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Virtex-5 FPGA ML561 User Guide www.xilinx.com 29
UG199 (v1.2) April 19, 2008
External Interfaces
R
33 MHz System ACE Controller Oscillator
A single-ended 33 MHz Epson SG-8002CA oscillator is provided on the board (Y3) as a
clock source for System ACE functionality.
GTP Clocks
Two SMA connectors are provided for the input of an off-board differential clock (J16 and
J21). A differential clock buffer (ICS8543BG) is used on the board (U20) to generate four
LVDS copies of the differential clock signal, two for FPGA #1, one for FPGA #2, and one for
FPGA #3.
A header is used to select between a clock forwarded by the GTP or from the external clock
source used to provide a clock to the FPGA logic.
User I/Os
This subsection describes the devices that connect to the User I/Os of the ML561 board.
These I/Os are provided to ease hardware development using the ML561.
General-Purpose Headers
The 16-pin test headers are surface mounted, one per FPGA. Of the two bytes of test
signals, traces are matched for signals within a byte.
DIP Switch
One four-position DIP switch per FPGA (for a total of three) is available to externally pull
up or pull down a signal on the FPGA. This can be used to manually set values used by the
design running on the FPGA.
Table 3-12: FPGA Slow Clock Sources
FPGA Signal Name
1 FPGA1_LOW_FREQ_CLK
2 FPGA2_LOW_FREQ_CLK
3 FPGA3_LOW_FREQ_CLK
Table 3-13: Test Headers
Header Signal Description Location Header Pin #
FPGA1_TEST_HDR_BY0_B[0:7] P20 (TEST1) Odd pins: 1, 3, 5, 7, 9, 11, 13, 15
FPGA1_TEST_HDR_BY1_B[0:7] P20 (TEST1) Even pins: 2, 4, 6, 8, 10, 12, 14, 16
FPGA2_TEST_HDR_BY0_B[0:7] P21 (TEST2) Odd pins: 1, 3, 5, 7, 9, 11, 13, 15
FPGA2_TEST_HDR_BY1_B[0:7] P21 (TEST2) Even pins: 2, 4, 6, 8, 10, 12, 14, 16
FPGA3_TEST_HDR_BY0_B[0:7] P93 (TEST3) Odd pins: 1, 3, 5, 7, 9, 11, 13, 15
FPGA3_TEST_HDR_BY1_B[0:7] P93 (TEST3) Even pins: 2, 4, 6, 8, 10, 12, 14, 16