62
Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
Chapter 5:
Tile Features
R
Description
The first step to using the GTP_DUAL tile is to set the output of the shared PLL (PLL clock)
to a rate that can be used by each GTP transceiver to generate an appropriate serial line rate
and corresponding parallel clock rate. Both GTP TX and RX blocks are equipped with an
independent divider that can divide the PLL clock by a factor of 1, 2, or 4. This divider
allows the TX and RX blocks of each GTP transceiver to run at different rates, related by an
integer multiple.
The PLL clock rate must be set to one-half the required line rate before the independent
dividers. For example, if an RX line rate of 2.5 Gb/s is desired in GTP0, and the
independent divider in the GTP RX block is set to 1, the PLL clock should be set to
1.25 GHz.
The shared PMA PLL has a nominal operation range. The
Virtex-5 Data Sheet
specifies the
operating range of the shared PLL including the marginal conditions. Set the PLL clock
must be within this operating range.
shows how to set the PLL clock based on
CLKIN (the reference clock), PLL_DIVSEL_FB, PLL_DIVSEL_REF, and INTDATAWIDTH.
PLL_DIVSEL_FB and PLL_DIVSEL_REF control dividers inside the PLL.
INTDATAWIDTH controls the internal parallel data width of the entire GTP_DUAL tile.
shows how to set the rate of the PLL clock.
Equation 5-1
The following conditions apply to
:
•
PLL_DIVSEL_REF = [1, 2]
•
PLL_DIVSEL_FB = [1, 2, 3, 4, 5]; where 3 and 5 cannot be used when
INTDATAWIDTH = 0.
When PLL_DIVSEL_FB = 1, set PCS_COM_CFG to 28’h1680A07, otherwise set to
28’h1680A0E (default)
•
If INTDATAWIDTH = 1, DIV = 5, otherwise DIV = 4
•
The PLL clock frequency range is as specified in the
Virtex-5 Data Sheet
•
The smallest possible divider values must be selected
The programmable dividers allow support for various standards.
shows a conceptual view of the shared PLL from which the PLL clock is
generated.
f
PLL
Clock
f
CLKIN
PLL_DIVSEL_FB
DIV
×
PLL
_
DIVSEL
_
REF
----------------------------------------------------------------
×
=
Содержание Virtex-5 RocketIO GTP
Страница 1: ...R Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007...
Страница 4: ...Virtex 5 RocketIO GTP Transceiver User Guide www xilinx com UG196 v1 3 May 25 2007...
Страница 88: ...88 www xilinx com Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007 Chapter 5 Tile Features R...
Страница 122: ...122 www xilinx com Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007 Chapter 6 GTP Transmitter TX R...
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...
Страница 200: ...200 www xilinx com Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007 Chapter 9 Loopback R...
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...