diff --git a/bootloaders/x1/.vs/samdx1_sam_ba/v14/.atsuo b/bootloaders/x1/.vs/samdx1_sam_ba/v14/.atsuo
index 118127d7..7241fcb6 100644
Binary files a/bootloaders/x1/.vs/samdx1_sam_ba/v14/.atsuo and b/bootloaders/x1/.vs/samdx1_sam_ba/v14/.atsuo differ
diff --git a/cores/arduino/USB/SAMD21_USBDevice.h b/cores/arduino/USB/SAMD21_USBDevice.h
index 2f50c03e..b2ec9c0e 100644
--- a/cores/arduino/USB/SAMD21_USBDevice.h
+++ b/cores/arduino/USB/SAMD21_USBDevice.h
@@ -81,6 +81,25 @@ public:
 	inline void enableStartOfFrameInterrupt()  { usb.INTENSET.bit.SOF = 1; }
 	inline void disableStartOfFrameInterrupt() { usb.INTENCLR.bit.SOF = 1; }
 
+#if defined(__SAMD51P20A__) || defined(__SAMD51G19A__)	
+	//inline void isLpmSuspInterrupt()		    { return usb.INTFLAG.bit.LPMSUSP; }
+		
+	inline bool isRamErrInterrupt()				{ return usb.INTFLAG.bit.RAMACER; }
+	inline void ackRamErrInterrupt()			{ usb.INTFLAG.reg = USB_DEVICE_INTFLAG_RAMACER; }
+	inline void enableRamErrInterrupt()			{ usb.INTENSET.reg = USB_DEVICE_INTFLAG_RAMACER; }
+	inline void disableRamErrInterrupt()		{ usb.INTENCLR.reg = USB_DEVICE_INTFLAG_RAMACER; }
+	
+	inline bool isWakeupInterrupt()				{ return usb.INTFLAG.reg & (USB_DEVICE_INTFLAG_UPRSM | USB_DEVICE_INTFLAG_EORSM | USB_DEVICE_INTFLAG_WAKEUP); }
+	inline void ackWakeupInterrupt()			{ usb.INTFLAG.reg = USB_DEVICE_INTFLAG_UPRSM | USB_DEVICE_INTFLAG_EORSM | USB_DEVICE_INTFLAG_WAKEUP; }
+	inline void enableUSBWakeupInterrupts()		{ usb.INTENSET.reg = USB_DEVICE_INTENSET_UPRSM | USB_DEVICE_INTENSET_EORSM | USB_DEVICE_INTENSET_WAKEUP; }
+	inline void disableUSBWakeuptInterrupts()   { usb.INTENCLR.reg = USB_DEVICE_INTENCLR_UPRSM | USB_DEVICE_INTENCLR_EORSM | USB_DEVICE_INTENCLR_WAKEUP; }
+	
+	inline bool isSuspendInterrupt()			{ return usb.INTFLAG.bit.SUSPEND; }
+	inline void ackSuspendInterrupt()			{ usb.INTFLAG.reg = USB_DEVICE_INTFLAG_SUSPEND; }
+	inline void enableUSBSuspendInterrupts()	{ usb.INTENSET.reg = (USB_DEVICE_INTFLAG_LPMSUSP | USB_DEVICE_INTFLAG_SUSPEND); }
+	inline void disableUSBSuspendInterrupts()	{ usb.INTENCLR.reg = (USB_DEVICE_INTFLAG_LPMSUSP | USB_DEVICE_INTFLAG_SUSPEND); }
+#endif
+
 	// USB Address
 	inline void setAddress(uint32_t addr)   { usb.DADD.bit.DADD = addr; usb.DADD.bit.ADDEN = 1; }
 	inline void unsetAddress()              { usb.DADD.bit.DADD = 0;    usb.DADD.bit.ADDEN = 0; }
@@ -180,7 +199,7 @@ private:
 void USBDevice_SAMD21G18x::reset() {
 	usb.CTRLA.bit.SWRST = 1;
 	memset(EP, 0, sizeof(EP));
-	while (usb.SYNCBUSY.bit.SWRST) {}
+	while (usb.SYNCBUSY.bit.SWRST || usb.SYNCBUSY.bit.ENABLE) {}
 	usb.DESCADD.reg = (uint32_t)(&EP);
 }
 
diff --git a/cores/arduino/USB/USBCore.cpp b/cores/arduino/USB/USBCore.cpp
index bfb17caf..e3d97873 100644
--- a/cores/arduino/USB/USBCore.cpp
+++ b/cores/arduino/USB/USBCore.cpp
@@ -380,10 +380,16 @@ void USBDeviceClass::init()
 	usbd.setFullSpeed();
 
 	// Configure interrupts
-#if defined(__SAMD51P20A__) || defined(__SAMD51G19A__) //TODO: verify the correct interrupts
+#if defined(__SAMD51P20A__) || defined(__SAMD51G19A__)
 	/* Attach to the USB host */
-	NVIC_SetPriority((IRQn_Type) USB_0_IRQn, 0UL);
-	NVIC_EnableIRQ((IRQn_Type) USB_0_IRQn);
+	NVIC_SetPriority(USB_0_IRQn, 0UL);
+	NVIC_SetPriority(USB_1_IRQn, 0UL);
+	NVIC_SetPriority(USB_2_IRQn, 0UL);
+	NVIC_SetPriority(USB_3_IRQn, 0UL);
+	NVIC_EnableIRQ(USB_0_IRQn);
+	NVIC_EnableIRQ(USB_1_IRQn);
+	NVIC_EnableIRQ(USB_2_IRQn);
+	NVIC_EnableIRQ(USB_3_IRQn);
 #else
 	NVIC_SetPriority((IRQn_Type) USB_IRQn, 0UL);
 	NVIC_EnableIRQ((IRQn_Type) USB_IRQn);
@@ -400,6 +406,7 @@ bool USBDeviceClass::attach()
 		return false;
 
 	usbd.attach();
+
 	usbd.enableEndOfResetInterrupt();
 	usbd.enableStartOfFrameInterrupt();
 
@@ -947,6 +954,20 @@ void USBDeviceClass::ISRHandler()
 		}
 #endif
 	}
+	
+#if defined(__SAMD51P20A__) || defined(__SAMD51G19A__)
+	if (usbd.isRamErrInterrupt()){
+		usbd.ackRamErrInterrupt();
+		//TODO: do something about this error
+	}
+	if (usbd.isWakeupInterrupt()){
+		usbd.ackWakeupInterrupt();
+	}
+	
+	if (usbd.isSuspendInterrupt()){
+		usbd.ackSuspendInterrupt();
+	}
+#endif
 
 	// Endpoint 0 Received Setup interrupt
 	if (usbd.epBank0IsSetupReceived(0))
diff --git a/cores/arduino/cortex_handlers.c b/cores/arduino/cortex_handlers.c
index 17a4af2a..c4790b7d 100644
--- a/cores/arduino/cortex_handlers.c
+++ b/cores/arduino/cortex_handlers.c
@@ -127,9 +127,9 @@ void SERCOM7_1_Handler           ( void ) __attribute__ ((weak, alias("Dummy_Han
 void SERCOM7_2_Handler           ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
 void SERCOM7_3_Handler           ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
 void USB_0_Handler               ( void ) __attribute__ ((weak));
-void USB_1_Handler               ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
-void USB_2_Handler               ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
-void USB_3_Handler               ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
+void USB_1_Handler               ( void ) __attribute__ ((weak));
+void USB_2_Handler               ( void ) __attribute__ ((weak));
+void USB_3_Handler               ( void ) __attribute__ ((weak));
 void TCC0_0_Handler              ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
 void TCC0_1_Handler              ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
 void TCC0_2_Handler              ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
@@ -506,6 +506,21 @@ void USB_0_Handler(void)
 	if (usb_isr)
 	usb_isr();
 }
+void USB_1_Handler(void)
+{
+	if (usb_isr)
+	usb_isr();
+}
+void USB_2_Handler(void)
+{
+	if (usb_isr)
+	usb_isr();
+}
+void USB_3_Handler(void)
+{
+	if (usb_isr)
+	usb_isr();
+}
 #else
 void USB_Handler(void)
 {