
Altera Corporation
21
FLEX 10KE Embedded Programmable Logic Family Data Sheet
LE Operating Modes
The FLEX 10KE LE can operate in the following four modes:
s
Normal mode
s
Arithmetic mode
s
Up/down counter mode
s
Clearable counter mode
Each of these modes uses LE resources differently. In each mode, seven
available inputs to the LE—the four data inputs from the LAB local
interconnect, the feedback from the programmable register, and the
carry-in and cascade-in from the previous LE—are directed to different
destinations to implement the desired logic function. Three inputs to the
LE provide clock, clear, and preset control for the register. The
MAX+PLUS 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 use a specific LE operating mode for optimal performance.
The architecture provides a synchronous clock enable to the register in all
four modes. The MAX+PLUS II software can set DATA1 to enable the
register synchronously, providing easy implementation of fully
synchronous designs.