M.2 (the bus formerly known as NGFF) is a new, more flexible alternative to PCI Express Mini Cards (mPCIe) for use as a multi-purpose small-form-factor embedded computer expansion bus. Designed for versatility, M.2 supports both smaller and larger footprints than mPCIe, and consumes less power, making it a perfect choice for a variety of embedded applications.
M.2 is quite versatile, with a flexible selection of busses provided at the 75-pin connector (like PCIe, SATA, USB, and I2C) as determined by each computer manufacturer. To ensure any given peripheral will be supported by any host computer's particular slot's features a connector-key system was implemented. Similar to the various "notches" on DIMM sticks each M.2 device will have notches that prevent installation in incompatible computer slots, and which indicate the specific bus capabilities they require. For example, M.2 cards with the "M" key-notch will work in host slots that provide 4-lane PCI Express, SATA, and SMBUS interfaces. Cards with the "B" key might need one or more of the 2-lane PCIe, SATA, USB3, USB2, UIM, SSIC, HSIC, I2C, SMBus, or audio interfaces. Multiple keys might be notched on a particular M.2 device, and much can be learned from this. A device with both the "B" and "M" key can work in either socket-type and thus must be using only interfaces present on both: 2-lane PCI Express, SATA, or SMBus, in this example.
A Variety of Footprints
Embedded applications come in all shapes and sizes, from wearables to aircraft, and M.2 provides a one-bus-fits-all solution to this myriad of target form-factors. Available in dozens of different footprints, from a 12mm × 16mm, soldered-in-place version and the largest at 30mm × 110mm, all use the same bus signals and software interfaces. This common electrical interface, common software interface, and well-defined feature/key system together ensure adding data acquisition and control devices to your project is easier than ever — even after your design is established.
ACCES standard footprint: TYPE 2280-D3-B-M, with a break-away to convert to TYPE 2260-D3-B-M
Where: 22 - width in mm
80 or 60 - height in mm
D31 - thickness, first is a letter denoting a single- (S) or double- (D) sided option, while second character is a number 1, 2 or 3 denoting the maximum allowable thickness
B - ACCES M.2 cards are compatible with all B-type sockets
M - ACCES M.2 cards are also compatible with all M-type sockets