Xilinx LogiCORE IP Spartan-6, Getting Started Manual

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32 www.xilinx.com Spartan-6 FPGA GTP Transceiver Wizard v1.8
UG546 (v1.8) December 14, 2010
Chapter 3: Running the Wizard
Table 3-17 details the PRBS settings.
The loss of sync state machine settings are described in Table 3-18 .
Table 3-17: PRBS
Option Description
Use PRBS Detector
Enables the internal Pseudo Random Bitstream Sequence detector (PRBS). This
feature can be used by an application to implement a built-in self-test.
Use RXPRBSERR LOOPBACK
Enables the PRBS loopback on the receiver side. This port allows synchronous and
asynchronous jitter tolerance testing without worrying about data clock domain
crossing.
Use Port TXENPRBSTST
Enables the PRBS Transmission control port. This port is used by the application to
start/stop PRBS generation.
Use Port TXPRBSFORCEERR
Enables the PRBS Force Error control port. This port allows the application to insert
errors into the bit stream.
Table 3-18: Loss of Sync State Machine
Option Description
RXLOSSOFSYNC Optional Port
Two-bit multi-purpose status port. The meaning of the bits is determined
by the settings below.
RXLOSSOFSYNC
Port Meaning
[0] = 8B/10B Error
[1] = CB Sequence
in Elastic Buffer Bit 0 of the RXLOSSOFSYNC status port indicates the detection of an
8B/10B coding error. Bit 1 indicates a Channel Bonding sequence is present
in the receive elastic buffer.
Loss of Sync State
Machine Status
Bit 0 of the RXLOSSOFSYNC status port indicates sync state is active due
to channel bonding or realignment. Bit 1 indicates sync lost due to invalid
characters or reset.
Errors Required to Lose Sync
Integer value between 4 and 512 representing the count of invalid
characters received, above which sync is determined to be lost.
The PCI EXPRESS example uses 128.
Good Bytes to Reduce Error Count by 1
Integer value between 1 and 128 representing the number of consecutive
valid characters needed to cancel out the appearance of one invalid
character.
The PCI EXPRESS example uses 8.