Pico-ITX packs a punch

It was only a matter of time: Thanks to Moore’s Law, the smallest embedded open standard single-board computer (SBC) form factor has broken into the quad-core ranks. At a mere 72 by 100 mm, Pico-ITX boards are now available from a number of suppliers with Intel, AMD, and Freescale ARM processors. Thanks to tiny semiconductor geometries down to 14 nm, these processors are implemented as feature-rich systems-on-chip (SoCs) with one, two, and four cores and average power consumption below 10 W.

The Small Form Factor Special Interest Group (SFF-SIG) convened a working group in 2007 to ascertain how to create a broad reaching standard based upon VIA Technologies’ first Pico-ITX board. The working group considered the inherent limitations in I/O, processor speeds, thermal dissipation, and mounting-hole locations. At the time, the VIA Eden family and Intel Atom family were just single-core processors running up to 1.6 GHz maximum, and the focus for Pico-ITX was solely x86 processors.

The overachieving form factor

Fast forward eight years: The Intel Atom E3845 clocks in – with quad core – at 1.91 GHz. In the same “Bay Trail” family, the Celeron J1900 supports TurboBoost, from 2.0 GHz to 2.42 GHz per core, as long as there is thermal headroom. For graphics-intensive applications, AMD offers the G-series SoC “Steppe Eagle” family up to quad core, with the tradeoff being lower superscalar CPU performance.

Not to be outdone, the rapidly growing ARM processor community offers up its own quad-core processor with PC-like I/O and 10-year life cycle, making it a good fit for Pico-ITX as well. Freescale’s i.MX6 family offers PCI Express, SATA, USB, UART, and HDMI interfaces, quite similar to its x86 counterparts. Although the processor performance is less than Intel’s and AMD’s, the power consumption of i.MX6 is also lower, only several watts.

Most of the Pico-ITX boards on the market use commercial small-outline dual-inline memory module (SODIMM) memory and have an I/O “coastline” with PC-style connectors such as USB, Ethernet, HDMI, serial port, and/or audio in/out. Some offer a SATA connector or a micro SD card connector for storage. Due to extreme space limitations, the rest of the I/O has to be on pin-header connectors around two or three edges of the board.

Room to expand

Embedded systems frequently need some custom I/O; it is incumbent upon SBC manufacturers to provide “hooks” for attaching such I/O. While SFF-SIG defined Pico-I/O using the SUMIT interface in an attempt to provide a consistent interface to a daughtercard, so far most of the industry is using the notebook PC market’s standard mini-PCIe (PCI Express Mini Card) socket for Pico-ITX expansion. One notable trend over the past two years has been for the embedded I/O manufacturers to implement A/D and other functions on mini-PCIe cards, therefore gaining momentum as a de facto approach for the embedded market. Leveraging mini-PCIe wireless (802.11 and Bluetooth) and m-SATA cards from the consumer space is giving embedded system OEMs a broad selection of proven expansion modules. The building-block approach allows the rapid deployment of systems with minimal hardware-design time.

What’s next for Pico?

Now that the market usage is picking up, additional suppliers have come on board, and there is closer adherence to processor-vendor roadmaps without generation gaps.

Intel has stepped up its GPU capabilities substantially for its SoCs, and the brand new “Braswell” platform can even drive 4K video running Linux. Branded as Pentium N3700 and Celeron N3000, this family of processors brings efficient computing to applications that required a Core i3 or i5 processor last year (at a much higher price tag). Look for special features with this family, like MIPI camera interfaces, remote manageability, and health monitoring.

Expect to see Pico-ITX boards in a variety of rugged applications as well, with industrial-temperature-range designs. Smaller and lighter boards are much easier to secure, with intrinsic shock and vibration resistance, compared to the much larger SBCs from a few years ago in this performance class.

Applications for Pico-ITX include medical devices, transportation, advertising displays, IoT gateways, soldier training, unmanned aerial vehicles (UAVs), and industrial automation. Although the gestation period has been long, Pico-ITX is now poised for explosive growth, fueled by unprecedented quad-core 1 GHz to 2 GHz performance.

Small Form Factor Special Interest Group 408-480-7900 info@sff-sig.org