Data Sheet
June 1999
ORCA Series 3C and 3T FPGAs
ally labeled for the upper-left, upper-right, lower-left,
and lower-right sections of the PFUs, respectively. The
xSW routing segments connect to the PFU inputs and
outputs as well as the BIDI routing segments, to be
described later. They also connect to both the horizon-
tal and vertical x1 and x5 routing segments (inter-PLC
routing resources, described later) in their specific cor-
ner. xSW segments can be used for fast connections
between adjacent PLCs or PICs without requiring the
use of inter-PLC routing resources. This capability not
only increases signal speed on adjacent PLC routing,
but also reduces routing congestion on the principal
inter-PLC routing resources. The SLL and SUR seg-
ments combine to provide connectivity to the PLCs to
the left and right of the current PLC; the SLR and SUL
segments combine to provide connectivity to the PLCs
above and below the current PLC.
Programmable Logic Cells (continued)
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. This
routing provides PFU feedback, corner turning, or
switching from one type of routing resource to another.
Flexible Input Structure (FINS)
The flexible input switching structure (FINS) in each
PLC of the ORCA Series 3 provides for the flexibility of
a crossbar switch from the routing resources to the
PFU inputs while taking advantage of the routability of
shared inputs. Connectivity between the PLC routing
resources and the PFU inputs is provided in two
stages. The primary FINS switch has 50 inputs that
connect the PLC routing to the 35 inputs on the sec-
ondary switch. The outputs of the second switch con-
nect to the 50 PFU inputs. The switches are
Fast routes on switching segments to diagonally adja-
cent PLCs/PICs are possible using the BIDI routing
segments (discussed below) and the SLL and SLR
switching segments. The BR BIDI routing segments
combine with the SUL switching segments of the PLC
below and to the right of the current PLC to connect to
that PLC. The BL BIDI routing segments combine with
the SLL switching segments of the PLC above and to
the right of the current PLC to connect to that PLC.
These fast diagonal connections provide a great
amount of flexibility in routing congested areas of logic
and in shifting data on a per-PLC basis such as per-
forming implicit multiplications/divisions in routing
between functional logic elements.
implemented to provide connectivity for bused signals
and individual connections.
PFU Output Switching
The PFU outputs are switched onto PLC routing
resources via the PFU output multiplexer (OMUX). The
PFU output switching segments from the output multi-
plexer provide ten connections to the PLC routing out
of 18 possible PFU outputs (F[7:0], Q[7:0], DOUT,
REGCOUT). These output switching segments con-
nect segment for segment to the SUR, SUL, SLR, and
SLL switching segments described below (e.g., O4
connects only to SUR4, not SUR5). The output switch-
ing segments also feed directly into the SLIC on a seg-
ment-by-segment basis. This connectivity is also
described below.
Switching routing segments are also the chief means
by which signals are transferred between the inter-PLC
routing resources and the PFU. Each set of switching
segments has connectivity to the x1 routing segments,
and there is varying connectivity to the x5, xH, and xL
inter-PLC routing segments. Detailed information on
switching segment/inter-PLC routing connectivity is
provided later in this section in the Inter-PLC Routing
Resources subsection.
Switching Routing Segments (xSW)
There are four sets of switching routing segments in
each PLC. Each set consists of ten switching elements:
SUL[9:0], SUR[9:0], SLL[9:0], and SLR[9:0], tradition-
Lucent Technologies Inc.
29
AGERE [ AGERE SYSTEMS ]
