USB Host Controller Registers
14-19
Universal Serial Bus Host
Table 14–7. HC Interrupt Disable Register (HcInterruptDisable) (Continued)
Bit
Reset
Value
Type
Description
Name
1
WDH
Write done head
Read always returns 0.
Write of 0 has no effect.
Write of 1 clears the HcInterruptEnable WDH bit.
R/W
0
0
SO
Scheduling overrun
Read always returns 0.
Write of 0 has no effect.
Write of 1 clears the HcInterruptEnable SO bit.
R/W
0
The HCAA address register defines the local bus virtual address of the begin-
ning of the HCCA.
Table 14–8. HC HCAA Address Register (HcHCCA)
Bit
Name
Description
Type
Reset
Value
31–8
HCCA
See Section 14.6.1, Local Bus Addressing, for the restrictions
on local bus virtual addresses.
R/W
0
7–0
Reserved
Reserved
R
0
The HC current periodic register defines the local bus virtual address of the
next endpoint descriptor (ED) on the periodic ED List.
Table 14–9. HC Current Periodic Register (HcPeriodCurrentED)
Bit
Name
Description
Type
Reset
Value
31–4
PCED
Local bus virtual address of current ED on the periodic ED
list.
This field represents bits 31:4 of the local bus virtual address
of the next ED on the periodic ED List. EDs are assumed to
begin at 16-byte-aligned address, so bits 3:0 of this pointer
are assumed to be 0. See Section 14.6.1, Local Bus
Addressing, for the restrictions on local bus virtual
addresses.
R/0
0x0000
000
3–0
Reserved
Reserved
R
0x0