![Intel IXP45X Developer'S Manual Download Page 397](http://html1.mh-extra.com/html/intel/ixp45x/ixp45x_developers-manual_2073092397.webp)
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262--, Revision: 004US
397
USB 2.0 Host Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
9.13.4.3
siTD Transfer State
DWords 3-6 are used to manage the state of the transfer.
Table 152.
Micro-Frame Schedule Control
Bit
Description
31:16
(Reserved). This field reserved for future use. It should be zero.
15:8
Split Completion Mask (
μ
Frame C-Mask). This field (along with the Active and SplitX- state
fields in the Status byte) is used to determine during which micro-frames the host controller
should execute complete-split transactions. When the criteria for using this field is met, an all
zeros value has undefined behavior. The host controller uses the value of the three low-order bits
of the FRINDEX register to index into this bit field. If the FRINDEX register value indexes to a
position where the
μ
Frame C-Mask field is a one, then this siTD is a candidate for transaction
execution. There may be more than one bit in this mask set.
7:0
Split Start Mask (
μ
Frame S-mask). This field (along with the Active and SplitX-state fields in
the Status byte) is used to determine during which micro-frames the host controller should
execute start-split transactions. The host controller uses the value of the three low-order bits of
the FRINDEX register to index into this bit field. If the FRINDEX register value indexes to a
position where the
μ
Frame S-mask field is a one, then this siTD is a candidate for transaction
execution. An all zeros value in this field, in combination with existing periodic frame list has
undefined results.
Table 153.
siTD Transfer Status and Control (Sheet 1 of 2)
Bit
Description
31
Interrupt On Complete (ioc).
0 = Do not interrupt when transaction is complete.
1 = Do interrupt when transaction is complete.
When the host controller determines that the split transaction has completed it will assert a
hardware interrupt at the next interrupt threshold.
30
Page Select (P).
Used to indicate which data page pointer should be concatenated with the
Cur-
rentOffset
field to construct a data buffer pointer (0 selects
Page 0
pointer and 1 selects
Page 1
).
The host controller is not required to write this field back when the siTD is retired (
Active
bit transi-
tioned from a one to a zero).
29:26
(Reserved).
This field reserved for future use and should be zero.
25:16
Total Bytes To Transfer.
This field is initialized by software to the total number of bytes expected in
this transfer. Maximum value is 1023 (3FFh)
15:8
μ
Frame Complete-split Progress Mask (C-prog-Mask). This field is used by the host controller to
record which split-completes has been executed.
7:0
Status.
This field records the status of the transaction executed by the host controller for this slot.
This field is a bit vector with the following encoding
7
Active. Set to one by software to enable the execution of an isochronous split transaction by the
Host Controller.
6
ERR. Set to a one by the Host Controller when an ERR response is received from the Companion
Controller.
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). In the case of an under run, the Host
Controller will transmit an incorrect CRC (thus invalidating the data at the endpoint). If an overrun
condition occurs, no action is necessary.
4
Babble Detected. Set to a one by the Host Controller during status update when” babble” is
detected during the transaction generated by 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.). This
bit will only be set for IN transactions.