Universal Serial Bus OHCI Host Controller User's Guide

3.4 HC Interrupt and Status Register (HCINTERRUPTSTATUS)
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The HC interrupt and status register (HCINTERRUPTSTATUS) reports the status of the USB host
controller internal interrupt sources. HCINTERRUPTSTATUS is shown in Figure 5 and described in
Table 5 .
Figure 5. HC Interrupt and Status Register (HCINTERRUPTSTATUS)
31 30 29 16
Rsvd OC Reserved
R-0 R-0 R-0
15 7 6 5 4 3 2 1 0
Reserved RHSC FNO UE RD SF WDH SO
R-0 R/W1C-0 R/W1C-0 R/W1C-0 R/W1C-0 R/W1C-0 R/W1C-0 R/W1C-0
LEGEND: R/W = Read/Write; R = Read only; W1C = Write 1 to clear (writing 0 has no effect); - n = value after reset
Table 5. HC Interrupt and Status Register (HCINTERRUPTSTATUS) Field Descriptions
Bit Field Value Description
31 Reserved 0 Reserved
30 OC 0-1 Ownership change.
29-7 Reserved 0 Reserved
6 RHSC Root hub status change. A write of 1 clears this bit; a write of 0 has no effect.
0 A root hub status change has not occurred.
1 A root hub status change has occurred.
5 FNO Frame number overflow. A write of 1 clears this bit; a write of 0 has no effect.
0 A frame number overflow has not occurred.
1 A frame number overflow has occurred.
4 UE Unrecoverable error. A write of 1 clears this bit; a write of 0 has no effect.
0 An unrecoverable error has not occurred.
1 An unrecoverable error has occurred on the OCPI bus, or that an isochronous TD PSW field condition
code was not set to Not Accessed when the USB host controller attempted to perform a transfer using
that PSW/offset pair.
3 RD Resume detected. A write of 1 clears this bit; a write of 0 has no effect.
0 A downstream device has not issued a resume request.
1 A downstream device has issued a resume request.
2 SF Start of frame. A write of 1 clears this bit; a write of 0 has no effect.
0 A SOF has not been issued.
1 A SOF has been issued.
1 WDH Write done head. The host controller driver must read the value from the HC head done register
(HCDONEHEAD) before writing 1 to this bit. A write of 1 clears this bit; a write of 0 has no effect.
0 USB host controller has not updated the HC head done register (HCDONEHEAD).
1 USB host controller has updated the HC head done register (HCDONEHEAD).
0 SO Scheduling overrun. A write of 1 clears this bit; a write of 0 has no effect.
0 A scheduling overrun has not occurred.
1 A scheduling overrun has occurred.
16 Universal Serial Bus OHCI Host Controller SPRUFM8 – September 2008
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