
18
Lucent Technologies Inc.
Data Sheet
June 1999
ORCA Series 2 FPGAs
Programmable Logic Cells
 (continued)
5-4479p2(F)
Figure 20. 3-Statable Bidirectional Buffers
Intra-PLC Routing
The function of the intra-PLC routing resources is to 
connect the PFU’s input and output ports to the routing 
resources used for entry to and exit from the PLC. 
These are nets for providing PFU feedback, turning 
corners, or switching from one type of routing resource 
to another.
PFU Input and Output Ports.
 There are 19 input ports 
to each PFU. The PFU input ports are labeled A[4:0], 
B[4:0], WD[3:0], C0, CK, LSR, CIN, and CE. The six 
output ports are O[4:0] and COUT. These ports corre-
spond to those described in the PFU section.
Switching Lines.
 There are four sets of switching lines 
in each PLC, one in each corner. Each set consists of 
five switching elements, labeled SUL[4:0], SUR[4:0], 
SLL[4:0], and SLR[4:0], for the upper-left, upper-right, 
lower-left, and lower-right sections of the PFUs, 
respectively. The switching lines connect to the PFU 
inputs and outputs as well as the BIDI and BIDIH lines, 
to be described later. They also connect to both the 
horizontal and vertical X1 and X4 lines (inter-PLC rout-
ing resources, described below) in their specific corner. 
One of the four sets of switching lines can be con-
nected to a set of switching lines in each of the four 
adjacent PLCs or PICs. This allows direct routing of up 
to five signals without using inter-PLC routing.
BIDI/BIDIH Lines.
 There are two sets of bidirectional 
lines in the PLC, each set consisting of four bidirec-
tional buffers. They are designated BIDI and BIDIH and 
have similar functionality. The BIDI lines are used in 
conjunction with the XL lines, and the BIDIH lines are 
used in conjunction with the XH lines. Each side of the 
four BIDIs in the PLC is connected to a BIDI line on the 
left (BL[3:0]) and on the right (BR[3:0]). These lines can 
be connected to the XL lines through CIPs, with BL[3:0] 
connected to the vertical XL lines and BR[3:0] con-
nected to the horizontal XL lines. Both BL[3:0] and 
BR[3:0] have CIPs which connect to the switching lines. 
Similarly, each side of the four BIDIHs is connected to a 
BIDIH line: BLH[3:0] on the left and BRH[3:0] on the 
right. These lines can also be connected to the XH 
lines through CIPs, with BLH[3:0] connected to the ver-
tical XH lines and BRH[3:0] connected to the horizontal 
XH lines. Both BLH[3:0] and BRH[3:0] have CIPs which 
connect to the switching lines.
CIPs are also provided to connect the BIDIH and BIDIL 
lines together on each side of the BIDIs. For example, 
BLH3 can connect to BL3, while BRH3 can connect to 
BR3.
RIGHT-LEFT BIDI
LEFT-RIGHT BIDI
UNUSED BIDI
LEFT-RIGHT BIDI
BIDI
CONTROLLER
TRI
RIGHT-LEFT BIDIH
LEFT-RIGHT BIDIH
UNUSED BIDIH
LEFT-RIGHT BIDIH
BIDIH
CONTROLLER