Logic Array Blocks
M4K RAM blocks, or DSP blocks from the left and right can also drive an
LAB’s local interconnect through the direct link connection. The direct
link connection feature minimizes the use of row and column
interconnects, providing higher performance and flexibility. Each LE can
drive 30 other LEs through fast local and direct link interconnects.
Figure 4–2 shows the direct link connection.
Figure 4–2. Direct Link Connection
Direct link interconnect from
left LAB, TriMatrix memory
block, DSP block, or IOE output
Direct link interconnect from
right LAB, TriMatrix memory
block, DSP block, or IOE output
Direct link
interconnect
to right
Direct link
interconnect
to left
Local
Interconnect
LAB
LAB Control Signals
Each LAB contains dedicated logic for driving control signals to its LEs.
The control signals include two clocks, two clock enables, two
asynchronous clears, synchronous clear, asynchronous preset/load,
synchronous load, and add/subtract control signals. This gives a
maximum of 10 control signals at a time. Although synchronous load and
clear signals are generally used when implementing counters, they can
also be used with other functions.
Each LAB can use two clocks and two clock enable signals. Each LAB’s
clock and clock enable signals are linked. For example, any LE in a
particular LAB using the labclk1signal also uses labclkena1. If the
LAB uses both the rising and falling edges of a clock, it also uses both
LAB-wide clock signals. De-asserting the clock enable signal turns off the
LAB-wide clock.
4–2
Stratix GX Device Handbook, Volume 1
Altera Corporation
February 2005
ALTERA [ ALTERA CORPORATION ]
