Miniaturisation: from credit card to postage stamp

The new specification aims to standardise the footprint and interface set of low-power and ultra-low-power application processors based on MCU32, ARM and x86 architectures across different sockets, manufacturers and architectures. Target applications of the new module standard include IoT-connected embedded, IoT, and edge systems that run open-source operating systems and are used in harsh industrial environments. 

“OSM modules give ODMs and OEMs an ultra-miniature form factor with attractive pricing and high scalability. Since the modules are application-ready and come with all necessary software drivers and BSPs, and since the specification is open source – both in terms of the hardware and software – we expect them to be of high interest for the globally active embedded and IoT system development community,” explained Martin Unverdorben, Chairman of the SGET STD.05 Standard Development Team, which started work in October 2019.

Like all Computer-on-Module standards, OSM modules simplify and accelerate the design-in of processors. At the same time, applications become processor-agnostic, which makes them scalable and future-proof. In addition, they protect NRE investments and extend the long-term availability, ultimately increasing the return on investment and sustainability of embedded systems.

Next to these advantages – which OSM modules have in common with all earlier Computer-on-Module specifications – the OSM specification offers an extra level of ruggedness thanks to the BGA design and automated surface mount technology (SMT), which can further reduce production costs in series production.

All OSM modules are also published and licensed under Creative Commons Plus (CC+) dual license. This allows an open licensing model, such as the Creative Commons Attribution-ShareAlike license (CC B-SA 4.0) for a defined set of materials, components and software, and a commercial license for everything not included in this set.

This ensures that development data, such as block diagrams, libraries and BOMs resulting from the development of OSM modules, will be publicly available. Yet it is still possible to license the Intellectual Properties (IP) of a carrier board design commercially without violating the open source idea.

The new OSM specification expands the portfolio of SGET module specifications with solderable BGA mini modules that are significantly smaller than previously available modules: Even the largest OSM module, measuring 45x45mm, is 28% smaller than the µQseven (40x70mm), a standard also hosted by SGET, and 51% smaller than SMARC (82x50mm).

Other module sizes in the new OSM specification are even smaller: OSM Size-0 (Zero) has the smallest footprint with 188 BGA pins on 30x15mm. OSM Size-S (Small) measures 30x30mm with 332 pins, OSM Size-M (Medium) offers 476 pins on 30x45mm, and Size-L (Large) – as mentioned earlier – measures 45x45mm with an impressive 662 BGA pins. SMARC, by comparison, specifies 314 pins and Qseven 230.

This means that BGA design makes it possible to implement significantly more interfaces on a smaller footprint.

The interfaces vary in type and design depending on the size of the OSM modules. In maximum configurations, OSM modules provide all functions that make up an open programmable embedded, IoT or edge system, including GUI. Modules from Size-S upwards offer video interfaces for up to one RGB and four-channel DSI. Size-M modules can additionally support two eDP/eDP++, and Size-L adds one LVDS interface for graphics.

So all in all, maximum configurations can provide up to 5 video outputs in parallel. All modules from Size-S upwards further offer a four-channel Camera Serial Interface (CSI). Size-L modules provide up to 10 PCIe lanes for quick connection of peripherals; Size-M offers two PCIe x1, and Size-S one PCIe x1. In view of their extremely miniaturised footprint, Size-0 modules do not feature any of the I/Os mentioned so far, but offer all the interfaces listed in the following.

The OSM specification provisions up to five Ethernet for system-to-system communication. In addition, all modules have what is called a communication area, providing 18 pins for antenna signals for wireless communication or the integration of field buses. Next, there are up to four USB 2.0 or two USB 3.0 (only in Size-L), up to two CAN, and four UART.

Flash storage media can be connected via UFS. Up to 19 pins are further available for manufacturer-specific signals. Finally and to complete the feature set, there are up to 39 GPIOs, SPI, I2C, I2S, SDIO and two analogue inputs. As a safeguard for the future and to ensure that any future expansions are backward compatible, up to 58 pins are reserved for future purposes.