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Universal Serial Bus Interface – On-The-Go Module
10-64
Freescale Semiconductor
TX-dTD is complete when:
•
All packets described in the dTD successfully transmit. Total bytes in dTD equal 0 when this
occurs.
RX-dTD is complete when:
•
All packets described in the dTD are successfully received. Total bytes in dTD equal 0 when this
occurs.
•
A short packet (number of bytes < maximum packet length) was received.
This is a successful transfer completion; DCD must check the total bytes field in the dTD to
determine the number of bytes remaining. From the total bytes remaining in the dTD, the DCD can
compute the actual bytes received.
•
A long packet was received (number of bytes > maximum packet size) or (total bytes received >
total bytes specified).
This is an error condition. The device controller discards the remaining packet and set the buffer
error bit in the dTD. In addition, the endpoint flushes and the USBERR interrupt becomes active.
NOTE
Disabling zero-length packet termination allows transfers larger than the
total bytes field spanning across two or more dTDs.
Upon successful completion of the packet(s) described by the dTD, the active bit in the dTD is cleared and
the next pointer is followed when the terminate bit is clear. When the terminate bit is set, USB OTG flushes
the endpoint/direction and ceases operations for that endpoint/direction.
Upon unsuccessful completion of a packet (see long packet above), the dQH is left pointing to the dTD in
error. To recover from this error condition, DCD must properly re-initialize the dQH by clearing the active
bit and update the nextTD pointer before attempting to re-prime the endpoint.
NOTE
All packet level errors, such as a missing handshake or CRC error, are
retried automatically by the device controller. There is no required
interaction with the DCD for managing such errors.
Table 10-55. Interrupt/Bulk Endpoint Bus Response Matrix
Token
Type
Stall
Not
Primed
Primed
Underflow
Overflow
Setup
Ignore
Ignore
Ignore
N/A
N/A
In
STALL
NAK
Transmit
BS Error
1
1
Force bit stuff error
N/A
Out
STALL
NAK
R NYET/ACK
2
N/A
NAK
Ping
STALL
NAK
ACK
N/A
N/A
Invalid
Ignore
Ignore
Ignore
Ignore
Ignore
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...