Diamond Systems wants to make it easier to interface chores while reducing costs and increasing the number of available options when using high-speed serial interfaces like PCI Express and USB. Its FeaturePak module (Fig. 1) is designed to provide peripheral expansion. Up to six modules can be connected to a host. A standard single-board computer typically might host one or two. In a sense, it is the opposite of the computer-on-module (COM) approach, where the host is on a board.
FeaturePak can work in several different configurations, such as having the processor on a COM board or in a stack. In this case the host would simply be a carrier board for the COM and FeaturePak modules.
The module is designed to be small enough to work with stackable architectures like PC/104, EPIC Express (see “An EPIC Tale: PC/104 Hitches On To PCI Express”), SUMIT (see “SUMIT Brings Big Improvements In Small Packages”), and Stackable USB (see “Micro/sys Dishes Out StackableUSB For Embedded I/O”).
A FeaturePak edge connector plugs into a high-density, low-cost MXM socket that has 230 I/O connections. The connections are different from other MXM-based standards such as those used by Qseven. It can handle data rates up to 2.5 Gbits/s, allowing it to work with PCI Express and USB 2.0. About half of the pins are used for the two application-specific I/O ports. There are 50 pins allocated for each port, with 34 unused pins for isolation between I/O signals and use with high-speed links such as Ethernet. The modules are designed for rugged environments. Each has a pair of mounting holes so it can be bolted to the carrier board.
MULTIPLE CONTROL OPTIONS
The module’s features can be accessed through PCI Express, USB, UART, or the SMBus (I2C) interface. However, PCI Express and USB are the primary means for controlling and accessing the peripherals on the module.
Modules can have multiple PCI Express and USB ports. Typically, though, a module will only need one. A host socket must provide either a PCI Express 1x and USB link (FeaturePak compliant) or a pair of USB links (FeaturePak USB compliant).
The modules are designed for 3.3-V operation with a minimum of 2 A available from the host. The 5-V supply is 1 A. The 12-V connection allows a module to monitor the supply.
Standard modules are 4.8 mm high. Tall modules can be up to 10 mm high. A standard module will fit within a PC/104 0.6-in. stacking height. FeaturePak is designed for developers. JTAG connections on the board allow modules to be part of a JTAG scan chain.
Diamond Systems created FeaturePak with the intent to move it to a standards group. Other companies such as Congatec are already working on FeaturePak modules like the Diamond Systems digital-to-analog converter (DAC) (Fig. 2) and digital I/O modules (Fig. 3). Of course, these modules will only be useful when combined with a carrier board, so expect announcements of single-board computers with FeaturePak sockets.
More details can be found on the FeaturePak Web site.