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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—USB 2.0 Host Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
402
Order Number: 306262-004US
10b
SETUP Token generates token (2DH) (undefined if endpoint is an Interrupt the queue
head is non-zero.) transfer type, e.g.
μ
Frame S-mask field in
11b
(Reserved)
7:0
Status. This field is used by the Host Controller to communicate individual command execution
states back to HCD. This field contains the status of the last transaction performed on this qTD.
The bit encodings are:
7
Active. Set to one by software to enable the execution of transactions by the Host
Controller.
6
Halted. Set to a one by the Host Controller during status updates to indicate that a
serious error has occurred at the device/endpoint addressed by this qTD. This can be
caused by babble, the error counter counting down to zero, or reception of the STALL
handshake from the device during a transaction. Any time that a transaction results in
the Halted bit being set to a one, the Active bit is also set to zero.
5
Data Buffer Error. Set to a one by the Host Controller during status update to
indicate that the Host Controller is unable to keep up with the reception of incoming
data (overrun) or is unable to supply data fast enough during transmission (under
run). If an overrun condition occurs, the Host Controller will force a timeout condition
on the USB, invalidating the transaction at the source. If the host controller sets this
bit to a one, then it remains a one for the duration of the transfer.
4
Babble Detected. Set to a one by the Host Controller during status update when”
babble” is detected during the transaction. In addition to setting this bit, the Host
Controller also sets the Halted bit to a one. Since “babble” is considered a fatal error
for the transfer, setting the Halted bit to a one insures that no more transactions occur
because of this descriptor.
3
Transaction Error (XactErr). Set to a one by the Host Controller during status
update in the case where the host did not receive a valid response from the device
(Timeout, CRC, Bad PID, etc.). If the host controller sets this bit to a one, then it
remains a one for the duration of the transfer.
2
Missed Micro-Frame. This bit is ignored unless the QH.EPS field indicates a full- or
low-speed endpoint and the queue head is in the periodic list. This bit is set when the
host controller detected that a host-induced hold-off caused the host controller to miss
a required complete-split transaction. If the host controller sets this bit to a one, then
it remains a one for the duration of the transfer.
1
Split Transaction State (SplitXstate). This bit is ignored by the host controller
unless the QH.EPS field indicates a full- or low-speed endpoint. When a Full- or Low-
speed device, the host controller uses this bit to track the state of the split-
transaction. The functional requirements of the host controller for managing this state
bit and the split transaction protocol depends on whether the endpoint is in the
periodic or asynchronous schedule. The bit encodings are:
Value
Meaning
0b
Do Start Split.
This value directs the host controller to issue a Start split transaction to the endpoint.
1b
Do Complete Split.
This value directs the host controller to issue a Complete split transaction to the
endpoint.
0
Ping State (P)/ERR. If the QH.EPS field indicates a High-speed device and the
PID_Code indicates an OUT endpoint, then this is the state bit for the Ping protocol.
The bit encodings are:
Value
Meaning
0b
Do OUT.
This value directs the host controller to issue an OUT PID to the endpoint.
1b
Do Ping.
This value directs the host controller to issue a PING PID to the endpoint.
If the QH.EPS field does not indicate a High-speed device, then this field is used as an
error indicator bit. It is set to a one by the host controller whenever a periodic split-
transaction receives an ERR handshake.
Table 158.
qTD Token (DWord 2) (Sheet 2 of 2)
Bit
Description