COM Express

Computer form factors
Listed by PCB size (mm)
WTX (356×425) AT (350×305) Baby-AT (330×216) BTX (325×266) ATX (305×244) EATX (Extended) (305×330) LPX (330×229) microBTX (264×267) NLX (254×228) Ultra ATX (367×244) microATX (244×244) DTX (244×203) FlexATX (229×191) Mini-DTX (203×170) EBX (203×146) microATX (min.) (171×171) Mini-ITX (170×170) EPIC (Express) (165×115) Mini ATX (150×150) ESM (149×71) Nano-ITX (120×120) COM Express (125×95) ESMexpress (125×95) ETX/XTX (114×95) Pico-ITX (100×72) PC/104 (-Plus) (96×90) ESMini (95×55) Qseven (70×70) mobile-ITX (60×60) CoreExpress (58×65)

COM Express, a computer-on-module (COM) form factor, is a highly integrated and compact PC that can be used in a design application much like an integrated circuit component. Each COM Express Module COM integrates core CPU and memory functionality, the common I/O of a PC/AT, USB, audio, graphics (PEG), and Ethernet. All I/O signals are mapped to two high density, low profile connectors on the bottom side of the module.

Types

There are 7 different pin outs defined in the specification. The most common used pin out is type 2. The latest pin-outs added in the revision 2.0 of the COM Express specification (available from www.picmg.org) are Type 6 and Type 10.

Maximum available interfaces for the defined types:

• Type 1: Single connector (220 pin), 6 PCI Express lanes, no PEG, no PCI, no IDE, 4 SATA, 1 LAN
• Type 10: Single connector (220 pin), 4 PCI Express lanes, no PEG, no PCI, no IDE, 2 SATA, 1 LAN, single channel LVDS only, DDI, no VGA, 2 Serial COM
• Type 2: Double connector (440 pin), 22 PCI Express lanes, PEG, PCI, 1 IDE, 4 SATA, 1 LAN
• Type 3: Double connector (440 pin), 22 PCI Express lanes, PEG, PCI, no IDE, 4 SATA, 3 LAN
• Type 4: Double connector (440 pin), 32 PCI Express lanes, PEG, no PCI, 1 IDE, 4 SATA, 1 LAN
• Type 5: Double connector (440 pin), 32 PCI Express lanes, PEG, no PCI, no IDE, 4 SATA, 3 LAN
• Type 6: Double connector (440 pin), 24 PCI Express lanes, PEG, no PCI, no IDE, DDI (for DisplayPort, HDMI, DVI or SDVO), 4 SATA, 1 LAN, 2 Serial COM, USB 3.0

Size

The specification defines 4 module sizes:

• Mini: 55 x 84 mm
• Compact: 95 x 95 mm
• Basic: 95 x 125 mm
• Extended: 110 x 155 mm

Specification

The COM Express specification is hosted by PICMG. It's not freely available but can be purchased from the PICMG website.

The current revision 2.1 (PICMG COM.0 R2.1) was released in May 2012. The original revision 1.0 was released July 10, 2005.

See also

• ETX
• XTX
• ESMexpress
• Qseven

External links

• PICMG website
• The Economics and use of COM Express in Embedded Applications
• COM Express Carrier Design Guide - Guidelines for designing COM Express Carrier Boards
• Purchase specification (scroll down to "PICMG COM.0 R2.1")
• COM Express Plug-and-Play Initiative