Rev. 3.0, 03/01, page 287 of 390
The FrameRemainingToggle field (bit) is loaded with FrameIntervalToggle coinciding with
FrameRemaining being loaded with FrameInterval. FrameRemainingToggle and
FrameIntervalToggle are used by the HCD to determine which value of FrameInterval is
being used in the current frame. If the toggle fields match when read, the Host Controller
loaded the current value of FrameInterval into FrameRemaining at the beginning of the
current frame (current frame is using a newly programmed value). If the toggle fields do not
match, the Host Controller loaded the previous value of FrameInterval into FrameRemaining
at the beginning of the current frame (current frame is not using a newly programmed value).
This information is provided so that the HCD may determine exactly which frame is using a
newly programmed value of FrameInterval.
3) HcFmNumber Register
The HcFmNumber register contains only the FrameNumber field.
FrameNumber is a 16 bit counter. FrameNumber is incremented by the Host Controller at
each frame boundary. Specifically, FrameNumber is incremented when FrameRemaining is
loaded with FrameInterval. The lower 11 bits of the frame number are used in the SOF token
data field. Each time the frame number is incremented the new value is written back to the
HCCA.
4) HcPeriodicStart Register
The HcPeriodicStart register contains only the PeriodicStart field.
PeriodicStart is a 14 bit programmable value which determines when the Host Controller must
start processing the periodic list. When processing lists while in the U
SB
O
PERATIONAL
state,
the Host Controller will start processing the periodic list in a given frame when
FrameRemaining is less than PeriodicStart (or if no other list is enabled).
5) HcLSThreshold Register
The HcLSThreshold register contains only the LSThreshold field.
LSThreshold is a 12 bit programmable value which provides a bit time threshold in a frame
beyond which low speed transactions are prohibited. When the Host Controller has a low speed
transaction to send, FrameRemaining is compared to LSThreshold. The low speed
transaction may be started if and only if FrameRemaining is greater than or equal to
LSThreshold.
Summary of Contents for HD64465
Page 25: ...Rev 3 0 03 01 page 6 of 390 ...
Page 59: ...Rev 3 0 03 01 page 40 of 390 ...
Page 97: ...Rev 3 0 03 01 page 78 of 390 ...
Page 147: ...Rev 3 0 03 01 page 128 of 390 ...
Page 199: ...Rev 3 0 03 01 page 180 of 390 ...
Page 247: ...Rev 3 0 03 01 page 228 of 390 ...
Page 385: ...Rev 3 0 03 01 page 366 of 390 ...
Page 389: ...Rev 3 0 03 01 page 370 of 390 ...
Page 409: ...Rev 3 0 03 01 page 390 of 390 ...