NHE6300ESB S L7XJ Intel, NHE6300ESB S L7XJ Datasheet - Page 482

• Manufacturer Part Number: NHE6300ESB S L7XJ
• Manufacturer: Intel

Specifications of NHE6300ESB S L7XJ

• Lead Free Status / RoHS Status: Compliant

10—Intel
10.2.6
Table 377. Offset Base + OCh: SOFMOD—Start of Frame Modify Register
Bits
Default Value:
November 2007
Order Number: 300641-004US
6:0
7
Note: This 1-byte register is used to modify the value used in the generation of SOF timing on
Device:
®
Offset:
6300ESB ICH
SOF Timing Value
Offset Base + OCh: SOFMOD—Start of
Frame Modify Register
the USB. Only the 7 least significant bits are used. When a new value is written into
these 7 bits, the SOF timing of the next frame will be adjusted. This feature may be
used to adjust out any offset from the clock source that generates the clock that drives
the SOF counter. This register may also be used to maintain real-time synchronization
with the rest of the system so that all devices have the same sense of real time. Using
this register, the frame length may be adjusted across the full range required by the
USB specification. Its initial programmed value is system dependent based on the
accuracy of hardware USB clock and is initialized by system BIOS. It may be
reprogrammed by USB system software at any time. Its value will take effect from the
beginning of the next frame. This register is reset upon a Host Controller Reset or
Global Reset. Software must maintain a copy of its value for reprogramming when
necessary.
Reserved
Name
29
Base + (0Ch)
40h
Reserved.
Guidelines for the modification of frame time are contained in
Chapter 7 of the USB Specification. The SOF cycle time
(number of SOF counter clock periods to generate a SOF
frame length) is equal to 11936 + value in this field. The
default value is decimal 64 which gives a SOF cycle time of
12000. For a 12 MHz SOF counter clock input, this produces a
1 ms Frame period. The following table indicates what SOF
Timing Value to program into this field for a certain frame
period.
Frame Length
(# 12 MHz Clocks) SOF Reg. Value
(decimal)
11936
11937
.
.
11999
12000
12001
.
.
12062
12063
(decimal)
Description
0
1
.
.
63
64
65
.
.
126
127
Attribute:
Function:
Size:
X
Read/Write
8-bit
Intel
®
6300ESB I/O Controller Hub
Access
R/W
482
DS