Isochronous Transaction Type; Control Transaction Type; Bulk Transaction Formats; Isochronous Transaction Formats - Intel IXP45X Developer's Manual

Table 114.

Bulk Transaction Formats

Host successfully received data from UDC
UDC temporarily unable to transmit data
UDC endpoint needs host intervention
Host detected PID, CRC, or bit stuff error
UDC successfully received data from host
UDC temporarily unable to receive data
UDC endpoint needs host intervention
UDC detected PID, CRC, or bit stuff error
† Packets from UDC to host are boldfaced.
8.3.5.2

Isochronous Transaction Type

Isochronous transactions ensure constant-rate, error-tolerant transmission of data
between the host and UDC. The host schedules isochronous packets during every
frame.
The USB protocol allows isochronous transfers to take up to 90% of the USB
bandwidth. Unlike bulk transactions, if corrupted data is received, the UDC will continue
to process the corrupted data that corresponds to the current start of frame indicator.
Isochronous transactions do not support a handshake phase or retry capability. Two
packet types are used to construct isochronous transactions: token and data. The types
of isochronous transactions based on data direction are shown in
Table 115.

Isochronous Transaction Formats

Host received data from UDC
UDC received data from host
† Packets from UDC to host are boldfaced.
8.3.5.3

Control Transaction Type

The host uses control transactions to configure endpoints and query their status. Like
bulk transactions, control transactions begin with a setup packet, followed by an
optional data packet, then a handshake packet. Control transactions, by default, use
DATA0 type transfers.
Table 116
Table 116.

Control Transaction Formats

UDC successfully received control from host
UDC temporarily unable to receive data
UDC endpoint needs host intervention
UDC detected PID, CRC, or bit stuff error
† Packets from UDC to host are boldfaced.
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shows the four types of control transactions.
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IXP46X Product Line of Network Processors—USB 1.1 Device
Token Packet Data Packet
IN DATA0/DATA1
IN
IN
IN DATA0/DATA1
OUT DATA0/DATA1
OUT DATA0/DATA1
OUT DATA0/DATA1
OUT DATA0/DATA1
†
Token Packet Data Packet
IN
OUT
Token Packet Data Packet
SETUP
SETUP
SETUP
SETUP
Controller
†
Handshake Packet
ACK
None NAK
None STALL
None
ACK
NAK
STALL
None
Table 115.
†
DATA0
DATA0
†
Handshake Packet
DATA0 ACK
DATA0 NAK
DATA0 STALL
DATA0 None
August 2006
Order Number: 306262-004US
†
†