COM Express

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The different COM Express form factors in size comparison
COMe module type 6 with VIA Nano X2
COMe carrier board (carrier board)

COM Express (COMe) is a PICMG specification for x86-based Computer-on-Module (COM). COM Express Computer-on-Modules integrate the core functionality of a bootable PC such as CPU , graphics processor , RAM and standard interfaces on a module that is plugged into an application-specific carrier board via a maximum of two connectors . COM Express is based on the ETXexpress form factor introduced by Intel and Kontron in 2003, but was renamed COM Express as part of the specification by the PICMG.

COM Express specifies the dimensions of the module , the placement of the mounting holes and the placement and pin assignment (pin-out type) of the connectors to the carrier board . These lead the typical serial PC interfaces such as PCI Express , USB , audio, graphics and Ethernet to the carrier board . By defining the pin assignment in the so-called pin-out types, it should be ensured that COM Express modules remain interchangeable with one another, so that COM Express can also be upgraded with new COM Express computer-on-modules at a later date. Depending on the type, one or two 220-pin connectors are used. The same connector type is also used with CoreExpress .

Pin-out types

The PICMG's COM Express specification currently defines seven different pin-outs. The most common pin-out is type 2. The pin-outs, type 6 and type 10, which were added with Revision 2.0 of the COM Express specification at the beginning of 2010, integrate up to three digital display interfaces in parallel with the PCI Express graphics port.

Type 7 was presented at the end of 2016. It differs from the previous types in that almost all video interfaces have been dispensed with. It only has one LVDS interface, which can also be used as an eDP (embedded display port ). The number of SATA and USB interfaces has also been reduced. This made it possible to implement 32 PCI Express lanes as well as four 10 GBaseKR Ethernet .

Pin-out Number of
connectors 		PCI Express
lanes 		PEG a PCI IDE SATA LAN Video outputs USB
2.0 		USB
3.0 		Others
Type 1 1 × 220 pins 06th - - - 4th 1 LVDS , VGA 8 × -
Type 10 1 × 220 pins 04th - - - 2 1 LVDS, DDI ( SDVO b , DP , HDMI / DVI ) 6 × 2 × 2 ×  RS-232
Type 2 2 × 220 pins 22nd Yes Yes 1 4th 1 LVDS, VGA, DDI (SDVO b , DP, HDMI / DVI) 8 × -
Type 3 2 × 220 pins 22nd Yes Yes - 4th 3 LVDS, VGA, SDVO b 8 × -
Type 4 2 × 220 pins 32 Yes - 1 4th 1 LVDS, VGA, SDVO b 8 × -
Type 5 2 × 220 pins 32 Yes - 2 4th 3 LVDS, VGA, SDVO b 8 × -
Type 6 2 × 220 pins 24 Yes - - 4th 1 LVDS, VGA, 3 × DDI (SDVO b , DP, HDMI / DVI) 4 × 4 × 2 × RS-232
Type 7 2 × 220 pins 32 - - - 2 1 eDP / LVDS - 4 × 2 × RS-232, 4 ×  10GBaseKR Ethernet
aPEG, P CI E xpress for G raphics
b multiplexed with PEG

Module sizes

The specifications define four module sizes:

Extended: 155 mm × 110 mm
Basic: 125 mm ×  095 mm
Compact: 095 mm ×  095 mm
Mini: 055 mm ×  084 mm (Type 1/10 pin-out)

COM Express specification

The COM Express specifications (COM.0) are defined by the PICMG . It can be purchased from PICMG for a fee.

  • Rev. 1.0 2005
  • Rev. 2.0 2010
  • Rev. 2.1 2012

COM Express Carrier Design Guide

The PICMG COM Express Carrier Design Guide provides additional information for the development of application-specific carrier boards for COM Express COMs. In addition to reference plans for external circuits to implement the various peripheral functions of the COM Express modules, it also describes the bus systems supported and also describes how additional peripherals and expansion slots can be integrated into a COM Express-based system. The COM Express Carrier Design Guide is available on the PICMG website as well as from the various embedded manufacturers.

Manufacturer

Web links

Commons : COM Express  - collection of images, videos and audio files

Individual evidence

  1. ↑ Jeff Munch: PICMG COM Express Type 7 includes 10GbE. In: embedded computing design. OpenSystems Media, August 8, 2016, accessed September 24, 2016 .
  2. ↑ COM Express Carrier Design Guide - Guidelines for designing COM Express Carrier Boards. (PDF; 2.3 MB) (No longer available online.) PICMG, archived from the original on January 13, 2012 ; Retrieved December 2, 2011 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.picmg.org