104
Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
Chapter 6:
GTP Transmitter (TX)
R
Ports and Attributes
defines the signals comprising the TX buffering and phase-alignment ports.
Table 6-7:
TX Buffering and Phase-Alignment Ports
Port
Dir
Clock Domain
Description
PLLLKDET
Out
Async
This port indicates that the VCO rate is within acceptable
tolerances of the desired rate when High. Neither GTP transceiver
in the tile operates reliably until this condition is met.
REFCLKOUT
Out
N/A
The REFCLKOUT port from each GTP_DUAL provides direct
access to the reference clock provided to the shared PLL (CLKIN).
It can be routed for use in the FPGA logic.
TXBUFSTATUS0[1:0]
TXBUFSTATUS1[1:0]
Out
TXUSRCLK2
TX buffer status.
TXBUFSTATUS[1]: TX buffer overflow or underflow
1
: FIFO has overflowed or underflowed
0
: No overflow/underflow error
TXBUFSTATUS[0]:
TX buffer
fullness
1
: FIFO is at least half full
0
: FIFO is less than half full
If TXBUFSTATUS[1] becomes set, it remains set until TXRESET is
asserted.
TXENPMAPHASEALIGN
In
Async
When activated, both GTP transmitters in a GTP_DUAL tile can
align their XCLKs with their TXUSRCLKs, allowing their TX
buffers to be bypassed. This also allows the XCLKs in multiple GTP
transmitters to be synchronized to reduce TX skew between them.
TXOUTCLK0
TXOUTCLK1
Out
N/A
This port provides a parallel clock generated by the GTP
transceiver. This clock can be used to drive TXUSRCLK for one or
more GTP transceivers. The rate of the clock depends on
INTDATAWIDTH:
•
INTDATAWIDTH = 0:
FTXOUTCLK = Line Rate/8
•
INTDATAWIDTH = 1:
FTXOUTCLK = Line Rate/10
Note:
When INTDATAWIDTH = 1, the duty cycle is 60/40 instead of
50/50. TXOUTCLK cannot drive TXUSRCLK when the TX phase-
alignment circuit is used.
TXPMASETPHASE
In
Async
When activated, TXPMASETPHASE aligns XCLK with
TXUSRCLK for both GTP transmitters in the GTP_DUAL tile.
TXUSRCLK0
TXUSRCLK1
In
N/A
Use this port to provide a clock for the internal TX PCS datapath.
This clock must always be provided. Its rate depends on
INTDATAWIDTH:
•
INTDATAWIDTH = 0:
FTXUSRCLK = Line Rate/8
•
INTDATAWIDTH = 1:
FTXUSRCLK = Line Rate/10
Содержание Virtex-5 RocketIO GTP
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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...