diff --git a/test/arduino_leonardo_bridge_castrated_cdc/CDC.cpp b/test/arduino_leonardo_bridge_castrated_cdc/CDC.cpp
new file mode 100644
index 00000000..6d2f8efa
--- /dev/null
+++ b/test/arduino_leonardo_bridge_castrated_cdc/CDC.cpp
@@ -0,0 +1,303 @@
+
+
+/* Copyright (c) 2011, Peter Barrett  
+**  
+** Permission to use, copy, modify, and/or distribute this software for  
+** any purpose with or without fee is hereby granted, provided that the  
+** above copyright notice and this permission notice appear in all copies.  
+** 
+** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL  
+** WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED  
+** WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR  
+** BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES  
+** OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,  
+** WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,  
+** ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS  
+** SOFTWARE.  
+*/
+
+#include "USBCore.h" // kai:added
+#include "USBAPI.h"
+#include <avr/wdt.h>
+#include <util/atomic.h>
+
+#if defined(USBCON)
+
+typedef struct
+{
+	u32	dwDTERate;
+	u8	bCharFormat;
+	u8 	bParityType;
+	u8 	bDataBits;
+	u8	lineState;
+} LineInfo;
+
+static volatile LineInfo _usbLineInfo = { 57600, 0x00, 0x00, 0x00, 0x00 };
+static volatile int32_t breakValue = -1;
+
+static u8 wdtcsr_save;
+
+#define WEAK __attribute__ ((weak))
+
+extern const CDCDescriptor _cdcInterface PROGMEM;
+const CDCDescriptor _cdcInterface =
+{
+	D_IAD(0,2,CDC_COMMUNICATION_INTERFACE_CLASS,CDC_ABSTRACT_CONTROL_MODEL,1),
+
+	//	CDC communication interface
+	D_INTERFACE(CDC_ACM_INTERFACE,3,CDC_COMMUNICATION_INTERFACE_CLASS,CDC_ABSTRACT_CONTROL_MODEL,0), // kai
+	D_CDCCS(CDC_HEADER,0x10,0x01),								// Header (1.10 bcd)
+	D_CDCCS(CDC_CALL_MANAGEMENT,1,1),							// Device handles call management (not)
+	D_CDCCS4(CDC_ABSTRACT_CONTROL_MANAGEMENT,6),				// SET_LINE_CODING, GET_LINE_CODING, SET_CONTROL_LINE_STATE supported
+	D_CDCCS(CDC_UNION,CDC_ACM_INTERFACE,CDC_DATA_INTERFACE),	// Communication interface is master, data interface is slave 0
+	D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_ACM),USB_ENDPOINT_TYPE_INTERRUPT,0x10,0x40),
+
+	//	CDC data interface
+	//D_INTERFACE(CDC_DATA_INTERFACE,2,CDC_DATA_INTERFACE_CLASS,0,0), // kai:removed
+	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)
+};
+
+bool isLUFAbootloader()
+{
+	return pgm_read_word(FLASHEND - 1) == NEW_LUFA_SIGNATURE;
+}
+
+int CDC_GetInterface(u8* interfaceNum)
+{
+	interfaceNum[0] += 1;	// kai
+	return USB_SendControl(TRANSFER_PGM,&_cdcInterface,sizeof(_cdcInterface));
+}
+
+bool CDC_Setup(USBSetup& setup)
+{
+	u8 r = setup.bRequest;
+	u8 requestType = setup.bmRequestType;
+
+	if (REQUEST_DEVICETOHOST_CLASS_INTERFACE == requestType)
+	{
+		if (CDC_GET_LINE_CODING == r)
+		{
+			USB_SendControl(0,(void*)&_usbLineInfo,7);
+			return true;
+		}
+	}
+
+	if (REQUEST_HOSTTODEVICE_CLASS_INTERFACE == requestType)
+	{
+		if (CDC_SEND_BREAK == r)
+		{
+			breakValue = ((uint16_t)setup.wValueH << 8) | setup.wValueL;
+		}
+
+		if (CDC_SET_LINE_CODING == r)
+		{
+			USB_RecvControl((void*)&_usbLineInfo,7);
+		}
+
+		if (CDC_SET_CONTROL_LINE_STATE == r)
+		{
+			_usbLineInfo.lineState = setup.wValueL;
+
+			// auto-reset into the bootloader is triggered when the port, already 
+			// open at 1200 bps, is closed.  this is the signal to start the watchdog
+			// with a relatively long period so it can finish housekeeping tasks
+			// like servicing endpoints before the sketch ends
+
+			uint16_t magic_key_pos = MAGIC_KEY_POS;
+
+// If we don't use the new RAMEND directly, check manually if we have a newer bootloader.
+// This is used to keep compatible with the old leonardo bootloaders.
+// You are still able to set the magic key position manually to RAMEND-1 to save a few bytes for this check.
+#if MAGIC_KEY_POS != (RAMEND-1)
+			// For future boards save the key in the inproblematic RAMEND
+			// Which is reserved for the main() return value (which will never return)
+			if (isLUFAbootloader()) {
+				// horray, we got a new bootloader!
+				magic_key_pos = (RAMEND-1);
+			}
+#endif
+
+			// We check DTR state to determine if host port is open (bit 0 of lineState).
+			if (1200 == _usbLineInfo.dwDTERate && (_usbLineInfo.lineState & 0x01) == 0)
+			{
+#if MAGIC_KEY_POS != (RAMEND-1)
+				// Backup ram value if its not a newer bootloader and it hasn't already been saved.
+				// This should avoid memory corruption at least a bit, not fully
+				if (magic_key_pos != (RAMEND-1) && *(uint16_t *)magic_key_pos != MAGIC_KEY) {
+					*(uint16_t *)(RAMEND-1) = *(uint16_t *)magic_key_pos;
+				}
+#endif
+				// Store boot key
+				*(uint16_t *)magic_key_pos = MAGIC_KEY;
+				// Save the watchdog state in case the reset is aborted.
+				wdtcsr_save = WDTCSR;
+				wdt_enable(WDTO_120MS);
+			}
+			else if (*(uint16_t *)magic_key_pos == MAGIC_KEY)
+			{
+				// Most OSs do some intermediate steps when configuring ports and DTR can
+				// twiggle more than once before stabilizing.
+				// To avoid spurious resets we set the watchdog to 120ms and eventually
+				// cancel if DTR goes back high.
+				// Cancellation is only done if an auto-reset was started, which is
+				// indicated by the magic key having been set.
+
+				wdt_reset();
+				// Restore the watchdog state in case the sketch was using it.
+				WDTCSR |= (1<<WDCE) | (1<<WDE);
+				WDTCSR = wdtcsr_save;
+#if MAGIC_KEY_POS != (RAMEND-1)
+				// Restore backed up (old bootloader) magic key data
+				if (magic_key_pos != (RAMEND-1)) {
+					*(uint16_t *)magic_key_pos = *(uint16_t *)(RAMEND-1);
+				} else
+#endif
+				{
+				// Clean up RAMEND key
+					*(uint16_t *)magic_key_pos = 0x0000;
+				}
+			}
+		}
+		return true;
+	}
+	return false;
+}
+
+
+void Serial_::begin(unsigned long /* baud_count */)
+{
+	peek_buffer = -1;
+}
+
+void Serial_::begin(unsigned long /* baud_count */, byte /* config */)
+{
+	peek_buffer = -1;
+}
+
+void Serial_::end(void)
+{
+}
+
+int Serial_::available(void)
+{
+	if (peek_buffer >= 0) {
+		return 1 + USB_Available(CDC_RX);
+	}
+	return USB_Available(CDC_RX);
+}
+
+int Serial_::peek(void)
+{
+	if (peek_buffer < 0)
+		peek_buffer = USB_Recv(CDC_RX);
+	return peek_buffer;
+}
+
+int Serial_::read(void)
+{
+	if (peek_buffer >= 0) {
+		int c = peek_buffer;
+		peek_buffer = -1;
+		return c;
+	}
+	return USB_Recv(CDC_RX);
+}
+
+int Serial_::availableForWrite(void)
+{
+	return USB_SendSpace(CDC_TX);
+}
+
+void Serial_::flush(void)
+{
+	USB_Flush(CDC_TX);
+}
+
+size_t Serial_::write(uint8_t c)
+{
+	return write(&c, 1);
+}
+
+size_t Serial_::write(const uint8_t *buffer, size_t size)
+{
+	/* only try to send bytes if the high-level CDC connection itself 
+	 is open (not just the pipe) - the OS should set lineState when the port
+	 is opened and clear lineState when the port is closed.
+	 bytes sent before the user opens the connection or after
+	 the connection is closed are lost - just like with a UART. */
+	
+	// TODO - ZE - check behavior on different OSes and test what happens if an
+	// open connection isn't broken cleanly (cable is yanked out, host dies
+	// or locks up, or host virtual serial port hangs)
+	if (_usbLineInfo.lineState > 0)	{
+		int r = USB_Send(CDC_TX,buffer,size);
+		if (r > 0) {
+			return r;
+		} else {
+			setWriteError();
+			return 0;
+		}
+	}
+	setWriteError();
+	return 0;
+}
+
+// This operator is a convenient way for a sketch to check whether the
+// port has actually been configured and opened by the host (as opposed
+// to just being connected to the host).  It can be used, for example, in 
+// setup() before printing to ensure that an application on the host is
+// actually ready to receive and display the data.
+// We add a short delay before returning to fix a bug observed by Federico
+// where the port is configured (lineState != 0) but not quite opened.
+Serial_::operator bool() {
+	bool result = false;
+	if (_usbLineInfo.lineState > 0) 
+		result = true;
+	delay(10);
+	return result;
+}
+
+unsigned long Serial_::baud() {
+	// Disable interrupts while reading a multi-byte value
+	uint32_t baudrate;
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		baudrate =  _usbLineInfo.dwDTERate;
+	}
+	return baudrate;
+}
+
+uint8_t Serial_::stopbits() {
+	return _usbLineInfo.bCharFormat;
+}
+
+uint8_t Serial_::paritytype() {
+	return _usbLineInfo.bParityType;
+}
+
+uint8_t Serial_::numbits() {
+	return _usbLineInfo.bDataBits;
+}
+
+bool Serial_::dtr() {
+	return _usbLineInfo.lineState & 0x1;
+}
+
+bool Serial_::rts() {
+	return _usbLineInfo.lineState & 0x2;
+}
+
+int32_t Serial_::readBreak() {
+	int32_t ret;
+	// Disable IRQs while reading and clearing breakValue to make
+	// sure we don't overwrite a value just set by the ISR.
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		ret = breakValue;
+		breakValue = -1;
+	}
+	return ret;
+}
+
+Serial_ Serial;
+
+#endif /* if defined(USBCON) */
diff --git a/test/arduino_leonardo_bridge_castrated_cdc/README.md b/test/arduino_leonardo_bridge_castrated_cdc/README.md
new file mode 100644
index 00000000..9e2c10a1
--- /dev/null
+++ b/test/arduino_leonardo_bridge_castrated_cdc/README.md
@@ -0,0 +1,8 @@
+## castrated CDC test (single interface with 3 endpoints)
+
+As mentioned [here](https://arduino.stackexchange.com/a/31695/62145), Arduino functions can be _overwritten_ by copying complete files into the own project. 
+
+This is used to create a castrated CDC device with a single interface containing 3 endpoints. 
+
+The modifications have been done against Arduino 1.8.10, for changes see comments containing `kai`.
+
diff --git a/test/arduino_leonardo_bridge_castrated_cdc/USBCore.h b/test/arduino_leonardo_bridge_castrated_cdc/USBCore.h
new file mode 100644
index 00000000..ef20030f
--- /dev/null
+++ b/test/arduino_leonardo_bridge_castrated_cdc/USBCore.h
@@ -0,0 +1,301 @@
+
+// Copyright (c) 2010, Peter Barrett 
+/*
+** Permission to use, copy, modify, and/or distribute this software for  
+** any purpose with or without fee is hereby granted, provided that the  
+** above copyright notice and this permission notice appear in all copies.  
+**  
+** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL  
+** WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED  
+** WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR  
+** BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES  
+** OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,  
+** WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,  
+** ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS  
+** SOFTWARE.  
+*/
+
+#ifndef __USBCORE_H__
+#define __USBCORE_H__
+
+#include "USBAPI.h"
+
+//	Standard requests
+#define GET_STATUS			0
+#define CLEAR_FEATURE		1
+#define SET_FEATURE			3
+#define SET_ADDRESS			5
+#define GET_DESCRIPTOR		6
+#define SET_DESCRIPTOR		7
+#define GET_CONFIGURATION	8
+#define SET_CONFIGURATION	9
+#define GET_INTERFACE		10
+#define SET_INTERFACE		11
+
+
+// bmRequestType
+#define REQUEST_HOSTTODEVICE	0x00
+#define REQUEST_DEVICETOHOST	0x80
+#define REQUEST_DIRECTION		0x80
+
+#define REQUEST_STANDARD		0x00
+#define REQUEST_CLASS			0x20
+#define REQUEST_VENDOR			0x40
+#define REQUEST_TYPE			0x60
+
+#define REQUEST_DEVICE			0x00
+#define REQUEST_INTERFACE		0x01
+#define REQUEST_ENDPOINT		0x02
+#define REQUEST_OTHER			0x03
+#define REQUEST_RECIPIENT		0x03
+
+#define REQUEST_DEVICETOHOST_CLASS_INTERFACE    (REQUEST_DEVICETOHOST | REQUEST_CLASS | REQUEST_INTERFACE)
+#define REQUEST_HOSTTODEVICE_CLASS_INTERFACE    (REQUEST_HOSTTODEVICE | REQUEST_CLASS | REQUEST_INTERFACE)
+#define REQUEST_DEVICETOHOST_STANDARD_INTERFACE (REQUEST_DEVICETOHOST | REQUEST_STANDARD | REQUEST_INTERFACE)
+
+//	Class requests
+
+#define CDC_SET_LINE_CODING			0x20
+#define CDC_GET_LINE_CODING			0x21
+#define CDC_SET_CONTROL_LINE_STATE	0x22
+#define CDC_SEND_BREAK				0x23
+
+#define MSC_RESET					0xFF
+#define MSC_GET_MAX_LUN				0xFE
+
+//	Descriptors
+
+#define USB_DEVICE_DESC_SIZE 18
+#define USB_CONFIGUARTION_DESC_SIZE 9
+#define USB_INTERFACE_DESC_SIZE 9
+#define USB_ENDPOINT_DESC_SIZE 7
+
+#define USB_DEVICE_DESCRIPTOR_TYPE             1
+#define USB_CONFIGURATION_DESCRIPTOR_TYPE      2
+#define USB_STRING_DESCRIPTOR_TYPE             3
+#define USB_INTERFACE_DESCRIPTOR_TYPE          4
+#define USB_ENDPOINT_DESCRIPTOR_TYPE           5
+
+// usb_20.pdf Table 9.6 Standard Feature Selectors
+#define DEVICE_REMOTE_WAKEUP                   1
+#define ENDPOINT_HALT                          2
+#define TEST_MODE                              3
+
+// usb_20.pdf Figure 9-4. Information Returned by a GetStatus() Request to a Device
+#define FEATURE_SELFPOWERED_ENABLED     (1 << 0)
+#define FEATURE_REMOTE_WAKEUP_ENABLED   (1 << 1)
+
+#define USB_DEVICE_CLASS_COMMUNICATIONS        0x02
+#define USB_DEVICE_CLASS_HUMAN_INTERFACE       0x03
+#define USB_DEVICE_CLASS_STORAGE               0x08
+#define USB_DEVICE_CLASS_VENDOR_SPECIFIC       0xFF
+
+#define USB_CONFIG_POWERED_MASK                0x40
+#define USB_CONFIG_BUS_POWERED                 0x80
+#define USB_CONFIG_SELF_POWERED                0xC0
+#define USB_CONFIG_REMOTE_WAKEUP               0x20
+
+// bMaxPower in Configuration Descriptor
+#define USB_CONFIG_POWER_MA(mA)                ((mA)/2)
+
+// bEndpointAddress in Endpoint Descriptor
+#define USB_ENDPOINT_DIRECTION_MASK            0x80
+#define USB_ENDPOINT_OUT(addr)                 (lowByte((addr) | 0x00))
+#define USB_ENDPOINT_IN(addr)                  (lowByte((addr) | 0x80))
+
+#define USB_ENDPOINT_TYPE_MASK                 0x03
+#define USB_ENDPOINT_TYPE_CONTROL              0x00
+#define USB_ENDPOINT_TYPE_ISOCHRONOUS          0x01
+#define USB_ENDPOINT_TYPE_BULK                 0x02
+#define USB_ENDPOINT_TYPE_INTERRUPT            0x03
+
+#define TOBYTES(x) ((x) & 0xFF),(((x) >> 8) & 0xFF)
+
+#define CDC_V1_10                               0x0110
+#define CDC_COMMUNICATION_INTERFACE_CLASS       0x02
+
+#define CDC_CALL_MANAGEMENT                     0x01
+#define CDC_ABSTRACT_CONTROL_MODEL              0x02
+#define CDC_HEADER                              0x00
+#define CDC_ABSTRACT_CONTROL_MANAGEMENT         0x02
+#define CDC_UNION                               0x06
+#define CDC_CS_INTERFACE                        0x24
+#define CDC_CS_ENDPOINT                         0x25
+#define CDC_DATA_INTERFACE_CLASS                0x0A
+
+#define MSC_SUBCLASS_SCSI						0x06 
+#define MSC_PROTOCOL_BULK_ONLY					0x50 
+
+#ifndef USB_VERSION
+#define USB_VERSION 0x200
+#endif
+
+//	Device
+typedef struct {
+	u8 len;				// 18
+	u8 dtype;			// 1 USB_DEVICE_DESCRIPTOR_TYPE
+	u16 usbVersion;		// 0x200 or 0x210
+	u8	deviceClass;
+	u8	deviceSubClass;
+	u8	deviceProtocol;
+	u8	packetSize0;	// Packet 0
+	u16	idVendor;
+	u16	idProduct;
+	u16	deviceVersion;	// 0x100
+	u8	iManufacturer;
+	u8	iProduct;
+	u8	iSerialNumber;
+	u8	bNumConfigurations;
+} DeviceDescriptor;
+
+//	Config
+typedef struct {
+	u8	len;			// 9
+	u8	dtype;			// 2
+	u16 clen;			// total length
+	u8	numInterfaces;
+	u8	config;
+	u8	iconfig;
+	u8	attributes;
+	u8	maxPower;
+} ConfigDescriptor;
+
+//	String
+
+//	Interface
+typedef struct
+{
+	u8 len;		// 9
+	u8 dtype;	// 4
+	u8 number;
+	u8 alternate;
+	u8 numEndpoints;
+	u8 interfaceClass;
+	u8 interfaceSubClass;
+	u8 protocol;
+	u8 iInterface;
+} InterfaceDescriptor;
+
+//	Endpoint
+typedef struct
+{
+	u8 len;		// 7
+	u8 dtype;	// 5
+	u8 addr;
+	u8 attr;
+	u16 packetSize;
+	u8 interval;
+} EndpointDescriptor;
+
+// Interface Association Descriptor
+// Used to bind 2 interfaces together in CDC compostite device
+typedef struct
+{
+	u8 len;				// 8
+	u8 dtype;			// 11
+	u8 firstInterface;
+	u8 interfaceCount;
+	u8 functionClass;
+	u8 funtionSubClass;
+	u8 functionProtocol;
+	u8 iInterface;
+} IADDescriptor;
+
+//	CDC CS interface descriptor
+typedef struct
+{
+	u8 len;		// 5
+	u8 dtype;	// 0x24
+	u8 subtype;
+	u8 d0;
+	u8 d1;
+} CDCCSInterfaceDescriptor;
+
+typedef struct
+{
+	u8 len;		// 4
+	u8 dtype;	// 0x24
+	u8 subtype;
+	u8 d0;
+} CDCCSInterfaceDescriptor4;
+
+typedef struct 
+{
+    u8	len;
+    u8 	dtype;		// 0x24
+    u8 	subtype;	// 1
+    u8 	bmCapabilities;
+    u8 	bDataInterface;
+} CMFunctionalDescriptor;
+	
+typedef struct 
+{
+    u8	len;
+    u8 	dtype;		// 0x24
+    u8 	subtype;	// 1
+    u8 	bmCapabilities;
+} ACMFunctionalDescriptor;
+
+typedef struct 
+{
+	//	IAD
+	IADDescriptor				iad;	// Only needed on compound device
+
+	//	Control
+	InterfaceDescriptor			cif;	// 
+	CDCCSInterfaceDescriptor	header;
+	CMFunctionalDescriptor		callManagement;			// Call Management
+	ACMFunctionalDescriptor		controlManagement;		// ACM
+	CDCCSInterfaceDescriptor	functionalDescriptor;	// CDC_UNION
+	EndpointDescriptor			cifin;
+
+	//	Data
+	//InterfaceDescriptor			dif; // kai:removed
+	EndpointDescriptor			in;
+	EndpointDescriptor			out;
+} CDCDescriptor;
+
+typedef struct 
+{
+	InterfaceDescriptor			msc;
+	EndpointDescriptor			in;
+	EndpointDescriptor			out;
+} MSCDescriptor;
+
+
+#define D_DEVICE(_class,_subClass,_proto,_packetSize0,_vid,_pid,_version,_im,_ip,_is,_configs) \
+	{ 18, 1, USB_VERSION, _class,_subClass,_proto,_packetSize0,_vid,_pid,_version,_im,_ip,_is,_configs }
+
+#define D_CONFIG(_totalLength,_interfaces) \
+	{ 9, 2, _totalLength,_interfaces, 1, 0, USB_CONFIG_BUS_POWERED | USB_CONFIG_REMOTE_WAKEUP, USB_CONFIG_POWER_MA(500) }
+
+#define D_INTERFACE(_n,_numEndpoints,_class,_subClass,_protocol) \
+	{ 9, 4, _n, 0, _numEndpoints, _class,_subClass, _protocol, 0 }
+
+#define D_ENDPOINT(_addr,_attr,_packetSize, _interval) \
+	{ 7, 5, _addr,_attr,_packetSize, _interval }
+
+#define D_IAD(_firstInterface, _count, _class, _subClass, _protocol) \
+	{ 8, 11, _firstInterface, _count, _class, _subClass, _protocol, 0 }
+
+#define D_CDCCS(_subtype,_d0,_d1)	{ 5, 0x24, _subtype, _d0, _d1 }
+#define D_CDCCS4(_subtype,_d0)		{ 4, 0x24, _subtype, _d0 }
+
+// Bootloader related fields
+// Old Caterina bootloader places the MAGIC key into unsafe RAM locations (it can be rewritten
+// by the running sketch before to actual reboot).
+// Newer bootloaders, recognizable by the LUFA "signature" at the end of the flash, can handle both
+// the usafe and the safe location.
+#ifndef MAGIC_KEY
+#define MAGIC_KEY 0x7777
+#endif
+
+#ifndef MAGIC_KEY_POS
+#define MAGIC_KEY_POS 0x0800
+#endif
+
+#ifndef NEW_LUFA_SIGNATURE
+#define NEW_LUFA_SIGNATURE 0xDCFB
+#endif
+
+#endif
diff --git a/test/arduino_leonardo_bridge_castrated_cdc/arduino_leonardo_bridge_castrated_cdc.ino b/test/arduino_leonardo_bridge_castrated_cdc/arduino_leonardo_bridge_castrated_cdc.ino
new file mode 100644
index 00000000..663292c1
--- /dev/null
+++ b/test/arduino_leonardo_bridge_castrated_cdc/arduino_leonardo_bridge_castrated_cdc.ino
@@ -0,0 +1,64 @@
+/*
+  bridge USB-serial to hardware-serial
+
+  for Arduinos based on ATmega32u4 (Leonardo and compatible Pro Micro, Micro)
+  hardware serial is configured with baud-rate, databits, stopbits, parity as send over USB
+
+  see https://github.com/arduino/Arduino/tree/master/hardware/arduino/avr/cores/arduino 
+  -> CDC.cpp|HardwareSerial.cpp for serial implementation details
+
+  this sketch is mainly for demonstration / test of CDC communication
+  performance as real usb-serial bridge would be inacceptable as each byte is send in separate USB packet
+*/
+
+uint32_t baud = 9600;
+uint8_t databits = 8;
+uint8_t stopbits = 1;
+uint8_t parity = 0;
+
+void setup() {
+  Serial.begin(baud); // USB
+  Serial1.begin(baud, SERIAL_8N1);
+}
+
+void loop() {
+  // show USB connected state
+  if (Serial) TXLED1;
+  else        TXLED0;
+
+  // configure hardware serial
+  if (Serial.baud() != baud ||
+      Serial.numbits() != databits ||
+      Serial.stopbits() != stopbits ||
+      Serial.paritytype() != parity) {
+    baud = Serial.baud();
+    databits = Serial.numbits();
+    stopbits = Serial.stopbits();
+    parity = Serial.paritytype();
+    uint8_t config = 0; // ucsrc register
+    switch (databits) {
+      case 5: break;
+      case 6: config |= 2; break;
+      case 7: config |= 4; break;
+      case 8: config |= 6; break;
+      default: config |= 6;
+    }
+    switch (stopbits) {
+      case 2: config |= 8;
+        // 1.5 stopbits not supported
+    }
+    switch (parity) {
+      case 1: config |= 0x30; break; // odd
+      case 2: config |= 0x20; break; // even
+        // mark, space not supported
+    }
+    Serial1.end();
+    Serial1.begin(baud, config);
+  }
+
+  // bridge
+  if (Serial.available() > 0)
+    Serial1.write(Serial.read());
+  if (Serial1.available() > 0)
+    Serial.write(Serial1.read());
+}
diff --git a/test/arduino_leonardo_bridge_multi_cdc/CDC.cpp b/test/arduino_leonardo_bridge_multi_cdc/CDC.cpp
new file mode 100644
index 00000000..f57e0817
--- /dev/null
+++ b/test/arduino_leonardo_bridge_multi_cdc/CDC.cpp
@@ -0,0 +1,320 @@
+
+
+/* Copyright (c) 2011, Peter Barrett  
+**  
+** Permission to use, copy, modify, and/or distribute this software for  
+** any purpose with or without fee is hereby granted, provided that the  
+** above copyright notice and this permission notice appear in all copies.  
+** 
+** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL  
+** WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED  
+** WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR  
+** BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES  
+** OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,  
+** WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,  
+** ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS  
+** SOFTWARE.  
+*/
+
+#include "USBCore.h" // kai:added
+#include "USBAPI.h"
+#include "USBDesc.h" // kai:added
+#include <avr/wdt.h>
+#include <util/atomic.h>
+
+#if defined(USBCON)
+
+typedef struct
+{
+	u32	dwDTERate;
+	u8	bCharFormat;
+	u8 	bParityType;
+	u8 	bDataBits;
+	u8	lineState;
+} LineInfo;
+
+static volatile LineInfo _usbLineInfo = { 57600, 0x00, 0x00, 0x00, 0x00 };
+static volatile int32_t breakValue = -1;
+
+static u8 wdtcsr_save;
+
+#define WEAK __attribute__ ((weak))
+
+extern const CDCDescriptor _cdcInterface PROGMEM;
+const CDCDescriptor _cdcInterface =
+{
+	D_IAD(0,2,CDC_COMMUNICATION_INTERFACE_CLASS,CDC_ABSTRACT_CONTROL_MODEL,1),
+
+	//	CDC communication interface
+	D_INTERFACE(CDC_ACM_INTERFACE1,1,CDC_COMMUNICATION_INTERFACE_CLASS,CDC_ABSTRACT_CONTROL_MODEL,0),
+	D_CDCCS(CDC_HEADER,0x10,0x01),								// Header (1.10 bcd)
+	D_CDCCS(CDC_CALL_MANAGEMENT,1,1),							// Device handles call management (not)
+	D_CDCCS4(CDC_ABSTRACT_CONTROL_MANAGEMENT,6),				// SET_LINE_CODING, GET_LINE_CODING, SET_CONTROL_LINE_STATE supported
+	D_CDCCS(CDC_UNION,CDC_ACM_INTERFACE1,CDC_DATA_INTERFACE1),	// Communication interface is master, data interface is slave 0
+	D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_ACM1),USB_ENDPOINT_TYPE_INTERRUPT,0x10,0x40),
+
+	//	CDC data interface
+	D_INTERFACE(CDC_DATA_INTERFACE1,2,CDC_DATA_INTERFACE_CLASS,0,0),
+	D_ENDPOINT(USB_ENDPOINT_OUT(CDC_ENDPOINT_OUT1),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0),
+	D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_IN1 ),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0)
+	
+	, // kai: added
+  D_IAD(2,2,CDC_COMMUNICATION_INTERFACE_CLASS,CDC_ABSTRACT_CONTROL_MODEL,1),
+
+  //  CDC communication interface
+  D_INTERFACE(CDC_ACM_INTERFACE2,1,CDC_COMMUNICATION_INTERFACE_CLASS,CDC_ABSTRACT_CONTROL_MODEL,0),
+  D_CDCCS(CDC_HEADER,0x10,0x01),                // Header (1.10 bcd)
+  D_CDCCS(CDC_CALL_MANAGEMENT,1,1),             // Device handles call management (not)
+  D_CDCCS4(CDC_ABSTRACT_CONTROL_MANAGEMENT,6),        // SET_LINE_CODING, GET_LINE_CODING, SET_CONTROL_LINE_STATE supported
+  D_CDCCS(CDC_UNION,CDC_ACM_INTERFACE2,CDC_DATA_INTERFACE2),  // Communication interface is master, data interface is slave 0
+  D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_ACM2),USB_ENDPOINT_TYPE_INTERRUPT,0x10,0x40),
+  
+  //  CDC data interface
+  D_INTERFACE(CDC_DATA_INTERFACE2,2,CDC_DATA_INTERFACE_CLASS,0,0),
+  D_ENDPOINT(USB_ENDPOINT_OUT(CDC_ENDPOINT_OUT2),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0),
+  D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_IN2),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0)
+};
+
+bool isLUFAbootloader()
+{
+	return pgm_read_word(FLASHEND - 1) == NEW_LUFA_SIGNATURE;
+}
+
+int CDC_GetInterface(u8* interfaceNum)
+{
+	interfaceNum[0] += 4;	// kai
+	return USB_SendControl(TRANSFER_PGM,&_cdcInterface,sizeof(_cdcInterface));
+}
+
+bool CDC_Setup(USBSetup& setup)
+{
+	u8 r = setup.bRequest;
+	u8 requestType = setup.bmRequestType;
+
+	if (REQUEST_DEVICETOHOST_CLASS_INTERFACE == requestType)
+	{
+		if (CDC_GET_LINE_CODING == r)
+		{
+			USB_SendControl(0,(void*)&_usbLineInfo,7);
+			return true;
+		}
+	}
+
+	if (REQUEST_HOSTTODEVICE_CLASS_INTERFACE == requestType)
+	{
+		if (CDC_SEND_BREAK == r)
+		{
+			breakValue = ((uint16_t)setup.wValueH << 8) | setup.wValueL;
+		}
+
+		if (CDC_SET_LINE_CODING == r)
+		{
+			USB_RecvControl((void*)&_usbLineInfo,7);
+		}
+
+		if (CDC_SET_CONTROL_LINE_STATE == r)
+		{
+			_usbLineInfo.lineState = setup.wValueL;
+
+			// auto-reset into the bootloader is triggered when the port, already 
+			// open at 1200 bps, is closed.  this is the signal to start the watchdog
+			// with a relatively long period so it can finish housekeeping tasks
+			// like servicing endpoints before the sketch ends
+
+			uint16_t magic_key_pos = MAGIC_KEY_POS;
+
+// If we don't use the new RAMEND directly, check manually if we have a newer bootloader.
+// This is used to keep compatible with the old leonardo bootloaders.
+// You are still able to set the magic key position manually to RAMEND-1 to save a few bytes for this check.
+#if MAGIC_KEY_POS != (RAMEND-1)
+			// For future boards save the key in the inproblematic RAMEND
+			// Which is reserved for the main() return value (which will never return)
+			if (isLUFAbootloader()) {
+				// horray, we got a new bootloader!
+				magic_key_pos = (RAMEND-1);
+			}
+#endif
+
+			// We check DTR state to determine if host port is open (bit 0 of lineState).
+			if (1200 == _usbLineInfo.dwDTERate && (_usbLineInfo.lineState & 0x01) == 0)
+			{
+#if MAGIC_KEY_POS != (RAMEND-1)
+				// Backup ram value if its not a newer bootloader and it hasn't already been saved.
+				// This should avoid memory corruption at least a bit, not fully
+				if (magic_key_pos != (RAMEND-1) && *(uint16_t *)magic_key_pos != MAGIC_KEY) {
+					*(uint16_t *)(RAMEND-1) = *(uint16_t *)magic_key_pos;
+				}
+#endif
+				// Store boot key
+				*(uint16_t *)magic_key_pos = MAGIC_KEY;
+				// Save the watchdog state in case the reset is aborted.
+				wdtcsr_save = WDTCSR;
+				wdt_enable(WDTO_120MS);
+			}
+			else if (*(uint16_t *)magic_key_pos == MAGIC_KEY)
+			{
+				// Most OSs do some intermediate steps when configuring ports and DTR can
+				// twiggle more than once before stabilizing.
+				// To avoid spurious resets we set the watchdog to 120ms and eventually
+				// cancel if DTR goes back high.
+				// Cancellation is only done if an auto-reset was started, which is
+				// indicated by the magic key having been set.
+
+				wdt_reset();
+				// Restore the watchdog state in case the sketch was using it.
+				WDTCSR |= (1<<WDCE) | (1<<WDE);
+				WDTCSR = wdtcsr_save;
+#if MAGIC_KEY_POS != (RAMEND-1)
+				// Restore backed up (old bootloader) magic key data
+				if (magic_key_pos != (RAMEND-1)) {
+					*(uint16_t *)magic_key_pos = *(uint16_t *)(RAMEND-1);
+				} else
+#endif
+				{
+				// Clean up RAMEND key
+					*(uint16_t *)magic_key_pos = 0x0000;
+				}
+			}
+		}
+		return true;
+	}
+	return false;
+}
+
+
+void Serial_::begin(unsigned long /* baud_count */)
+{
+	peek_buffer = -1;
+}
+
+void Serial_::begin(unsigned long /* baud_count */, byte /* config */)
+{
+	peek_buffer = -1;
+}
+
+void Serial_::end(void)
+{
+}
+
+int Serial_::available(void)
+{
+	if (peek_buffer >= 0) {
+		return 1 + USB_Available(CDC_RX);
+	}
+	return USB_Available(CDC_RX);
+}
+
+int Serial_::peek(void)
+{
+	if (peek_buffer < 0)
+		peek_buffer = USB_Recv(CDC_RX);
+	return peek_buffer;
+}
+
+int Serial_::read(void)
+{
+	if (peek_buffer >= 0) {
+		int c = peek_buffer;
+		peek_buffer = -1;
+		return c;
+	}
+	return USB_Recv(CDC_RX);
+}
+
+int Serial_::availableForWrite(void)
+{
+	return USB_SendSpace(CDC_TX);
+}
+
+void Serial_::flush(void)
+{
+	USB_Flush(CDC_TX);
+}
+
+size_t Serial_::write(uint8_t c)
+{
+	return write(&c, 1);
+}
+
+size_t Serial_::write(const uint8_t *buffer, size_t size)
+{
+	/* only try to send bytes if the high-level CDC connection itself 
+	 is open (not just the pipe) - the OS should set lineState when the port
+	 is opened and clear lineState when the port is closed.
+	 bytes sent before the user opens the connection or after
+	 the connection is closed are lost - just like with a UART. */
+	
+	// TODO - ZE - check behavior on different OSes and test what happens if an
+	// open connection isn't broken cleanly (cable is yanked out, host dies
+	// or locks up, or host virtual serial port hangs)
+	if (_usbLineInfo.lineState > 0)	{
+		int r = USB_Send(CDC_TX,buffer,size);
+		if (r > 0) {
+			return r;
+		} else {
+			setWriteError();
+			return 0;
+		}
+	}
+	setWriteError();
+	return 0;
+}
+
+// This operator is a convenient way for a sketch to check whether the
+// port has actually been configured and opened by the host (as opposed
+// to just being connected to the host).  It can be used, for example, in 
+// setup() before printing to ensure that an application on the host is
+// actually ready to receive and display the data.
+// We add a short delay before returning to fix a bug observed by Federico
+// where the port is configured (lineState != 0) but not quite opened.
+Serial_::operator bool() {
+	bool result = false;
+	if (_usbLineInfo.lineState > 0) 
+		result = true;
+	delay(10);
+	return result;
+}
+
+unsigned long Serial_::baud() {
+	// Disable interrupts while reading a multi-byte value
+	uint32_t baudrate;
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		baudrate =  _usbLineInfo.dwDTERate;
+	}
+	return baudrate;
+}
+
+uint8_t Serial_::stopbits() {
+	return _usbLineInfo.bCharFormat;
+}
+
+uint8_t Serial_::paritytype() {
+	return _usbLineInfo.bParityType;
+}
+
+uint8_t Serial_::numbits() {
+	return _usbLineInfo.bDataBits;
+}
+
+bool Serial_::dtr() {
+	return _usbLineInfo.lineState & 0x1;
+}
+
+bool Serial_::rts() {
+	return _usbLineInfo.lineState & 0x2;
+}
+
+int32_t Serial_::readBreak() {
+	int32_t ret;
+	// Disable IRQs while reading and clearing breakValue to make
+	// sure we don't overwrite a value just set by the ISR.
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		ret = breakValue;
+		breakValue = -1;
+	}
+	return ret;
+}
+
+Serial_ Serial;
+
+#endif /* if defined(USBCON) */
diff --git a/test/arduino_leonardo_bridge_multi_cdc/README.md b/test/arduino_leonardo_bridge_multi_cdc/README.md
new file mode 100644
index 00000000..091f3cee
--- /dev/null
+++ b/test/arduino_leonardo_bridge_multi_cdc/README.md
@@ -0,0 +1,8 @@
+## multiple CDC interface test
+
+As mentioned [here](https://arduino.stackexchange.com/a/31695/62145),  Arduino functions can be _overwritten_ by copying complete files into the own project. 
+
+This is used to create a device with 2 CDC interfaces. For simplicity only one of both is functional (configurable in USBDesc.h)
+
+The modifications have been done against Arduino 1.8.10, for changes see comments containing `kai`.
+
diff --git a/test/arduino_leonardo_bridge_multi_cdc/USBCore.cpp b/test/arduino_leonardo_bridge_multi_cdc/USBCore.cpp
new file mode 100644
index 00000000..7637b70c
--- /dev/null
+++ b/test/arduino_leonardo_bridge_multi_cdc/USBCore.cpp
@@ -0,0 +1,870 @@
+
+
+/* Copyright (c) 2010, Peter Barrett
+** Sleep/Wakeup support added by Michael Dreher
+**  
+** Permission to use, copy, modify, and/or distribute this software for  
+** any purpose with or without fee is hereby granted, provided that the  
+** above copyright notice and this permission notice appear in all copies.  
+** 
+** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL  
+** WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED  
+** WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR  
+** BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES  
+** OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,  
+** WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,  
+** ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS  
+** SOFTWARE.  
+*/
+
+#include "USBAPI.h"
+#include "USBDesc.h" // kai:added
+#include "PluggableUSB.h"
+#include <stdlib.h>
+
+#if defined(USBCON)
+
+/** Pulse generation counters to keep track of the number of milliseconds remaining for each pulse type */
+#define TX_RX_LED_PULSE_MS 100
+volatile u8 TxLEDPulse; /**< Milliseconds remaining for data Tx LED pulse */
+volatile u8 RxLEDPulse; /**< Milliseconds remaining for data Rx LED pulse */
+
+//==================================================================
+//==================================================================
+
+extern const u16 STRING_LANGUAGE[] PROGMEM;
+extern const u8 STRING_PRODUCT[] PROGMEM;
+extern const u8 STRING_MANUFACTURER[] PROGMEM;
+extern const DeviceDescriptor USB_DeviceDescriptorIAD PROGMEM;
+
+const u16 STRING_LANGUAGE[2] = {
+	(3<<8) | (2+2),
+	0x0409	// English
+};
+
+#ifndef USB_PRODUCT
+// If no product is provided, use USB IO Board
+#define USB_PRODUCT     "USB IO Board"
+#endif
+
+const u8 STRING_PRODUCT[] PROGMEM = USB_PRODUCT;
+
+#if USB_VID == 0x2341
+#  if defined(USB_MANUFACTURER)
+#    undef USB_MANUFACTURER
+#  endif
+#  define USB_MANUFACTURER "Arduino LLC"
+#elif USB_VID == 0x1b4f
+#  if defined(USB_MANUFACTURER)
+#    undef USB_MANUFACTURER
+#  endif
+#  define USB_MANUFACTURER "SparkFun"
+#elif !defined(USB_MANUFACTURER)
+// Fall through to unknown if no manufacturer name was provided in a macro
+#  define USB_MANUFACTURER "Unknown"
+#endif
+
+const u8 STRING_MANUFACTURER[] PROGMEM = USB_MANUFACTURER;
+
+
+#define DEVICE_CLASS 0x02
+
+//	DEVICE DESCRIPTOR
+const DeviceDescriptor USB_DeviceDescriptorIAD =
+	D_DEVICE(0xEF,0x02,0x01,64,USB_VID,USB_PID,0x100,IMANUFACTURER,IPRODUCT,ISERIAL,1);
+
+//==================================================================
+//==================================================================
+
+volatile u8 _usbConfiguration = 0;
+volatile u8 _usbCurrentStatus = 0; // meaning of bits see usb_20.pdf, Figure 9-4. Information Returned by a GetStatus() Request to a Device
+volatile u8 _usbSuspendState = 0; // copy of UDINT to check SUSPI and WAKEUPI bits
+
+static inline void WaitIN(void)
+{
+	while (!(UEINTX & (1<<TXINI)))
+		;
+}
+
+static inline void ClearIN(void)
+{
+	UEINTX = ~(1<<TXINI);
+}
+
+static inline void WaitOUT(void)
+{
+	while (!(UEINTX & (1<<RXOUTI)))
+		;
+}
+
+static inline u8 WaitForINOrOUT()
+{
+	while (!(UEINTX & ((1<<TXINI)|(1<<RXOUTI))))
+		;
+	return (UEINTX & (1<<RXOUTI)) == 0;
+}
+
+static inline void ClearOUT(void)
+{
+	UEINTX = ~(1<<RXOUTI);
+}
+
+static inline void Recv(volatile u8* data, u8 count)
+{
+	while (count--)
+		*data++ = UEDATX;
+	
+	RXLED1;					// light the RX LED
+	RxLEDPulse = TX_RX_LED_PULSE_MS;	
+}
+
+static inline u8 Recv8()
+{
+	RXLED1;					// light the RX LED
+	RxLEDPulse = TX_RX_LED_PULSE_MS;
+
+	return UEDATX;	
+}
+
+static inline void Send8(u8 d)
+{
+	UEDATX = d;
+}
+
+static inline void SetEP(u8 ep)
+{
+	UENUM = ep;
+}
+
+static inline u8 FifoByteCount()
+{
+	return UEBCLX;
+}
+
+static inline u8 ReceivedSetupInt()
+{
+	return UEINTX & (1<<RXSTPI);
+}
+
+static inline void ClearSetupInt()
+{
+	UEINTX = ~((1<<RXSTPI) | (1<<RXOUTI) | (1<<TXINI));
+}
+
+static inline void Stall()
+{
+	UECONX = (1<<STALLRQ) | (1<<EPEN);
+}
+
+static inline u8 ReadWriteAllowed()
+{
+	return UEINTX & (1<<RWAL);
+}
+
+static inline u8 Stalled()
+{
+	return UEINTX & (1<<STALLEDI);
+}
+
+static inline u8 FifoFree()
+{
+	return UEINTX & (1<<FIFOCON);
+}
+
+static inline void ReleaseRX()
+{
+	UEINTX = 0x6B;	// FIFOCON=0 NAKINI=1 RWAL=1 NAKOUTI=0 RXSTPI=1 RXOUTI=0 STALLEDI=1 TXINI=1
+}
+
+static inline void ReleaseTX()
+{
+	UEINTX = 0x3A;	// FIFOCON=0 NAKINI=0 RWAL=1 NAKOUTI=1 RXSTPI=1 RXOUTI=0 STALLEDI=1 TXINI=0
+}
+
+static inline u8 FrameNumber()
+{
+	return UDFNUML;
+}
+
+//==================================================================
+//==================================================================
+
+u8 USBGetConfiguration(void)
+{
+	return _usbConfiguration;
+}
+
+#define USB_RECV_TIMEOUT
+class LockEP
+{
+	u8 _sreg;
+public:
+	LockEP(u8 ep) : _sreg(SREG)
+	{
+		cli();
+		SetEP(ep & 7);
+	}
+	~LockEP()
+	{
+		SREG = _sreg;
+	}
+};
+
+//	Number of bytes, assumes a rx endpoint
+u8 USB_Available(u8 ep)
+{
+	LockEP lock(ep);
+	return FifoByteCount();
+}
+
+//	Non Blocking receive
+//	Return number of bytes read
+int USB_Recv(u8 ep, void* d, int len)
+{
+	if (!_usbConfiguration || len < 0)
+		return -1;
+	
+	LockEP lock(ep);
+	u8 n = FifoByteCount();
+	len = min(n,len);
+	n = len;
+	u8* dst = (u8*)d;
+	while (n--)
+		*dst++ = Recv8();
+	if (len && !FifoByteCount())	// release empty buffer
+		ReleaseRX();
+	
+	return len;
+}
+
+//	Recv 1 byte if ready
+int USB_Recv(u8 ep)
+{
+	u8 c;
+	if (USB_Recv(ep,&c,1) != 1)
+		return -1;
+	return c;
+}
+
+//	Space in send EP
+u8 USB_SendSpace(u8 ep)
+{
+	LockEP lock(ep);
+	if (!ReadWriteAllowed())
+		return 0;
+	return USB_EP_SIZE - FifoByteCount();
+}
+
+//	Blocking Send of data to an endpoint
+int USB_Send(u8 ep, const void* d, int len)
+{
+	if (!_usbConfiguration)
+		return -1;
+
+	if (_usbSuspendState & (1<<SUSPI)) {
+		//send a remote wakeup
+		UDCON |= (1 << RMWKUP);
+	}
+
+	int r = len;
+	const u8* data = (const u8*)d;
+	u8 timeout = 250;		// 250ms timeout on send? TODO
+	bool sendZlp = false;
+
+	while (len || sendZlp)
+	{
+		u8 n = USB_SendSpace(ep);
+		if (n == 0)
+		{
+			if (!(--timeout))
+				return -1;
+			delay(1);
+			continue;
+		}
+
+		if (n > len) {
+			n = len;
+		}
+
+		{
+			LockEP lock(ep);
+			// Frame may have been released by the SOF interrupt handler
+			if (!ReadWriteAllowed())
+				continue;
+
+			len -= n;
+			if (ep & TRANSFER_ZERO)
+			{
+				while (n--)
+					Send8(0);
+			}
+			else if (ep & TRANSFER_PGM)
+			{
+				while (n--)
+					Send8(pgm_read_byte(data++));
+			}
+			else
+			{
+				while (n--)
+					Send8(*data++);
+			}
+
+			if (sendZlp) {
+				ReleaseTX();
+				sendZlp = false;
+			} else if (!ReadWriteAllowed()) { // ...release if buffer is full...
+				ReleaseTX();
+				if (len == 0) sendZlp = true;
+			} else if ((len == 0) && (ep & TRANSFER_RELEASE)) { // ...or if forced with TRANSFER_RELEASE
+				// XXX: TRANSFER_RELEASE is never used can be removed?
+				ReleaseTX();
+			}
+		}
+	}
+	TXLED1;					// light the TX LED
+	TxLEDPulse = TX_RX_LED_PULSE_MS;
+	return r;
+}
+
+u8 _initEndpoints[USB_ENDPOINTS] =
+{
+	0,                      // Control Endpoint
+	
+  EP_TYPE_INTERRUPT_IN,   // CDC_ENDPOINT_ACM
+  EP_TYPE_BULK_OUT,       // CDC_ENDPOINT_OUT
+  EP_TYPE_BULK_IN,        // CDC_ENDPOINT_IN
+
+  // kai:added
+  EP_TYPE_INTERRUPT_IN,   // CDC_ENDPOINT_ACM
+  EP_TYPE_BULK_OUT,       // CDC_ENDPOINT_OUT
+  EP_TYPE_BULK_IN,        // CDC_ENDPOINT_IN
+
+	// Following endpoints are automatically initialized to 0
+};
+
+#define EP_SINGLE_64 0x32	// EP0
+#define EP_DOUBLE_64 0x36	// Other endpoints
+#define EP_SINGLE_16 0x12
+
+static
+void InitEP(u8 index, u8 type, u8 size)
+{
+	UENUM = index;
+	UECONX = (1<<EPEN);
+	UECFG0X = type;
+	UECFG1X = size;
+}
+
+static
+void InitEndpoints()
+{
+	for (u8 i = 1; i < sizeof(_initEndpoints) && _initEndpoints[i] != 0; i++)
+	{
+		UENUM = i;
+		UECONX = (1<<EPEN);
+		UECFG0X = _initEndpoints[i];
+#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;
+}
+
+//	Handle CLASS_INTERFACE requests
+static
+bool ClassInterfaceRequest(USBSetup& setup)
+{
+	u8 i = setup.wIndex;
+
+  if (CDC_CLASS_INTERFACE == i) // kai
+    return CDC_Setup(setup);
+
+#ifdef PLUGGABLE_USB_ENABLED
+	return PluggableUSB().setup(setup);
+#endif
+	return false;
+}
+
+static int _cmark;
+static int _cend;
+void InitControl(int end)
+{
+	SetEP(0);
+	_cmark = 0;
+	_cend = end;
+}
+
+static
+bool SendControl(u8 d)
+{
+	if (_cmark < _cend)
+	{
+		if (!WaitForINOrOUT())
+			return false;
+		Send8(d);
+		if (!((_cmark + 1) & 0x3F))
+			ClearIN();	// Fifo is full, release this packet
+	}
+	_cmark++;
+	return true;
+}
+
+//	Clipped by _cmark/_cend
+int USB_SendControl(u8 flags, const void* d, int len)
+{
+	int sent = len;
+	const u8* data = (const u8*)d;
+	bool pgm = flags & TRANSFER_PGM;
+	while (len--)
+	{
+		u8 c = pgm ? pgm_read_byte(data++) : *data++;
+		if (!SendControl(c))
+			return -1;
+	}
+	return sent;
+}
+
+// Send a USB descriptor string. The string is stored in PROGMEM as a
+// plain ASCII string but is sent out as UTF-16 with the correct 2-byte
+// prefix
+static bool USB_SendStringDescriptor(const u8*string_P, u8 string_len, uint8_t flags) {
+        SendControl(2 + string_len * 2);
+        SendControl(3);
+        bool pgm = flags & TRANSFER_PGM;
+        for(u8 i = 0; i < string_len; i++) {
+                bool r = SendControl(pgm ? pgm_read_byte(&string_P[i]) : string_P[i]);
+                r &= SendControl(0); // high byte
+                if(!r) {
+                        return false;
+                }
+        }
+        return true;
+}
+
+//	Does not timeout or cross fifo boundaries
+int USB_RecvControl(void* d, int len)
+{
+	auto length = len;
+	while(length)
+	{
+		// Dont receive more than the USB Control EP has to offer
+		// Use fixed 64 because control EP always have 64 bytes even on 16u2.
+		auto recvLength = length;
+		if(recvLength > 64){
+			recvLength = 64;
+		}
+
+		// Write data to fit to the end (not the beginning) of the array
+		WaitOUT();
+		Recv((u8*)d + len - length, recvLength);
+		ClearOUT();
+		length -= recvLength;
+	}
+	return len;
+}
+
+static u8 SendInterfaces()
+{
+	u8 interfaces = 0;
+
+	CDC_GetInterface(&interfaces);
+
+#ifdef PLUGGABLE_USB_ENABLED
+	PluggableUSB().getInterface(&interfaces);
+#endif
+
+	return interfaces;
+}
+
+//	Construct a dynamic configuration descriptor
+//	This really needs dynamic endpoint allocation etc
+//	TODO
+static
+bool SendConfiguration(int maxlen)
+{
+	//	Count and measure interfaces
+	InitControl(0);
+	u8 interfaces = SendInterfaces();
+	ConfigDescriptor config = D_CONFIG(_cmark + sizeof(ConfigDescriptor),interfaces);
+
+	//	Now send them
+	InitControl(maxlen);
+	USB_SendControl(0,&config,sizeof(ConfigDescriptor));
+	SendInterfaces();
+	return true;
+}
+
+static
+bool SendDescriptor(USBSetup& setup)
+{
+	int ret;
+	u8 t = setup.wValueH;
+	if (USB_CONFIGURATION_DESCRIPTOR_TYPE == t)
+		return SendConfiguration(setup.wLength);
+
+	InitControl(setup.wLength);
+#ifdef PLUGGABLE_USB_ENABLED
+	ret = PluggableUSB().getDescriptor(setup);
+	if (ret != 0) {
+		return (ret > 0 ? true : false);
+	}
+#endif
+
+	const u8* desc_addr = 0;
+	if (USB_DEVICE_DESCRIPTOR_TYPE == t)
+	{
+		desc_addr = (const u8*)&USB_DeviceDescriptorIAD;
+	}
+	else if (USB_STRING_DESCRIPTOR_TYPE == t)
+	{
+		if (setup.wValueL == 0) {
+			desc_addr = (const u8*)&STRING_LANGUAGE;
+		}
+		else if (setup.wValueL == IPRODUCT) {
+			return USB_SendStringDescriptor(STRING_PRODUCT, strlen(USB_PRODUCT), TRANSFER_PGM);
+		}
+		else if (setup.wValueL == IMANUFACTURER) {
+			return USB_SendStringDescriptor(STRING_MANUFACTURER, strlen(USB_MANUFACTURER), TRANSFER_PGM);
+		}
+		else if (setup.wValueL == ISERIAL) {
+#ifdef PLUGGABLE_USB_ENABLED
+			char name[ISERIAL_MAX_LEN];
+			PluggableUSB().getShortName(name);
+			return USB_SendStringDescriptor((uint8_t*)name, strlen(name), 0);
+#endif
+		}
+		else
+			return false;
+	}
+
+	if (desc_addr == 0)
+		return false;
+	u8 desc_length = pgm_read_byte(desc_addr);
+
+	USB_SendControl(TRANSFER_PGM,desc_addr,desc_length);
+	return true;
+}
+
+//	Endpoint 0 interrupt
+ISR(USB_COM_vect)
+{
+    SetEP(0);
+	if (!ReceivedSetupInt())
+		return;
+
+	USBSetup setup;
+	Recv((u8*)&setup,8);
+	ClearSetupInt();
+
+	u8 requestType = setup.bmRequestType;
+	if (requestType & REQUEST_DEVICETOHOST)
+		WaitIN();
+	else
+		ClearIN();
+
+    bool ok = true;
+	if (REQUEST_STANDARD == (requestType & REQUEST_TYPE))
+	{
+		//	Standard Requests
+		u8 r = setup.bRequest;
+		u16 wValue = setup.wValueL | (setup.wValueH << 8);
+		if (GET_STATUS == r)
+		{
+			if (requestType == (REQUEST_DEVICETOHOST | REQUEST_STANDARD | REQUEST_DEVICE))
+			{
+				Send8(_usbCurrentStatus);
+				Send8(0);
+			}
+			else
+			{
+				// TODO: handle the HALT state of an endpoint here
+				// see "Figure 9-6. Information Returned by a GetStatus() Request to an Endpoint" in usb_20.pdf for more information
+				Send8(0);
+				Send8(0);
+			}
+		}
+		else if (CLEAR_FEATURE == r)
+		{
+			if((requestType == (REQUEST_HOSTTODEVICE | REQUEST_STANDARD | REQUEST_DEVICE))
+				&& (wValue == DEVICE_REMOTE_WAKEUP))
+			{
+				_usbCurrentStatus &= ~FEATURE_REMOTE_WAKEUP_ENABLED;
+			}
+		}
+		else if (SET_FEATURE == r)
+		{
+			if((requestType == (REQUEST_HOSTTODEVICE | REQUEST_STANDARD | REQUEST_DEVICE))
+				&& (wValue == DEVICE_REMOTE_WAKEUP))
+			{
+				_usbCurrentStatus |= FEATURE_REMOTE_WAKEUP_ENABLED;
+			}
+		}
+		else if (SET_ADDRESS == r)
+		{
+			WaitIN();
+			UDADDR = setup.wValueL | (1<<ADDEN);
+		}
+		else if (GET_DESCRIPTOR == r)
+		{
+			ok = SendDescriptor(setup);
+		}
+		else if (SET_DESCRIPTOR == r)
+		{
+			ok = false;
+		}
+		else if (GET_CONFIGURATION == r)
+		{
+			Send8(1);
+		}
+		else if (SET_CONFIGURATION == r)
+		{
+			if (REQUEST_DEVICE == (requestType & REQUEST_RECIPIENT))
+			{
+				InitEndpoints();
+				_usbConfiguration = setup.wValueL;
+			} else
+				ok = false;
+		}
+		else if (GET_INTERFACE == r)
+		{
+		}
+		else if (SET_INTERFACE == r)
+		{
+		}
+	}
+	else
+	{
+		InitControl(setup.wLength);		//	Max length of transfer
+		ok = ClassInterfaceRequest(setup);
+	}
+
+	if (ok)
+		ClearIN();
+	else
+	{
+		Stall();
+	}
+}
+
+void USB_Flush(u8 ep)
+{
+	SetEP(ep);
+	if (FifoByteCount())
+		ReleaseTX();
+}
+
+static inline void USB_ClockDisable()
+{
+#if defined(OTGPADE)
+	USBCON = (USBCON & ~(1<<OTGPADE)) | (1<<FRZCLK); // freeze clock and disable VBUS Pad
+#else // u2 Series
+	USBCON = (1 << FRZCLK); // freeze clock
+#endif
+	PLLCSR &= ~(1<<PLLE);  // stop PLL
+}
+
+static inline void USB_ClockEnable()
+{
+#if defined(UHWCON)
+	UHWCON |= (1<<UVREGE);			// power internal reg
+#endif
+	USBCON = (1<<USBE) | (1<<FRZCLK);	// clock frozen, usb enabled
+
+// ATmega32U4
+#if defined(PINDIV)
+#if F_CPU == 16000000UL
+	PLLCSR |= (1<<PINDIV);                   // Need 16 MHz xtal
+#elif F_CPU == 8000000UL
+	PLLCSR &= ~(1<<PINDIV);                  // Need  8 MHz xtal
+#else
+#error "Clock rate of F_CPU not supported"
+#endif
+
+#elif defined(__AVR_AT90USB82__) || defined(__AVR_AT90USB162__) || defined(__AVR_ATmega32U2__) || defined(__AVR_ATmega16U2__) || defined(__AVR_ATmega8U2__)
+	// for the u2 Series the datasheet is confusing. On page 40 its called PINDIV and on page 290 its called PLLP0
+#if F_CPU == 16000000UL
+	// Need 16 MHz xtal
+	PLLCSR |= (1 << PLLP0);
+#elif F_CPU == 8000000UL
+	// Need 8 MHz xtal
+	PLLCSR &= ~(1 << PLLP0);
+#endif
+
+// AT90USB646, AT90USB647, AT90USB1286, AT90USB1287
+#elif defined(PLLP2)
+#if F_CPU == 16000000UL
+#if defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
+	// For Atmel AT90USB128x only. Do not use with Atmel AT90USB64x.
+	PLLCSR = (PLLCSR & ~(1<<PLLP1)) | ((1<<PLLP2) | (1<<PLLP0)); // Need 16 MHz xtal
+#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__)
+	// For AT90USB64x only. Do not use with AT90USB128x.
+	PLLCSR = (PLLCSR & ~(1<<PLLP0)) | ((1<<PLLP2) | (1<<PLLP1)); // Need 16 MHz xtal
+#else
+#error "USB Chip not supported, please defined method of USB PLL initialization"
+#endif
+#elif F_CPU == 8000000UL
+	// for Atmel AT90USB128x and AT90USB64x
+	PLLCSR = (PLLCSR & ~(1<<PLLP2)) | ((1<<PLLP1) | (1<<PLLP0)); // Need 8 MHz xtal
+#else
+#error "Clock rate of F_CPU not supported"
+#endif
+#else
+#error "USB Chip not supported, please defined method of USB PLL initialization"
+#endif
+
+	PLLCSR |= (1<<PLLE);
+	while (!(PLLCSR & (1<<PLOCK)))		// wait for lock pll
+	{
+	}
+
+	// Some tests on specific versions of macosx (10.7.3), reported some
+	// strange behaviors when the board is reset using the serial
+	// port touch at 1200 bps. This delay fixes this behavior.
+	delay(1);
+#if defined(OTGPADE)
+	USBCON = (USBCON & ~(1<<FRZCLK)) | (1<<OTGPADE);	// start USB clock, enable VBUS Pad
+#else
+	USBCON &= ~(1 << FRZCLK);	// start USB clock
+#endif
+
+#if defined(RSTCPU)
+#if defined(LSM)
+	UDCON &= ~((1<<RSTCPU) | (1<<LSM) | (1<<RMWKUP) | (1<<DETACH));	// enable attach resistor, set full speed mode
+#else // u2 Series
+	UDCON &= ~((1 << RSTCPU) | (1 << RMWKUP) | (1 << DETACH));	// enable attach resistor, set full speed mode
+#endif
+#else
+	// AT90USB64x and AT90USB128x don't have RSTCPU
+	UDCON &= ~((1<<LSM) | (1<<RMWKUP) | (1<<DETACH));	// enable attach resistor, set full speed mode
+#endif
+}
+
+//	General interrupt
+ISR(USB_GEN_vect)
+{
+	u8 udint = UDINT;
+	UDINT &= ~((1<<EORSTI) | (1<<SOFI)); // clear the IRQ flags for the IRQs which are handled here, except WAKEUPI and SUSPI (see below)
+
+	//	End of Reset
+	if (udint & (1<<EORSTI))
+	{
+		InitEP(0,EP_TYPE_CONTROL,EP_SINGLE_64);	// init ep0
+		_usbConfiguration = 0;			// not configured yet
+		UEIENX = 1 << RXSTPE;			// Enable interrupts for ep0
+	}
+
+	//	Start of Frame - happens every millisecond so we use it for TX and RX LED one-shot timing, too
+	if (udint & (1<<SOFI))
+	{
+		USB_Flush(CDC_TX);				// Send a tx frame if found
+		
+		// check whether the one-shot period has elapsed.  if so, turn off the LED
+		if (TxLEDPulse && !(--TxLEDPulse))
+			TXLED0;
+		if (RxLEDPulse && !(--RxLEDPulse))
+			RXLED0;
+	}
+
+	// the WAKEUPI interrupt is triggered as soon as there are non-idle patterns on the data
+	// lines. Thus, the WAKEUPI interrupt can occur even if the controller is not in the "suspend" mode.
+	// Therefore the we enable it only when USB is suspended
+	if (udint & (1<<WAKEUPI))
+	{
+		UDIEN = (UDIEN & ~(1<<WAKEUPE)) | (1<<SUSPE); // Disable interrupts for WAKEUP and enable interrupts for SUSPEND
+
+		//TODO
+		// WAKEUPI shall be cleared by software (USB clock inputs must be enabled before).
+		//USB_ClockEnable();
+		UDINT &= ~(1<<WAKEUPI);
+		_usbSuspendState = (_usbSuspendState & ~(1<<SUSPI)) | (1<<WAKEUPI);
+	}
+	else if (udint & (1<<SUSPI)) // only one of the WAKEUPI / SUSPI bits can be active at time
+	{
+		UDIEN = (UDIEN & ~(1<<SUSPE)) | (1<<WAKEUPE); // Disable interrupts for SUSPEND and enable interrupts for WAKEUP
+
+		//TODO
+		//USB_ClockDisable();
+
+		UDINT &= ~((1<<WAKEUPI) | (1<<SUSPI)); // clear any already pending WAKEUP IRQs and the SUSPI request
+		_usbSuspendState = (_usbSuspendState & ~(1<<WAKEUPI)) | (1<<SUSPI);
+	}
+}
+
+//	VBUS or counting frames
+//	Any frame counting?
+u8 USBConnected()
+{
+	u8 f = UDFNUML;
+	delay(3);
+	return f != UDFNUML;
+}
+
+//=======================================================================
+//=======================================================================
+
+USBDevice_ USBDevice;
+
+USBDevice_::USBDevice_()
+{
+}
+
+void USBDevice_::attach()
+{
+	_usbConfiguration = 0;
+	_usbCurrentStatus = 0;
+	_usbSuspendState = 0;
+	USB_ClockEnable();
+
+	UDINT &= ~((1<<WAKEUPI) | (1<<SUSPI)); // clear already pending WAKEUP / SUSPEND requests
+	UDIEN = (1<<EORSTE) | (1<<SOFE) | (1<<SUSPE);	// Enable interrupts for EOR (End of Reset), SOF (start of frame) and SUSPEND
+	
+	TX_RX_LED_INIT;
+}
+
+void USBDevice_::detach()
+{
+}
+
+//	Check for interrupts
+//	TODO: VBUS detection
+bool USBDevice_::configured()
+{
+	return _usbConfiguration;
+}
+
+void USBDevice_::poll()
+{
+}
+
+bool USBDevice_::wakeupHost()
+{
+	// clear any previous wakeup request which might have been set but could be processed at that time
+	// e.g. because the host was not suspended at that time
+	UDCON &= ~(1 << RMWKUP);
+
+	if(!(UDCON & (1 << RMWKUP))
+	  && (_usbSuspendState & (1<<SUSPI))
+	  && (_usbCurrentStatus & FEATURE_REMOTE_WAKEUP_ENABLED))
+	{
+		// This short version will only work, when the device has not been suspended. Currently the
+		// Arduino core doesn't handle SUSPEND at all, so this is ok.
+		USB_ClockEnable();
+		UDCON |= (1 << RMWKUP); // send the wakeup request
+		return true;
+	}
+
+	return false;
+}
+
+bool USBDevice_::isSuspended()
+{
+	return (_usbSuspendState & (1 << SUSPI));
+}
+
+
+#endif /* if defined(USBCON) */
diff --git a/test/arduino_leonardo_bridge_multi_cdc/USBCore.h b/test/arduino_leonardo_bridge_multi_cdc/USBCore.h
new file mode 100644
index 00000000..6614fe42
--- /dev/null
+++ b/test/arduino_leonardo_bridge_multi_cdc/USBCore.h
@@ -0,0 +1,317 @@
+
+// Copyright (c) 2010, Peter Barrett 
+/*
+** Permission to use, copy, modify, and/or distribute this software for  
+** any purpose with or without fee is hereby granted, provided that the  
+** above copyright notice and this permission notice appear in all copies.  
+**  
+** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL  
+** WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED  
+** WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR  
+** BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES  
+** OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,  
+** WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,  
+** ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS  
+** SOFTWARE.  
+*/
+
+#ifndef __USBCORE_H__
+#define __USBCORE_H__
+
+#include "USBAPI.h"
+
+//	Standard requests
+#define GET_STATUS			0
+#define CLEAR_FEATURE		1
+#define SET_FEATURE			3
+#define SET_ADDRESS			5
+#define GET_DESCRIPTOR		6
+#define SET_DESCRIPTOR		7
+#define GET_CONFIGURATION	8
+#define SET_CONFIGURATION	9
+#define GET_INTERFACE		10
+#define SET_INTERFACE		11
+
+
+// bmRequestType
+#define REQUEST_HOSTTODEVICE	0x00
+#define REQUEST_DEVICETOHOST	0x80
+#define REQUEST_DIRECTION		0x80
+
+#define REQUEST_STANDARD		0x00
+#define REQUEST_CLASS			0x20
+#define REQUEST_VENDOR			0x40
+#define REQUEST_TYPE			0x60
+
+#define REQUEST_DEVICE			0x00
+#define REQUEST_INTERFACE		0x01
+#define REQUEST_ENDPOINT		0x02
+#define REQUEST_OTHER			0x03
+#define REQUEST_RECIPIENT		0x03
+
+#define REQUEST_DEVICETOHOST_CLASS_INTERFACE    (REQUEST_DEVICETOHOST | REQUEST_CLASS | REQUEST_INTERFACE)
+#define REQUEST_HOSTTODEVICE_CLASS_INTERFACE    (REQUEST_HOSTTODEVICE | REQUEST_CLASS | REQUEST_INTERFACE)
+#define REQUEST_DEVICETOHOST_STANDARD_INTERFACE (REQUEST_DEVICETOHOST | REQUEST_STANDARD | REQUEST_INTERFACE)
+
+//	Class requests
+
+#define CDC_SET_LINE_CODING			0x20
+#define CDC_GET_LINE_CODING			0x21
+#define CDC_SET_CONTROL_LINE_STATE	0x22
+#define CDC_SEND_BREAK				0x23
+
+#define MSC_RESET					0xFF
+#define MSC_GET_MAX_LUN				0xFE
+
+//	Descriptors
+
+#define USB_DEVICE_DESC_SIZE 18
+#define USB_CONFIGUARTION_DESC_SIZE 9
+#define USB_INTERFACE_DESC_SIZE 9
+#define USB_ENDPOINT_DESC_SIZE 7
+
+#define USB_DEVICE_DESCRIPTOR_TYPE             1
+#define USB_CONFIGURATION_DESCRIPTOR_TYPE      2
+#define USB_STRING_DESCRIPTOR_TYPE             3
+#define USB_INTERFACE_DESCRIPTOR_TYPE          4
+#define USB_ENDPOINT_DESCRIPTOR_TYPE           5
+
+// usb_20.pdf Table 9.6 Standard Feature Selectors
+#define DEVICE_REMOTE_WAKEUP                   1
+#define ENDPOINT_HALT                          2
+#define TEST_MODE                              3
+
+// usb_20.pdf Figure 9-4. Information Returned by a GetStatus() Request to a Device
+#define FEATURE_SELFPOWERED_ENABLED     (1 << 0)
+#define FEATURE_REMOTE_WAKEUP_ENABLED   (1 << 1)
+
+#define USB_DEVICE_CLASS_COMMUNICATIONS        0x02
+#define USB_DEVICE_CLASS_HUMAN_INTERFACE       0x03
+#define USB_DEVICE_CLASS_STORAGE               0x08
+#define USB_DEVICE_CLASS_VENDOR_SPECIFIC       0xFF
+
+#define USB_CONFIG_POWERED_MASK                0x40
+#define USB_CONFIG_BUS_POWERED                 0x80
+#define USB_CONFIG_SELF_POWERED                0xC0
+#define USB_CONFIG_REMOTE_WAKEUP               0x20
+
+// bMaxPower in Configuration Descriptor
+#define USB_CONFIG_POWER_MA(mA)                ((mA)/2)
+
+// bEndpointAddress in Endpoint Descriptor
+#define USB_ENDPOINT_DIRECTION_MASK            0x80
+#define USB_ENDPOINT_OUT(addr)                 (lowByte((addr) | 0x00))
+#define USB_ENDPOINT_IN(addr)                  (lowByte((addr) | 0x80))
+
+#define USB_ENDPOINT_TYPE_MASK                 0x03
+#define USB_ENDPOINT_TYPE_CONTROL              0x00
+#define USB_ENDPOINT_TYPE_ISOCHRONOUS          0x01
+#define USB_ENDPOINT_TYPE_BULK                 0x02
+#define USB_ENDPOINT_TYPE_INTERRUPT            0x03
+
+#define TOBYTES(x) ((x) & 0xFF),(((x) >> 8) & 0xFF)
+
+#define CDC_V1_10                               0x0110
+#define CDC_COMMUNICATION_INTERFACE_CLASS       0x02
+
+#define CDC_CALL_MANAGEMENT                     0x01
+#define CDC_ABSTRACT_CONTROL_MODEL              0x02
+#define CDC_HEADER                              0x00
+#define CDC_ABSTRACT_CONTROL_MANAGEMENT         0x02
+#define CDC_UNION                               0x06
+#define CDC_CS_INTERFACE                        0x24
+#define CDC_CS_ENDPOINT                         0x25
+#define CDC_DATA_INTERFACE_CLASS                0x0A
+
+#define MSC_SUBCLASS_SCSI						0x06 
+#define MSC_PROTOCOL_BULK_ONLY					0x50 
+
+#ifndef USB_VERSION
+#define USB_VERSION 0x200
+#endif
+
+//	Device
+typedef struct {
+	u8 len;				// 18
+	u8 dtype;			// 1 USB_DEVICE_DESCRIPTOR_TYPE
+	u16 usbVersion;		// 0x200 or 0x210
+	u8	deviceClass;
+	u8	deviceSubClass;
+	u8	deviceProtocol;
+	u8	packetSize0;	// Packet 0
+	u16	idVendor;
+	u16	idProduct;
+	u16	deviceVersion;	// 0x100
+	u8	iManufacturer;
+	u8	iProduct;
+	u8	iSerialNumber;
+	u8	bNumConfigurations;
+} DeviceDescriptor;
+
+//	Config
+typedef struct {
+	u8	len;			// 9
+	u8	dtype;			// 2
+	u16 clen;			// total length
+	u8	numInterfaces;
+	u8	config;
+	u8	iconfig;
+	u8	attributes;
+	u8	maxPower;
+} ConfigDescriptor;
+
+//	String
+
+//	Interface
+typedef struct
+{
+	u8 len;		// 9
+	u8 dtype;	// 4
+	u8 number;
+	u8 alternate;
+	u8 numEndpoints;
+	u8 interfaceClass;
+	u8 interfaceSubClass;
+	u8 protocol;
+	u8 iInterface;
+} InterfaceDescriptor;
+
+//	Endpoint
+typedef struct
+{
+	u8 len;		// 7
+	u8 dtype;	// 5
+	u8 addr;
+	u8 attr;
+	u16 packetSize;
+	u8 interval;
+} EndpointDescriptor;
+
+// Interface Association Descriptor
+// Used to bind 2 interfaces together in CDC compostite device
+typedef struct
+{
+	u8 len;				// 8
+	u8 dtype;			// 11
+	u8 firstInterface;
+	u8 interfaceCount;
+	u8 functionClass;
+	u8 funtionSubClass;
+	u8 functionProtocol;
+	u8 iInterface;
+} IADDescriptor;
+
+//	CDC CS interface descriptor
+typedef struct
+{
+	u8 len;		// 5
+	u8 dtype;	// 0x24
+	u8 subtype;
+	u8 d0;
+	u8 d1;
+} CDCCSInterfaceDescriptor;
+
+typedef struct
+{
+	u8 len;		// 4
+	u8 dtype;	// 0x24
+	u8 subtype;
+	u8 d0;
+} CDCCSInterfaceDescriptor4;
+
+typedef struct 
+{
+    u8	len;
+    u8 	dtype;		// 0x24
+    u8 	subtype;	// 1
+    u8 	bmCapabilities;
+    u8 	bDataInterface;
+} CMFunctionalDescriptor;
+	
+typedef struct 
+{
+    u8	len;
+    u8 	dtype;		// 0x24
+    u8 	subtype;	// 1
+    u8 	bmCapabilities;
+} ACMFunctionalDescriptor;
+
+typedef struct 
+{
+	//	IAD
+	IADDescriptor				iad;	// Only needed on compound device
+
+	//	Control
+	InterfaceDescriptor			cif;	// 
+	CDCCSInterfaceDescriptor	header;
+	CMFunctionalDescriptor		callManagement;			// Call Management
+	ACMFunctionalDescriptor		controlManagement;		// ACM
+	CDCCSInterfaceDescriptor	functionalDescriptor;	// CDC_UNION
+	EndpointDescriptor			cifin;
+
+	//	Data
+	InterfaceDescriptor			dif;
+	EndpointDescriptor			in;
+	EndpointDescriptor			out;
+
+  // kai:added
+  IADDescriptor       iad2;  // Only needed on compound device
+
+  //  Control
+  InterfaceDescriptor     cif2;  // 
+  CDCCSInterfaceDescriptor  header2;
+  CMFunctionalDescriptor    callManagement2;     // Call Management
+  ACMFunctionalDescriptor   controlManagement2;    // ACM
+  CDCCSInterfaceDescriptor  functionalDescriptor2; // CDC_UNION
+  EndpointDescriptor      cifin2;
+
+  //  Data
+  InterfaceDescriptor     dif2;
+  EndpointDescriptor      in2;
+  EndpointDescriptor      out2;
+} CDCDescriptor;
+
+typedef struct 
+{
+	InterfaceDescriptor			msc;
+	EndpointDescriptor			in;
+	EndpointDescriptor			out;
+} MSCDescriptor;
+
+
+#define D_DEVICE(_class,_subClass,_proto,_packetSize0,_vid,_pid,_version,_im,_ip,_is,_configs) \
+	{ 18, 1, USB_VERSION, _class,_subClass,_proto,_packetSize0,_vid,_pid,_version,_im,_ip,_is,_configs }
+
+#define D_CONFIG(_totalLength,_interfaces) \
+	{ 9, 2, _totalLength,_interfaces, 1, 0, USB_CONFIG_BUS_POWERED | USB_CONFIG_REMOTE_WAKEUP, USB_CONFIG_POWER_MA(500) }
+
+#define D_INTERFACE(_n,_numEndpoints,_class,_subClass,_protocol) \
+	{ 9, 4, _n, 0, _numEndpoints, _class,_subClass, _protocol, 0 }
+
+#define D_ENDPOINT(_addr,_attr,_packetSize, _interval) \
+	{ 7, 5, _addr,_attr,_packetSize, _interval }
+
+#define D_IAD(_firstInterface, _count, _class, _subClass, _protocol) \
+	{ 8, 11, _firstInterface, _count, _class, _subClass, _protocol, 0 }
+
+#define D_CDCCS(_subtype,_d0,_d1)	{ 5, 0x24, _subtype, _d0, _d1 }
+#define D_CDCCS4(_subtype,_d0)		{ 4, 0x24, _subtype, _d0 }
+
+// Bootloader related fields
+// Old Caterina bootloader places the MAGIC key into unsafe RAM locations (it can be rewritten
+// by the running sketch before to actual reboot).
+// Newer bootloaders, recognizable by the LUFA "signature" at the end of the flash, can handle both
+// the usafe and the safe location.
+#ifndef MAGIC_KEY
+#define MAGIC_KEY 0x7777
+#endif
+
+#ifndef MAGIC_KEY_POS
+#define MAGIC_KEY_POS 0x0800
+#endif
+
+#ifndef NEW_LUFA_SIGNATURE
+#define NEW_LUFA_SIGNATURE 0xDCFB
+#endif
+
+#endif
diff --git a/test/arduino_leonardo_bridge_multi_cdc/USBDesc.h b/test/arduino_leonardo_bridge_multi_cdc/USBDesc.h
new file mode 100644
index 00000000..a903ff1f
--- /dev/null
+++ b/test/arduino_leonardo_bridge_multi_cdc/USBDesc.h
@@ -0,0 +1,77 @@
+/*
+   Copyright (c) 2011, Peter Barrett
+   Copyright (c) 2015, Arduino LLC
+
+   Permission to use, copy, modify, and/or distribute this software for
+   any purpose with or without fee is hereby granted, provided that the
+   above copyright notice and this permission notice appear in all copies.
+
+   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+   WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+   WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR
+   BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES
+   OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+   WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+   ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+   SOFTWARE.
+ */
+
+#define PLUGGABLE_USB_ENABLED
+
+#if defined(EPRST6)
+#define USB_ENDPOINTS 7 // AtMegaxxU4
+#else
+#define USB_ENDPOINTS 5 // AtMegaxxU2
+#endif
+
+#define ISERIAL_MAX_LEN     20
+
+#define CDC_INTERFACE_COUNT	2
+#define CDC_ENPOINT_COUNT	3
+
+// kai:begin
+#undef CDC_ACM_INTERFACE
+#undef CDC_DATA_INTERFACE
+#undef CDC_FIRST_ENDPOINT
+#undef CDC_ENDPOINT_ACM
+#undef CDC_ENDPOINT_OUT
+#undef CDC_ENDPOINT_IN
+#undef CDC_RX
+#undef CDC_TX
+
+#define CDC_ACM_INTERFACE1	0	// CDC ACM
+#define CDC_DATA_INTERFACE1	1	// CDC Data
+#define CDC_FIRST_ENDPOINT1	1
+#define CDC_ENDPOINT_ACM1	(CDC_FIRST_ENDPOINT1)							// CDC First
+#define CDC_ENDPOINT_OUT1	(CDC_FIRST_ENDPOINT1+1)
+#define CDC_ENDPOINT_IN1		(CDC_FIRST_ENDPOINT1+2)
+
+#define CDC_ACM_INTERFACE2  2 // CDC ACM
+#define CDC_DATA_INTERFACE2  3 // CDC Data
+#define CDC_FIRST_ENDPOINT2  4 
+#define CDC_ENDPOINT_ACM2  (CDC_FIRST_ENDPOINT2)              // CDC First
+#define CDC_ENDPOINT_OUT2  (CDC_FIRST_ENDPOINT2+1)
+#define CDC_ENDPOINT_IN2  (CDC_FIRST_ENDPOINT2+2)
+
+// only one of both interfaces is functional:
+#define ACTIVE_INTERFACE 1
+
+#if ACTIVE_INTERFACE == 1
+# define CDC_CLASS_INTERFACE CDC_ACM_INTERFACE1
+# define CDC_RX              CDC_ENDPOINT_OUT1
+# define CDC_TX              CDC_ENDPOINT_IN1
+#else
+# define CDC_CLASS_INTERFACE CDC_ACM_INTERFACE2
+# define CDC_RX              CDC_ENDPOINT_OUT2
+# define CDC_TX              CDC_ENDPOINT_IN2
+#endif
+
+#undef USB_VID
+#define USB_VID 0x2342
+// kai:end
+
+#define INTERFACE_COUNT    (MSC_INTERFACE + MSC_INTERFACE_COUNT)
+
+#define IMANUFACTURER   1
+#define IPRODUCT        2
+#define ISERIAL         3
diff --git a/test/arduino_leonardo_bridge_multi_cdc/arduino_leonardo_bridge_multi_cdc.ino b/test/arduino_leonardo_bridge_multi_cdc/arduino_leonardo_bridge_multi_cdc.ino
new file mode 100644
index 00000000..663292c1
--- /dev/null
+++ b/test/arduino_leonardo_bridge_multi_cdc/arduino_leonardo_bridge_multi_cdc.ino
@@ -0,0 +1,64 @@
+/*
+  bridge USB-serial to hardware-serial
+
+  for Arduinos based on ATmega32u4 (Leonardo and compatible Pro Micro, Micro)
+  hardware serial is configured with baud-rate, databits, stopbits, parity as send over USB
+
+  see https://github.com/arduino/Arduino/tree/master/hardware/arduino/avr/cores/arduino 
+  -> CDC.cpp|HardwareSerial.cpp for serial implementation details
+
+  this sketch is mainly for demonstration / test of CDC communication
+  performance as real usb-serial bridge would be inacceptable as each byte is send in separate USB packet
+*/
+
+uint32_t baud = 9600;
+uint8_t databits = 8;
+uint8_t stopbits = 1;
+uint8_t parity = 0;
+
+void setup() {
+  Serial.begin(baud); // USB
+  Serial1.begin(baud, SERIAL_8N1);
+}
+
+void loop() {
+  // show USB connected state
+  if (Serial) TXLED1;
+  else        TXLED0;
+
+  // configure hardware serial
+  if (Serial.baud() != baud ||
+      Serial.numbits() != databits ||
+      Serial.stopbits() != stopbits ||
+      Serial.paritytype() != parity) {
+    baud = Serial.baud();
+    databits = Serial.numbits();
+    stopbits = Serial.stopbits();
+    parity = Serial.paritytype();
+    uint8_t config = 0; // ucsrc register
+    switch (databits) {
+      case 5: break;
+      case 6: config |= 2; break;
+      case 7: config |= 4; break;
+      case 8: config |= 6; break;
+      default: config |= 6;
+    }
+    switch (stopbits) {
+      case 2: config |= 8;
+        // 1.5 stopbits not supported
+    }
+    switch (parity) {
+      case 1: config |= 0x30; break; // odd
+      case 2: config |= 0x20; break; // even
+        // mark, space not supported
+    }
+    Serial1.end();
+    Serial1.begin(baud, config);
+  }
+
+  // bridge
+  if (Serial.available() > 0)
+    Serial1.write(Serial.read());
+  if (Serial1.available() > 0)
+    Serial.write(Serial1.read());
+}
diff --git a/usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java b/usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java
index 9a820939..d7d166bf 100644
--- a/usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java
+++ b/usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java
@@ -164,6 +164,11 @@ public void setUp() throws Exception {
         context = InstrumentationRegistry.getContext();
         usbManager = (UsbManager) context.getSystemService(Context.USB_SERVICE);
         List<UsbSerialDriver> availableDrivers = UsbSerialProber.getDefaultProber().findAllDrivers(usbManager);
+        if(availableDrivers.isEmpty()) {
+            ProbeTable customTable = new ProbeTable();
+            customTable.addProduct(0x2342, 0x8036, CdcAcmSerialDriver.class); // arduino multiport cdc witch custom VID
+            availableDrivers = new UsbSerialProber(customTable).findAllDrivers(usbManager);
+        }
         assertEquals("no USB device found", 1, availableDrivers.size());
         usbSerialDriver = availableDrivers.get(0);
         if(test_device_driver != null) {
diff --git a/usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CdcAcmSerialDriver.java b/usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CdcAcmSerialDriver.java
index 3f617d09..0994d58a 100644
--- a/usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CdcAcmSerialDriver.java
+++ b/usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CdcAcmSerialDriver.java
@@ -29,7 +29,7 @@
 import android.util.Log;
 
 import java.io.IOException;
-import java.util.Collections;
+import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -47,11 +47,26 @@ public class CdcAcmSerialDriver implements UsbSerialDriver {
     private final String TAG = CdcAcmSerialDriver.class.getSimpleName();
 
     private final UsbDevice mDevice;
-    private final UsbSerialPort mPort;
+    private final List<UsbSerialPort> mPorts;
 
     public CdcAcmSerialDriver(UsbDevice device) {
         mDevice = device;
-        mPort = new CdcAcmSerialPort(device, 0);
+        mPorts = new ArrayList<>();
+
+        int controlInterfaceCount = 0;
+        int dataInterfaceCount = 0;
+        for( int i = 0; i < device.getInterfaceCount(); i++) {
+            if(device.getInterface(i).getInterfaceClass() == UsbConstants.USB_CLASS_COMM)
+                controlInterfaceCount++;
+            if(device.getInterface(i).getInterfaceClass() == UsbConstants.USB_CLASS_CDC_DATA)
+                dataInterfaceCount++;
+        }
+        for( int port = 0; port < Math.min(controlInterfaceCount, dataInterfaceCount); port++) {
+            mPorts.add(new CdcAcmSerialPort(mDevice, port));
+        }
+        if(mPorts.size() == 0) {
+            mPorts.add(new CdcAcmSerialPort(mDevice, -1));
+        }
     }
 
     @Override
@@ -61,7 +76,7 @@ public UsbDevice getDevice() {
 
     @Override
     public List<UsbSerialPort> getPorts() {
-        return Collections.singletonList(mPort);
+        return mPorts;
     }
 
     class CdcAcmSerialPort extends CommonUsbSerialPort {
@@ -95,7 +110,7 @@ public UsbSerialDriver getDriver() {
 
         @Override
         public void openInt(UsbDeviceConnection connection) throws IOException {
-            if (1 == mDevice.getInterfaceCount()) {
+            if (mPortNumber == -1) {
                 Log.d(TAG,"device might be castrated ACM device, trying single interface logic");
                 openSingleInterface();
             } else {
@@ -105,77 +120,51 @@ public void openInt(UsbDeviceConnection connection) throws IOException {
         }
 
         private void openSingleInterface() throws IOException {
-            // the following code is inspired by the cdc-acm driver
-            // in the linux kernel
+            // the following code is inspired by the cdc-acm driver in the linux kernel
 
             mControlIndex = 0;
             mControlInterface = mDevice.getInterface(0);
-            Log.d(TAG, "Control iface=" + mControlInterface);
-
             mDataInterface = mDevice.getInterface(0);
-            Log.d(TAG, "data iface=" + mDataInterface);
-
             if (!mConnection.claimInterface(mControlInterface, true)) {
                 throw new IOException("Could not claim shared control/data interface");
             }
 
-            int endCount = mControlInterface.getEndpointCount();
-
-            if (endCount < 3) {
-                Log.d(TAG,"not enough endpoints - need 3. count=" + mControlInterface.getEndpointCount());
-                throw new IOException("Insufficient number of endpoints (" + mControlInterface.getEndpointCount() + ")");
-            }
-
-            // Analyse endpoints for their properties
-            mControlEndpoint = null;
-            mReadEndpoint = null;
-            mWriteEndpoint = null;
-            for (int i = 0; i < endCount; ++i) {
+            for (int i = 0; i < mControlInterface.getEndpointCount(); ++i) {
                 UsbEndpoint ep = mControlInterface.getEndpoint(i);
-                if ((ep.getDirection() == UsbConstants.USB_DIR_IN) &&
-                    (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_INT)) {
-                    Log.d(TAG,"Found controlling endpoint");
+                if ((ep.getDirection() == UsbConstants.USB_DIR_IN) && (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_INT)) {
                     mControlEndpoint = ep;
-                } else if ((ep.getDirection() == UsbConstants.USB_DIR_IN) &&
-                           (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
-                    Log.d(TAG,"Found reading endpoint");
+                } else if ((ep.getDirection() == UsbConstants.USB_DIR_IN) && (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
                     mReadEndpoint = ep;
-                } else if ((ep.getDirection() == UsbConstants.USB_DIR_OUT) &&
-                        (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
-                    Log.d(TAG,"Found writing endpoint");
+                } else if ((ep.getDirection() == UsbConstants.USB_DIR_OUT) && (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
                     mWriteEndpoint = ep;
                 }
-
-
-                if ((mControlEndpoint != null) &&
-                    (mReadEndpoint != null) &&
-                    (mWriteEndpoint != null)) {
-                    Log.d(TAG,"Found all required endpoints");
-                    break;
-                }
             }
-
-            if ((mControlEndpoint == null) ||
-                    (mReadEndpoint == null) ||
-                    (mWriteEndpoint == null)) {
-                Log.d(TAG,"Could not establish all endpoints");
-                throw new IOException("Could not establish all endpoints");
+            if (mControlEndpoint == null) {
+                throw new IOException("No control endpoint");
             }
         }
 
         private void openInterface() throws IOException {
             Log.d(TAG, "claiming interfaces, count=" + mDevice.getInterfaceCount());
 
+            int controlInterfaceCount = 0;
+            int dataInterfaceCount = 0;
             mControlInterface = null;
             mDataInterface = null;
             for (int i = 0; i < mDevice.getInterfaceCount(); i++) {
                 UsbInterface usbInterface = mDevice.getInterface(i);
                 if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_COMM) {
-                    mControlIndex = i;
-                    mControlInterface = usbInterface;
+                    if(controlInterfaceCount == mPortNumber) {
+                        mControlIndex = i;
+                        mControlInterface = usbInterface;
+                    }
+                    controlInterfaceCount++;
                 }
                 if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_CDC_DATA) {
-                    mDataInterface = usbInterface;
+                    if(dataInterfaceCount == mPortNumber) {
+                        mDataInterface = usbInterface;
+                    }
+                    dataInterfaceCount++;
                 }
             }
 
@@ -202,8 +191,6 @@ private void openInterface() throws IOException {
                 throw new IOException("Could not claim data interface");
             }
 
-            mReadEndpoint = null;
-            mWriteEndpoint = null;
             for (int i = 0; i < mDataInterface.getEndpointCount(); i++) {
                 UsbEndpoint ep = mDataInterface.getEndpoint(i);
                 if (ep.getDirection() == UsbConstants.USB_DIR_IN && ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)