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Sunday, October 23, 2011

Wifi industry standard interfaces

| Wireless Driver & Software

miniPCI/PCI/CardBus

miniPCI is a 32-bit, 33 MHz computer bus standard, adapted from the PCI bus, for attaching peripheral devices to a computer motherboard. It was designed for laptops and other small-footprint computer systems.

The miniPCI bus has powered connections and support for bus mastering and DMA. Mini PCI cards support CLKRUN# PCI signals used to start and stop the PCI clock for power management purposes. The standard size for Mini PCI cards is approximately 1/4 of their full-sized counterparts.

PCIe

PCI Express (PCIe) is an implementation of the PCI computer bus using existing PCI programming concepts based on a completely different and much faster serial physical-layer communications protocol. PCIe transfers data at 250 MiB/s per channel for up to 16 channels to achieve a transfer rate of 4 GiB/s.

The PCIe physical layer consists of a network of serial interconnects much like twisted pair Ethernet. A single hub with many pins on the mainboard allows all kinds of switching and parallelism. As clock rates increase, synchronization of parallel connections is hindered by timing skew. PCIe exemplifies a general trend away from parallel buses to serial interconnects.

Based on the existing PCI system, cards and systems can be converted to PCIe by changing the physical layer and adapting to PCI Express without any change in software. Higher speeds on PCI Express displace most existing internal buses, including AGP and PCI.  

PCIe is the major new PC backplane standard, designed to be transparent to software developers, with the enhanced performance required for today’s WLAN applications.

USB

Universal Serial Bus (USB) is a popular serial bus standard to interface devices designed for computers, video game consoles, PDAs, cellphones, TVs and stereos, MP3 players and portable memory devices.

The radio spectrum-based USB implementation is known as Wireless USB.

USB connects peripheral devices with no need to plug expansion cards into the computer’s ISA, EISA, or PCI bus, and improves plug-and-play capabilities with hot-swapping.

USB connects mouse devices, keyboards, gamepads, scanners, digital cameras, printers, external storage, networking components and other peripherals.

miniCard

miniCard is a replacement for the miniPCI form factor (with x1 PCIe, USB 2.0 and  SMBus buses on the connector).

MII (Media Independent Interface)

The Media Independent Interface (MII) is a standard interface used to connect a Fast Ethernet MAC-block to a PHY. The MII may connect to an external transceiver device via a pluggable connector (see photo) or simply connect two chips on the same printed circuit board. Being media independent means that any of several different types of PHY devices can be used without redesigning or replacing the MAC hardware. The equivalents of MII for other speeds are AUI (for 10 megabit Ethernet), GMII (for gigabit Ethernet), and XAUI (for 10 gigabit Ethernet).

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