Arduino to SOMs: Is Modular Design Better?

April 26, 2021 by Jake Hertz

On the tails of Xilinx’s newest SOM announcement, we take a look at the role modular design plays in electrical engineering.

Modular design has long played an essential role in the education of electrical engineers and the development of products. Development boards like Raspberry Pi and Arduino are often the starting point of electrical prototyping where later engineers take this proof of concept and spin out custom boards and systems.


A Raspberry Pi is used in a modular design. 

A Raspberry Pi is used in a modular design. Image used courtesy of NWES


In recent years, the sophistication of modular design has moved beyond tools for tinkerers and into fully-fledged systems meant to be integrated into production devices. One of the more significant developments has been the system on module (SOM), which takes modular design to the next level. 

In this article, we’ll go look back on our interview with Xilinx to discuss the rise of SOMs and the role of modular design in electrical engineering. 


A Quick Background – What is a SOM? 

As Xilinx’s Director of Product Marketing for Dev Kits, Evan Leal, explained to us: “SOMs are small, embedded boards… that include a system on a chip (like a microprocessor or GPU or an FPGA), memory, power management, and other supporting peripherals and circuitry…they essentially abstract away the hardware so developers can design at the board level instead of having to design at the chip level.” 


The basic breakdown of the K26 SOM.

The basic breakdown of the K26 SOM. Image used courtesy of Xilinx


In essence, SOMs do the heavy lifting by bypassing the step of creating a custom PCB with your desired functionality to instead allow for software engineers to design on a full system immediately. 

An example of a SOM is Xilinx’s new K26, which is explicitly designed for vision-based AI applications for edge deployment. Instead of building up the hardware infrastructure for a computer vision system to run on, companies can use this SOM and quickly start the development process. 


Benefits of SOMs for EEs 

The most significant benefit of utilizing modular design and SOMs specifically in your design is the time savings it offers electrical engineers.
As AAC contributor Kate Smith explains, from a purely logistical standpoint, the use of modules by EEs may equate to less time spent on granular design. Modular design can decrease time to market and allow for electrical engineers to focus on other tasks instead of low-level board design. SOM designers work to make their systems easy to use to integrate into any existing design without the hassle.

For this reason, along with subsequent cost savings, many smaller companies are moving towards SOMs in their product design. 


Why Modular Design Isn’t Perfect 

While a modular design may sound like a great solution, certain aspects can limit its overall efficacy. 

One of the main limitations of modular design is that it can limit a system’s design flexibility. No two electrical systems are ever the same. There is often a lot of custom work necessary to make a unique product, including custom form factors, power requirements, and other application-specific needs. 

Utilizing a modular design can limit the freedom of design in this respect. Instead of designing a system as you see fit, you are instead inserting this module into your system, causing you to develop your system around it instead of the other way around. 


A high-level depiction of the engineering design process, which changes when using a modular design.

A high-level depiction of the engineering design process, which changes when using a modular design. Image used courtesy of Works Museum


Another setback is that SOMs cannot be changed or modified since the engineers don’t have the schematic docs or Gerber files of these modules. 

What happens if something in the system needs to be altered or if a next-generation product is made? 

With a modular design approach, your options are essentially limited to buying the SOM maker’s next-generation product (should it exist) or modifying your existing system (if possible). 


Final Thoughts

The modular design versus custom design argument can be analogous to the FPGA versus ASIC argument. Where an FPGA may help you get to market quicker, but it will never achieve the system-specific performance ASIC will provide you. 

However, an FPGA is different than a SOM in this analogy because one strength of an FPGA is its ability to be modified, which is one of the weaknesses of modular design. 

When it comes to figuring out which is better, the truth is that there is a time and a place for both. While the modular design is increasing in popularity, nothing will ever replace developing fully custom electrical systems.