August 22, 2024

SOM vs SBC | What is the Difference and How to Choose the Right Solution

It can be confusing to select between a SOM (System on Module) or SBC (Single Board Computer) for embedded systems. These two options have different strengths depending on the application, from industrial automation and IoT to robotics and networking. This article explores the differences, pros, and cons to help you make an informed decision for your specific application or project.

What is a SOM?

You can identify a SOM, or System on Module, by its few ICs, such as a CPU, DRAM, and flash. SOMs also lack standard peripheral connectors like RJ45 Ethernet jacks, USB ports, Mini-PCIe slots, or GPIO headers.

A SOM usually consists of a small, bare-bones PCB that includes a CPU processor, DRAM, and flash storage (eMMC). The SOM usually features one or two high-density interface connectors that expose all the peripheral buses, such as USB, UART, SPI, GPIO, and PCIe. These buses are presented in a raw form, lacking supporting circuitry, which a baseboard connected to the SOM must handle. Additionally, standard connectors like USB Type-C or RJ45 Ethernet jacks are not usually found on a SOM.

When you purchase a SOM, you plug it into a baseboard. The baseboard includes extensive supporting circuitry and connectors for interfacing with external systems such as RJ45 Ethernet, UART/GPIO headers, a barrel jack for power input, and any other connectors needed to expose specific buses.

Advantages and Challenges of Using a SOM

Because a SOM is very small and contains the minimum amount of circuitry, the price can be attractive. However, a low-cost SOM can require a large investment in design, complexity and circuity cost for the baseboard. The investment in developing a custom baseboard can lead to total costs exceeding that of a high-end SBC.

The baseboard, or carrier board, is a large investment, mostly on the time and risk side. Designing and laying out a baseboard to the required specifications demands talented hardware engineers. This design can take months and typically requires multiple revisions to provide a stable platform. The design requires a schematic with specific circuitry as well as complicated PCB routing for high-speed interfaces and usually requires multi-layer PCBs. The baseboard will require additional software, such as drivers and device tree additions to support the peripherals, such as Ethernet controllers and PHYs, PCIe switches, serial transceivers, and wireless interfaces.

Device tree fragments can be complex and demand proper configuration to ensure all the hardware on the baseboard functions correctly. Designing a custom baseboard allows you to tailor it without worrying about the system’s core functionality handled by the SOM. However, developers often underestimate the amount of additional software needed for integration, which may exceed their standard skill set.

SOM Standards and Longevity Considerations

Another term often used interchangeably with SOM is COM or Computer on Module. Over the years, there have been several different mechanical and electrical standards that have come out for a SOM/COM. These include COM Express, Qseven and SMARC. While standard, they still are at the mercy of design longevity and the discretion of manufacturing companies. If a new standard is developed, a baseboard using a SMARC connection could become obsolete in 15 years.

For advanced applications, SOMs often expose high-speed interfaces such as PCIe, USB 3.0, and Gigabit Ethernet through high-density connectors, requiring careful attention to signal integrity on the baseboard. Additionally, peripherals like CAN bus, SPI, and I2C are commonly supported but must be implemented through custom circuitry on the carrier board. In contrast, SBCs typically include high-speed interfaces with built-in power regulation circuitry and standard connectors, such as RS232/RS485, ready to interface with industrial-grade peripherals.

What is an SBC?

An SBC or single board computer, appears as a complete computer board including standard peripheral connectors such as power input, RJ45 Ethernet jacks, USB ports, Mini-PCIe slots and GPIO headers.

An SBC is an embedded system that contains all the brains (CPU, DRAM, Flash), supporting external bus circuitry, and connectors for peripherals and add-ons. This is truly an all-in-one solution with zero extra hardware or low-level software engineering required. It essentially is a SOM and carrier board sold all in one.

Software and Support for SBC

SBCs usually come with a software board support package or BSP. A BSP is essential for developers because it includes the bootloader, device tree, kernel and root file system to ensure peripheral components work with the hardware. SBC manufacturers turn on specific options in the Linux kernel to support peripheral chipsets on the SBC, such as PCIe switches, Ethernet controllers, serial transceivers etc. Gateworks SBCs come with a robust Board Support Package (BSP) which includes support for operating systems such as Linux (Ubuntu, Yocto). This ensures seamless integration with industrial applications, offering pre-configured kernel options and device tree fragments that accelerate development. With comprehensive driver support for peripherals like Ethernet, Wi-Fi, and PCIe, developers can focus on application-specific code rather than low-level system configurations, reducing both complexity and time-to-market.

Industrial-Grade Features of SBCs

Gateworks Venice Single Board Computers are designed for industrial-grade applications. They feature power circuitry that accepts an 8 to 60V DC supply and comes with built-in USB ports. Each board includes RJ45 Ethernet jacks, MAC/PHY, and PoE circuitry. Engineers configure locking headers for peripheral buses such as RS232, GPIO, SPI, and I2C, while transceivers on the UART lines support RS232/RS485. Mini-PCIe and M.2 slots facilitate quick integration of wireless and cellular cards, and we place ESD diodes on many exposed interfaces to enhance durability.

Advantages and Challenges of Using an SB

An SBC is ultimately the fastest time to market. You don’t need to design a custom PCB for standard operation with the most common peripheral buses. Most companies choose an SBC to quickly integrate their custom software onto an already working and proven hardware platform. SOM-baseboard solutions can take up to 3-6 months of design, validation, and iteration, while an SBC may reduce this by 50% or more, depending on application needs.

If an off-the-shelf SBC does not meet all of the specifications, you have to inquire about customizations. With SBCs, there is the potential for unused components or interfaces that can increase costs and power consumption, especially in low-power or cost-sensitive applications. Fortunately, companies like Gateworks provide extensive customization options. From designing specialized baseboards to depopulating components on existing designs, we are a flexible partner for any embedded system project. Customization options may include connectors and other peripherals to be changed or depopulated to save cost or a customized baseboard may be designed, with new or different interfaces available for specific applications.

SOM vs SBC | Should I choose a SOM or SBC? Conclusion & Recommendations

SOMs and SBCs are both popular options for an embedded system. SOMs are popular because, off the cuff, they seem very small and are a lower price. However, the hidden cost is designing a baseboard to expose any needed buses. This baseboard will always increase the size, cost and time to market of the entire solution. If your project demands specific hardware integration and you have the resources for custom board design, a SOM offers flexibility.

An SBC is ready to go out of the box and does not require further hardware development assuming it meets the required specifications. So for projects where time-to-market is critical an SBC provides a ready-made solution that reduces development time.

For harsh environments that demand ruggedness and extended temperature ranges, Gateworks’ SBCs withstand industrial-grade conditions. However, you will need to perform additional testing and qualification for SOMs paired with custom baseboards.

Even when a design starts with a SOM, the SOM and baseboard end up as an SBC in the end. Gateworks recommends using an SBC from the beginning and is always happy to discuss custom SBC designs as needed.

	Pros	Cons
SOM	– Low initial cost – Allows for custom baseboard	– Typically doesn’t include standard peripheral connectors such as RJ45, USB, Mini-PCIe, M.2, etc.. – Requires baseboard design and manufacturing complexities – Requires additional cost of baseboard – Requires troubleshooting and debugging of integration with baseboard – Myriad of different standards on the market limits customization – Requires procurement of SOM and Baseboard separately – Requires a lot of extra low level software (drivers, device tree) for baseboard interfaces
SBC	– Hardware design completed – Hardware already proven – Fast time to market – One source for entire platform – Software drivers and device tree complete	– Higher initial cost – Rarely will require custom design for special interfaces (often Mini-PCIe or M.2 cards can be used instead)

Contact our team to discuss your unique needs or explore a full range of customizable SBC solutions below.

• Venice GW7100 – 1x Ethernet, 1x Mini-PCIe, 1x USB Linked Here
• Venice GW7200 – 2x Ethernet, 2x Mini-PCIe, 1x USB Linked Here
• Venice GW7300 – 2x Ethernet, 3x Mini-PCIe, 2x USB Linked Here
• Venice GW7400 – 6x Ethernet, 3x Mini-PCIe, 1x USB, 1x M.2 Linked Here

View the entire line of Gateworks SBCs here.