▷ Mini pci express what is it and why is it on laptops?

Mini PCI Express (mPCIe) slots began to appear on Mini-ITX format motherboards at the time of the arrival of Intel's Santa Rosa platform, just over ten years ago. Since then, Mini PCI Express cards have been working, and are used in many of the laptops that we can find in the market, mainly to offer a wireless connectivity module. In this article we are going to see the characteristics of the Mini PCI Express format and why it is so widely used today.

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Mini PCI Express What is it and why is it so used?

Mini PCI Express cards came as a replacement for the Mini PCI card found on many Mini-ITX motherboards before the arrival of the new standard. This Mini PCI Express card measures approximately 30mm x 51mm, and has a 52-pin edge connector, compared to the 100-pin connector on Mini PCI Type I and II cards, and the 124-pin connector of the Mini PCI Type III. The new card is modeled after the Mini PCI Type III, but is without side retention clips.

The Mini PCI Express slot on a motherboard must support a PCI Express x1 link and a USB 3.0 link, because the Mini PCI Express card can use PCI Express 3.0 and / or USB 3.0 connectivity. The Mini PCI Express card has an 8Gb / s serial bus, which provides a significant improvement in connectivity.

The following table summarizes the characteristics of the different PCI Express generations:

PCI Express version	Year	Line code	Transfer	Bandwidth
× 1	× 2	× 4	× 8	× 16
1.0	2003	8b / 10b	2.5 GT / s	250 MB / s	0.50 GB / s	1.0 GB / s	2.0 GB / s	4.0 GB / s
2.0	2007	8b / 10b	5.0 GT / s	500 MB / s	1.0 GB / s	2.0 GB / s	4.0 GB / s	8.0 GB / s
3.0	2010	128b / 130b	8.0 GT / s	984.6 MB / s	1.97 GB / s	3.94 GB / s	7.88 GB / s	15.8 GB / s
4.0	Q2 2019	128b / 130b	16.0 GT / s	1969 MB / s	3.94 GB / s	7.88 GB / s	15.75 GB / s	31.5 GB / s

Mini PCI Express expansion modules are as diverse as their full-size PCI Express counterparts, including graphics cards, network adapters, serial ports, and more. By using Mini PCI Express, system designers can provide numerous configurations to customers easily and inexpensively, and extend product functionality or signal handling capabilities.

While it can be described as a reduced version of PCI Express, mPCIe has a few differences from its full-size counterpart. Although the desktop PCI Express supports up to 32 lanes, standard Mini PCI Express cards only use one lane. It also includes support for USB 2.0 signals in addition to PCI Express. The additional pins reserved for the SIM card signals make 3G / 4G connectivity easy to add via Mini PCI Express. The pins are reserved for a second PCI Express communication lane, although these are used less frequently and are considered non-standard.

Differences with Mini-SATA (mSATA)

Despite sharing the Mini PCI Express form factor, an mSATA slot is not necessarily electrically compatible with Mini PCI Express. For this reason, only some laptops are compatible with mSATA drives. Some laptops use a variant of the PCI Express Mini card as an SSD. This variant uses reserved and several non-reserved pins to implement pass-through of the SATA and IDE interface, keeping intact only the USB, ground lines, and sometimes the central PCIe × 1 bus. This makes the sold Mini PCI Express solid-state and flash drives largely incompatible with true Mini PCI Express implementations.

Although the shared form factor and physical connector have been beneficial to manufacturers and end users, it also creates plenty of room for confusion. That's simply because these two card formats look the same, but are not necessarily compatible. While mSATA cards fit in any mPCIe card slot, they only work properly if that slot is connected to a SATA host controller. This will usually be clearly labeled in the system specifications, and the supported slots will be labeled as shared mSATA or mPCIe / mSATA. Some systems offer dedicated mSATA slots, although that is rare. These slots only work with mSATA cards; the mPCIe cards installed in them will not work correctly.

Mini PCI Express vs mSATA

MSATA SSDs are an obvious choice for solid state storage in embedded systems. However, certain systems, especially in the industrial sector, may not include mSATA slots or may only have a shared slot without mSATA support. For these situations, some Mini PCI Express SSDs on the market allow legacy systems to easily expand their capacity with flash based storage. Some proprietary Mini PCI Express SSDs require special drivers or controllers to function, so system integrators should verify that the mPCIe SSD they are viewing works natively with the Mini PCI Express standard.

The similarity of the mSATA and mPCIE cards creates plenty of room for confusion. Although based on the same physical standard, these two peripheral card formats use different electrical and logical interfaces. System integrators and designers who understand the background, capabilities, and use of mPCIe and mSATA can make full use of these miniature peripheral cards to easily improve the storage capacity and signal handling capabilities of their products.

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