
Universal Serial Bus Interface – On-The-Go Module
Freescale Semiconductor
21-67
21.5.3.5
Managing Queue Heads
The device queue head (dQH) points to the linked list of transfer tasks, each depicted by the device transfer
descriptor (dTD). An area of memory pointed to by EPLISTADDR contains a group of all dQH's in a
sequential list (
). The even elements in the list of dQH's receive endpoints (OUT/SETUP) and
the odd elements transmit endpoints (IN/INTERRUPT). Device transfer descriptors are linked head to tail
starting at the queue head and ending at a terminate bit. After the dTD retires, it is no longer part of the
linked list from the queue head. Therefore, software is required to track all transfer descriptors because
pointers no longer exist within the queue head after the dTD is retired (see
).
Figure 21-42. Endpoint Queue Head Diagram
In addition to current and next pointers and the dTD overlay examined in
the dQH also contains the following parameters for the associated endpoint: multipler,
maximum packet length, and interrupt on setup. The next section includes demonstration of complete
initialization of the dQH including these fields.
Out
Ignore
Ignore
Receive
N/A
Drop
Packet
Ping
Ignore
Ignore
Ignore
Ignore
Ignore
Invalid
Ignore
Ignore
Ignore
Ignore
Ignore
1
Zero length packet
2
Force bit stuff error
Table 21-55. Isochronous Endpoint Bus Response Matrix (continued)
Token
Type
Stall
Not
Primed
Primed
Underflow
Overflow
Endpoint QH1 - Out
Endpoint QH0 - In
Endpoint QH0 - Out
ENDPOINTLISTADDR
Endpoint Queue Heads
(up to 32 elements)
Transfer
Buffer
Transfer Buffer
Pointer
Transfer
Buffer
Transfer
Buffer
Transfer
Buffer
Transfer Buffer
Pointer
Endpoint
Transfer
Descriptors
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
Страница 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 902: ...Register Memory Map Quick Reference A 26 Freescale Semiconductor MCF5329 Reference Manual Rev 3...