EP2S15 ALTERA [Altera Corporation], EP2S15 Datasheet - Page 24

• Manufacturer Part Number: EP2S15
• Description: Stratix II Device Family
• Manufacturer: ALTERA [Altera Corporation]

Adaptive Logic Modules
2–16
Stratix II Device Handbook, Volume 1
Figure 2–12. Conditional Operation Example
The arithmetic mode also offers clock enable, counter enable,
synchronous up/down control, add/subtract control, synchronous clear,
synchronous load. The LAB local interconnect data inputs generate the
clock enable, counter enable, synchronous up/down and add/subtract
control signals. These control signals are good candidates for the inputs
that are shared between the four LUTs in the ALM. The synchronous clear
and synchronous load options are LAB-wide signals that affect all
registers in the LAB. The Quartus II software automatically places any
registers that are not used by the counter into other LABs.
Carry Chain
The carry chain provides a fast carry function between the dedicated
adders in arithmetic or shared arithmetic mode. Carry chains can begin in
either the first ALM or the fifth ALM in an LAB. The final carry-out signal
is routed to an ALM, where it is fed to local, row, or column interconnects.
Carry Chain
syncdata
X[0]
X[1]
X[2]
Y[0]
Y[1]
Y[2]
ALM 1
ALM 2
Comb &
Comb &
Comb &
Comb &
Adder
Adder
Adder
Adder
Logic
Logic
Logic
Logic
X[2]
X[0]
X[1]
Adder output
is not used.
syncload
syncload
syncload
D
D
D
reg0
reg1
reg0
carry_out
Q
Q
Q
R[0]
R[1]
R[2]
Altera Corporation
To general or
local routing
To general or
local routing
To general or
local routing
To local routing &
then to LAB-wide
syncload
May 2007