Datasheet

8−8
SLLS535E − April 2008TUSB6250
8.3.2.4 Register Settings Affect the WAKCLK Interrupt
The seven enable bits listed in Table 8−1 greatly affect the behavior and function of the WAKCLK interrupt
function.
Table 8−1. Register Setting for the WAKCLK Interrupt and Remote Wakeup
BIT NAME
BIT LOCATION
IN REGISTER
FUNCTION CONTROLLED
LPEN USBCTL[6]
Low-power enable.
LPEN controls whether the core clock of the TUSB6250 is shut down when the TUSB6250 enters the USB
suspend state.
WAKCLK USBMSK[2]
WAKCLK interrupt enable. WAKCLK controls:
Whether the WAKCLK interrupt is generated when VBUS or any other status-change events occur.
Whether the core clock of the TUSB6250 is awakened in the suspend state along with the RWUPEN bit
setting.
RWUPEN USBCTL[5]
Remote wakeup enable. RWUPEN controls:
Whether the core clock of the TUSB6250 is awakened in the suspend state along with the WAKCLK bit
setting.
Whether the USB resume signaling is sent to the upstream USB host when any remote wakeup event occurs
at either the VBUS pin or any of the four remote wakeup-capable GPIOs.
P34STEN MCUCNFG[2]
GPIO port3.4 status-change detection enable.
P34STEN allows the firmware to enable/disable the status-change detection on the port3.4 pin.
P35STEN MCUCNFG[3]
GPIO port3.5 status-change detection enable.
P35STEN allows the firmware to enable/disable the status-change detection on the port3.5 pin.
CD1STEN MCUCNFG[4]
Card detection-1 status-change enable.
CD1STEN allows the firmware to enable/disable the status-change detection on the port3.2 pin.
CD2STEN MCUCNFG[5]
Card detection-2 status-change enable.
CD2STEN allows the firmware to enable/disable the status-change detection on the port3.3 pin.
In summary, to configure the WAKCLK interrupt and remote wakeup, it is important to ensure that:
When the remote wakeup is desired (this means sending resume signaling to the host is desired), both
WAKCLK and RWUPEN must be set.
If the remote wakeup is not desired (this means no resume signaling to the host is desired), while the
end-product application cannot afford losing any status-change event that might occur when the
TUSB6250 is in the USB suspend state, the WAKCLK bit can be set, and the RWUPEN bit can be disabled.