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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262--, Revision: 004US
301
USB 1.1 Device Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network
Processors
8.5.5.2
Transmit Packet Complete (TPC)
The UDC sets transmit packet complete bit when an entire packet is sent to the host.
When this bit is set, the IR3 bit in the appropriate UDC status/interrupt register is set if
transmit interrupts are enabled.
This bit can be used to validate the other status/error bits in the endpoint 3control/
status register. The UDCCS3[TPC] bit gets cleared by writing a 1 to it. This clears the
interrupt source for the IR3 bit in the appropriate UDC status/interrupt register, but the
IR3 bit must also be cleared.
Setting this bit does not prevent the UDC from transmitting the next buffer. The UDC
issues NAK handshakes to all IN tokens if this bit is set and neither buffer has been
triggered by writing 64 bytes or setting UDCCS3[TSP].
8.5.5.3
Flush Tx FIFO (FTF)
The Flush Tx FIFO bit triggers a reset for the endpoint's transmit FIFO. The Flush Tx
FIFO bit is set when software writes a 1 to it or when the host performs a
SET_CONFIGURATION or SET_INTERFACE.
The bit’s read value is 0.
8.5.5.4
Transmit Underrun (TUR)
The transmit underrun bit is be set if the transmit FIFO experiences an underrun. When
the UDC experiences an underrun, UDCCS3[TUR] generates an interrupt.
UDCCS3[TUR] is cleared by writing a 1 to it.
8.5.5.5
Bit 4 Reserved
Bit 4 is reserved for future use.
8.5.5.6
Bit 5 Reserved
Bit 5 is reserved for future use.
8.5.5.7
Bit 6 Reserved
Bit 6 is reserved for future use.
8.5.5.8
Transmit Short Packet (TSP)
Software uses the transmit short packet to indicate that the last byte of a data transfer
has been sent to the FIFO. This indicates to the UDC that a short packet or zero-sized
packet is ready to transmit. Software should always check TSP after loading a packet to
determine if more data can be loaded.
Software must not set this bit if a packet of 256 bytes is to be transmitted. When the
data packet is successfully transmitted, this bit is cleared by the UDC.