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1. Introduction
NII-PRG | 2018.04.18
Because the pins and logic resources in Intel FPGA devices are programmable, many
customizations are possible:
•
You can rearrange the pins on the chip to simplify the board design. For example,
you can move address and data pins for external SDRAM memory to any side of
the chip to shorten board traces.
•
You can use extra pins and logic resources on the chip for functions unrelated to
the processor. Extra resources can provide a few extra gates and registers as glue
logic for the board design; or extra resources can implement entire systems. For
example, a Nios II processor system consumes only 5% of a large Intel FPGA,
leaving the rest of the chip's resources available to implement other functions.
•
You can use extra pins and logic on the chip to implement additional peripherals
for the Nios II processor system. Intel FPGA offers a library of peripherals that
easily connect to Nios II processor systems.
1.4. Configurable Soft Processor Core Concepts
This section introduces Nios II concepts that are unique or different from other
discrete microcontrollers. The concepts described in this section provide a foundation
for understanding the rest of the features discussed in this handbook.
1.4.1. Configurable Soft Processor Core
The Nios II processor is a configurable soft IP core, as opposed to a fixed, off-the-shelf
microcontroller. You can add or remove features on a system-by-system basis to meet
performance or price goals. Soft means the processor core is not fixed in silicon and
can be targeted to any Intel FPGA family.
You are not required to create a new Nios II processor configuration for every new
design. Intel FPGA provides ready-made Nios II system designs that you can use as is.
If these designs meet your system requirements, there is no need to configure the
design further. In addition, you can use the Nios II instruction set simulator to begin
writing and debugging Nios II applications before the final hardware configuration is
determined.
1.4.2. Flexible Peripheral Set and Address Map
A flexible peripheral set is one of the most notable differences between Nios II
processor systems and fixed microcontrollers. Because the Nios II processor is
implemented in programmable logic, you can easily build made-to-order Nios II
processor systems with the exact peripheral set required for the target applications.
Intel FPGA provides software constructs to access memory and peripherals generically,
independently of address location. Therefore, the flexible peripheral set and address
map does not affect application developers.
There are two broad classes of peripherals: standard peripherals and custom
peripherals.
1.4.2.1. Standard Peripherals
Intel FPGA provides a set of peripherals commonly used in microcontrollers, such as
timers, serial communication interfaces, general-purpose I/O, SDRAM controllers, and
other memory interfaces. The list of available peripherals continues to increase as
Intel FPGA and third-party vendors release new peripherals.
Nios II Processor Reference Guide
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