2–174
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Native Modes
Figure 2–125. IEEE 802.3ae PCS Deskew State Diagram
Clock Compensation ||R|| (Rate Matcher)
XAUI can operate in multi-crystal environments, which can tolerate
frequency variations of ±100 PPM between crystals. Stratix II GX devices
contain embedded circuitry to perform clock rate compensation, which is
achieved by inserting or removing the PCS SKIP code group (/R/) from
the IPG or idle stream. This process is called rate matching and is
sometimes referred to as clock rate compensation.
The rate matcher in Stratix II GX devices consists of a 12-word-deep FIFO
buffer along with control logic that you can configure to support XAUI,
GIGE, or custom modes. In XAUI mode the controller begins to write data
into the FIFO buffer whenever the
rx_channelaligned
signal is
asserted. Within the control logic there is a FIFO counter that keeps track
of the read and write executions. When the FIFO counter reaches a value
of greater than nine, the receivers delete the /R/ code-group
reset +
(sync_status=FAIL * SUDI)
sync_status OK * SUDI(![/||A||/])
!deskew_error
* SUDI(![/||A||/])
!deskew_error
* SUDI(![/||A||/])
!deskew_error
* SUDI(![/||A||/])
SUDI(![/||A||/])
SUDI(![/||A||/])
SUDI(![/||A||/])
deskew_error * SUDI
deskew_error * SUDI
deskew_error * SUDI
deskew_error * SUDI
deskew_error * SUDI
deskew_error * SUDI
deskew_error * SUDI
SUDI(![/||A||/])
LOSS_OF_ALIGNMENT
align_status
⇐
FAIL
enable_deskew
⇐
TRUE
AUDI
ALIGN_DETECT_1
enable_deskew
⇐
FALSE
AUDI
ALIGN_DETECT_2
AUDI
ALIGN_DETECT_3
AUDI
3
!deskew_error
* SUDI(![/||A||/])
!deskew_error
* SUDI(![/||A||/])
!deskew_error
* SUDI(![/||A||/])
SUDI(![/||A||/])
ALIGN_ACQUIRED_1
enable_deskew
⇐
FALSE
AUDI
ALIGN_ACQUIRED_2
AUDI
ALIGN_ACQUIRED_3
AUDI
1
2
3
!deskew_error
* SUDI(![/||A||/])
SUDI(![/||A||/])
ALIGN_ACQUIRED_4
AUDI
2
SUDI(![/||A||/])
1
SUDI(![/||A||/])
Содержание Stratix II GX
Страница 640: ...4 244 Altera Corporation Stratix II GX Device Handbook Volume 2 October 2007 Document Revision History ...
Страница 642: ...4 246 Altera Corporation Stratix II GX Device Handbook Volume 2 October 2007 Document Revision History ...
Страница 672: ...6 14 Altera Corporation Stratix II GX Device Handbook Volume 2 October 2007 Document Revision History ...