Universal Serial Bus Interface
MCF5253 Reference Manual, Rev. 1
24-106
Freescale Semiconductor
There exists a one-to-one relationship between a high-speed isochronous split transaction (including all
start- and complete-splits) and one full-speed isochronous transaction. An siTD contains (amongst other
things) buffer state and split transaction scheduling information. An siTD's buffer state always maps to one
full-speed isochronous data payload. This means that for any full-speed transaction payload, a single
siTD's data buffer must be used. This rule applies to both IN an OUTs. An siTD's scheduling information
usually also maps to one high-speed isochronous split transaction. The exception to this rule is the
H-Frame boundary wrap cases mentioned above.
The siTD data structure describes at most, one frame's worth of high-speed transactions and that
description is strictly bounded within a frame boundary.
illustrates some examples. On the
top are examples of the full-speed transaction footprints for the boundary scheduling cases described
above. In the middle are time-frame references for both the B-Frames (HS/FS/LS Bus) and the H-Frames.
On the bottom is illustrated the relationship between the scope of an siTD description and the time
references. Each H-Frame corresponds to a single location in the periodic frame list. The implication is
that each siTD is reachable from a single periodic frame list location at a time.
Figure 24-58. siTD Scheduling Boundary Examples
Each case is described as follows:
•
Case 1: One siTD is sufficient to describe and complete the isochronous split transaction because
the whole isochronous split transaction is tightly contained within a single H-Frame.
•
Case 2a, 2b: Although both INs and OUTs can have these footprints, OUTs always take only one
siTD to schedule. However, INs (for these boundary cases) require two siTDs to complete the
scheduling of the isochronous split transaction. siTDX is used to always issue the start-split and
the first N complete-splits. The full-speed transaction (for these cases) can deliver data on the
full-speed bus segment during micro-frame 7 of H-Frame
Y+1
, or micro-frame 0 of H-Frame
Y+2
.
The complete splits are scheduled using siTD
X+2
(not shown). The complete-splits to extract this
data must use the buffer pointer from siTD
X+1
. The only way for the host controller to reach
siTD
X+1
from H-Frame
Y+2
is to use siTD
X+2
's back pointer.
0
7
6
5
4
3
2
1
0
0
7
6
5
4
3
2
1
2
1
7
6
5
4
B-Frame
Y
B-Frame
Y+1
B-Frame
Y+2
B-Frame
Y–1
0
7
6
5
4
3
2
1
0
0
7
6
5
4
3
2
1
2
1
7
6
5
H-Frame
Y
H-Frame
Y+1
3
H-Frame
Y+2
H-Frame
Y–1
Case 1
Case 2a
Case 2b
siTD
X
siTD
X+1
Back Pointer
Full-Speed Transaction
Summary of Contents for MCF5253
Page 1: ...Document Number MCF5253RM Rev 1 08 2008 MCF5253 Reference Manual...
Page 26: ...MCF5253 Reference Manual Rev 1 xxvi Freescale Semiconductor...
Page 32: ...MCF5253 Reference Manual Rev 1 xxxii Freescale Semiconductor...
Page 46: ...MCF5253 Introduction MCF5253 Reference Manual Rev 1 1 14 Freescale Semiconductor...
Page 62: ...Signal Description MCF5253 Reference Manual Rev 1 2 16 Freescale Semiconductor...
Page 98: ...Instruction Cache MCF5253 Reference Manual Rev 1 5 10 Freescale Semiconductor...
Page 104: ...Static RAM SRAM MCF5253 Reference Manual Rev 1 6 6 Freescale Semiconductor...
Page 128: ...Synchronous DRAM Controller Module MCF5253 Reference Manual Rev 1 7 24 Freescale Semiconductor...
Page 144: ...Bus Operation MCF5253 Reference Manual Rev 1 8 16 Freescale Semiconductor...
Page 176: ...System Integration Module SIM MCF5253 Reference Manual Rev 1 9 32 Freescale Semiconductor...
Page 198: ...Analog to Digital Converter ADC MCF5253 Reference Manual Rev 1 12 6 Freescale Semiconductor...
Page 246: ...DMA Controller MCF5253 Reference Manual Rev 1 14 18 Freescale Semiconductor...
Page 282: ...UART Modules MCF5253 Reference Manual Rev 1 15 36 Freescale Semiconductor...
Page 344: ...Audio Interface Module AIM MCF5253 Reference Manual Rev 1 17 46 Freescale Semiconductor...
Page 362: ...I2 C Modules MCF5253 Reference Manual Rev 1 18 18 Freescale Semiconductor...
Page 370: ...Boot ROM MCF5253 Reference Manual Rev 1 19 8 Freescale Semiconductor...