Cyclone FPGA Family Data Sheet
Preliminary Information
The R4 interconnects span four LABs, or two LABs and one M4K RAM
block. These resources are used for fast row connections in a four-LAB
region. Every LAB has its own set of R4 interconnects to drive either left
or right. Figure 9 shows R4 interconnect connections from an LAB. R4
interconnects can drive and be driven by M4K memory blocks, PLLs, and
row IOEs. For LAB interfacing, a primary LAB or LAB neighbor can drive
a given R4 interconnect. For R4 interconnects that drive to the right, the
primary LAB and right neighbor can drive on to the interconnect. For R4
interconnects that drive to the left, the primary LAB and its left neighbor
can drive on to the interconnect. R4 interconnects can drive other R4
interconnects to extend the range of LABs they can drive. R4 interconnects
can also drive C4 interconnects for connections from one row to another.
Figure 9. R4 Interconnect Connections
Adjacent LAB can
Drive onto Another
LAB's R4 Interconnect
R4 Interconnect
Driving Right
C4 Column Interconnects (1)
R4 Interconnect
Driving Left
LAB
Neighbor
Primary
LAB (2)
LAB
Neighbor
Notes to Figure 9:
(1) C4 interconnects can drive R4 interconnects.
(2) This pattern is repeated for every LAB in the LAB row.
The column interconnect operates similarly to the row interconnect. Each
column of LABs is served by a dedicated column interconnect, which
vertically routes signals to and from LABs, M4K memory blocks, and row
and column IOEs. These column resources include:
■
■
■
LUT chain interconnects within an LAB
Register chain interconnects within an LAB
C4 interconnects traversing a distance of four blocks in an up and
down direction
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