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COM Express

COM Express® is a PICMG® standard that defines a Computer-On-Module, or COM, packaged as a super component. The defined interfaces provide a smooth transition path from legacy interfaces to modern differential signals. This includes DisplayPort, PCI Express®, USB 3.0 and Serial ATA. congatec is specification editor for the most recent revision 3.0 of this PICMG® standard. This version includes the new Type 7 definition which extends the use for COM Express modules to server class applications.

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Interfaces

COM Express® defines up to 440 interconnect pins between the COM Express® module and the carrier board. Older interfaces such as PCI, parallel ATA are supported with legacy Type 2 modules. Type 6 modules feature additional PCI Express® 2.0 Lanes, USB 3.0, 3 DisplayPort/HDMI outputs and no longer multiplexes the PEG port with graphic signals.

Server-on-Module

The newly introduced Type 7 pinout was generated to enable server class applications. It features up to four 10 Gb Ethernet ports and up to 32 PCI Express lanes. It‘s designed for headless operation. It does not support any video or audio interfaces but allows for out-of-band management.

Customization

COM Express® is a legacy free standard. Legacy interfaces or custom features are generated on a customized carrier board.

Size

COM Express® describes four different sizes. The low power Type 10 modules are implemented utilizing the Mini (84x55mm²) size. Type 6 modules are implemented for Compact (95 x 95 mm²) and Basic (95 x 125 mm²) form factors while Type 7 modules are currently only available in Basic size. The Extended (155x110 mm²) size is a potential extension for Type 7 modules.

GPIO

COM Express® defines freely usable general purpose inputs and outputs.

Thermal Design

As with Qseven® and SMARC, the COM Express® definition includes a heatspreader that acts as a thermal interface between the COM Express® module and the system‘s cooling solution. All heat generating components are thermally conducted to the heatspreader in order to avoid hot spots. The heatspreaders and cooling solutions for the high power modules utilize congatec’s patented high efficient flat heat pipes in order to allow for maximum performance and highest reliability.

PCI Express®

COM Express® offers up to 32 PCI Express® lanes. This allows the customer to equip their embedded PC application with the next generation of PC performance. PCI Express® is a low pin count interface with maximum bandwidth per pin. PCI Express® is defined for a maximum bandwidth of up to 8 GBit/s per lane and direction.

Video Output

Common video outputs for COM Express modules are LVDS for direct flat panel support and up to 3 DDIs (Digital Display Interfaces). Each of the DDI can be switched to TMDS (for DVI or HDMI) or DisplayPort. Future Type 6 modules will also allow for an embedded Displayport. This eDP interface will be multiplexed with the LVDS A channel. Type 7 modules are designed for headless use and does not support direct video outputs.

Consortium

http://www.picmg.org/

COM Express Design Guide

https://www.picmg.org/wp-content/uploads/PICMG_COMDG_2.0-RELEASED-2013-12-06.pdf