
Universal Serial Bus Interface – On-The-Go Module
Freescale Semiconductor
21-71
In addition to checking the status bit, the DCD must read the transfer bytes field to determine the actual
bytes transferred. When a transfer is complete, the total bytes transferred decrements by the actual bytes
transferred. For transmit packets, a packet is only complete after the actual bytes reaches zero. However,
for receive packets, the host may send fewer bytes in the transfer according the USB variable length packet
protocol.
21.5.3.6.5
Flushing/De-priming an Endpoint
It is necessary for the DCD to flush or de-prime endpoints during a USB device reset or during a broken
control transfer. There may also be application specific requirements to stop transfers in progress. The
DCD can use this procedure to stop a transfer in progress:
1. Set the corresponding bit(s) in the EPFLUSH register.
2. Wait until all bits in the EPFLUSH register are cleared.
NOTE
This operation may take a large amount of time depending on the USB bus
activity. It is not desirable to have this wait loop within an interrupt service
routine.
3. Read the EPSR register to ensure that for all endpoints commanded to be flushed, that the
corresponding bits are now cleared. If the corresponding bits are set after step #2 has finished, flush
failed as described below:
In very rare cases, a packet is in progress to the particular endpoint when commanded to flush using
EPFLUSH. A safeguard is in place to refuse the flush to ensure that the packet in progress
completes successfully. The DCD may need to repeatedly flush any endpoints that fail to flush by
repeating steps 1-3 until each endpoint successfully flushes.
21.5.3.6.6
Device Error Matrix
The following table summarizes packet errors not automatically managed by the USB OTG module.
The device controller manages all errors on bulk/control/interrupt endpoints except for a data buffer
overflow. However, for ISO endpoints, errors packets are not retried and errors are tagged as indicated.
Table 21-56. Device Error Matrix
Error
Direction
Packet
Type
Data Buffer
Error Bit
Transaction
Error Bit
Data Buffer Overflow
RX
Any
1
0
ISO Packet Error
RX
ISO
0
1
ISO Fulfillment Error
Both
ISO
0
1
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...