DS00002142A-page 33

USB3250

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 SIE 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 SIE 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 SIE sampling the LIN-

ESTATE signals.

FIGURE 8-4:

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

!K

State

Detect J?

INC

Chirp

J State

!J

Chirp Count != 6

& !SE0

Chirp

Count = 0

Chirp Count

!= 6

& !SE0

Chirp

Valid

Chirp

Invalid

SE0

Chirp Count

=6 6 66