Open source comes to high speed Internet chips

Open source ideas are moving from operating systems such as Linux to the chips being used for the latest DSL equipment. Nick Flaherty reports.

The idea of open source ­ freely available source code that is modified by anyone ­ has been pioneered by the large number of developers of the Linux operating system. But the idea has been recently making its way into the world of communications and chips for high speed Digital Subscriber Line (DSL) systems

Agere Systems, formerly the Microelectronics division of Lucent Technologies, has developed an ADSL chipset that it says is the first to support the Linux operating system.

Although Linux started as an alternative operating system for the PC, manufacturers of residential gateways and home networking equipment are now starting to use it in these embedded systems because of its low licensing fees and its open software code architecture. While this promotes interoperability among different systems and appliances, so far there has been no chipset and driver to support ADSL on these systems.

The Agere chipset consists of a PCI ADSL network interface card based around Agere's client access DSP chips for both the 8Mbit/s G.dmt full rate standard and the 2Mbit/s splitterless G.lite standard.

In addition to supporting Linux operating systems, Agere's software supplied with the chip set also offers communications equipment manufacturers an adaptation layer for ATM and segmentation and reassembly of ATM packets functions; network protocols including point-to-point protocol (PPP) over Ethernet and ATM; and Internet Protocol over ATM bridging and routing functions. The software also includes an extensive diagnostics tool to help the modem user and the service provider to improve modem connectivity and check the status of ADSL network connections.

The PCI card has been qualified for use in the Interoperability Showcase sponsored by the DSL Forum at the recent Consumer electronics show, showing compatibility with DSLAM equipment from a range of operators.

Massachusetts-based Ucentric Systems will use the new chipset in the company's hardware reference design, which is available to original equipment manufacturers designing home networking products.

"Ucentric is the first to offer a Linux-based home networking solution that's available today,“ said Rick Edson, chief executive officer of Ucentric Systems. "We have chosen Agere Systems' chip set solution for use in our hardware reference design because Agere is ready to offer us support for that platform right now.“

"Our customers, such as Ucentric Systems, now have a broader range of operating system choices to meet their DSL gateway needs,“ said Bob Rango, general manager with Agere Systems. "Linux offers a platform to deliver these features in an open environment and in a cost effective way.“

But the open source approach is even getting into the chip level. Media processor designer Metaflow Technologies has developed a system on a chip architecture based around an open source processor core developed by the European Space Agency. One of the first target markets for the chip is systems built around ADSL.

Built around the open AMBA bus architecture developed by Advanced RISC Machines, Metaflow's Implosion platform consists of basic and application specific hardware components that can be pre-assembled and verified, shortening time to market and lowering costs. The platform can be customized by Metaflow to produce a full custom IC that meet specific needs by adding or removing validated application-specific components or by adding third party or full-custom blocks.

"The Linux phenomenon has proven that Open Source is an effective way for producing world-class IP, and has created legitimate business models for commercial companies adding value around this IP,“ said Cosma Pabouctsidis, Metaflow's marketing director, "The same is now happening with hardware IP and Metaflow intends to be at the forefront of this revolution as it applies to Systems on Chip.“

Implosion is powered by the Leon-1 CPU core developed by the European Space Agency. It is a 32bit RISC processor core whose VHDL source code is freely available on the Internet and modeled after the architecture and Instruction Set of the IEEE 1754 Sparc V8 instruction set standard. It uses a five-stage pipeline for operation at speeds in excess of 125MHz, 8 register windows, a coprocessor extension bus, a separate data and instruction cache, and an AMBA bus interface.

The basic components of the Implosion platform include two 10/100 Ethernet media access controllers (MAC) with DMA, a line-speed DES/3DES data encryption engine, on-chip SRAM, and an SDRAM and Flash controller for external Memory. The dual-Ethernet architecture allows Implosion-based devices to perform simple IP routing and switching function. Other foundation blocks include a UART, general-purpose timers, watchdog timer, interrupt controller, and multichannel DMA controller.

Among the wired and portable products that can be built on the Implosion platform are Web-browsing appliances, e-mail stations, home servers and gateways, Internet music and video distribution devices, as well as equipment for Internet telephony.

Implosion's optional application-specific components include USB host controller, USB device controller, and a color LCD controller with programmable resolution from quarter-VGA (320 x 200 pixels) to XGA (1024 x 768 pixels). Other components are available from a third-party IP catalogue, or can be custom-designed by Metaflow. Optional digital signal processing (DSP) extensions are also available to boost performance in multimedia and communication algorithms.

Metaflow supports Implosion with an prototyping and emulation board based around a field programmable chip that can be used to evaluate the Leon core, validate custom Systems on Chip and serves as a near real-time software development platform.

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