Download NEC uPD720102 USB Controller - User Manual / Programming

CHAPTER 5 EHCI HOST CONTROLLER
5.3
Split Transaction Isochronous Transfer Descriptor
All full-speed isochronous transfers through Transaction Translators are managed using the siTD data structure.
This always allocated in 7-Dword units to system memory.
5.3.1 Split transaction isochronous transfer descriptor format
Table 5-3. Split Transaction Isochronous Transfer Descriptor Format
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Dword0
Dword1
Next Link Pointer (NLP)
D
PN
0
Dword2
Dword3
HA
0
0
0
I P
0
TBT
Dword4
Buffer Pointer (BP Page 0)
Dword5
Buffer Pointer (BP Page 1)
Dword6
EP
0
UFCM
TYP T
DA
UFSM
CPM
STA
Current Offset (CO)
0
TP
Back Pointer (BKP)
TC
0
T
5.3.2 Split transaction isochronous transfer descriptor field definitions
Table 5-4. Description of Split Transaction Isochronous Transfer Descriptors
(1/2)
Name
NLP
HC Access
R
Description
Next Link Pointer
This field indicates another Isochronous Transaction descriptor (iTD or siTD) or Queue Head (QH).
TYP
R
QH/(s)iTD/FSTN select
This indicates the descriptor type.
00b: iTD
01b: QH
10b: siTD
11b: FSTN
T
R
Terminate
1: Link Pointer field or Back Pointer field is not valid.
0: Link Pointer field or Back Pointer field is valid.
D
R
Direction
Indicates the data flow direction (IN or OUT)
1: IN
0: OUT
PN
R
Port Number
This field indicates the port number of the recipient transaction translator.
HA
R
Hub Address
This field holds the device address of the transaction translator’s hub.
EP
R
Endpoint Number
DA
R
Device Address
UFCM
R
Split Completion Mask (μFrame C-mask)
This field are used to determine during which micro-frames HC should execute complete-split
transactions.
User’s Manual S17999EJ4V0UD
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