Accelerator Series FPGAs – ACT 3 Family
R e visio n 3
2 -3
The S-module contains a full implementation of the C-module plus a clearable sequential element that
can either implement a latch or flip-flop function. The S-module can therefore implement any function
implemented by the C-module. This allows complex combinatorial-sequential functions to be
implemented with no delay penalty. The Designer Series Development System will automatically
combine any C-module macro driving an S-module macro into the S-module, thereby freeing up a logic
module and eliminating a module delay.
The clear input CLR is accessible from the routing channel. In addition, the clock input may be connected
to one of three clock networks: CLKA, CLKB, or HCLK. The C-module and S-module functional
multiplexer select at the clock input to the S-module.
I/Os
I/O Modules
I/O modules provide an interface between the array and the I/O Pad Drivers. I/O modules are located in
the array and access the routing channels in a similar fashion to logic modules. The I/O module
schematic is shown in Figure 4. The signals DataIn and DataOut connect to the I/O pad driver.
Each I/O module contains two D-type flip-flops. Each flip-flop is connected to the dedicated I/O clock
(IOCLK). Each flip-flop can be bypassed by nonsequential I/Os. In addition, each flip-flop contains a data
enable input that can be accessed from the routing channels (ODE and IDE). The asynchronous
preset/clear input is driven by the dedicated preset/clear network (IOPCL). Either preset or clear can be
selected individually on an I/O module by I/O module basis.
Figure 2-4
Functional Diagram for I/O Module
D
DATAOUT
D
Q
CLR/PRE
DATAIN
IOCLK
IOPCL
Y
D
Q
CLR/PRE
ODE
MUX
1
0
MUX
1
0
MUX
0
1
MUX
3
0
1
2
S1
S0