Comparing FPGA vs Microcontroller: Optimal for Your Needs?

When designing embedded systems, engineers utilize a variety of components to construct a functional setup, incorporating a blend of a computing processor, memory modules, and input/output peripheral devices. Each embedded system exhibits uniqueness and complexity levels tailored to its specific objectives. Among the pivotal decisions engineers face during the development phase is the selection of the processor or processing system tasked with executing computational operations and overseeing the system's diverse components. Two prevalent options are a microcontroller and a field programmable gate array (FPGA).

This article aims to furnish insights into the processors employed in embedded systems, elucidate the disparities between a microcontroller and an FPGA, and delineate the respective merits and demerits of each option.

Processing Systems in Embedded Systems

An embedded system functions as a specialized computer tasked with controlling or executing specific operations, either independently or as part of a larger system. At its core, a processing system is responsible for executing computations and real-time tasks.

Various processing systems found within embedded systems include:

Microcontroller: Comprising one or more CPUs, memory, and programmable input/output peripherals.
Microprocessor: Also known as a central processing unit, responsible for executing and managing logical instructions.
Digital signal processing (DSP): Utilized for processing digital signals like images and videos.
Field-programmable gate arrays (FPGAs): Integrated circuits configurable by users or designers post-manufacturing.

The suitability of each depends on the specific application. Microcontrollers and FPGAs, in particular, are often compared, so we'll delve into each and their respective strengths for different purposes.

Understanding Microcontrollers

A microcontroller, residing on an integrated circuit (IC) or chip, serves as a compact computer comprising a CPU, memory, and peripheral input/output mechanisms. These devices are tailored to execute precise functions and oversee other system elements, encompassing memory components like RAM or ROM, as well as input/output apparatuses such as LED displays, switches, and diverse sensor types. Embedded software is pivotal for the operation of hardware components, furnishing directives to the system. Typically, microcontrollers are programmed employing higher-level languages like JavaScript, Python, and C.

Microcontrollers

Understanding Field-Programmable Gate Arrays (FPGAs)

FPGAs represent integrated circuits (ICs), housing arrays of circuits on a chip, devised to undergo configuration post-manufacturing by customers or designers. The architectural framework of an FPGA encompasses myriad Configurable Logic Blocks (CLBs), incorporating Look-Up Tables (LUTs), Flip-Flops (FFs), and Multiplexers (Muxes). LUTs, constituting the crux of FPGAs, execute Boolean equations and serve as the primary conduit for logical operations.

Encircling these CLBs is a network of programmable interconnects, comprising switches and wires, facilitating connectivity between CLBs, logic blocks, and Input/Output (I/O) blocks. These I/O blocks furnish the interface linking the FPGA to external devices. Together, these constituents form an extensive multi-core processor.

When harnessing FPGAs, engineers configure the device's hardware instead of crafting software tailored for a predefined processor. The programming of FPGAs predominantly employs Hardware Description Languages (HDLs).

FPGA

Distinguishing Between FPGA and Microcontroller

One significant contrast between a microcontroller and an FPGA lies in their hardware configuration. Unlike a microcontroller, which possesses a predetermined hardware structure, an FPGA offers a flexible architecture. While FPGAs incorporate fixed logic cells, these, in conjunction with interconnects, can be programmed simultaneously using Hardware Description Language (HDL) coding. Consequently, FPGAs lack predefined functions and can be customized according to the user's requirements.

Conversely, microcontrollers feature a fixed hardware layout, wherein all components, encompassing the processor, memory, peripheral devices, and connections, are preestablished. Utilizing software, designers can instruct the processor to execute designated tasks within the predetermined hardware framework.

Deciding Between FPGA and Microcontroller

Determining the optimal choice between an FPGA and a microcontroller hinges on various factors. Generally, microcontrollers are preferable for routine circuit control tasks, such as simple device activation through a switch. Conversely, FPGAs excel in tailored applications demanding heightened processing power or speed, such as processing high-resolution video data.

Embedded engineers frequently opt for microcontrollers in embedded devices due to their ease of programming, debugging, and design, coupled with their cost-effectiveness. Nonetheless, microcontrollers lack flexibility compared to FPGAs. Unlike FPGAs, which permit hardware/firmware reprogramming, microcontrollers only facilitate firmware reprogramming, constraining modification options.

Furthermore, FPGAs boast parallel processing capabilities, enabling concurrent execution of identical operations across hundreds or thousands of Configurable Logic Blocks (CLBs). This feature renders them well-suited for tasks like image processing or artificial intelligence. In contrast, microcontrollers execute operations sequentially, processing each program line individually, resulting in comparatively lower processing power.

While either component can function as the primary processor, integrating both a microcontroller and an FPGA concurrently is also viable. In this scenario, the microcontroller manages complex controls while the FPGA undertakes intensive computational tasks. By harnessing the strengths of both processors, developers can craft resilient designs capable of executing sophisticated operations.

Resources for Creating and Troubleshooting Embedded Systems

Embedded systems reliant on microcontrollers frequently employ communication protocols like I2C and SPI to facilitate device interaction. Effective development and debugging of these systems necessitate appropriate tools. Host adapters and protocol analyzers, among others, empower engineers to test and scrutinize systems, providing insights into bus operations.

Adapter Solutions

Adapter solutions, particularly host adapters, enable engineers to emulate both master and slave devices and prototype entire systems. Acting as a master, these tools facilitate the evaluation of peripherals like sensors and memory chips, while functioning as a slave allows for the testing of commands sent from microcontrollers (MCUs).

Total Phase offers a range of host adapters tailored to various I2C and SPI testing and programming needs.

The Aardvark I2C/SPI Host Adapter serves as Total Phase’s versatile host adapter, adaptable for use as either an I2C or SPI master or slave device. It supports speeds of up to 800 kHz as an I2C master and slave, and up to 8 MHz as an SPI master or 4 MHz as an SPI slave.

Designed as a high-speed programming device, the Cheetah SPI Host Adapter excels in quickly programming SPI-based EEPROMs and Flash memory, boasting signaling capabilities of up to 40 MHz as an SPI master.

For more advanced serial device requirements, the Promira Serial Platform stands out as Total Phase’s premier offering. With its FPGA-based platform, users have access to a wide range of I2C and SPI applications, offering varying speeds and functionalities to suit diverse project needs. As an I2C device, it supports signaling of up to 3.4 MHz as both a master and slave, while as an SPI device, it enables signaling of up to 80 MHz as a master and 20 MHz as a slave.

Analytical Solutions

Protocol analyzers serve as invaluable aids in capturing and monitoring data on the bus, facilitating the identification of bus errors and their origins. Total Phase provides an array of protocol analyzers tailored to different protocols, such as I2C and SPI.

The Beagle I2C/SPI Protocol Analyzer enables non-intrusive monitoring of an I2C bus at speeds of up to 4 MHz and an SPI bus at speeds of up to 24 MHz.

Differences Between FPGA vs Microcontroller