diff --git a/apps/apps_container.cpp b/apps/apps_container.cpp
index ac8b18de3..4f974f1ee 100644
--- a/apps/apps_container.cpp
+++ b/apps/apps_container.cpp
@@ -1,6 +1,7 @@
 #include "apps_container.h"
 #include "global_preferences.h"
 #include <ion.h>
+#include <kandinsky.h>//TODO REMOVE
 
 extern "C" {
 #include <assert.h>
@@ -78,6 +79,13 @@ void AppsContainer::suspend(bool checkIfPowerKeyReleased) {
 }
 
 bool AppsContainer::dispatchEvent(Ion::Events::Event event) {
+  if (event == Ion::Events::USBEnumeration) {
+    switchTo(appSnapshotAtIndex(0));
+    // TODO remove include kandinsky.h
+    Ion::Display::pushRectUniform(KDRect(KDPointZero, 320,240), KDColorBlue);
+    Ion::USB::DFU();
+  }
+
   bool alphaLockWantsRedraw = updateAlphaLock();
 
   bool didProcessEvent = Container::dispatchEvent(event);
diff --git a/escher/src/run_loop.cpp b/escher/src/run_loop.cpp
index c35fcbd6a..7f5916f1a 100644
--- a/escher/src/run_loop.cpp
+++ b/escher/src/run_loop.cpp
@@ -31,7 +31,6 @@ bool RunLoop::step() {
   int eventDuration = Timer::TickDuration;
   int timeout = eventDuration;
   Ion::Events::Event event = Ion::Events::getEvent(&timeout);
-  assert(event.isDefined());
   eventDuration -= timeout;
 
   assert(eventDuration >= 0);
@@ -54,6 +53,12 @@ bool RunLoop::step() {
     }
   }
 
+  if (event == Ion::Events::USBEnumeration) {
+    dispatchEvent(event);
+  }
+
+  assert(event.isDefined());
+
 #if ESCHER_LOG_EVENTS_BINARY
   Ion::Console::writeChar((char)event.id());
 #endif
diff --git a/ion/include/ion/events.h b/ion/include/ion/events.h
index b79842ca7..5784816ec 100644
--- a/ion/include/ion/events.h
+++ b/ion/include/ion/events.h
@@ -215,6 +215,7 @@ constexpr Event UpperZ = Event::ShiftAlphaKey(Keyboard::Key::H4);
 constexpr Event None = Event::Special(0);
 constexpr Event Termination = Event::Special(1);
 constexpr Event TimerFire = Event::Special(2);
+constexpr Event USBEnumeration = Event::Special(3);
 
 }
 }
diff --git a/ion/include/ion/usb.h b/ion/include/ion/usb.h
index 760d9cc63..f30aacbaa 100644
--- a/ion/include/ion/usb.h
+++ b/ion/include/ion/usb.h
@@ -5,6 +5,7 @@ namespace Ion {
 namespace USB {
 
 bool isPlugged();
+void DFU();
 
 }
 }
diff --git a/ion/src/device/Makefile b/ion/src/device/Makefile
index 4d1ccd6c4..3597947ec 100644
--- a/ion/src/device/Makefile
+++ b/ion/src/device/Makefile
@@ -29,7 +29,7 @@ objs += $(addprefix ion/src/device/, \
   wakeup.o \
 )
 
-objs += $(addprefix ion/src/device/usb/, \
+usb_objs += $(addprefix ion/src/device/usb/, \
   calculator.o \
   device.o\
   dfu_interface.o\
@@ -39,6 +39,10 @@ objs += $(addprefix ion/src/device/usb/, \
   setup_packet.o\
 )
 
+$(usb_objs): SFLAGS += -fPIC
+
+objs += $(usb_objs)
+
 objs += $(addprefix ion/src/device/usb/stack/, \
   configuration_descriptor.o \
   descriptor.o\
diff --git a/ion/src/device/boot/flash.ld b/ion/src/device/boot/flash.ld
index e5ddcc9e4..4aa70d303 100644
--- a/ion/src/device/boot/flash.ld
+++ b/ion/src/device/boot/flash.ld
@@ -38,6 +38,16 @@ SECTIONS {
     KEEP(*(.header))
   } >FLASH
 
+  .usb : {
+    . = ALIGN(4);
+    _flash_usb_stack_start = .;
+    *(.text.*3Ion3USB6Device*)
+    *(.text.memcpy)
+    *(.text.strlen)
+    *(.text.*Register*)
+    _flash_usb_stack_end = .;
+  } >FLASH
+
   .text : {
     . = ALIGN(4);
     *(.text)
diff --git a/ion/src/device/events_keyboard.cpp b/ion/src/device/events_keyboard.cpp
index 36487a0a8..ae6bcf14e 100644
--- a/ion/src/device/events_keyboard.cpp
+++ b/ion/src/device/events_keyboard.cpp
@@ -1,4 +1,5 @@
 #include <ion.h>
+#include "regs/otg.h"
 #include <assert.h>
 
 namespace Ion {
@@ -33,6 +34,12 @@ Event getEvent(int * timeout) {
   uint64_t keysSeenUp = 0;
   uint64_t keysSeenTransitionningFromUpToDown = 0;
   while (true) {
+    // Check if the USB is plugged and if we are being enumerated by a host.
+    if (OTG.GINTSTS()->getUSBRST()) {
+      // The device is being enumerated. Fire an event.
+      return Events::USBEnumeration;
+    }
+
     Keyboard::State state = Keyboard::scan();
     keysSeenUp |= ~state;
     keysSeenTransitionningFromUpToDown = keysSeenUp & state;
diff --git a/ion/src/device/usb.cpp b/ion/src/device/usb.cpp
index 80c861209..bd5877e64 100644
--- a/ion/src/device/usb.cpp
+++ b/ion/src/device/usb.cpp
@@ -4,6 +4,11 @@
 #include "device.h"
 #include "display.h"
 #include "regs/regs.h"
+#include <stdlib.h>
+#include <new>
+
+extern char _flash_usb_stack_start;
+extern char _flash_usb_stack_end;
 
 namespace Ion {
 namespace USB {
@@ -12,6 +17,43 @@ bool isPlugged() {
   return Device::VbusPin.group().IDR()->get(Device::VbusPin.pin());
 }
 
+typedef void (*PollFunctionPointer)(Device::Calculator *);
+
+void DFU() {
+  size_t usb_stack_size = &_flash_usb_stack_end - &_flash_usb_stack_start;
+
+  /* 1 - Allocate a buffer in RAM that's large enough to contain all the code
+   * and objects of our USB stack. */
+
+  size_t ram_buffer_size = usb_stack_size + sizeof(Device::Calculator);
+  char * ram_buffer = static_cast<char *>(malloc(ram_buffer_size));
+  if (ram_buffer == nullptr) {
+    // Allocation failure
+    return;
+  }
+
+  // 2 - Copy the USB stack code from Flash to RAM
+  char * ram_usb_stack_start = ram_buffer;
+  memcpy(ram_usb_stack_start, &_flash_usb_stack_start, usb_stack_size);
+
+  // 3 - Initialize data in RAM buffer
+  Device::Calculator * calculator = new (ram_buffer + usb_stack_size) Device::Calculator();
+
+  // 4 - Figure out the address of Ion::USB::Device::poll() in RAM
+  char * flash_poll_function_address = reinterpret_cast<char *>(&Ion::USB::Device::poll);
+  assert(flash_poll_function_address >= &_flash_usb_stack_start);
+  assert(flash_poll_function_address < &_flash_usb_stack_end);
+  char * ram_poll_function_address = flash_poll_function_address - &_flash_usb_stack_start + ram_usb_stack_start;
+  PollFunctionPointer ram_poll_function = reinterpret_cast<PollFunctionPointer>(ram_poll_function_address);
+
+  // 5 - Execute Ion::USB::Device::poll() from RAM
+  ram_poll_function(calculator);
+
+  // 6 - Upon return, delete data and free the buffer in RAM
+  calculator->~Calculator();
+  free(ram_buffer);
+}
+
 }
 }
 
@@ -19,18 +61,23 @@ namespace Ion {
 namespace USB {
 namespace Device {
 
-Calculator * calculator() {
-  static Calculator calculator;
-  return &calculator;
+void poll(Calculator * calculator) {
+  // Wait for speed enumeration done
+  while (!OTG.GINTSTS()->getENUMDNE()) {
+  }
+
+  while (true) {
+    calculator->poll();
+  }
 }
 
 void init() {
   initGPIO();
-  calculator()->init();
+  initOTG();
 }
 
 void shutdown() {
-  calculator()->shutdown();
+  shutdownOTG();
   shutdownGPIO();
 }
 
@@ -74,6 +121,68 @@ void shutdownGPIO() {
   }
 }
 
+void initOTG() {
+  // Wait for AHB idle
+  while (!OTG.GRSTCTL()->getAHBIDL()) {
+  }
+
+  // Core soft reset
+  OTG.GRSTCTL()->setCSRST(true);
+  while (OTG.GRSTCTL()->getCSRST()) {
+  }
+
+  // Enable the USB transceiver
+  OTG.GCCFG()->setPWRDWN(true);
+  // FIXME: Understand why VBDEN is required
+  OTG.GCCFG()->setVBDEN(true);
+
+  // Get out of soft-disconnected state
+  OTG.DCTL()->setSDIS(false);
+
+  // Force peripheral only mode
+  OTG.GUSBCFG()->setFDMOD(true);
+
+  /* Configure the USB turnaround time.
+   * This has to be configured depending on the AHB clock speed. */
+  OTG.GUSBCFG()->setTRDT(0x6);
+
+  // Clear the interrupts
+  OTG.GINTSTS()->set(0);
+
+  // Full speed device
+  OTG.DCFG()->setDSPD(OTG::DCFG::DSPD::FullSpeed);
+
+  // FIFO-size = 128 * 32bits
+  // FIXME: Explain :-) Maybe we can increase it.
+  OTG.GRXFSIZ()->setRXFD(128);
+
+  // Unmask the interrupt line assertions
+  OTG.GAHBCFG()->setGINTMSK(true);
+
+  // Restart the PHY clock.
+  OTG.PCGCCTL()->setSTPPCLK(0);
+
+  // Pick which interrupts we're interested in
+  class OTG::GINTMSK intMask(0); // Reset value
+  intMask.setENUMDNEM(true); // Speed enumeration done
+  intMask.setUSBRST(true); // USB reset
+  intMask.setRXFLVLM(true); // Receive FIFO non empty
+  intMask.setIEPINT(true); // IN endpoint interrupt
+  intMask.setWUIM(true); // Resume / wakeup
+  intMask.setUSBSUSPM(true); // USB suspend
+  OTG.GINTMSK()->set(intMask);
+
+  // Unmask IN endpoint interrupt 0
+  OTG.DAINTMSK()->setIEPM(true);
+
+  // Unmask the transfer completed interrupt
+  OTG.DIEPMSK()->setXFRCM(true);
+}
+
+void shutdownOTG() {
+  //TODO ?
+}
+
 }
 }
 }
diff --git a/ion/src/device/usb.h b/ion/src/device/usb.h
index 81ed46f4a..1f404c6d8 100644
--- a/ion/src/device/usb.h
+++ b/ion/src/device/usb.h
@@ -24,8 +24,11 @@ void init();
 void shutdown();
 void initGPIO();
 void shutdownGPIO();
+void initOTG();
+void shutdownOTG();
 
-Calculator * calculator();
+// Enters DFU mode, returns when detached.
+void poll(Calculator * calculator);
 
 }
 }
diff --git a/ion/src/device/usb/calculator.h b/ion/src/device/usb/calculator.h
index fde11162b..2b34ae5ba 100644
--- a/ion/src/device/usb/calculator.h
+++ b/ion/src/device/usb/calculator.h
@@ -9,7 +9,7 @@
 #include "stack/dfu_functional_descriptor.h"
 #include "stack/interface_descriptor.h"
 #include "stack/language_id_string_descriptor.h"
-#include "stack/string_descriptor.h"
+#include "stack/relocatable_string_descriptor.h"
 #include <stddef.h>
 #include <assert.h>
 
@@ -90,10 +90,10 @@ private:
   InterfaceDescriptor m_interfaceDescriptor;
   ConfigurationDescriptor m_configurationDescriptor;
   LanguageIDStringDescriptor m_languageStringDescriptor;
-  StringDescriptor m_manufacturerStringDescriptor;
-  StringDescriptor m_productStringDescriptor;
-  StringDescriptor m_serialNumberStringDescriptor;
-  StringDescriptor m_interfaceStringDescriptor;
+  RelocatableStringDescriptor<9> m_manufacturerStringDescriptor;
+  RelocatableStringDescriptor<11> m_productStringDescriptor;
+  RelocatableStringDescriptor<6> m_serialNumberStringDescriptor;
+  RelocatableStringDescriptor<47> m_interfaceStringDescriptor;
 
   Descriptor * m_descriptors[7]; // We do not need to include m_interfaceDescriptor nor m_dfuFunctionalDescriptor, because they are inluded in other descriptors.
 
diff --git a/ion/src/device/usb/device.cpp b/ion/src/device/usb/device.cpp
index 700bab310..cd77a39a7 100644
--- a/ion/src/device/usb/device.cpp
+++ b/ion/src/device/usb/device.cpp
@@ -7,82 +7,7 @@ namespace Device {
 
 static inline uint16_t min(uint16_t x, uint16_t y) { return (x<y ? x : y); }
 
-void Device::init() {
-  // Wait for AHB idle
-  while (!OTG.GRSTCTL()->getAHBIDL()) {
-  }
-
-  // Core soft reset
-  OTG.GRSTCTL()->setCSRST(true);
-  while (OTG.GRSTCTL()->getCSRST()) {
-  }
-
-  // Enable the USB transceiver
-  OTG.GCCFG()->setPWRDWN(true);
-  // FIXME: Understand why VBDEN is required
-  OTG.GCCFG()->setVBDEN(true);
-
-  // Get out of soft-disconnected state
-  OTG.DCTL()->setSDIS(false);
-
-  // Force peripheral only mode
-  OTG.GUSBCFG()->setFDMOD(true);
-
-  /* Configure the USB turnaround time.
-   * This has to be configured depending on the AHB clock speed. */
-  OTG.GUSBCFG()->setTRDT(0x6);
-
-  // Clear the interrupts
-  OTG.GINTSTS()->set(0);
-
-  // Full speed device
-  OTG.DCFG()->setDSPD(OTG::DCFG::DSPD::FullSpeed);
-
-  // FIFO-size = 128 * 32bits
-  // FIXME: Explain :-) Maybe we can increase it.
-  OTG.GRXFSIZ()->setRXFD(128);
-
-  // Unmask the interrupt line assertions
-  OTG.GAHBCFG()->setGINTMSK(true);
-
-  // Restart the PHY clock.
-  OTG.PCGCCTL()->setSTPPCLK(0);
-
-  // Pick which interrupts we're interested in
-  class OTG::GINTMSK intMask(0); // Reset value
-  intMask.setENUMDNEM(true); // Speed enumeration done
-  intMask.setUSBRST(true); // USB reset
-  intMask.setRXFLVLM(true); // Receive FIFO non empty
-  intMask.setIEPINT(true); // IN endpoint interrupt
-  intMask.setWUIM(true); // Resume / wakeup
-  intMask.setUSBSUSPM(true); // USB suspend
-  OTG.GINTMSK()->set(intMask);
-
-  // Unmask IN endpoint interrupt 0
-  OTG.DAINTMSK()->setIEPM(1);
-
-  // Unmask the transfer completed interrupt
-  OTG.DIEPMSK()->setXFRCM(true);
-
-  // Wait for an USB reset
-  while (!OTG.GINTSTS()->getUSBRST()) {
-  }
-
-  // Wait for ENUMDNE
-  while (!OTG.GINTSTS()->getENUMDNE()) {
-  }
-
-  while (true) {
-    poll();
-  }
-}
-
-void Device::shutdown() {
-  //TODO ?
-}
-
 void Device::poll() {
-
   // Read the interrupts
   class OTG::GINTSTS intsts(OTG.GINTSTS()->get());
 
diff --git a/ion/src/device/usb/device.h b/ion/src/device/usb/device.h
index c80da4a70..030204ef5 100644
--- a/ion/src/device/usb/device.h
+++ b/ion/src/device/usb/device.h
@@ -20,13 +20,7 @@ public:
     m_ep0(this, interface)
   {
   }
-
-  void init();
-  void shutdown();
   void poll();
-
-  //virtual bool controlTransfer(struct usb_setup_data *req, uint8_t **buf, uint16_t *len);/*, void (**complete)(usbd_device *usbd_dev, struct usb_setup_data *req));*/
-
 protected:
   virtual Descriptor * descriptor(uint8_t type, uint8_t index) = 0;
   virtual void setActiveConfiguration(uint8_t configurationIndex) = 0;
diff --git a/ion/src/device/usb/stack/relocatable_string_descriptor.h b/ion/src/device/usb/stack/relocatable_string_descriptor.h
new file mode 100644
index 000000000..56e9d19f9
--- /dev/null
+++ b/ion/src/device/usb/stack/relocatable_string_descriptor.h
@@ -0,0 +1,31 @@
+#ifndef ION_DEVICE_USB_STACK_RELOCATABLE_STRING_DESCRIPTOR_H
+#define ION_DEVICE_USB_STACK_RELOCATABLE_STRING_DESCRIPTOR_H
+
+#include "string_descriptor.h"
+#include <string.h>
+
+namespace Ion {
+namespace USB {
+namespace Device {
+
+template <int T>
+class RelocatableStringDescriptor : public StringDescriptor {
+public:
+  RelocatableStringDescriptor(const char * string) :
+    StringDescriptor()
+  {
+    strlcpy(m_string, string, T);
+  }
+protected:
+  const char * string() const override {
+    return m_string;
+  }
+private:
+  char m_string[T];
+};
+
+}
+}
+}
+
+#endif
diff --git a/ion/src/device/usb/stack/string_descriptor.cpp b/ion/src/device/usb/stack/string_descriptor.cpp
index a3afb1482..9ba7ef663 100644
--- a/ion/src/device/usb/stack/string_descriptor.cpp
+++ b/ion/src/device/usb/stack/string_descriptor.cpp
@@ -1,4 +1,5 @@
 #include "string_descriptor.h"
+#include <string.h>
 
 namespace Ion {
 namespace USB {
@@ -6,7 +7,7 @@ namespace Device {
 
 void StringDescriptor::push(Channel * c) const {
   Descriptor::push(c);
-  const char * stringPointer = m_string;
+  const char * stringPointer = string();
   while (*stringPointer != 0) {
     uint16_t stringAsUTF16CodePoint = *stringPointer;
     c->push(stringAsUTF16CodePoint);
@@ -16,7 +17,7 @@ void StringDescriptor::push(Channel * c) const {
 
 uint8_t StringDescriptor::bLength() const {
   // The script is returned in UTF-16, hence the multiplication.
-  return Descriptor::bLength() + 2*strlen(m_string);
+  return Descriptor::bLength() + 2*strlen(string());
 }
 
 }
diff --git a/ion/src/device/usb/stack/string_descriptor.h b/ion/src/device/usb/stack/string_descriptor.h
index f8b708956..1c9b5e6d9 100644
--- a/ion/src/device/usb/stack/string_descriptor.h
+++ b/ion/src/device/usb/stack/string_descriptor.h
@@ -2,7 +2,6 @@
 #define ION_DEVICE_USB_STACK_STRING_DESCRIPTOR_H
 
 #include "descriptor.h"
-#include <string.h>
 
 namespace Ion {
 namespace USB {
@@ -10,16 +9,11 @@ namespace Device {
 
 class StringDescriptor : public Descriptor {
 public:
-  constexpr StringDescriptor(const char * string) :
-    Descriptor(0x03),
-    m_string(string)
-  {
-  }
+  StringDescriptor() : Descriptor(0x03) { }
 protected:
   void push(Channel * c) const override;
   virtual uint8_t bLength() const override;
-private:
-  const char * m_string;
+  virtual const char * string() const = 0;
 };
 
 }
diff --git a/ion/src/shared/dummy/usb.cpp b/ion/src/shared/dummy/usb.cpp
index 208058977..bc077012e 100644
--- a/ion/src/shared/dummy/usb.cpp
+++ b/ion/src/shared/dummy/usb.cpp
@@ -3,3 +3,6 @@
 bool Ion::USB::isPlugged() {
   return false;
 }
+
+void Ion::USB::DFU() {
+}
diff --git a/ion/src/simulator/usb.cpp b/ion/src/simulator/usb.cpp
index 447cca33a..bc077012e 100644
--- a/ion/src/simulator/usb.cpp
+++ b/ion/src/simulator/usb.cpp
@@ -4,3 +4,5 @@ bool Ion::USB::isPlugged() {
   return false;
 }
 
+void Ion::USB::DFU() {
+}