M.2-Features-Custom Design Circuit Board
Buses exposed through the M.2 connector are PCI Express 3.0, Serial ATA (SATA) 3.0 and USB 3.0, which is backward compatible with USB 2.0. As a result, M.2 modules can integrate multiple functions, including the following device classes: Wi-Fi, Bluetooth, satellite navigation, near field communication (NFC), digital radio, Wireless Gigabit Alliance (WiGig), wireless WAN (WWAN), and solid-state drives (SSDs). The SATA revision 3.2 specification, in its gold revision as of August 2013, standardizes the M.2 as a new format for storage devices and specifies its hardware layout.
The M.2 specification provides up to four PCI Express lanes and one logical SATA 3.0 (6 Gbit/s) port, and exposes them through the same connector so both PCI Express and SATA storage devices may exist in form of M.2 modules. Exposed PCI Express lanes provide a pure PCI Express connection between the host and storage device, with no additional layers of bus abstraction. PCI-SIG M.2 specification, in its revision 1.0 as of December 2013, provides detailed M.2 specifications.
There are three options available for the logical device interfaces and command sets used for interfacing with M.2 storage devices, which may be used depending on the type of M.2 storage device and available operating system support: