Host USB on tm4C123GH6PM seam to create some problem with the debugger

Hi, 

I'm Jonny and this is the first time that i try to open a POST;

I'm trying to configure  a TM4C123GH6PM microcontroller like an host device in order to have the possibility to connect a pen drive.

i'm using an example i found for the tm4c123g CAN+USB development board to configure my microcontroller; I have configure everything in the property of the project to use it for my device ( or better i hope there is no strange setting that i completely forget to set ).

When i try do debug it i found a strange error when i reach a precise point of the program; in the following i will try to give you some piece of my code and the exact point where i have the problem 

CONFIGURATION OF THE USB ( BASICALLY I COPY IT FROM THE EXAMPLE )

*IMPORTANT : In my custom board the EPEN pin is active low so you will see that i have configure it for this behaviour*

ConfigureUSBInterface(void)
{
//
// Enable the uDMA controller and set up the control table base.
// This is required by usblib.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_UDMA);
uDMAEnable();
uDMAControlBaseSet(g_sDMAControlTable);

//
// Enable the USB controller.
//

//
// Set the USB pins to be controlled by the USB controller.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
GPIOPinConfigure(GPIO_PC6_USB0EPEN);
GPIOPinTypeUSBDigital(GPIO_PORTC_BASE, GPIO_PIN_6);
GPIOPinConfigure(GPIO_PC7_USB0PFLT);
GPIOPinTypeUSBDigital(GPIO_PORTC_BASE, GPIO_PIN_7);
GPIOPinTypeUSBAnalog(GPIO_PORTD_BASE, GPIO_PIN_5 | GPIO_PIN_4);
GPIOPinTypeUSBAnalog(GPIO_PORTB_BASE, GPIO_PIN_0 | GPIO_PIN_1);
SysCtlPeripheralEnable(SYSCTL_PERIPH_USB0);
//
// Register the host class driver
//
USBHCDRegisterDrivers(0, g_ppHostClassDrivers, NUM_CLASS_DRIVERS);

//
// Open an instance of the mass storage class driver.
//
g_psMSCInstance = USBHMSCDriveOpen(0, MSCCallback);

//
// Initialize the power configuration. This sets the power enable signal
// to be active high and does not enable the power fault.
//
USBHCDPowerConfigInit(0, USBHCD_VBUS_AUTO_LOW | USBHCD_VBUS_FILTER );//| USBHCD_VBUS_FILTER

//
// Force the USB mode to host with no callback on mode changes since
// there should not be any.
//
USBStackModeSet(0, eUSBModeForceHost, 0);

//
// Wait 10ms for the pin to go low.
//

clock = SysCtlClockGet();
SysCtlDelay(SysCtlClockGet()/100);

//
// Initialize the host controller.
//
USBHCDInit(0, g_pHCDPool, HCD_MEMORY_SIZE);
}

*THIS IS THE EXACT POINT WHERE I HAVE THE PROBLEM*

So it seam like when i try to power on the USB the debug give me a fault

////////                 ERROR I RECEIVE ON CODECOMPOSER

CORTEX_M4_0: Error connecting to the target
CORTEX_M4_0: Can't Run Target CPU: Debug Port error occurred.

///////

void
USBHostPwrEnable(uint32_t ui32Base)
{
//
// Check the arguments.
//
ASSERT(ui32Base == USB0_BASE);

//
// Enable the external power supply enable signal.
//
HWREGH(ui32Base + USB_O_EPC) |= USB_EPC_EPENDE;    <--------this register configuration give me the fault 
}

i have try a lot of different solution but nothing seam to work ; the pen drive has a led on it so i can see that it light on for 1 sec ;i measure the VBUS , the EPEN and the PFLT and everything is ok.

Thanks in advance for you help and for any other question just ask