AMD SB600 - Manual (Page 60)

©2008 Advanced Micro Devices, Inc. OCHI USB 1.1 and EHCI USB 2.0 Controllers
AMD SB600 Register Reference Manual Proprietary Page 60
HcFmRemaining - 32 bits - [MEM_Reg : 38h]
Field Name Bits Default HCD HC Description
FR 13:0 0000h R RW FrameRemaining
This counter is decremented at each bit time. When it
reaches zero, it is reset by loading the FrameInterval
value specified in HcFmInterval at the next bit time
boundary. When entering the
US B OPERATIONAL
state, HC re-loads the content with the
FrameInterval
of HcFmInterval and uses the updated
value from the next SOF.
Reserved 30:14 Reserved
FRT 31 0b R RW FrameRemainingToggle
This bit is loaded from the FrameIntervalToggle field
of HcFmInterval whenever FrameRemaining
reaches 0. This bit is used by HCD for the
synchronization between FrameInterval and
FrameRemainin
g.
HcFmNumber - 32 bits - [MEM_Reg : 3Ch]
Field Name Bits Default HCD HC Description
FN 15:0 0000h R RW This is incremented when HcFmRemaining is re-
loaded. It will be rolled over to 0h after ffffh. When
entering the
US B OPERATIONAL state, this will be
incremented automatically. The content will be written
to HCCA after HC has incremented the
FrameNumber
at each frame boundary and sent a
SOF but before HC reads the first ED in that Frame.
After writing to HCCA, HC will set the
StartofFrame
in HcInterruptStatus.
Reserved 31:16 Reserved
HcPeriodicStart - 32 bits - [MEM_Reg : 40h]
Field Name Bits Default HCD HC Description
PS 13:0 0000h RW R PeriodicStart
After a hardware reset, this field is cleared. This is
then set by HCD during the HC initialization. The
value is calculated roughly as 10% off from
HcFmInterva
l. A typical value will be 3E67h. When
HcFmRemaining reaches the value specified,
processing of the periodic lists will have priority over
Control/Bulk processing. HC will therefore start
processing the Interrupt list after completing the
current Control or Bulk transaction that is in progress.
Reserved 31:14 Reserved
HcLSThreshold - 32 bits - [MEM_Reg : 44h]
Field Name Bits Default HCD HC Description
LST 11:0 0628h RW R LSThreshold
This field contains a value which is compared to the
FrameRemaining
field prior to initiating a Low Speed
transaction. The transaction is started only if
FrameRemaining
this field. The value is calculated
by HCD with the consideration of transmission and
setup overhead.
Reserved 31:12 Reserved