Configurable Loss-Of-Sync State Machine; Overview; Ports And Attributes - Xilinx Virtex-5 RocketIO GTP User Manual

R

Configurable Loss-of-Sync State Machine

Overview

Several 8B/10B protocols make use of a standard Loss-of-Sync (LOS) state machine to
detect when the channel is malfunctioning. Each GTP receiver includes a LOS state
machine that can be activated for protocols requiring it. When the state machine is not
used, the LOS state machine's ports can be re-used to monitor the condition of incoming
data.

Ports and Attributes

Table 7-22
Table 7-22: RX Loss-of-Sync State Machine Ports
Port
RXLOSSOFSYNC0[1:0]
RXLOSSOFSYNC1[1:0]
Table 7-23
Table 7-23: RX Loss-of-Sync State Machine Attributes
Attribute
RX_LOS_INVALID_INCR_0
RX_LOS_INVALID_INCR_1
RX_LOS_THRESHOLD_0
RX_LOS_THRESHOLD_1
RX_LOSS_OF_SYNC_FSM_0
RX_LOSS_OF_SYNC_FSM_1
Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
defines the RX loss-of-sync state machine ports.
Dir Clock Domain
FPGA Status related to byte stream synchronization. Meaning
depends on the state of the RX_LOSS_OF_SYNC_FSM attribute.
If RX_LOSS_OF_SYNC_FSM = TRUE, this output reflects the state of
an internal Loss-of-Sync FSM as follows:
[1] = 1: Sync lost due to either sequence of invalid characters or
reset
Out RXUSRCLK2 [0] = 1: In the resync state due to a channel bonding sequence or
realignment
If RX_LOSS_OF_SYNC_FSM = FALSE, this output presents the
following information about incoming data:
[1] = 1: Received data is not an 8B/10B character or has a disparity
error
[0] = 1: Channel bonding sequence detected in data
defines the RX loss-of-sync state machine attributes.
Defines the number of valid characters required to cancel out the appearance of one
invalid character for the purpose of loss-of-sync determination. Valid settings are
1, 2, 4, 8, 16, 32, 64, and 128.
When divided by RX_LOS_INVALID_INCR_(0/1), defines the number of invalid
characters required to cause an FSM transition to the sync lost state. Valid settings
are 4, 8, 16, 32, 64, 128, 256, and 512.
RX_LOSS_OF_SYNC_FSM defines the behavior of the RXLOSSOFSYNC[1:0]
outputs.
FALSE: RXLOSSOFSYNC[1] goes High when invalid data (not in table or
disparity error) is found in 8B/10B decoding. RXLOSSOFSYNC[0] goes High
when a channel bonding sequence has been written into the elastic buffer.
TRUE (default): Loss of sync FSM is in operation and its state is reflected on
RXLOSSOFSYNC[1].
www.xilinx.com
Configurable Loss-of-Sync State Machine
Description
Description
155