Explaining FPGAs: Why Makers Love Them?

FPGA stands for Field Programmable Gate Array which is an IC that can be programmed to perform defined customized functions for the multiple purpose of a specific application. They have thousands of gates. In the field of VLSI FPGAs have gained increased popularity in this modern times. Languages such as VHDL and Verilog are usually used for writing the code required for FPGA programming.

Discover top-quality electronic components at Ersa electronics! From Integrated circuits and embedded IC chips to FPGA boards, find high-quality items at affordable prices.

What is an FPGA?

An FPGA, or field-programmable gate array, is an electronic device composed of a patterned array of metal interconnections on a silicon wafer opposing a patterned array of pass-gate transistors.

This programmable array can be used to create custom circuits, which can be customized for specific tasks or applications.

Originally invented by Ross Freeman and Bernard Vonderschmitt of Xilinx,major manufacturers such as Xilinx, Altera (acquired by Intel in 2015), MicroSem, Lattice Semiconductor, and Atmel have contributed to their improvement.

FPGAs are used in industries for the development of digital integrated circuits and research centers to create digital circuits for prototyping and small series of ASICs.

How is it different from a processor?

A processor and an FPGA are two different types of machines that can be used to perform tasks. Processors are the heart of a computer while FPGA is a motherboard that provides the interfaces between different parts of a computer.

Processors operate based on a set of instructions, exec

using operations on binary data. They have registers for data input/output, memory for storage, and an instruction stack housing the program in machine code, executing instructions in clock cycles.

Finally, a processor has a stack of instructions, which has the program to be executed in machine code, and a clock.

When we program the processor we use one of the many languages ​​available, in a format that is understandable and comfortable for users.

The code is decoded into machine language during linking and collection, then stored in the processor's memory for execution, constituting our program's performance.

From there, the processor performs the instructions, and therefore our program.

However, when programming an FPGA what we are doing is modifying a connection matrix. The individual blocks are made out of elements that allow them to adopt different transfer functions.

These blocks can connect in different ways, like building circuits in a creative way.

Together, the different blocks, linked by the connections that we program, are an electronic circuit, similar to what we would do on a training board or when creating our own chip.

The difference is substantial. A processor (in its many variants) has a fixed structure and we modify its behavior through the program that we write, translate it into machine code, and execute sequentially.

General Architecture of FPGAs

An FPGA contains multiple programmable logic blocks connected via vertical and horizontal channels to input/output cells, as depicted in the below figure. While generally featuring a mostly regular structure, there are variations in the logic block and routing architecture across different manufacturers.

How do you program an FPGA?

FPGAs are not “programmed” in the sense to which we are accustomed, with a language such as C, C++, or Python.

In fact, FPGAs use a different type of language called descriptive language, rather than a programming language.

Afterward, an integrator (similar to a "compiler" in programming languages) translates the device description into a workable design using FPGA blocks, determining the necessary connections.These languages used for defining hardware are known as HDL or Hardware Description Languages. Examples include Verilog, HDL, and ABEL.

Learning HDL languages can be difficult due to their very low degree of abstraction level, in describing electronic circuits in detail. As code expands, projects tend to become much bigger.

Manufacturers provide commercial tools to program their own FPGAs. Today, they provide complete environments with a large number of tools and functionalities. Unfortunately, most are not free or are only free for some FPGA models from the manufacturer.

Examples of HDL languages include Verilog, HDL, or ABEL. Verilog, being open-source, is commonly encountered among them.

The programming languages ​​for FPGAs are known as HDL (Hardware Description Language), the most used being:

• VHDL.
• Verilog.
• ABEL.

Difference between Microcontroller and FPGA

The differences between Microcontroller and FPGA are: