/******************************************************************************
* Function: void USBCheckBusStatus(void)
*
* PreCondition: None
*
* Input: None
*
* Output: None
*
* Side Effects: None
*
* Overview: This routine enables/disables the USB module by monitoring
* the USB power signal.
*
* Note: None
*****************************************************************************/
void USBCheckBusStatus(void)
{
/**************************************************************************
* Bus Attachment & Detachment Detection
* usb_bus_sense is an i/o pin defined in io_cfg.h
*************************************************************************/
#define USB_BUS_ATTACHED 1
#define USB_BUS_DETACHED 0
if(usb_bus_sense == USB_BUS_ATTACHED) // Is USB bus attached?
{
if(UCONbits.USBEN == 0) // Is the module off?
USBModuleEnable(); // Is off, enable it
}
else
{
if(UCONbits.USBEN == 1) // Is the module on?
USBModuleDisable(); // Is on, disable it
}//end if(usb_bus_sense...)
/*
* After enabling the USB module, it takes some time for the voltage
* on the D+ or D- line to rise high enough to get out of the SE0 condition.
* The USB Reset interrupt should not be unmasked until the SE0 condition is
* cleared. This helps preventing the firmware from misinterpreting this
* unique event as a USB bus reset from the USB host.
*/
if(usb_device_state == ATTACHED_STATE)
{
if(!UCONbits.SE0)
{
UIR = 0; // Clear all USB interrupts
UIE = 0; // Mask all USB interrupts
UIEbits.URSTIE = 1; // Unmask RESET interrupt
UIEbits.IDLEIE = 1; // Unmask IDLE interrupt
usb_device_state = POWERED_STATE;
}//end if // else wait until SE0 is cleared
}//end if(usb_device_state == ATTACHED_STATE)
}//end USBCheckBusStatus
/******************************************************************************
* Function: void USBSoftDetach(void)
*
* PreCondition: None
*
* Input: None
*
* Output: None
*
* Side Effects: The device will have to be re-enumerated to function again.
*
* Overview: USBSoftDetach electrically disconnects the device from
* the bus. This is done by stop supplying Vusb voltage to
* pull-up resistor. The pull-down resistors on the host
* side will pull both differential signal lines low and
* the host registers the event as a disconnect.
*
* Since the USB cable is not physically disconnected, the
* power supply through the cable can still be sensed by
* the device. The next time USBCheckBusStatus() function
* is called, it will reconnect the device back to the bus.
*
* Note: None
*****************************************************************************/
void USBSoftDetach(void)
{
USBModuleDisable();
}//end USBSoftDetach
