NHE6300ESB S L7XJ Intel, NHE6300ESB S L7XJ Datasheet - Page 213

• Manufacturer Part Number: NHE6300ESB S L7XJ
• Manufacturer: Intel

Specifications of NHE6300ESB S L7XJ

• Lead Free Status / RoHS Status: Compliant

5—Intel
5.17.6.4 Handshake Packets
5.17.6.5 Handshake Responses
November 2007
Order Number: 300641-004US
®
6300ESB ICH
Handshake packets consist of only a PID. Handshake packets are used to report the
status of a data transaction and may return values indicating successful reception of
data, flow control, and stall conditions. Only transaction types that support flow control
may return handshakes. Handshakes are always returned in the handshake phase of a
transaction and may be returned, instead of data, in the data phase. Handshake
packets are delimited by an EOP after one byte of packet field. When a packet is
decoded as an otherwise valid handshake but does not terminate with an EOP after one
byte, it must be considered invalid and ignored by the receiver.
There are three types of handshake packets:
IN Transaction
A function may respond to an IN transaction with a STALL or NAK. When the token
received was corrupted, the function will issue no response. When the function may
transmit data, it will issue the data packet. The Intel
may return only one type of handshake on an IN transaction, an ACK. When it receives
a corrupted data, or cannot accept data due to a condition such as an internal buffer
overrun, it discards the data and issues no response.
OUT Transaction
A function may respond to an OUT transaction with a STALL, ACK, or NAK. When the
transaction contained corrupted data, it will issue no response.
SETUP Transaction
Setup defines a special type of host to function data transaction which permits the host
to initialize an endpoint’s synchronization bits to those of the host. Upon receiving a
Setup transaction, a function must accept the data. Setup transactions cannot be
STALLed or NAKed and the receiving function must accept the Setup transfer’s data.
When a non-control endpoint receives a SETUP PID, it must ignore the transaction and
return no response.
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ACK indicates that the data packet was received without bit stuff or CRC errors
over the data field and that the data PID was received correctly. An ACK handshake
is applicable only in transactions in which data has been transmitted and where a
handshake is expected. ACK may be returned by the host for IN transactions and
by a function for OUT transactions.
NAK indicates that a function was unable to accept data from the host (OUT) or
that a function has no data to transmit to the host (IN). NAK may only be returned
by functions in the data phase of IN transactions or the handshake phase of OUT
transactions. The host may not issue a NAK. NAK is used for flow control purposes
to indicate that a function is temporarily unable to transmit or receive data, but will
eventually be able to do so without need of host intervention. NAK is also used by
interrupt endpoints to indicate that no interrupt is pending.
STALL is returned by a function in response to an IN token or after the data phase
of an OUT. STALL indicates that a function is unable to transmit or receive data, and
that the condition requires host intervention to remove the stall. Once a function’s
endpoint is stalled, the function must continue returning STALL until the condition
causing the stall has been cleared through host intervention. The host is not
permitted to return a STALL under any condition.
®
6300ESB ICH, as the USB host,
Intel
®
6300ESB I/O Controller Hub
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