Core Architecture of IGLOO and ProASIC3 Devices
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v1.1
Routing Architecture
The routing structure of low-power flash devices is designed to provide high performance through
a flexible four-level hierarchy of routing resources: ultra-fast local resources; efficient long-line
resources; high-speed, very-long-line resources; and the high-performance VersaNet networks.
The ultra-fast local resources are dedicated lines that allow the output of each VersaTile to connect
to this is that the SET/CLR input of a VersaTile configured as a D-flip-flop is driven only by the
VersaTile global network.
The efficient long-line resources provide routing for longer distances and higher-fanout
connections. These resources vary in length (spanning one, two, or four VersaTiles), run both
drive signals onto the efficient long-line resources, which can access every input of every VersaTile.
Routing software automatically inserts active buffers to limit loading effects.
The high-speed, very-long-line resources, which span the entire device with minimal delay, are used
to route very long or high-fanout nets: length ±12 VersaTiles in the vertical direction and length
in low-power flash devices have been enhanced over those in previous ProASIC families. This
provides a significant performance boost for long-reach signals.
The high-performance VersaNet global networks are low-skew, high-fanout nets that are accessible
from external pins or internal logic. These nets are typically used to distribute clocks, resets, and
other high-fanout nets requiring minimum skew. The VersaNet networks are implemented as clock
trees, and signals can be introduced at any junction. These can be employed hierarchically, with
signals accessing every input of every VersaTile. For more details on VersaNets, refer to Global Note: Input to the core cell for the D-flip-flop set and reset is only available via the VersaNet global
network connection.
Figure 1-7 Ultra-Fast Local Lines Connected to the Eight Nearest Neighbors
L
Inputs
Output
Ultra-Fast Local Lines
(connects a VersaTile to the
adjacent VersaTile, I/O buffer,
or memory block)
L
LL
Long Lines