Cyclone Device Handbook, Volume 1
performance and flexibility. Each LE can drive 30 other LEs through fast
local and direct link interconnects. Figure 2–3 shows the direct link
connection.
Figure 2–3. Direct Link Connection
Direct link interconnect from
left LAB, M4K memory
block, PLL, or IOE output
Direct link interconnect from
right LAB, M4K memory
block, PLL, 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 will also use 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 will turn off
the LAB-wide clock.
Each LAB can use two asynchronous clear signals and an asynchronous
load/preset signal. The asynchronous load acts as a preset when the
asynchronous load data input is tied high.
2–4
Preliminary
Altera Corporation
January 2007
ALTERA [ ALTERA CORPORATION ]
