
28
Lucent Technologies Inc.
Data Sheet
ORCA Series 2 FPGAs
June 1999
Programmable Input/Output Cells
(continued)
PIC Routing Resources
The PIC routing is designed to route 4-bit wide buses
efficiently. For example, any four consecutive I/O pads
can have both their input and output signals routed into
one PLC. Using only PIC routing, either the input or
output data can be routed to/from a single PLC from/to
The connections between PLCs and the I/O pad are
provided by two basic types of routing resources.
These are routing resources internal to the PIC and
routing resources used for PIC-PLC connection.
view of these routing resources, respectively.
5-4504(F)
Figure 25. Simplified PIC Routing Diagram
The PIC’s name is represented by a two-letter designa-
tion to indicate on which side of the device it is located
followed by a number to indicate in which row or col-
umn it is located. The first letter, P, designates that the
cell is a PIC and not a PLC. The second letter indicates
the side of the array where the PIC is located. The four
sides are left (L), right (R), top (T), and bottom (B). The
individual I/O pad is indicated by a single letter (either
A, B, C, or D) placed at the end of the PIC name. As an
example, PL10A indicates a pad located on the left
side of the array in the tenth row.
Each PIC has four pads and each pad can be config-
ured as an input, an output (3-statable), a direct output,
or a bidirectional I/O. When the pads are used as
inputs, the external signals are provided to the internal
circuitry at IN[3:0]. When the pads are used to provide
direct inputs to the latches/FFs, they are connected
through DIN[3:0]. When the pads are used as outputs,
the internal signals connect to the pads through
OUT[3:0]. When the pads are used as direct outputs,
the output from the latches/flip-flops in the PLCs to the
PIC is designated DOUT[3:0]. When the outputs are
3-statable, the 3-state enable signals are TS[3:0].
Routing Resources Internal to the PIC
For inter-PIC routing, the PIC contains 14 lines used to
route signals around the perimeter of the FPGA.
Figure25 shows these lines running vertically for a PIC
located on the left side.
Figure 26 shows the lines run-
FPGA.
PXL Lines. Each PIC has two PXL lines, labeled
PXL[1:0]. Like the XL lines of the PLC, the PXL lines
span the entire edge of the FPGA.
PXH Lines. Each PIC has four PXH lines, labeled
span half the edge of the FPGA.
PX2 Lines. There are four PX2 lines in each PIC,
labeled PX2[3:0]. The PX2 lines pass through two adja-
cent PICs before being broken. These are used to
route nets around the perimeter equally a distance of
two or more PICs.
PX1 Lines. Each PIC has four PX1 lines, labeled
PX1[3:0]. The PX1 lines are one PIC long and are
extended to adjacent PICs by enabling CIPs.
PAD D
I/O3
4
PXL
2
CK
2
PIC
SWITCHING
MATRIX
PAD C
I/O2
4
PAD B
I/O1
4
PAD A
I/O0
4
PXH
4
PX2
4
PX1
4
PLC X4
4
PLC X1
4
PLC PSW
5
PLC DOUT
4
PLC XL
4
PLC XH
4
PLC X1
4
PLC X4
4
PLC DIN
4
PXL
2
PXH
4
PX2
4
PX1
4