Embedded developers know their applications won’t get deployed in the field without the right hardware platform. Today, many single-board computer platforms have made their way into areas like industrial automation and defense, where computing used to be done only on system-on-modules and larger computers. With single-board computers being so competitive to other embedded hardware platforms, which is best for a new embedded system, and what advantages does it have in different scenarios?
Like most engineering questions, the answer is a solid “it depends.” Some tasks are much easier when a single-board computer is used, whereas a system-on-module gives systems designers more flexibility. If you’re unsure which of these is the best embedded hardware platform for your system, we’ll help you compare system-on-module vs. single-board computer options.
Comparing System-on-Module vs. Single-board Computers
For any embedded system running an OS and applications, the hardware and chipset needs to mimic a typical computer and provide some of the same functions. Single-board computers and system-on-modules are two options that provide a standard chipset and supporting components needed to build an embedded application. How these integrate into a larger system depends on the specific product, as well as the use case you’re targeting.
System-on-Module
The term “system-on-module” has two possible meanings, depending on who you ask. Specifically, a system-on-module is sometimes meant to be equivalent to:
- System-on-chip (SoC): I’ve seen some hardware guides that equate systems-on-module with an SoC. In some ways, a system-on-module is like an SoC, it’s just built on a PCB rather than on silicon. SoCs provide computing power in specialized products (such as tablets and smartphones), while a system-on-module is meant to be much more general.
- Computer-on-module: These hardware platforms normally have an edge card form factor and are meant to provide nearly all the required components for embedded computing on a single board. These will attach to a carrier board through an edge connector, although some newer and specialty modules will attach through a mezzanine connector (the Raspberry Pi CM4 module is one popular example).
If you look at computer-on-module vendors, they will sometimes call their products systems-on-module. These products, where the entire chipset required to run an OS and other applications is packaged on a single board, are one option for giving your embedded system the processing power it needs. The alternative is a single-board computer, which has additional components and features.
The CM4 development board from Gumstix uses the new Raspberry Pi CM4 as an SoM.
Single-board Computers
A single-board computer is just as its name suggests: everything you would expect to find on a typical computer is placed on a single board, including memory, networking, display, USB, and even cameras for computer vision applications. Many single-board computers also include a pin header that will be connected to GPIOs on the main processor and can be accessed within an application.
On a single-board computer, you get everything you’d find on a system-on-module, but the board includes connectors and interfaces you might not find on a system-on-module. For example, if you want to access Ethernet and USB on a system-on-module, you need to build a carrier board that includes the required connectors for these interfaces (see the image above for the Raspberry Pi 4 Model B). A single-board computer includes all of this and minimizes the number of add-ons required to make your system functional.
Comparison
The table below shows the important dimensions that should be considered when selecting a system-on-module vs. a single board computer as the host processor for an embedded system. The first point to note is that many SBCs and SoMs have comparable performance specs, and they may even have some of the same components. Beyond this, you’ll need to worry more about form factor and required peripherals when comparing these platforms.
| Single-board computer | System-on-module | |
|---|---|---|
| Future-proofing | Only possible at application level | Possible at application and hardware level |
| Interfaces | Standard interfaces (USB, Ethernet, HDMI or other display) | Same as a single-board computer, but built onto the carrier board |
| Development | Usually simple if vendor provides libraries or an SDK | Same as a single-board computer |
| Footprint | Typically small, limited by on-board connector and interface options | Limited by the size of the carrier board, can be larger than single-board computers |
| Expandability | Uses standard computing interfaces, may include a pin header | Carrier boards can be designed with greater expandability than a single-board computer |
To summarize: a single-board computer is very useful for prototyping an application, or in a production system that doesn’t require hardware changes or upgrades. A system-on-module is a better choice when you want some flexibility to modify the system (either with a new module or a new carrier board). However, you would have to design your own carrier board to suit your application and product.
Whether you’re designing an ultra-rugged aerospace system or feature-rich embedded computing products, make sure your design firm understands how to coordinate with electronics manufacutring services and contract manufacturers to help you produce and scale with maximum quality. NWES helps aerospace OEMs, defense primes, and private companies in multiple industries design modern PCBs and create cutting-edge embedded technology, including power systems for high reliability applications and precision control systems. We’ve also partnered directly with EDA companies and advanced ITAR-compliant PCB manufacturers, and we’ll make sure your next high speed digital system is fully manufacturable at scale. Contact NWES for a consultation.
