Revision 4 2-1
2 – Device Architecture
Fusion Stack Architecture
To manage the unprecedented level of integration in Fusion devices, Microsemi developed the Fusion
technology stack (Figure 2-1). This layered model offers a flexible design environment, enabling design
at very high and very low levels of abstraction. Fusion peripherals include hard analog IP and hard and
soft digital IP. Peripherals communicate across the FPGA fabric via a layer of soft gates—the Fusion
backbone. Much more than a common bus interface, this Fusion backbone integrates a micro-sequencer
within the FPGA fabric and configures the individual peripherals and supports low-level processing of
peripheral data. Fusion applets are application building blocks that can control and respond to
peripherals and other system signals. Applets can be rapidly combined to create large applications. The
technology is scalable across devices, families, design types, and user expertise, and supports a well-
defined interface for external IP and tool integration.
At the lowest level, Level 0, are Fusion peripherals. These are configurable functional blocks that can be
hardwired structures such as a PLL or analog input channel, or soft (FPGA gate) blocks such as a UART
or two-wire serial interface. The Fusion peripherals are configurable and support a standard interface to
facilitate communication and implementation.
Connecting and controlling access to the peripherals is the Fusion backbone, Level 1. The backbone is a
soft-gate structure, scalable to any number of peripherals. The backbone is a bus and much more; it
manages peripheral configuration to ensure proper operation. Leveraging the common peripheral
interface and a low-level state machine, the backbone efficiently offloads peripheral management from
the system design. The backbone can set and clear flags based upon peripheral behavior and can define
performance criteria. The flexibility of the stack enables a designer to configure the silicon, directly
bypassing the backbone if that level of control is desired.
One step up from the backbone is the Fusion applet, Level 2. The applet is an application building block
that implements a specific function in FPGA gates. It can react to stimuli and board-level events coming
through the backbone or from other sources, and responds to these stimuli by accessing and
manipulating peripherals via the backbone or initiating some other action. An applet controls or responds
to the peripheral(s). Applets can be easily imported or exported from the design environment. The applet
structure is open and well-defined, enabling users to import applets from Microsemi, system developers,
third parties, and user groups.
Note: Levels 1, 2, and 3 are implemented in FPGA logic gates.
Figure 2-1 • Fusion Architecture Stack
Flash
Memory
Analog
Smart
Peripheral 1
Analog
Smart
Peripheral 2
Analog
Smart
Peripheral n
Smart Peripherals
in FPGA
Fabric
(e.g., Logic, PLL, FIFO)
Fusion Smart Backbone
Fusion Applets
User Applications
Level 1
Level 0
Level 2
Level 3
Optional ARM or 8051 Processor
