SMALL FORM FACTOR BOARDS
Pico-ITX–The Next Big Thing in Small Form Factors
With the new diminutive dimensions of the Pico-ITX form factor, you can expect to see a lot of ingenious devices that break ground in previously impossible applications. As a PC main board with such small dimensions, Pico-ITX-based computing can pop up just about anywhere.
JOHN LIN, VIA TECHNOLOGIES
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Space can be a major concern when designing embedded systems. Certain applications have requirements for dimensions. For example, a backseat entertainment computer should ideally fit within the dimensions of a seat. There is no exception and no flexibility in those space requirements. It would be completely unacceptable (not to mention hazardous) to have parts of the system sticking out of front end of the headrest. While it may be possible to extend cables from a display to a system mounted on the floorboard or under a seat, space in a vehicle is still limited.
Generally, for an embedded system, small is a good thing because quite often, the embedded computer will be integrated as part of another object. In such situations, smaller dimensions make it easier for embedded systems designers to orient the embedded computer without affecting the outer design of the device too much (if at all).
The Pico-ITX form factor is the smallest form factor currently available that is intended to support a complete x86 platform. Its dimensions are a mere 100 mm by 72 mm. That’s about the size of a standard notebook hard disk drive.
There are many choices in form factors. What makes the Pico-ITX stand out? Why choose this form factor over another? First, the small dimensions of the Pico-ITX form factor make it possible for you to design for small spaces instead of trying hard to design around a form factor. Trying to design around a form factor is like trying to hammer a square peg into a round hole. With enough persistence, it can be accomplished, but the end result is not likely to be pretty.
The small dimensions of the Pico-ITX form factor make it so that the embedded system designer does not have to compromise too much on the aesthetics of the design. The small dimensions make it possible to orient the board in different ways.
For example, the Pico-ITX form factor can be applied across many industries. One example is an industrial PC called the DeLOCK DL-18HD. This computer was designed for use in industrial zones. Its chassis is designed to be DIN rail mountable. Because it is based on a Pico-ITX form factor mainboard, its overall size is ultra compact–making it suitable for industrial automation control applications where space is an issue. To give an idea about the size of the DL-18HD, it is not much larger than a typical DIN rail circuit breaker. Even with such compact dimensions, the DL-18HD affords full x86 computing power.
Second, it is completely independent. Unlike COM Express or PC/104, the Pico-ITX form factor is intended to be a self-reliant mainboard. It does not need a carrier board or other boards to become a functioning system. Though the PC/104 and COM Express form factors are also similarly small, they require additional boards to become functional. These additional boards end up increasing the dimensions of the embedded system (Figure 1).
Third, according to the Small Form Factors Special Interest Group (SFF-SIG), the official Pico-ITX form factor specification, which is being drafted by the Pico-ITX Incubator Group, will include support for the SUMIT expansion interface in the future. This new technology integrates common serial and legacy expansion buses into one compact connector. SUMIT connector A provides access to one x1 PCIe 2.0, three Hi-Speed USB 2.0, LPC, SPI, SMBus and ExpressCard devices. SUMIT connector B provides additional support for one x1 PCIe 2.0 and one x4 PCIe 2.0 device (Figure 2).
Robert Kuo, the father of the Mini-ITX and Nano-ITX, commented that this new Pico-ITX specification will most likely be named “Pico-ITX Express” in order to differentiate it from the original Pico-ITX small form factor. Like the original Pico-ITX form factor, boards based on the Pico-ITX Express form factor will retain full functionality without the need for additional I/O boards. Though the Pico-ITX Express small form factor has the ability to use stackable modules with SUMIT connectors, it is not designed to be dependent on other I/O boards. The Pico-ITX Express is the only small form factor that possesses the duality of both independence and modularity.
Possible Applications for Pico-ITX
Because of the diminutive size of the Pico-ITX form factor, new areas of application are now more likely to be possible. One new area of application is in the education sector. More and more universities and schools are requiring students to bring a notebook computer to school. As far as education goes, there are several problems with notebook computers: 1) they can be easily dropped and broken, 2) they can be stolen, 3) when open, they obstruct the view, and 4) when open they create a psychological barrier between two people. In a classroom setting, that would mean a barrier between student and teacher.
So what kind of embedded system could solve all of these problems? An embedded system integrated with the school desk. In a classroom setting, the connection between teacher and student should remain unobstructed. Flipping open a notebook creates a barrier that impedes learning and enables students to hide a PSP behind the display. So a tablet PC might seem to be the answer. Yes, except that tablet PCs are prone to problems 1 and 2. On the other hand, it would be difficult to drop a desk because typical school desks are awkwardly shaped and easily weigh in at 30 to 70 pounds (never mind stealing one).
A Pico-ITX main board can easily be mounted under the desktop. Meanwhile, the desktop can also serve as the touch screen display, ensuring that nothing obstructs the view between the teacher and student (except other students) (Figure 4). Without a psychological barrier between student and teacher, information can be more easily communicated from the teacher to the student. Teachers can ensure that students are not cheating on tests if only the school desk PC is allowed. A common platform also makes it easier for a school IT department to control. It is easier to ensure that no one is installing programs they shouldn’t be installing.