127,18 @@ bool WEAK CDC_Setup(Setup& setup)
 				// To avoid spurious resets we set the watchdog to 250ms and eventually
 				// cancel if DTR goes back high.
 
+				// edit by NicoHood
+#if defined(__AVR_ATmega32U4__)
 				wdt_disable();
 				wdt_reset();
 				*(uint16_t *)0x0800 = 0x0;
+#else
+				// not used because of the workaround above
+				//wdt_disable();
+				//wdt_reset();
+				//MagicBootKey = 0x00;
+				//*(uint8_t *)0x0280 = 0x00;
+#endif
 			}
 		}
 		return true;
diff --git a/HID.cpp b/HID.cpp
index 6923607..b578c4b 100644
--- a/HID.cpp
+++ b/HID.cpp
@@ -131,7 +131,8 @@ const HIDDescriptor _hidInterface =
 {
 	D_INTERFACE(HID_INTERFACE, 1, 3, 0, 0),
 	D_HIDREPORT(sizeof(_hidReportDescriptor)),
-	D_ENDPOINT(USB_ENDPOINT_IN(HID_ENDPOINT_INT), USB_ENDPOINT_TYPE_INTERRUPT, 0x40, 0x01)
+	// edit by NicoHood
+	D_ENDPOINT(USB_ENDPOINT_IN(HID_ENDPOINT_INT), USB_ENDPOINT_TYPE_INTERRUPT, USB_EP_SIZE, 0x01)
 };
 
 //================================================================================
diff --git a/USBCore.cpp b/USBCore.cpp
index a44cce4..82aa372 100644
--- a/USBCore.cpp
+++ b/USBCore.cpp
@@ -271,7 +271,8 @@ u8 USB_SendSpace(u8 ep)
 	LockEP lock(ep);
 	if (!ReadWriteAllowed())
 		return 0;
-	return 64 - FifoByteCount();
+	// edit by NicoHood
+	return USB_EP_SIZE - FifoByteCount();
 }
 
 //	Blocking Send of data to an endpoint
@@ -344,6 +345,8 @@ const u8 _initEndpoints[] =
 
 #define EP_SINGLE_64 0x32	// EP0
 #define EP_DOUBLE_64 0x36	// Other endpoints
+// edit by NicoHood
+#define EP_SINGLE_16 0x12
 
 static
 void InitEP(u8 index, u8 type, u8 size)
@@ -362,7 +365,14 @@ void InitEndpoints()
 		UENUM = i;
 		UECONX = (1 << EPEN);
 		UECFG0X = pgm_read_byte(_initEndpoints + i);
+		// edit by NicoHood
+#if USB_EP_SIZE == 16
+		UECFG1X = EP_SINGLE_16;
+#elif USB_EP_SIZE == 64
 		UECFG1X = EP_DOUBLE_64;
+#else
+#error Unsupported value for USB_EP_SIZE
+#endif
 	}
 	UERST = 0x7E;	// And reset them
 	UERST = 0;
@@ -666,16 +676,55 @@ USBDevice_::USBDevice_()
 {
 }
 
+// edit by NicoHood
+// added from teensy definition by paul stoffregen
+#if defined(__AVR_AT90USB82__) || defined(__AVR_AT90USB162__) || defined(__AVR_ATmega32U2__) || defined(__AVR_ATmega16U2__) || defined(__AVR_ATmega8U2__)
+#define HW_CONFIG() 
+#define PLL_CONFIG() (PLLCSR = ((1<<PLLE)|(1<<PLLP0)))
+#define USB_CONFIG() (USBCON = (1<<USBE))
+#define USB_FREEZE() (USBCON = ((1<<USBE)|(1<<FRZCLK)))
+#elif defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega16U4__)
+#define HW_CONFIG() (UHWCON = 0x01)
+#define PLL_CONFIG() (PLLCSR = 0x12)
+#define USB_CONFIG() (USBCON = ((1<<USBE)|(1<<OTGPADE)))
+#define USB_FREEZE() (USBCON = ((1<<USBE)|(1<<FRZCLK)))
+#elif defined(__AVR_AT90USB646__)
+#define HW_CONFIG() (UHWCON = 0x81)
+#define PLL_CONFIG() (PLLCSR = 0x1A)
+#define USB_CONFIG() (USBCON = ((1<<USBE)|(1<<OTGPADE)))
+#define USB_FREEZE() (USBCON = ((1<<USBE)|(1<<FRZCLK)))
+#elif defined(__AVR_AT90USB1286__)
+#define HW_CONFIG() (UHWCON = 0x81)
+#define PLL_CONFIG() (PLLCSR = 0x16)
+#define USB_CONFIG() (USBCON = ((1<<USBE)|(1<<OTGPADE)))
+#define USB_FREEZE() (USBCON = ((1<<USBE)|(1<<FRZCLK)))
+#endif
+
 void USBDevice_::attach()
 {
+	// edit by NicoHood
+	// added support for u2 and u4 Series. Other MCUs not tested, but they could work.
 	_usbConfiguration = 0;
-	UHWCON = 0x01;						// power internal reg
-	USBCON = (1 << USBE) | (1 << FRZCLK);		// clock frozen, usb enabled
+	HW_CONFIG();						// power internal reg
+
+	// from Paul Brook source, TODO needed? (we might change this in a future commit with the USB wakeup)
+	//USBCON = 0;							// Reset controller
+	USB_FREEZE();		// clock frozen, usb enabled
+
 #if F_CPU == 16000000UL
-	PLLCSR = 0x12;						// Need 16 MHz xtal
+	// Need 16 MHz xtal
+#ifdef PINDIV
+	PLLCSR = (1 << PINDIV) | (1 << PLLE);
+#else
+	// added from Paul Brook source, no idea for what board this is used for
+	PLLCSR = (1 << PLLP0) | (1 << PLLE);
+#endif	
+
 #elif F_CPU == 8000000UL
-	PLLCSR = 0x02;						// Need 8 MHz xtal
+	// Need 8 MHz xtal
+	PLLCSR = (1 << PLLE);
 #endif
+
 	while (!(PLLCSR & (1 << PLOCK)))		// wait for lock pll
 		;
 
@@ -684,7 +733,7 @@ void USBDevice_::attach()
 	// port touch at 1200 bps. This delay fixes this behaviour.
 	delay(1);
 
-	USBCON = ((1 << USBE) | (1 << OTGPADE));	// start USB clock
+	USB_CONFIG();	// start USB clock
 	UDIEN = (1 << EORSTE) | (1 << SOFE);		// Enable interrupts for EOR (End of Reset) and SOF (start of frame)
 	UDCON = 0;							// enable attach resistor
 
diff --git a/USBDesc.h b/USBDesc.h
index fb5895a..93e9048 100644
--- a/USBDesc.h
+++ b/USBDesc.h
@@ -58,6 +58,13 @@
 #define HID_TX HID_ENDPOINT_INT
 #endif
 
+// edit by NicoHood
+// this definitions is usefull if you want to reduce the EP_SIZE to 16
+// at the moment only 64 and 16 as EP_SIZE for all EPs are supported except the control endpoint
+#ifndef USB_EP_SIZE
+#define USB_EP_SIZE 64
+#endif
+
 #define IMANUFACTURER	1
 #define IPRODUCT		2
 
diff --git a/wiring_private.h b/wiring_private.h
index d95576a..97e547e 100644
--- a/wiring_private.h
+++ b/wiring_private.h
@@ -52,7 +52,9 @@ extern "C"{
 #define EXTERNAL_INT_6 6
 #define EXTERNAL_INT_7 7
 
-#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(__AVR_ATmega128RFA1__) || defined(__AVR_ATmega256RFR2__)
+	// edit by NicoHood
+#if defined(__AVR_AT90USB82__) || defined(__AVR_AT90USB162__) || defined(__AVR_ATmega32U2__) || defined(__AVR_ATmega16U2__) || defined(__AVR_ATmega8U2__) \
+|| defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(__AVR_ATmega128RFA1__) || defined(__AVR_ATmega256RFR2__)
 #define EXTERNAL_NUM_INTERRUPTS 8
 #elif defined(__AVR_ATmega1284__) || defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega644__) || defined(__AVR_ATmega644A__) || defined(__AVR_ATmega644P__) || defined(__AVR_ATmega644PA__)
 #define EXTERNAL_NUM_INTERRUPTS 3