Sometimes technologies converge to produce a whole that's decidedly greater than the sum of its parts. Bus-Tech's highly flexible Embedded Linux Controller achieves just such a synergy. The highly flexible network appliance device consists of a relatively simple PowerPC based single-board computer with four PCI Mezzanine Card (PMC) expansion sockets, packaged in a 1U rackmount package, and powered by… MontaVista Hard Hat Linux. Its elegant simplicity, I/O modularity, and open-source embedded operating system combine to create what might be called the “Swiss army knife” of 1U appliances. (See photo.)

Bus-Tech, a 13-year old specialist in mainframe connectivity solutions, created the new Embedded Linux Controller in order to address a wide range of emerging storage and network appliance applications. Typical uses envisioned for the device are as Internet servers (web, cache, DNS, FTP, news, mail, etc.), network firewalls, VPN gateways, ISP access devices, Storage Area Network (SAN) bridges and routers, and Network Attached Storage processors. But many more possibilities exist, including such applications as industrial control, data acquisition, and medical electronics. Bus-Tech intends to offer the Embedded Linux Controller to original equipment manufacturers (OEMs) both as a complete 1U system, and as a standalone single-board computer without packaging.

What's inside?

The Embedded Linux Controller includes the following internal features and functions:

• 300 MHz PowerPC processor (Motorola PPC 740)
  
• Two internal 32-bit PCI buses (via Galileo 64130 host bridge)
  
• 128 MB SDRAM with ECC
  
• 16 MB Flash memory (emulates a hard disk)
  
• RS232C serial port
  
• Four character display
  
• Reset switch
  
• Temperature sensor
  
• Four slots for PMC (IEEE-1386) I/O expansion modules
  
• Packaged in a 1U rack mount chassis with power supply and fan
  
• Supported by MontaVista Hard Hat Linux

Rather than burdening the base system with a large number of predefined built-in I/O interfaces, Bus-Tech instead chose to provide four configurable PMC slots. That modular approach allows OEMs to adapt the system to unique specialized applications in a simple plug-and-play manner. In general, PMC modules are more rugged than normal desktop PCI cards, so the use of PMC results in increased overall system reliability as compared with traditional embedded motherboard designs. Another nice feature of PMC modules is that each comes with built-in interface connectors mounted on an I/O bracket, making system packaging simple and clean.

The PMC standard was originally developed for Eurocard packaging schemes and is the standard mezzanine expansion technology used in most CompactPCI systems (often used in telecom and industrial environments). Bus-Tech's use of PMC to expand an embedded single-board computer, packaged in a 1U case, represents a relatively unique application of PMC technology.

Sliding down the slippery slope to Linux

Although all previous Bus-Tech products have been based on the pSOS real-time operating system, the company decided to switch to embedded Linux in order to take advantage of its extensive and readily available driver and system-level open source software. Having come from a pSOS-style embedded operating system past, Bus-Tech naturally desired to retain embedded OS features in the new system design. This included the ability to use Flash memory for system boot and file system support, to avoid reliability compromises due to magnetic media drives. Other embedded features include a high availability framework and headless operation (i.e. without display and keyboard). To expedite the bring-up of an embedded Linux that could meet these and other system requirements, Bus-Tech turned to embedded Linux provider, MontaVista Software.

What drove the specific selection of embedded Linux partner? Ralph Armstrong, Bus-Tech VP of product management, explains that the company “selected MontaVista based on their extensive experience with the PowerPC processor, and also because of MontaVista's highly proactive professional services.” “They made the transition from pSOS to Hard Hat Linux extremely smooth. In just two weeks, our platform was up and running with Hard Hat Linux. Our engineers were extremely impressed with the knowledge and capabilities of the MontaVista team,” adds Armstrong.

According to Armstrong, Bus-Tech will continue to support pSOS on older product lines, but intends to use embedded Linux in as many future product developments as possible. “We think open source software is a real asset,” says Armstrong. “Open source is an enabler for both us and our OEM customers. Since our business is based on selling hardware, not software, having open source is extremely valuable since it allows us to make the exact adjustments we require to get our hardware to work the way we want.”

Bus-Tech plans to begin shipping the Embedded Linux Controller during August, 2000. The company plans to develop a new family of specialized PMC modules and associated Linux drivers to go with the new system, and will also support custom-specific system- and board-level requirements.

 
This article was originally published on LinuxDevices.com and has been donated to the open source community by QuinStreet Inc. Please visit LinuxToday.com for up-to-date news and articles about Linux and open source.