Agere Systems Inc.
175
Data Sheet
July 2001
T8302 Internet Protocol Telephone
Advanced RISC Machine (
ARM
)
13 USB Host Controller
(continued)
Table 158
.
Hc Fm Interval
Register
13.5.2 Hc Fm Remaining Register
The
Hc Fm remaining register
is a 14-bit down counter showing the bit time remaining in the current frame.
Table 159
.
Hc Fm Remaining
Register
Address 0xE000 7034
Bit #
Name
Bit #
31
FI
30:16
FSMPS
Read/Write
HCD
R/W
15
14
13:0
FIT
RSVD
Key
Reset
Description
HC
R
31
FI
2EDF
Frame interval. This specifies the interval between two consecutive
SOFs in bit times. The nominal value is set to be 11,999. HCD
should store the current value of this field before resetting HC. Set-
ting the
HCR
field of
Hc command status register
will cause the
HC to reset this field to its nominal value. HCD may choose to
restore the stored value upon the completion of the reset
sequence.
FS largest data packet. This field specifies a value that is loaded
into the largest data packet counter at the beginning of each
frame. The counter value represents the largest amount of data in
bits that can be sent or received by the HC in a single transaction
at any given time without causing scheduling overrun. The field
value is calculated by the HCD.
Reserved.
Frame interval toggle. HCD toggles this bit whenever it loads a
new value to
FI
.
30:16
FSMPS
TBD
R/W
R
15:14
13:0
RSVD
FIT
—
0b
—
R/W
R
Address 0xE000 7038
Bit #
Name
Bit #
31
FRT
30:14
RSVD
13:0
FR
Key
Reset
Read/Write
HCD
R
Description
HC
R/W
31
FRT
0b
Frame remaining toggle. This bit is loaded from the
FIT
field of the
Hc Fm interval register
whenever
FR
reaches 0. This bit is used
by HCD for the synchronization between frame interval and frame
remaining.
Reserved.
Frame remaining. This counter is decremented at each bit time.
When it reaches 0, it is reset by loading the frame interval value
specified in the
Hc Fm interval register
at the next bit time bound-
ary. When entering the USB operational state, HC reloads the con-
tent with the
FI
of the
Hc Fm interval register
and uses the
updated value from the next SOF.
30:14
13:0
RSVD
FR
—
0h
—
R
—
R/W