Intel
82801BA ICH2 Datasheet
5-105
Functional Description
7. Wait for data to arrive (from USB). Write incoming bytes into memory beginning at TD
BufferPointer. Internal HC buffer should signal end of data packet. Number of bytes received
must be (TD Max-Length; The length of the memory area referenced by TD BufferPointer
must be (TD Max-Length. [
Concurrent system memory and USB Accesses
].
8. Issue handshake based on status of data received (Ack or Time-out). Go to 10.
9. Wait for handshake, if required [
End of USB Transaction
].
10. Update Status [
PCI Access
] (TD.Status and TD.ActualLength).
If the TD was an isochronous TD, mark the TD inactive. Go to 12.
If not an isochronous TD, and the TD completed successfully, mark the TD inactive. Go to 11.
If not successful, and the error count has not been reached, leave the TD active. If the error
count has been reached, mark the TD inactive. Go to 12.
11. Write the link pointer from the current TD into the element pointer field of the QH structure. If
the Vf bit is set in the TD link pointer, go to 2.
12. Proceed to next entry.
5.16.2.3
Command Register, Status Register, and TD Status Bit Interaction
NOTES:
1. Only If error counter counted down from 1 to 0
2. Suspend mode can be entered only when Run/Stop bit is 0
Table 5-65. Command Register, Status Register and TD Status Bit Interaction
Condition
ICH2 USB Status Register Actions
TD Status Register Actions
CRC/Time Out Error
Set USB Error Int bit
1
, Clear HC Halted bit
Clear Active bit
1
and set Stall
bit
1
Illegal PID, PID Error,
Max Length (illegal)
Clear Run/Stop bit in command register
Set HC Process Error and HC Halted bits
PCI Master/Target
Abort
Clear Run/Stop bit in command register
Set Host System Error and HC Halted bits
Suspend Mode
Clear Run/Stop bit in command register
2
Set HC Halted bit
Resume Received and
Suspend Mode = 1
Set Resume received bit
Run/Stop = 0
Clear Run/Stop bit in command register
Set HC Halted bit
configuration Flag Set
Set configuration Flag in command register
HC Reset/Global Reset
Clear Run/Stop and configuration Flag in
command register
Clear USB Int, USB Error Int, Resume received,
Host System Error, HC Process Error, and HC
Halted bits
IOC = 1 in TD Status
Set USB Int bit
Stall
Set USB Error Int bit
Clear Active bit
1
and set Stall bit
Bit Stuff/Data Buffer
Error
Set USB Error Int bit
1
Clear Active bit
1
and set Stall
bit
1
Short Packet Detect
Set USB Int bit
Clear Active bit
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