USB3450 datasheet(33/40 Pages) SMSC

33 / 40 page

Hi-Speed USB Host or Device PHY With UTMI+ Interface

Datasheet

SMSC USB3450

Revision 0.1 (05-11-05)

DATASHEET

7.9

HS Detection Handshake – HS Downstream Facing Port

Upon entering the HS Detection process (T0) XCVRSELECT and TERMSELECT are in FS mode. The

DP pull-up is asserted and the HS terminations are disabled. The Link then sets OPMODE to Disable

Bit Stuffing and NRZI encoding, XCVRSELECT to HS mode, and begins the transmission of all 0's

data, which asserts a HS K (chirp) on the bus (T1). The device chirp must last at least 1.0ms, and

must end no later than 7.0ms after HS Reset T0. At time T1 the device begins listening for a chirp

sequence from the downstream facing port. If the downstream facing port is HS capable then it will

begin generating an alternating sequence of Chirp K’s and Chirp J’s (T3) after the termination of the

chirp from the device (T2). After the device sees the valid chirp sequence Chirp K-J-K-J-K-J (T6), it

will enter HS mode by setting TERMSELECT to HS mode (T7).

Figure 7.4 provides a state diagram for Chirp K-J-K-J-K-J validation. Prior to the end of reset (T9) the

device port must terminate the sequence of Chirp K’s and Chirp J’s (T8) and assert SE0 (T8-T9). Note

that the sequence of Chirp K’s and Chirp J’s constitutes bus activity.

The Chirp K-J-K-J-K-J sequence occurs too slow to propagate through the serial data path, therefore

LINESTATE signal transitions must be used by the Link to step through the Chirp K-J-K-J-K-J state

diagram, where “K State” is equivalent to LINESTATE = K State and “J State” is equivalent to

LINESTATE = J State. The Link must employ a counter (Chirp Count) to count the number of Chirp K

and Chirp J states. Note that LINESTATE does not filter the bus signals so the requirement that a bus

state must be “continuously asserted for 2.5µs” must be verified by the Link sampling the LINESTATE

signals.

Figure 7.4 Chirp K-J-K-J-K-J Sequence Detection State Diagram

Detect K?

Start Chirp

K-J-K-J-K-J

detection

INC Chirp

Count

K State

Detect J?

INC Chirp

Count

J State

Chirp Count != 6

& !SE0

Chirp Count

= 0

Chirp Count != 6

& !SE0

Chirp Valid

Chirp

Invalid

SE0

Chirp Count

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