Network Systems DesignLine
2006-06-09   Provide broadband access for home mobile devices with embedded Ethernet
  By Jason Wang and Harvey Jan, ASIX Electronics Corp. [2006-06-09]

The proliferation of the broadband infrastructure and the associated new business model has made the services such as IPTV and Media on Demand (MOD) possible. In the future, users will demand higher quality multimedia content that can be downloaded through a home broadband connection and transferred onto mobile devices. Satellite broadcast companies are already using current technology to allow users to download their favorite television programs onto their handheld devices., the world largest Internet retailer, offers a complete music downloading service, which allows customers to download MP3 through a long term licensing contract. Amazon also offers an MP3 player with 1-2G of memory space free of charge, allowing users to download a limited or unlimited number of songs per month. In essence, this type of service is much like cable television.

With the continuing features and performance advancement in mobile devices, design engineers constantly face a two-fold problem: on one hand, they face pressures to cut costs and produce smaller devices with lower power consumption; on the other hand, they must offer more functionalities and higher connection speed.

The traditional way of accessing multimedia content for a mobile device is by connecting its USB port to a computer through a higher speed cable or "cradle". The downside to this procedure is that the user cannot connect to the Internet independently without turning on a PC or Notebook computer, and hence must go through a PC intermediary.

Another way of accessing multimedia content is through a build-in Wi-Fi module, where the connectivity can be limited by the surrounding environment such as concrete walls, the distances between the devices, nearby microwave and cordless phone, radio waves, the use of Wi-Fi and Bluetooth modules simultaneously, and other forms of interference. The limitation to this procedure is that the current wireless technology such as Wi-Fi cannot achieve broadband connection speeds suitable for multimedia streaming with good enough QoS. The stability of a consistent and reliable wireless connection is also another concern.

Yet another way is to leverage the existing Ethernet network at home or in the office for broadband access. The problem is the build-in PCI or Non-PCI Ethernet module or Ethernet card increase the bulkiness of mobile devices. A possible remedy to preserve compactness is to use a separate cradle or docking station to connect the mobile devices to the network. The downsides to this procedure are the added costs of additional connectors due to the use of parallel bus in PCI or Non-PCI controller, and the signal interference that it generates.

The Solution: USB-to-LAN

USB-to-LAN offers a natural solution to each of the downsides described in the present scenarios described above.

The idea of so called USB-to-LAN converts an USB 2.0 signal to the Fast Ethernet/Gigabit Ethernet interface through an USB-to-LAN controller used in the cradle or docking station for the mobile devices. Because the USB 2.0 uses a compact four-pin connector, this solution reduces many pins-out connections between the cradle/docking station and the mobile devices. Another more flexible way is to use an external USB-to-LAN dongle to connect the mobile devices to the network if the microcontroller within the devices has a build-in USB host interface. This will leverage the high-speed and serial bus characteristic of USB2.0, to increase the performance of the devices, and in the meantime, solve the downside of bulkiness described above.

The concept behind USB-to-LAN should be obvious – harnessing USB's "plug-and-play" convenience as well as its 480 Mbps connection speeds, both without compromising portability and connection performance.

Six Different Embedded Ethernet Solutions

The so-called Embedded System usually denotes a Non-PC system that includes many of the functions of a computer. The main components of embedded system are a microcontroller, custom hardware, the embedded operating system, and the application software. The applications of an embedded system can range from factory automated industrial control machines to every day mobile devices, such as cell phones, PDAs, PMPs, and MP3 players. The manufacturing, communications, and consumer electronics industries benefit significantly from the embedded systems, allowing the embedded systems to command a greater importance in the market today.

There is a growing need to add network connectivity into every embedded systems, particularly with Ethernet or Wi-Fi function. Based on reports by Forrester Research, by the year 2010, up to 95% of the devices used to access the Internet will be non-PC devices that use an embedded system. In other words, the network connectivity of Machine-to-Machine (M2M) communication will be the primary market demand for the embedded networking system for the years to come.

Ethernet's ease of use, cost effectiveness, high bandwidth, stability, security, and a high degree of compatibility makes it a natural solution for accessing the Internet. In addition to SOHO and corporate networks, Ethernet is gradually making its way into consumer and household devices as a primary way to access the Internet, satisfying both the stability and reliability demanded by industrial users and the bandwidth and multimedia connectivity demanded by home consumers.

There are six different embedded Ethernet solutions, as can be seen in the figure above. The first solution targets those devices with micro-controller embedded with PCI bus interface. The PCI bus Ethernet MAC+PHY controller is used to connect these devices to Ethernet. Nonetheless, there are only about 20% of the 32-bit micro-controllers that have an internal PCI bus, the majority of 8 or 16-bit micro-controllers do not use PCI bus for the cost reason. The micro-controllers normally use SRAM-like bus interface to extend the memory access and to inter-connect with the peripherals. In order to support PCI bus, the micro-controller will need extra more pins, which in turn adding more cost for the system. Also, the advanced PCI bus is designed mainly for the PC systems, and some of its features are indeed redundant for many embedded systems, such as plug-and-play.

The second solution targets devices with micro-controller, which comes without PCI bus interface, but with a non-PCI or SRAM type interface. In this case, the highly integrated Non-PCI bus Ethernet MAC+PHY controller is used to connect these devices to Ethernet. This solution provides the easiest way to connect the embedded system to the network for the reason that majority of the micro-controller all support Non-PCI local bus interface. The engineers are able to design very low cost, and yet high performance embedded systems, which offer remotes access capabilities in addition to Internet connectivity. This solution is suitable for home appliances, factory/building automation, industrial equipments, security systems, remote control/monitoring/management, streaming media, and multimedia networking. In addition, broadband applications such as POS terminals, WLAN AP, broadband router, VoIP, content distribution, IP STB, IP camera, digital video recorder, DVD recorder/player, high definition TV (HDTV), digital media adapter, game consoles, home gateway, and IPTV, etc., can also find this solution attractive and cost effective.

The third solution is targeted those devices which require two Ethernet connections simultaneously while being able to preserve existing processor hardware and software development investment. In this case, the highly integrated two-port Non-PCI bus Ethernet MAC+PHY controller is used to connect these devices to Ethernet through devices' internal layer 2 switching hardware. Normally in these devices, one port is used to connect to LAN while the other port is used to connect to WAN.

The fourth solution is for those devices with micro-controllers embedded either one or two port Ethernet MAC interfaces. With external Ethernet PHY controller, these devices can be easily connected to Ethernet.

The fifth solution is those micro-controllers, which already integrate both Ethernet MAC and PHY functions, the so-called single chip SoC solution. This solution makes the devices very compact, and is suitable for home appliances, factory/building automation, industrial equipments, security systems, remote control/monitoring/management, and streaming media applications such as POS terminals, vending machines, IP camera, Internet radio, automatic meter reading, environmental monitoring systems, network sensors, networked UPS, Serial to Ethernet adapter, and Ethernet to ZigBee bridge, can also find this solution quite attractive in cost, space, and power consumption-wise.

The sixth solution targets those micro-controllers that already have USB Host interface embedded. In this case, an internal or external USB-to-LAN controller can be used to connect these devices to Ethernet. This is exactly the USB-to-LAN solution described above for mobile devices. This solution is suitable for computer peripherals, handheld devices, home electronics and appliances, streaming media, broadband media, and other consumer electronics such as USB to Ethernet converter, USB WiMax adaptor, docking stations, cradles, and USB KVM Ethernet switches etc.

In summary, this white paper presents several ways of connecting mobile devices and the embedded systems to the network, particularly the Ethernet. As the need of network connectivity for the embedded systems are becoming more and more popular today, this will certainly change the dynamics of the whole embedded systems markets. This will also create a vast opportunity for the embedded systems and its providers for the future to come.

About the Authors

Jason Wang is director of Marketing at ASIX Electronics. He can be reached at:

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