USB Host Controller
1539
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Universal Serial Bus (USB)
29.2.4.3 HC Command and Status Register (HCCOMMANDSTATUS)
The HC command and status register shows the current state of the host controller and accepts
commands from the host controller driver.
Figure 29-3. HC Command and Status Register (HCCOMMANDSTATUS) [address = FCF78B08h]
31
18
17
16
Reserved
SOC
R-0
R-0
15
4
3
2
1
0
Reserved
OCR
BLF
CLF
HCR
R-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value at reset
Table 29-5. HC Command and Status Register (HCCOMMANDSTATUS) Bit Field Descriptions
Bit
Field
Value
Description
31-18
Reserved
0
Reserved
17-16
SOC
0-3h
Scheduling overrun count
Counts the number of times a scheduling overrun occurs. This count is incremented even if the host
controller driver has not acknowledged any previous pending scheduling overrun interrupt.
15-4
Reserved
0
Reserved
3
OCR
0-1
Ownership change request
This bit is set by the host controller driver to gain ownership of the host controller.
The device does not support SMI interrupts, so no ownership change interrupt occurs.
2
BLF
0-1
Bulk list filled
The host controller driver must set this bit if it modifies the bulk list to include new TDs. If
HCBULKCURRENTED is 0, the USB host controller does not begin processing bulk list EDs unless
this bit is set. When the USB host controller sees this bit set and begins processing the bulk list, it
clears this bit.
1
CLF
0-1
Control list filled
The host controller driver must set this bit if it modifies the control list to include new TDs. If
HCCONTROLHEADED is 0, the USB host controller does not begin processing control list EDs
unless this bit is set. When the USB host controller sees this bit set and begins processing the
control list, it clears this bit.
0
HCR
0-1
Host controller reset. Write of 0 has no effect. Value of 1 initiates a software reset of the USB host
controller. This transitions the USB host controller to the USB suspend state. This resets most USB
host controller OHCI registers. OHCI register accesses must not be attempted until a read of this bit
returns a 0. A write of 1 to this bit does not reset the root hub and does not signal USB reset to
downstream USB functions.