CYP15G0401TB Cypress Semiconductor Corporation., CYP15G0401TB Datasheet - Page 12

• Manufacturer Part Number: CYP15G0401TB
• Description: Quad Hotlink Ii Transmitter
• Manufacturer: Cypress Semiconductor Corporation.

Document #: 38-02112 Rev. **
Table 5. TX Modes 3 and 6 Encoding
To avoid the possible ambiguities that may arise due to the
uncontrolled arrival of SCSEL relative to the characters in the
alternate channels, SCSEL is often used as static control
input.
Word Sync Sequence
When TXCTx[1:0] = 11, a 16-character sequence of K28.5
characters, known as a Word Sync Sequence, is generated on
the associated channel. This sequence of K28.5 characters
may start with either a positive or negative disparity K28.5 (as
determined by the current running disparity and the 8B/10B
coding rules). The disparity of the second and third K28.5
characters in this sequence are reversed from what normal
8B/10B coding rules would generate. The remaining K28.5
characters in the sequence follow all 8B/10B coding rules. The
disparity of the generated K28.5 characters in this sequence
follow a pattern of either ++––+–+–+–+–+–+– or
––++–+–+–+–+–+–+.
When TXMODE[1] = MID (open, TX modes 3, 4, and 5), the
generation of this character sequence is an atomic (non-inter-
ruptible) operation. Once it has been successfully started, it
cannot be stopped until all sixteen characters have been
generated. The content of the associated Input Registers is
ignored for the duration of this 16-character sequence. At the
end of this sequence, if the TXCTx[1:0] = 11 condition is
sampled again, the sequence restarts and remains uninter-
ruptible for the following fifteen character clocks.
If parity checking is enabled, the character used to start the
Word Sync Sequence must also have correct ODD parity.
Once the sequence is started, parity is not checked on the
following fifteen characters in the Word Sync Sequence.
When TXMODE[1] = HIGH (TX modes 6, 7, and 8), the gener-
ation of the Word Sync Sequence becomes an interruptible
operation. In TX Mode 6, this sequence is started as soon as
the TXCTx[1:0] = 11 condition is detected on a channel. In
order for the sequence to continue on that channel, the
TXCTx[1:0] inputs must be sampled as 00 for the remaining
fifteen characters of the sequence.
If at any time a sample period exists where TXCTx[1:0] ≠ 00,
the Word Sync Sequence is terminated, and a character repre-
senting the associated data and control bits is generated by
the Encoder. This resets the Word Sync Sequence state
machine such that it will start at the beginning of the sequence
at the next occurrence of TXCTx[1:0] = 11.
When parity checking is enabled and TXMODE[1] = HIGH, all
characters (including those in the middle of a Word Sync
Sequence) must have correct parity. The detection of a
character with incorrect parity during a Word Sync Sequence
will interrupt that sequence and force generation of a C0.7
X
X
0
1
X
0
0
1
0 Encoded data character
1 K28.5 fill character
1 Special character code
1 16-character Word Sync Sequence
Characters Generated
PRELIMINARY
SVS character. Any interruption of the Word Sync Sequence
causes the sequence to terminate.
When TXCKSEL = LOW, the Input Registers for all four
transmit
TXCKSEL = HIGH, the Input Registers for all four transmit
channels are clocked with TXCLKA↑. In these clock modes all
four sets of TXCTx[1:0] inputs operate synchronous to the
SCSEL input.
TX Mode 4—Atomic Word Sync and SCSEL Control of Word
Sync Sequence Generation
When configured in TX Mode 4, the SCSEL input is captured
along with the associated TXCTx[1:0] data control inputs.
These bits combine to control the interpretation of the
TXDx[7:0] bits and the characters generated by them. These
bits are interpreted as listed in Table 6.
When TXCKSEL = MID, all transmit channels operate
independently. In this mode, the SCSEL input is sampled only
by TXCLKA↑. When the character accepted in the Channel-A
Input Register has passed any selected validation and is ready
to be passed to the Encoder, the level captured on SCSEL is
passed to the Encoders of the remaining channels during this
same cycle.
Table 6. TX Modes 4 and 7 Encoding
Changing the state of SCSEL will change the relationship of
the characters to other channels. SCSEL should either be
used as a static configuration input, or changed only when the
state of TXCTx[1:0] on the alternate channels are such that
SCSEL is ignored during the change.
TX Mode 4 also supports an Word Sync Sequence. Unlike TX
Mode 3, this sequence starts when SCSEL and TXCTx[0] are
both high. With the exception of the combination of control bits
used to initiate the sequence, the generation and operation of
this Word Sync Sequence is the same as for TX Mode 3.
TX Mode 5—Atomic Word Sync generation without SCSEL.
When configured in TX Mode 5, the SCSEL signal is not used.
The TXCTx[1:0] inputs for each channel control the characters
generated by that channel. The specific characters generated
by these bits are listed in Table 7.
TX Mode 5 also has the capability of generating an atomic
Word Sync Sequence. For the sequence to be started, the
TXCTx[1:0] inputs must both be sampled HIGH. The gener-
ation and operation of this Word Sync Sequence is the same
as TX Mode 3.
Transmit BIST
Each transmit channel contains an internal pattern generator
that can be used to validate both device and link operation.
X
0
0
1
X
X
0
1
channels
0
1
1
1
Encoded data character
K28.5 fill character
Special character code
16-character Word Sync Sequence
are
Characters Generated
clocked
CYP15G0401TB
by
REFCLK.
Page 12 of 30
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