Chan_Bond_Wait = 8; Chan_Bond_Offset; Chan_Bond_Limit; Chbonddone - Xilinx RocketIO User Manual

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These CBSs should be unique from other delimiters in the data stream, including Clock Correction
Sequence, IDLE, Start of Frame, and End of Frame. As with clock correction, there are multiple
sequences that can be defined (GT_CUSTOM only). The primary CBS is defined by
CHAN_BOND_SEQ_1_*, where * = a number from 1 to 4.
If a second CBS is required, CHAN_BOND_SEQ_2_USE must be set to TRUE, and
CHAN_BOND_SEQ_2_* used to define the second CBS; otherwise, CHAN_BOND_SEQ_2_USE
should be left at its default value, FALSE. See
page
Finally, CHAN_BOND_SEQ_LEN defines the CBS length as 1 to 4 bytes. When set to anything
other than 4, only those sequences are defined. For example, if CHAN_BOND_SEQ_LEN is set to
2, only CHAN_BOND_SEQ_1_1 and CHAN_BOND_SEQ_1_2 need to be defined.
CHAN_BOND_WAIT,

CHAN_BOND_OFFSET,

CHAN_BOND_LIMIT

These three attributes define how the Master performs channel alignment of the RX buffer. The
typical values of these attributes are:

CHAN_BOND_WAIT = 8

CHAN_BOND_WAIT roughly defines the maximum number of bytes by which the Slave can lag
the Master. Due to internal pipelining, the equation should be (CHAN_BOND_WAIT - 3.5) bytes =
# of bytes Slave may lag Master. For example, if CHAN_BOND_WAIT = 8, the Slave may lag the
Master by 4.5 bytes. While this type of lag is equivalent to approximately 14 ns at 3.125 Gb/s, it is
recommended that channel links be matched as closely as possible.
The equation that produces this maximum lag time result is
or, for schemes that do not use 8B/10B encoding,
In the example above, 1/3.125 Gb/s
The recommended setting of 8 is set for protocols such as Infiniband and XAUI, which can repeat
the CBS every 16 and 17 bytes respectively. However, CHAN_BOND_WAIT can grow accordingly
if CBSs are spaced farther apart.
CHAN_BOND_OFFSET = CHAN_BOND_WAIT
CHAN_BOND_OFFSET measures the number of bytes past the beginning of the channel bonding
sequence. However, this value must always equal CHAN_BOND_WAIT.
CHAN_BOND_LIMIT = 2X CHAN_BOND_WAIT
CHAN_BOND_LIMIT defines the expiration time after which the Slave will invalidate the most
recently seen CBS location in the RX buffer. For proper alignment, this value must always be set to
two times CHAN_BOND_WAIT.

CHBONDDONE

This port indicates when a channel alignment has occurred in the MGT. When it is asserted,
RXDATA is valid after RXCLKCORCNT goes to a 101.
82
66, for the bit breakdown of the sequence definition.
lag time [ns] = (1 / serial speed [Gb/s] )
(1 / serial speed [Gb/s] )
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Chapter 2: Digital Design Considerations
"Receiving Vitesse Channel Bonding Sequence,"
number of lag bytes
•
number of 10-bit lag characters
•
4.5 bytes 10 bits/byte = 14.4 ns.
• •
RocketIO™ Transceiver User Guide
10 bits/byte
•
10 bits/character
•
UG024 (v2.3.2) June 24, 2004