The commercial-off-the-shelf (COTS) market is showing quite a bit of growth. The European Union's Restrictions on Hazardous Substances (RoHS) have had a significant impact on new designs due to the need to find new sources. Purchasing COTS products can cut out a major portion of the design work, decreasing time-to-market.
Some platforms like Itox's $465 G5C900-B-G COM Express module assume the custom portion will be supplied in the form of a carrier board with the module itself remaining unchanged (Fig. 1). There is still some variance available to designers. For example, the module uses Intel's Mobile 945GM Express chip set, which can support a range of processors, though the board is optimized for Intel's Core Duo processor.
Invariably, it's easier to turn a portion of a standard design custom than it is to start from scratch. Standard modules like COM Express, ETX, and even platforms like VME, VPX, CompactPCI, and AdvancedTCA are available off-the-shelf without modifications. But get the volume or price up enough, and they become the basis for custom designs. In fact, over half of the COTS products on the military side are custom, with more industrial applications moving in this direction.
There's a range of approaches for addressing incremental levels of customization. The standard method is to use custom boards and add them to something like a PC/104 stack or National Instruments' CompactRIO (Fig. 2). Of course, CompactRIO has a few tricks up its backplane, including an FPGA (see "NI-RIO: Fast Prototyping"). The FPGA actually makes it easier to utilize standard modules.
On the other hand, Diamond Systems' GPIO-MM uses an FPGA to make its I/O board easier to customize (Fig. 3). In theory, it's one way to make a single COTS platform perform multiple custom duties.