TQ9303 Просмотр технического описания (PDF) - TriQuint Semiconductor

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TQ9303

Fibre Channel Encoder/Decoder

TriQuint Semiconductor 

TQ9303

Figure 4. Check CRC Mode TIming

CRC Computation

CTXD0..31

SOF

D0

D1

Dn

CRC

EOF

Idle

CTXC1

CTXC0

CTCXERR

BTXD0..9

4 Bytes

SOF

D0

Dn-1

Dn

CRC

EOF

and ends before EOF. CTXCERR remains low if the

computed CRC matches the CRC input on CTXD0..31.

CTXCERR is driven high for one word cycle after the

end of EOF.

If CTXC1␣ is␣ high (generate CRC) then the ENDEC will

add one word (the CRC) to the user’s data frame before

encoding the EOF. In this situation, when the user

commands the ENDEC to encode an EOF, it is latched

for one CTXCLK cycle while the ENDEC inserts the

generated CRC in the data stream. Then the requested

EOF is encoded. During the encoding of the EOF (that

is, the one that was latched for encoding after the CRC

was inserted) the ENDEC ignores the CTX inputs.

Ordered Set Generator Block

An ordered set is a Fibre Channel word in which the

first byte is a K28.5 special character, followed by valid

data characters. Appendix B contains tables for the

ordered set coding scheme. When CTXC0 is high, the

ordered set generator generates an ordered set from

the most significant byte of the input data, CTXD24..31.

Although only the most significant byte of the input

word is required for generating an ordered set, and

lower order bits CTXD0..23 are “don’t cares” for

encoding the ordered set, parity checking is performed

on the word. Valid word parity must be maintained to

prevent parity errors.

If a parity or CRC error is detected within a frame,

some EOF ordered sets are modified, indicating an

invalid frame. Ordered sets EOFN (EOF Normal) and

EOFT (EOF Terminate) are modified to EOFNI (EOF

Normal–Invalid).

Any ordered set can be sent or received. If the ordered

set desired is not in the predefined set of Fibre Channel

ordered sets, the user can create it using the “special”

ordered set commands (see Appendix B). For instance,

to send “K28.5, D0.0, D31.7, D0.0,” the user would

send 8500FF00h on CTXD0..31 while holding CTXC0

high. When receiving this same “special” ordered set

For additional information and latest specifications, see our website: www.triquint.com

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