Rx_Los_Invalid_Incr Rx_Los_Threshold - Xilinx RocketIO User Manual

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Synchronization Logic
Table 2-17: RXCLKCORCNT Definition (Continued)
RX_LOS_INVALID_INCR,
RX_LOS_THRESHOLD
These two signals determine how fast an invalid character advances the RXLOSSOFSYNC
FSM counter before loss of sync is considered to have occurred. RX_LOS_INVALID_INCR
determines how quickly the occurrence of invalid characters is "forgotten" in the presence
of subsequent valid characters. For example, RX_LOS_INVALID_INCR = 4 means that
four consecutive valid characters after an invalid character will reset the counter.
RX_LOS_THRESHOLD determines when the counter has reached the point where the link
is considered to be "out of sync."
RX_LOSS_OF_SYNC_FSM
The transceiver's FSM is driven by RXRECCLK and uses status from the data stream prior
to the elastic buffer. This is intended to give early warning of possible problems well before
corrupt data appears on RXDATA. RX_LOSS_OF_SYNC_FSM, a TRUE/FALSE attribute,
indicates what the output of the RXLOSSOFSYNC port (see below) means.
Note:
The values are undefined if the PLL is not locked.
RXLOSSOFSYNC
If RX_LOSS_OF_SYNC_FSM = FALSE, then RXLOSSOFSYNC[1] High indicates that the
transceiver has received an invalid character, and RXLOSSOFSYNC[0] High indicates that
a channel-bonding sequence has been recognized.
If RX_LOSS_OF_SYNC_FSM = TRUE, then the two bits of RXLOSSOFSYNC reflect the
state of the RXLOSSOFSYNC FSM. The state machine diagram in
subsections following describe the three states of the RXLOSSOFSYNC FSM
RocketIO™ Transceiver User Guide
UG024 (v3.0) February 22, 2007
RXCLKCORCNT[2:0]
Elastic buffer skipped four clock correction sequence for
100
current RXDATA
Elastic buffer executed channel bonding for current RXDATA
101
Elastic buffer repeated two clock correction sequences for
110
current RXDATA
Elastic buffer repeated one clock correction sequences for
111
current RXDATA
RX_LOSS_OF_SYNC_FSM only indicates valid data. It is assumed that the PLL is locked.
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Significance
Figure 2-21 and the three
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