R
Virtex™-II Platform FPGAs: Detailed Description
Place-and-route software takes advantage of this regular
array to deliver optimum system performance and fast com-
pile times. The segmented routing resources are essential
to guarantee IP cores portability and to efficiently handle an
incremental design flow that is based on modular imple-
mentations. Total design time is reduced due to fewer and
shorter design iterations.
Hierarchical Routing Resources
Most Virtex-II signals are routed using the global routing
resources, which are located in horizontal and vertical rout-
ing channels between each switch matrix.
As shown in Figure 49, Virtex-II has fully buffered program-
mable interconnections, with a number of resources
counted between any two adjacent switch matrix rows or
columns. Fanout has minimal impact on the performance of
each net.
24 Horizontal Long Lines
24 Vertical Long Lines
120 Horizontal Hex Lines
120 Vertical Hex Lines
40 Horizontal Double Lines
40 Vertical Double Lines
16 Direct Connections
(total in all four directions)
8 Fast Connects
DS031_60_110200
Figure 49: Hierarchical Routing Resources
•
•
The long lines are bidirectional wires that distribute
signals across the device. Vertical and horizontal long
lines span the full height and width of the device.
•
The fast connect lines are the internal CLB local
interconnections from LUT outputs to LUT inputs.
Dedicated Routing
In addition to the global and local routing resources, dedi-
cated signals are available.
The hex lines route signals to every third or sixth block
away in all four directions. Organized in a staggered
pattern, hex lines can only be driven from one end.
Hex-line signals can be accessed either at the endpoints
or at the midpoint (three blocks from the source).
•
There are eight global clock nets per quadrant (see
Global Clock Multiplexer Buffers).
•
•
The double lines route signals to every first or second
block away in all four directions. Organized in a
staggered pattern, double lines can be driven only at
their endpoints. Double-line signals can be accessed
either at the endpoints or at the midpoint (one block
from the source).
•
Horizontal routing resources are provided for on-chip
3-state busses. Four partitionable bus lines are
provided per CLB row, permitting multiple busses
within a row. (See 3-State Buffers.)
•
Two dedicated carry-chain resources per slice column
(two per CLB column) propagate carry-chain MUXCY
output signals vertically to the adjacent slice. (See
CLB/Slice Configurations.)
The direct connect lines route signals to neighboring
blocks: vertically, horizontally, and diagonally.
DS031-2 (v3.0) August 1, 2003
Product Specification
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