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Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
Chapter 7:
GTP Receiver (RX)
R
Configurable Clock Correction
Overview
The RX elastic buffer has an additional benefit: it can tolerate frequency differences
between the XCLK and RXUSRCLK domains by performing clock correction. Clock
correction actively prevents the RX elastic buffer from getting too full or too empty by
deleting or replicating special idle characters in the data stream.
shows a conceptual view of clock correction.
Clock correction should be used whenever there is a frequency difference between XCLK
and RXUSRCLK. It can be avoided by using the same frequency source for TX and RX, or
by using the recovered clock to drive RXUSRCLK. The
“Configurable RX Elastic Buffer
section has more details about the steps required if clock correction
is not used.
Figure 7-25:
Clock Correction
W
rite
XCLK
“Nominal” Condition: Buffer Half Full
Buffer Less Than Half Full (Emptyin
g
)
Buffer More Than Half Full (Fillin
g
Up)
Read
RXUSRCLK
W
rite
Read
Repeata
b
le Se
qu
ence
W
rite
UG196_c7_22_092606
Repeata
b
le Se
qu
ence
Read
Содержание Virtex-5 RocketIO GTP
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Страница 88: ...88 www xilinx com Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007 Chapter 5 Tile Features R...
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Страница 186: ...186 www xilinx com Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007 Chapter 7 GTP Receiver RX R...
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Страница 222: ...222 www xilinx com Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007 Section 2 Board Level Design R...
Страница 256: ...256 www xilinx com Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007 Section 3 Appendices R...
Страница 312: ...312 www xilinx com Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007 Appendix E Low Latency Design R...