SIS5595 Datasheet, PDF (192/216 Pages) List of Unclassifed Manufacturers – Pentium PCI System I/O Chipset

SiS5595 PCI System I/O Chipset
Register 3Ch
HcFmNumber Register
Default Value: 00000000h
Access: Read
The HcFmNumber register is a 16-bit counter. It provides a timing reference among events
occurring in the Host Controller and the Host Controller Driver. The Host Controller Driver
may use the 16-bit value specified in this register and generate a 32-bit frame number
without requiring frequent access to the register.
BIT
31:16
15:0
ACCESS
DESCRIPTION
Reserved
RO FrameNumber
This is incremented when HcFmRemaining is re-loaded. It will be
rolled over to 0h after ffffh. When entering the UsbOperational
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.
Register 40h
HcPeriodicStart Register
Default Value: 00000000h
Access: Read/Write
The HcPeriodicStart register has a 14-bit programmable value which determines when is the
earliest time HC should start processing the periodic list.
BIT
ACCESS
DESCRIPTION
31:14
13:0
Reserved
R/W 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 HcFmInterval. 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.
Register 44h
HcLSThreshold Register
Default Value: 00000000h
Access: Read/Write
The HcLSThreshold register contains an 11-bit value used by the Host Controller to
determine whether to commit to the transfer of a maximum of 8-byte LS packet before EOF.
Neither the Host Controller nor the Host Controller Driver is allowed to change this value.
Preliminary V2.0 Nov. 2, 1998
186 Silicon Integrated Systems Corporation