Virtex-5 RocketIO GTP Transceiver User Guide
47
UG196 (v1.3) May 25, 2007
Examples
R
The period of the PLL can be calculated using
.
Equation 3-2
Equation 3-3
The terms used in
are defined as follows:
•
REFCLK is the speed of the clock tied to the CLKIN input of the GTP_DUAL tile in
MHz.
•
PLL_DIVSEL_REF is an attribute that defines the dividing factor of the reference clock
divider of the shared PLL.
•
PLL_DIVSEL_FB is an attribute that defines the dividing factor of the feedback
divider (which acts like a multiplication factor) of the shared PLL
.
•
DIV = 5 when INTDATAWIDTH =
1
(10-bit mode)
•
DIV = 4 when INTDATAWIDTH =
0
(8-bit mode)
PCI Express Example
To calculate PLL SPEED and SIM_PLL_PERDIV2 for the PCI Express example, the
following values are assigned:
•
REFCLK = 100 MHz
•
PLL_DIVSEL_REF = 2
•
DIV = 5
•
PLL_DIVSEL_FB = 5
Using
, PLL SPEED is 1.25 GHz, meaning that the period is 800 ps. Using
, SIM_PLL_PERDIV2 is 800 divided by 2 equal to 400 decimal or
190
hexadecimal.
Gigabit Ethernet Example
To calculate PLL SPEED and SIM_PLL_PERDIV2 for the Gigabit Ethernet example, the
following values are assigned:
•
REFCLK = 125 MHz
•
PLL_DIVSEL_REF = 1
•
DIV = 5
•
PLL_DIVSEL_FB = 2
Using
, PLL SPEED is 1.25 GHz, meaning that the period is 800 ps. Using
, SIM_PLL_PERDIV2 is 800 divided by 2 or 400 decimal (
190
hexadecimal).
XAUI Example
To calculate PLL SPEED and SIM_PLL_PERDIV2 for the XAUI example, the following
values are assigned:
•
REFCLK = 156.25 MHz
•
PLL_DIVSEL_REF = 1
•
DIV = 5
•
PLL_DIVSEL_FB = 2
PLL SPEED
REFCLK
PLL_DIV_REF
---------------------------------------
⎝
⎠
⎛
⎞
DIV
×
PLL_DIVSEL_FB
(
)
×
=
SIM_PLL_PERDIV2
1 PLL SPEED
⁄
(
)
2
-------------------------------------------
=
Содержание Virtex-5 RocketIO GTP
Страница 1: ...R Virtex 5 RocketIO GTP Transceiver User Guide UG196 v1 3 May 25 2007...
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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...
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...