
Universal Serial Bus Interface
MCF5253 Reference Manual, Rev. 1
24-48
Freescale Semiconductor
Frame List Link pointers always reference memory objects that are 32-byte aligned. The referenced object
may be an isochronous transfer descriptor for high-speed devices, a split-transaction isochronous transfer
descriptor (for full-speed isochronous endpoints), or a queue head (used to support high-, full- and
low-speed interrupt). The system software should not place non-periodic schedule items into the periodic
schedule. The least significant bits in a frame list pointer are used to key the host controller as to the type
of object the pointer is referencing.
The least significant bit is the T-Bit (bit 0). When this bit is set, the host controller will never use the value
of the frame list pointer as a physical memory pointer. The Typ field is used to indicate the exact type of
data structure being referenced by this pointer. The value encodings for the Typ field are given in
.
24.8.2
Asynchronous List Queue Head Pointer
The Asynchronous Transfer List (based at the ASYNCLISTADDR register) is where all the control and
bulk transfers are managed. Host controllers use this list only when it reaches the end of the periodic list,
the periodic list is disabled, or the periodic list is empty.
Figure 24-37. Asynchronous Schedule Organization
The Asynchronous list is a simple circular list of queue heads. The ASYNCLISTADDR register is simply
pointer to the next queue head. This implements a pure round-robin service for all queue heads linked into
the asynchronous list.
31
5
4
3
2
1
0
Frame List Link Pointer
00
Typ
T
Figure 24-36. Frame List Link Pointer Format
Table 24-37. Typ Field Encodings
Typ
Description
00 Isochronous
Transfer
Descriptor
01 Queue
Head
10
Split Transaction Isochronous Transfer Descriptor
11
Frame Span Traversal Node.
AsyncListAddr
Operational
Registers
Bulk/Control Queue Heads
H
Содержание MCF5253
Страница 1: ...Document Number MCF5253RM Rev 1 08 2008 MCF5253 Reference Manual...
Страница 26: ...MCF5253 Reference Manual Rev 1 xxvi Freescale Semiconductor...
Страница 32: ...MCF5253 Reference Manual Rev 1 xxxii Freescale Semiconductor...
Страница 46: ...MCF5253 Introduction MCF5253 Reference Manual Rev 1 1 14 Freescale Semiconductor...
Страница 62: ...Signal Description MCF5253 Reference Manual Rev 1 2 16 Freescale Semiconductor...
Страница 98: ...Instruction Cache MCF5253 Reference Manual Rev 1 5 10 Freescale Semiconductor...
Страница 104: ...Static RAM SRAM MCF5253 Reference Manual Rev 1 6 6 Freescale Semiconductor...
Страница 128: ...Synchronous DRAM Controller Module MCF5253 Reference Manual Rev 1 7 24 Freescale Semiconductor...
Страница 144: ...Bus Operation MCF5253 Reference Manual Rev 1 8 16 Freescale Semiconductor...
Страница 176: ...System Integration Module SIM MCF5253 Reference Manual Rev 1 9 32 Freescale Semiconductor...
Страница 198: ...Analog to Digital Converter ADC MCF5253 Reference Manual Rev 1 12 6 Freescale Semiconductor...
Страница 246: ...DMA Controller MCF5253 Reference Manual Rev 1 14 18 Freescale Semiconductor...
Страница 282: ...UART Modules MCF5253 Reference Manual Rev 1 15 36 Freescale Semiconductor...
Страница 298: ...Queued Serial Peripheral Interface QSPI Module MCF5253 Reference Manual Rev 1 16 16 Freescale Semiconductor...
Страница 344: ...Audio Interface Module AIM MCF5253 Reference Manual Rev 1 17 46 Freescale Semiconductor...
Страница 362: ...I2 C Modules MCF5253 Reference Manual Rev 1 18 18 Freescale Semiconductor...
Страница 370: ...Boot ROM MCF5253 Reference Manual Rev 1 19 8 Freescale Semiconductor...