EP1M350 datasheet(19/86 Pages) ALTERA

19 / 86 page

Altera Corporation

Mercury Programmable Logic Device Family Data Sheet

Each LE has two outputs that drive the local, row, and column routing

resources. Each output can be driven independently by the LUT’s or

improves device utilization because the register and the LUT can be used

for unrelated functions. The LE can also drive out registered and

unregistered versions of the LUT output.

LE Operating Modes

The Mercury LE can operate in one of the following modes:

■

Normal

■

Arithmetic

■

Multiplier

Each operating mode uses LE resources differently. In each operating

mode, eight available inputs to the LE—the four data inputs from the LAB

local interconnect; carry-in0, carry-in1 from the previous LE; the

LAB carry-in from the previous carry-chain generation; and the FastLUT

Connection input from the previous LE—are directed to different

destinations to implement the desired logic function. LAB-wide signals

provide clock, asynchronous clear, asynchronous preset, asynchronous

load, synchronous clear, synchronous load, and clock enable control for

the register. These LAB-wide signals are available in all normal and

arithmetic LE modes.

The Quartus II software, in conjunction with parameterized functions

such as LPM and DesignWare functions, automatically chooses the

appropriate mode for common functions, such as counters, adders, and

multipliers. If required, the designer can also create special-purpose

functions that specify which LE operating mode to use for optimal

performance.

Normal Mode

The normal mode is suitable for general logic applications and

combinatorial functions. In normal mode, four data inputs from the LAB

local interconnect and a single carry-in are inputs to a four-input LUT. The

Quartus II Compiler automatically selects the carry-in or the data3 signal

as one of the inputs to the LUT. The LUT (combinatorial) output can be

driven to the FastLUT connection to the next LE in the LAB. LEs in normal

mode support packed registers. Figure 8 shows an LE in normal mode.

EP1M350 Datasheet(PDF) 19 Page - Altera Corporation