NO:
W90P710 Programming Guide
VERSION:
2.1
PAGE:
85
The above information is the exclusive intellectual property of Winbond Electronics and shall not be disclosed,
distributed or reproduced without permission from Winbond.
Table No.: 1200-0003-07-A
•
UnrecoverableError
•
FrameNumberOverflow
•
RootHubStatusChange
•
OwnershipChange
6.5.6.1
SchedulingOverrun Interrupt
This interrupt is set when the USB schedule for the current frame overruns. The presence of this
interrupt means that
HCD
has scheduled too many transfers.
HCD
may temporarily stop one or more
endpoints to reduce bandwidth.
6.5.6.2
WritebackDoneHead Interrupt
This interrupt is set after
Host Controller
has written
HcDoneHead
to
HccaDoneHead
. On this
interrupt,
HCD
can obtain the
TD
done queue by reading
HccaDoneHead
.
HCD
may first reverse the
done queue by traveling the done queue, because the
TD
s were retired in stack order. Then
HCD
can
start processing on each
TD
. More detailed description is introduced in the next section.
6.5.6.3
StartOfFrame Interrupt
This interrupt is set on each start of a frame. Generally,
HCD
will not enable this interrupt. This
interrupt is generally used to identify the starting of a next frame. For example, if you are going to
remove a
TD
, you must ensure that the endpoint is not currently processed by
Host Controller
. To
accomplish this,
HCD
can temporarily set the
sKip
bit of its
ED
and enable
StartOfFrame
interrupt. In
the next coming StartOfFrame interrupt,
HCD
can ensure that the endpoint is not currently processed
by
Host Controller
, and it can remove the
TD
.