The MIPI Alliance and PCI-SIG have joined forces to deliver the M-PCIe or Mobile PCI Express specification. Hardware that would be based on the specification is likely to show up in the 2014 to 2105 timeframe.
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Mobile PCI Express utilizes the PCI-SIG's PCI Express software and protocol with the MIPI PHY found on a wide range of high performance mobile devices. The MIPI PHY (M-PHY) has a number of advantages including low EMI and low power requirements. It is tuned for short channels between devices where PCI Express can be used on backplanes and even for cable connections outside of box. The M-PCIe replaces the PCIe logical PHY layer (Fig. 1). The top levels of the stack remain the same allowing the same device drivers and software to be used regardless of the underlying physical connetion.
The new standard can take advantage of the improved PCIe power management support while idle which is key to the kinds of mobile application areas where the MIPI PHY is found. In theory, the configuration would support something like a PCIe switch but the number of devices connected using this technology tends to be low and fixed versus PCs and servers with multiple board slots. Still, the software used in all these environments could be the same without regard to the underlying hardware.
Some other differences include the symmetric nature of PCIe versus the optional asymmetric support availble with MIPI. For example, MIPI can be configured with three links operating in one direction and one in the other. There are scenarios where this asymmetric configuration are beneficial.
Designers using M-PCIe must be members of both alliances. Of course, users and programmers that are buying the hardware do not have to concern themselves with these issues.
The technology targets spaces where MIPI is utilized including smartphones and tablets for support of high speed wireless interfaces. The technology is applicable to other mobile and non-mobile applications.