Ports And Attributes; Rxclkcorcnt; Rx_Los_Invalid_Incr; Rx_Los_Threshold - Xilinx RocketIO User Manual

Synchronization Logic
RX_LOSS_OF_SYNC FSM does this. It can be programmed to lose sync after a specified number
of invalid data characters are received.

Ports and Attributes

RXCLKCORCNT

Clock correction count (RXCLKCORCNT) is a three-bit signal. It signals if clock correction has
occurred, and whether the elastic buffer realigned the data by skipping or repeating data in the
buffer. It also signals if channel bonding has occurred.
RXCLKCORCNT.
Table 2-17: RXCLKCORCNT Definition

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.
RocketIO™ Transceiver User Guide
UG024 (v2.3.2) June 24, 2004
RXCLKCORCNT[2:0]
000
001
010
011
100
101
110
111
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Table 2-17
Significance
No channel bonding or clock correction occurred for current
RXDATA
Elastic buffer skipped one clock correction sequence for current
RXDATA
Elastic buffer skipped two clock correction sequence for current
RXDATA
Elastic buffer skipped three clock correction sequence for current
RXDATA
Elastic buffer skipped four clock correction sequence for current
RXDATA
Elastic buffer executed channel bonding for current RXDATA
Elastic buffer repeated two clock correction sequences for current
RXDATA
Elastic buffer repeated one clock correction sequences for current
RXDATA
defines the eight binary states of
R
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