SOM / SBC adoption guide

Overview of the setup

Development with a SoM goes through four broad stages. Each stage involves different decisions.

1. SelectionNarrow down candidates by application, performance, interfaces, operating temperature, and supply period. Decisions made here affect every later step.
2. EvaluationVerify on actual hardware using an evaluation kit or evaluation unit. This is the stage to check heat generation, real-world performance, and BSP maturity, which catalog values do not reveal.
3. DesignDesign the carrier board, following the SoM specifications (pinout, power requirements, and mechanical dimensions).
4. Mass productionConfirm the supply plan and EOL (end of life) handling. In industrial equipment, supply over a decade or more is not unusual.

How to approach product selection

Starting from “which SoC is best?” leaves too many options to decide. It is more practical to narrow down from your requirements.

Items to check in order of priority

The pin-compatible family option

Our Chinchilla series is designed to be Pin2Pin compatible. You can swap in SoMs with different performance while keeping the same carrier board.

This structure has two practical advantages. One is product lineup expansion: higher-end and lower-end models can be built on the same carrier board. The other is diversification of SoC supply risk: even if the adopted SoC becomes hard to obtain, you can migrate to another SoC without redesigning the carrier board.

Carrier board design

The biggest advantage of using a SoM is that the difficult routing is confined to the module. Length-matched DDR memory routing and the SoC power sequencing are handled entirely within the module and are not dealt with on the carrier board.

Documents to check during design

• Pinout table — Which signal is on each pin of the connector. Some are published on the drawings tab of the product page
• Mechanical drawings — Outline, mounting hole positions, connector positions, and component heights
• Power requirements — Input voltage, inrush current, and whether a power-up sequence is specified
• Reference circuit — Design examples provided by the manufacturer. Following these first is the safe approach

Handling differential signals

Differential pairs such as USB 3.0, PCIe, MIPI, and Ethernet also require trace length and impedance control on the carrier board. Match lengths within each pair, match impedance through the layer stackup, and avoid unnecessary vias — miss any of these three and operation becomes unstable.

About design reviews

We review carrier board schematics and artwork. Many problems can be prevented by checking before the board is fabricated, so please consult us, especially if you are working with a SoM for the first time. We also offer contract design.

Bring-up procedure

When the board arrives, do not boot the OS right away; verify step by step. This makes it easier to isolate problems.

1. Check supply voltagesWithout the SoM mounted, check the voltage and power-up sequence of each power rail with an oscilloscope. Any abnormality here could destroy the SoM.
2. Secure the serial consoleSet up the debug UART first. It will be your only way to see what is happening in every subsequent step.
3. Confirm the bootloader startsMount the SoM and check whether bootloader messages appear. If you get this far, the SoM side is working correctly.
4. Kernel bootConfirm that the OS boots and that you can log in on the console.
5. Check peripherals one by oneCheck Ethernet, USB, cameras, and so on one at a time. Enabling them all at once makes it difficult to isolate the cause of problems.

Device tree adjustment

In Linux, the carrier board–specific configuration is described in the device tree. The usual approach is to start from the manufacturer’s device tree for the evaluation kit and rewrite it for your own carrier board configuration.

# Typical items that need to be changed
- Enable/disable the UART/I2C/SPI in use
- Ethernet PHY address and connection type
- Camera and display connections and lane counts
- GPIO function assignments
- Power regulator definitions

Because this work is a common stumbling point, we also offer bring-up support on a contract basis.

Choosing the BSP and OS

SoM manufacturers typically provide a BSP (Board Support Package) for several operating systems. Which one you choose affects how smoothly development proceeds.

In practice, the approach of Debian-based for prototypes, Yocto for mass production is common. It prioritizes speed at the prototype stage, then optimizes the configuration for mass production.

Long-term availability and EOL handling

Industrial equipment may require supply for 10 years or more after the start of mass production. Here we summarize the points to check when selecting a SoM.

• SoC lifecycle — The guaranteed supply period published by the SoC manufacturer. Industrial grades often commit to 10–15 years
• Supply plan for the SoM itself — Even if the SoC remains available, SoM production will not necessarily continue. Memory and PMIC supply also play a role
• EOL notification terms — How many months before end of production notice is given. Also confirm the last-time-buy deadline.
• Migration to alternatives — With a Pin2Pin compatible family, you can avoid redesigning the carrier board when migrating

As a distributor, we continuously track EOL information from manufacturers. For products you have adopted, we notify you of changes in supply status early.

Common pitfalls

Performance falls short

In most cases, heat dissipation is the cause. Under continuous load, thermal throttling kicks in and lowers the clock. Measure the temperature first. The next most common cause is saturated memory bandwidth, in which case you need to rethink how data flows.

A specific peripheral does not work

Most cases are an omission in the device tree or an incorrect pin multiplexer setting. Because a single pin has multiple functions, the intended function may not be enabled.

Won’t boot / unstable

Check the power-on sequence and reset timing. Especially in configurations with multiple power supplies, the power-on order may be specified. The boot media (eMMC/SD/USB) selection pin settings should also be checked.

Worked in prototyping but fails in mass production

Phenomena caused by unit-to-unit variation or temperature conditions are suspected. This is a pattern where a lack of margin that did not appear in a few prototype units surfaces at mass production volumes. The countermeasure is to secure temperature and voltage margins at the design stage.

Evaluation unit loans and support

Positive ONE supports you all the way from selection to mass production.

• Evaluation unit loans — We support advance verification on actual hardware. Availability depends on stock, so please contact us first
• Selection advice — We hear your requirements and propose candidates. If something we do not carry is the best fit, we will tell you so
• Design review — We review carrier board schematics and artwork
• Contract development — Carrier board design, BSP adjustment, bring-up, and application development
• Supply management — Sharing EOL information, proposing alternatives, and consultation on long-term stock