Specifications

CHAPTER 6: BLOCK-BASED DESIGN
INTRODUCTION
114 ■ INTRODUCTION TO QUARTUS II ALTERA CORPORATION
Introduction
The Quartus
®
II LogicLock
™
feature enables a block-based design flow by
allowing you to create modular designs, designing and optimizing each
module separately before incorporating it into the top-level design.
Incorporating each module into the top-level design does not affect the
performance of the lower level modules, as long as each module has
registered inputs and outputs.
LogicLock regions are flexible, reusable constraints that increase your ability
to guide logic placement on the target device. You can define any arbitrary
rectangular region of physical resources on the target device as a LogicLock
region. Assigning nodes or entities to a LogicLock region directs the Fitter to
place those nodes or entities inside the region during fitting.
LogicLock regions support team-oriented, block-based design by enabling
you to optimize logic blocks individually, and then import them and their
placement constraints into a larger design. The LogicLock methodology also
promotes module reuse, because modules can be developed separately and
then constrained to LogicLock regions to be used in other designs with no
loss in performance, allowing you to leverage resources and shorten design
cycles.
The LogicLock feature also allows you to assign design partitions to physical
locations in the device as part of a top-down, incremental compilation flow.
Quartus II Block-Based Design Flow
In traditional top-down design flows, there is only one netlist for the design.
In a top-down design flow, individual modules of the design can have
different performance from the overall design when implemented on their
own. In bottom-up block-based design flows, there are separate netlists for
each module. This allows designers to create block-based designs, where
each module is optimized independently and then incorporated into the
top-level design. You can use block-based design in the following flows:
■ Modular design flow: In the modular design flow, you divide a design
into a top-level design that instantiates separate submodules. You can
develop each module separately and then incorporate each module
into the top-level design. Placement is determined manually by you or
by the Quartus II software.