diff --git a/include/unicore-mx/common/dwc_otg.ucd b/include/unicore-mx/common/dwc_otg.ucd
index 2ce16e35..1c9bb653 100644
--- a/include/unicore-mx/common/dwc_otg.ucd
+++ b/include/unicore-mx/common/dwc_otg.ucd
@@ -56,6 +56,9 @@ bit SRQ 1
 bit SRQSCS 0
 
 reg GOTGINT 0x004
+% Session end detected. The core sets this bit to indicate that the level of the voltage 
+%   on VBUS is no longer valid for a B-Peripheral session when VBUS < 0.8 V //STM32F4
+bit SEDET  2
 
 % OTG AHB configuration register
 reg GAHBCFG 0x008
@@ -847,6 +850,16 @@ bits XFRSIZ 7 0
 
 % Power and clock gating control and status register
 reg PCGCCTL 0xE00
+% Stop PHY clock. The application sets this bit to stop the PHY clock when the USB is suspended, the session 
+%   is not valid, or the device is disconnected. 
+%    The application clears this bit when the USB is resumed or a new session starts //STM32F4
+bit STPPCLK  0
+% Gate HCLK. The application sets this bit to gate HCLK to modules other than the AHB Slave and Master 
+%   and wakeup logic when the USB is suspended or the session is not valid.
+%   The application clears this bit when the USB is resumed or a new session starts. //STM32F4
+bit GATEHCLK 1
+% Indicates that the PHY has been suspended.
+bit PHYSUSP  4
 
 % Data FIFO
 register
diff --git a/include/unicore-mx/usbd/usbd.h b/include/unicore-mx/usbd/usbd.h
index 53df4d99..c3efa343 100644
--- a/include/unicore-mx/usbd/usbd.h
+++ b/include/unicore-mx/usbd/usbd.h
@@ -135,6 +135,16 @@ enum usbd_speed {
 
 typedef enum usbd_speed usbd_speed;
 
+	/** Optional features */
+enum usbd_backend_features{
+		  USBD_FEATURE_NONE   = 0
+		, USBD_PHY_EXT        = (1 << 0)
+		, USBD_VBUS_SENSE     = (1 << 1)
+		, USBD_VBUS_EXT       = (1 << 2)
+		//* provide usb-core auto power-up/down on connect/disconnect
+		, USBD_USE_POWERDOWN  = (1 << 3)
+};
+
 struct usbd_backend_config {
 	/** Number of endpoints. (Including control endpoint) */
 	uint8_t ep_count;
@@ -145,13 +155,8 @@ struct usbd_backend_config {
 	/** Device speed */
 	usbd_speed speed;
 
-	/** Optional features */
-	enum {
-		USBD_FEATURE_NONE = 0,
-		USBD_PHY_EXT = (1 << 0),
-		USBD_VBUS_SENSE = (1 << 1),
-		USBD_VBUS_EXT = (1 << 2)
-	} feature;
+	/** Optional features see usbd_backend_features*/
+	unsigned int feature;
 };
 
 typedef struct usbd_backend_config usbd_backend_config;
@@ -279,7 +284,7 @@ enum usbd_transfer_flags {
 	USBD_FLAG_PACKET_PER_FRAME_MASK = (0x3 << 5)
 };
 
-typedef enum usbd_transfer_flags usbd_transfer_flags;
+typedef unsigned char usbd_transfer_flags;
 
 /**
  * USB Transfer status
@@ -431,6 +436,8 @@ typedef void (*usbd_set_interface_callback)(usbd_device *dev,
 typedef void (*usbd_setup_callback)(usbd_device *dev, uint8_t addr,
 					const struct usb_setup_data *setup_data);
 
+typedef void (* usbd_session_callback)(usbd_device *dev, bool online);
+
 typedef void (* usbd_generic_callback)(usbd_device *dev);
 
 /**
@@ -515,6 +522,16 @@ void usbd_register_resume_callback(usbd_device *dev,
 void usbd_register_sof_callback(usbd_device *dev,
 					usbd_generic_callback callback);
 
+/**
+ * Register session connect/disconnect callback
+ *   with USBD_VBUS_SENSE feature primary need for cable 
+ *   plug detection
+ * @param[in] dev USB Device
+ * @param[in] callback callback to be invoked
+ */
+void usbd_register_session_callback(usbd_device *dev,
+					usbd_session_callback callback);
+
 /**
  * Register SET_CONFIGURATION callback \n
  * stack will invoke @a callback when ever SET_CONFIGURATION is received
@@ -643,6 +660,30 @@ uint8_t usbd_get_address(usbd_device *dev);
  */
 usbd_speed usbd_get_speed(usbd_device *dev);
 
+
+/**
+ * Get status of connected cable.
+ * @param[in] dev USB Device
+ * @return true - cable connected, and Vbus active
+ */
+bool usbd_is_vbus(usbd_device *dev);
+
+/**
+ * Controls power state of usb-core and PHY
+ * @param[in] dev USB Device
+ * @param[in] onoff  - true turn on device in action, and power PHY
+ *                     false disconnects, disable PHY and stops usb-core
+ */
+void usbd_enable(usbd_device *dev, bool onoff);
+
+/**
+ * Checks power state of usb-core and PHY
+ * @param[in] dev USB Device
+ * @param[in] \return  true  - device in action, and power PHY
+ *                     false - disabled PHY and stops usb-core
+ */
+bool usbd_is_enabled(usbd_device *dev);
+
 /**
  * Perform a transfer
  *
diff --git a/lib/usbd/backend/dwc_otg_private.h b/lib/usbd/backend/dwc_otg_private.h
index e1a1f247..2b181233 100644
--- a/lib/usbd/backend/dwc_otg_private.h
+++ b/lib/usbd/backend/dwc_otg_private.h
@@ -88,6 +88,7 @@ struct dwc_otg_private_data {
 #define USBD_DEVICE_EXTRA												\
 	struct dwc_otg_private_data private_data;
 
+//#include "../usbd_private.h"
 void dwc_otg_init(usbd_device *dev);
 
 void dwc_otg_set_address(usbd_device *dev, uint8_t addr);
diff --git a/lib/usbd/backend/usbd_dwc_otg.c b/lib/usbd/backend/usbd_dwc_otg.c
index ebb42f89..c2b21a3a 100644
--- a/lib/usbd/backend/usbd_dwc_otg.c
+++ b/lib/usbd/backend/usbd_dwc_otg.c
@@ -979,6 +979,8 @@ static inline void alloc_fifo_for_ep0_only(usbd_device *dev)
 
 void dwc_otg_poll(usbd_device *dev)
 {
+	if (usbd_is_enabled(dev)){
+
 	if (REBASE(DWC_OTG_GINTSTS) & DWC_OTG_GINTSTS_ENUMDNE) {
 		REBASE(DWC_OTG_DCFG) &= ~DWC_OTG_DCFG_DAD_MASK;
 		disable_all_non_ep0(dev);
@@ -1033,14 +1035,31 @@ void dwc_otg_poll(usbd_device *dev)
 		usbd_handle_suspend(dev);
 	}
 
+	if (REBASE(DWC_OTG_GINTSTS) & DWC_OTG_GINTSTS_SOF) {
+		REBASE(DWC_OTG_GINTSTS) = DWC_OTG_GINTSTS_SOF;
+		usbd_handle_sof(dev);
+	}
+
+	} //if (usbd_is_enabled(dev))
+	else
+		REBASE(DWC_OTG_GINTSTS) = DWC_OTG_GINTSTS_ENUMDNE | DWC_OTG_GINTSTS_USBRST
+	                          | DWC_OTG_GINTSTS_RXFLVL
+	                          | DWC_OTG_GINTSTS_IEPINT | DWC_OTG_GINTSTS_OEPINT
+	                          | DWC_OTG_GINTSTS_SOF 
+	                          | DWC_OTG_GINTSTS_USBSUSP | DWC_OTG_GINTSTS_ESUSP;
+	
 	if (REBASE(DWC_OTG_GINTSTS) & DWC_OTG_GINTSTS_WKUPINT) {
 		REBASE(DWC_OTG_GINTSTS) = DWC_OTG_GINTSTS_WKUPINT;
 		usbd_handle_resume(dev);
 	}
 
-	if (REBASE(DWC_OTG_GINTSTS) & DWC_OTG_GINTSTS_SOF) {
-		REBASE(DWC_OTG_GINTSTS) = DWC_OTG_GINTSTS_SOF;
-		usbd_handle_sof(dev);
+	if ( (REBASE(DWC_OTG_GINTSTS) & (DWC_OTG_GINTSTS_SRQINT)) != 0) {
+		REBASE(DWC_OTG_GINTSTS) = (DWC_OTG_GINTSTS_SRQINT);
+		usbd_handle_session(dev, true);
+	}
+	if ( (REBASE(DWC_OTG_GOTGINT) & (DWC_OTG_GOTGINT_SEDET)) != 0) {
+		REBASE(DWC_OTG_GOTGINT) = DWC_OTG_GOTGINT_SEDET;
+		usbd_handle_session(dev, false);
 	}
 }
 
diff --git a/lib/usbd/backend/usbd_stm32_otg_fs.c b/lib/usbd/backend/usbd_stm32_otg_fs.c
index 24eb754f..06e2af8a 100644
--- a/lib/usbd/backend/usbd_stm32_otg_fs.c
+++ b/lib/usbd/backend/usbd_stm32_otg_fs.c
@@ -28,6 +28,8 @@
 #include <unicore-mx/usbd/usbd.h>
 
 static usbd_device *init(const usbd_backend_config *config);
+static bool otgfs_is_powered(usbd_device *dev);
+static usbd_power_status otgfs_power_control(usbd_device *dev, usbd_power_action action);
 
 static struct usbd_device _usbd_dev;
 
@@ -51,6 +53,8 @@ const struct usbd_backend usbd_stm32_otg_fs = {
 	.get_speed = dwc_otg_get_speed,
 	.set_address_before_status = true,
 	.base_address = USB_OTG_FS_BASE,
+	  .is_vbus        = otgfs_is_powered
+	, .power_control  = otgfs_power_control
 };
 
 #define REBASE(REG, ...)	REG(usbd_stm32_otg_fs.base_address, ##__VA_ARGS__)
@@ -74,16 +78,20 @@ static usbd_device *init(const usbd_backend_config *config)
 	_usbd_dev.backend = &usbd_stm32_otg_fs;
 	_usbd_dev.config = config;
 
+	//* stm32f4 use FS CID=0x1100, HS CID=0x02000600
+	//* stm32f7            0x3000,    CID=0x00003100
+	const unsigned otg_hs_cid_boundary = 0x3100;
+
 	if (config->feature & USBD_VBUS_SENSE) {
-		if (OTG_FS_CID >= 0x00002000) { /* 2.0 */
+		if (OTG_FS_CID >= otg_hs_cid_boundary) { /* 2.0 HS core*/
 			/* Enable VBUS detection */
 			OTG_FS_GCCFG |= OTG_GCCFG_VBDEN;
-		} else { /* 1.x */
+		} else { /* 1.x  FS core*/
 			/* Enable VBUS sensing in device mode */
 			OTG_FS_GCCFG |= OTG_GCCFG_VBUSBSEN;
 		}
 	} else {
-		if (OTG_FS_CID >= 0x00002000) { /* 2.0 */
+		if (OTG_FS_CID >= otg_hs_cid_boundary) { /* 2.0 */
 			/* Disable VBUS detection. */
 			OTG_FS_GCCFG &= ~OTG_GCCFG_VBDEN;
 			REBASE(DWC_OTG_GOTGCTL) |= DWC_OTG_GOTGCTL_BVALOEN |
@@ -108,3 +116,50 @@ static usbd_device *init(const usbd_backend_config *config)
 
 	return &_usbd_dev;
 }
+
+static
+bool otgfs_is_powered(usbd_device *dev){
+	uint32_t base = dev->backend->base_address;
+	return (DWC_OTG_GOTGCTL(base) & DWC_OTG_GOTGCTL_BSVLD) != 0;
+}
+
+static
+usbd_power_status otgfs_power_control(usbd_device *dev, usbd_power_action action){
+	uint32_t base = dev->backend->base_address;
+	switch (action){
+		case usbd_paActivate:{
+			DWC_OTG_PCGCCTL(base) = 0;
+			OTG_FS_GCCFG |= OTG_GCCFG_PWRDWN;
+			REBASE(DWC_OTG_GINTMSK) |= DWC_OTG_GINTMSK_ENUMDNEM | DWC_OTG_GINTSTS_USBSUSP
+			                        | DWC_OTG_GINTMSK_RXFLVLM | DWC_OTG_GINTMSK_IEPINT ;
+			break;
+		}
+		case usbd_paShutdown: {
+		/* Wait for AHB idle. */
+			uint32_t save_dis = REBASE(DWC_OTG_DCTL) & DWC_OTG_DCTL_SDIS;
+			//disable device connection before poweroff
+			REBASE(DWC_OTG_DCTL) |= DWC_OTG_DCTL_SDIS;
+			while (( (DWC_OTG_GRSTCTL(base) & DWC_OTG_GRSTCTL_AHBIDL) == 0) );
+			//* drop ISRs, cause stoped Core cant handle them
+			REBASE(DWC_OTG_GINTSTS) = ~( DWC_OTG_GINTSTS_USBSUSP
+			                           | DWC_OTG_GINTSTS_WKUPINT
+			                           | DWC_OTG_GINTSTS_SRQINT
+			                           );
+			REBASE(DWC_OTG_GINTMSK) &= ~( DWC_OTG_GINTMSK_ENUMDNEM 
+			                             | DWC_OTG_GINTMSK_RXFLVLM | DWC_OTG_GINTMSK_IEPINT
+			                            );
+			//poser down PHY
+			OTG_FS_GCCFG &= ~OTG_GCCFG_PWRDWN;
+			DWC_OTG_PCGCCTL(base) = DWC_OTG_PCGCCTL_STPPCLK; //| DWC_OTG_PCGCCTL_GATEHCLK ;
+			//destore connection disable state after PHY poweroff
+			REBASE(DWC_OTG_DCTL) |= save_dis;
+			break;
+		}
+	}
+	usbd_power_status res = 0;
+	if ( (DWC_OTG_PCGCCTL(base) & DWC_OTG_PCGCCTL_PHYSUSP) == 0)
+		res |= usbd_psPHYOn;
+	if ((OTG_FS_GCCFG & OTG_GCCFG_PWRDWN) != 0)
+		res |= usbd_psCoreEnabled;
+	return res;
+}
diff --git a/lib/usbd/usbd.c b/lib/usbd/usbd.c
index cd382b91..c69e19f0 100644
--- a/lib/usbd/usbd.c
+++ b/lib/usbd/usbd.c
@@ -128,6 +128,14 @@ void usbd_register_sof_callback(usbd_device *dev,
 	}
 }
 
+void usbd_register_session_callback(usbd_device *dev,
+					usbd_session_callback callback)
+{
+	dev->callback.session = callback;
+}
+
+
+
 /* Functions to be provided by the hardware abstraction layer */
 void usbd_poll(usbd_device *dev, uint32_t us)
 {
@@ -145,9 +153,21 @@ void usbd_poll(usbd_device *dev, uint32_t us)
 
 void usbd_disconnect(usbd_device *dev, bool disconnect)
 {
+	if (!disconnect) {
+		// power-up on connect
+		if ( ((dev->config->feature & USBD_USE_POWERDOWN) != 0)
+		   && (dev->backend->power_control) )
+			dev->backend->power_control(dev, usbd_paActivate);
+  }
 	if (dev->backend->disconnect) {
 		dev->backend->disconnect(dev, disconnect);
 	}
+	if (disconnect) {
+		// power-down after disconnect
+		if ( ((dev->config->feature & USBD_USE_POWERDOWN) != 0)
+		   && (dev->backend->power_control) )
+			dev->backend->power_control(dev, usbd_paShutdown );
+  }
 }
 
 void usbd_ep_prepare(usbd_device *dev, uint8_t addr, usbd_ep_type type,
@@ -208,5 +228,28 @@ usbd_speed usbd_get_speed(usbd_device *dev)
 	return dev->backend->get_speed(dev);
 }
 
+bool usbd_is_vbus(usbd_device *dev){
+	if (dev->backend->is_vbus)
+		return dev->backend->is_vbus(dev);
+	else
+		return true;
+}
+
+void usbd_enable(usbd_device *dev, bool onoff){
+	if (dev->backend->power_control)
+		dev->backend->power_control(dev, (onoff)? usbd_paActivate : usbd_paShutdown );
+	else
+		// try emulate enable via disconnect
+		usbd_disconnect(dev, !onoff);
+}
+
+bool usbd_is_enabled(usbd_device *dev){
+	if (dev->backend->power_control)
+		return dev->backend->power_control(dev, usbd_paCheck ) == usbd_psOn;
+	else
+		return true;
+}
+
+
 /**@}*/
 
diff --git a/lib/usbd/usbd_private.h b/lib/usbd/usbd_private.h
index 6b7ddcfd..d0f99163 100644
--- a/lib/usbd/usbd_private.h
+++ b/lib/usbd/usbd_private.h
@@ -41,6 +41,7 @@
 #ifndef UNICOREMX_USBD_PRIVATE_H
 #define UNICOREMX_USBD_PRIVATE_H
 
+#include <stdbool.h>
 #include <unicore-mx/usbd/usbd.h>
 
 /**
@@ -109,6 +110,10 @@ struct usbd_device {
 
 		/** invoked when sof received */
 		usbd_generic_callback sof;
+		
+		//* invoked on Session New / End
+		//*    with USBD_VBUS_SENSE feature detects cable plug
+		usbd_session_callback session;
 
 		/** invoked on SETUP packet */
 		usbd_setup_callback setup;
@@ -174,6 +179,22 @@ struct usbd_device {
 #endif
 };
 
+enum _usbd_power_action{
+	  usbd_paCheck
+	, usbd_paShutdown
+	, usbd_paActivate
+};
+enum _usbd_power_status{
+	  usbd_psCoreDisabled = 0
+	, usbd_psCoreEnabled  = 1
+	, usbd_psPHYOff       = 0
+	, usbd_psPHYOn        = 2
+	, usbd_psOff          = 0
+	, usbd_psOn           = usbd_psCoreEnabled | usbd_psPHYOn // ~0
+};
+typedef enum _usbd_power_action usbd_power_action;
+typedef unsigned usbd_power_status;
+
 /* Functions provided by the hardware abstraction. */
 struct usbd_backend {
 	usbd_device * (*init)(const usbd_backend_config *config);
@@ -197,6 +218,10 @@ struct usbd_backend {
 	/* Frame number */
 	uint16_t (*frame_number)(usbd_device *dev);
 
+	//* power control
+	bool (*is_vbus)(usbd_device *dev);
+	usbd_power_status (*power_control)(usbd_device *dev, usbd_power_action action);
+
 	/*
 	 * this is to tell usb generic code
 	 *  that address need to be set before status-stage.
@@ -359,6 +384,14 @@ static inline void usbd_handle_sof(usbd_device *dev)
 	}
 }
 
+static inline
+void usbd_handle_session(usbd_device *dev, bool onoff)
+{
+	if (dev->callback.session != NULL) {
+		dev->callback.session(dev, onoff);
+	}
+}
+
 /**
  * Called by backend to pass the setup data when a SETUP packet is recevied
  *  on control endpoint.