Lab Interconnects; Lab Control Signals - Altera Cyclone IV Device Handbook

2–6

LAB Interconnects

The LAB local interconnect is driven by column and row interconnects and LE
outputs in the same LAB. Neighboring LABs, phase-locked loops (PLLs), M9K RAM
blocks, and embedded multipliers from the left and right can also drive the local
interconnect of a LAB 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 up to 48 LEs through fast local and
direct link interconnects.
Figure 2–5
Figure 2–5. Cyclone IV Device Direct Link Connection

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
■ One synchronous clear
■ One synchronous load
You can use up to eight control signals at a time. Register packing and synchronous
load cannot be used simultaneously.
Each LAB can have up to four non-global control signals. You can use additional LAB
control signals as long as they are global signals.
Synchronous clear and load signals are useful for implementing counters and other
functions. The synchronous clear and synchronous load signals are LAB-wide signals
that affect all registers in the LAB.
Cyclone IV Device Handbook,
Volume 1
Chapter 2: Logic Elements and Logic Array Blocks in Cyclone IV Devices
shows the direct link connection.
Direct link interconnect from
left LAB, M9K memory
block, embedded multiplier,
PLL, or IOE output
Direct link
interconnect
to left
Local
Interconnect
LAB Control Signals
Direct link interconnect from
right LAB, M9K memory
block, embedded multiplier,
PLL, or IOE output
Direct link
interconnect
to right
LAB
November 2009 Altera Corporation