Information

Universal Serial Bus Interface
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
13-106 Freescale Semiconductor
The B-Frame boundaries are marked with a large, bold, dashed line. The bottom of Figure 13-57 illustrates
the relationship of an siTD to the H-Frame.
Figure 13-57. Split Transaction, Isochronous Scheduling Boundary Conditions
When the endpoint is an isochronous OUT, there are only start-splits, and no complete-splits. When the
endpoint is an isochronous IN, there is at most one start-split and one to N complete-splits. The scheduling
boundary cases are:
• Case 1: The entire split transaction is completely bounded by an H-Frame. For example, the
start-splits and complete-splits are all scheduled to occur in the same H-Frame.
• Case 2a: This boundary case is where one or more (at most two) complete-splits of a split
transaction IN are scheduled across an H-Frame boundary. This can only occur when the split
transaction has the possibility of moving data in B-Frame, microframes 6 or 7 (H-Frame
microframe 7 or 0). When an H-Frame boundary wrap condition occurs, the scheduling of the split
7
C
2
C
1
C
0
S
076543210
Periodic Schedule
Micro-Frame
1
Case 1:
Normal Case
C
3
C
0
S
Case 2a:
Frame Wrap at
S
0
C
6
C
5
C
4
S
6765432107
HS/FS/LS Bus
Micro-Frame
0
Case 2b:
Start & Complete
B-Frame N B-Frame N+1B-Frame N–1
H-Frame N
S
3
S
2
S
0
C
3
S
1
C
6
S
C
0
C
1
C
2
C
3
C
1
C
2
S
1
S
2
S
3
H-Frame N+1
siTD
x
siTD
x+1
End of H-Frame
in H-Frame,
Micro-Frame 0
IN
OUT
IN
OUT
IN