AlphaPowered CompactPCI + VME? Almost turnkey! by Glen Lowry, Alta Technology The combination of CompactPCI® and VME represents an extremely attractive alternative for those applications caught between older VME applications and more current CompactPCI environments. This article describes an application where the most effective solution merges the two worlds of CompactPCI and VME - in a single chassis. Today's real-time problems Many real-time problems are solved by storing real-time data until computers can analyze it in non-real-time. With the introduction of faster processors such as Digital's Alpha 21164™, data can be processed as it is received. However, an AlphaPowered™ CompactPCI system running under Windows NT™ or Linux is not exactly a "hard real-time" system. The problems of speed and real-time blur with the Alpha, but some tasks still belong with the VME hardware that has been used for years. CompactPCI, for all its advantages and benefits, still lags behind VME in the number and variety of peripherals available for data acquisition, embedded control and other speedy applications. However, the "best available" solution is often found not on either platform, but on a combination of the two. Real-time VME peripherals connected to off-the-shelf CompactPCI computing provided an optimal solution to one customer's system requirements. Old data, new computation. The customer, White Sands Missile Range Army Research Labs, needed the power of a 500 MHz Alpha - expandable to possibly two or more processors in a clustered computing environment. Incoming analog data was to be handed to a Celerity Systems Inc. Access256™ VME card, digitized, and moved to the Alpha across a Front Panel Data Port (FPDP) interface. This data movement is pretty straightforward -- but the data would have to be processed and recorded to disk before the next timestep occurred. The mixture of VME and PCI peripherals proved to be more challenging. For example, communications with remote systems through the SCRAMNet® interface were used to signal the receipt and processing of the Analog data and obtain real-time parameters. Coordinating the VME and CompactPCI data exchange relied on low-latency communications between Alpha and VME peripherals through an embedded VME controller. The [customer mandated] use of Microsoft Windows NT operating system in a real-time application was made possible by segregating the real-time and the computation to separate backplanes - with the NT Alpha running on the CompactPCI backplane. The final problem - a space constraint - was solved by combining the two back planes and peripherals in a single 19" rack mounted chassis. The solution: mix and match! Alta proposed the AlphaPowered system with both back planes, mixed peripherals, and the 19" chassis, and was engaged to perform the integration. The accompanying sidebar describes the components which were used. Of the many component suppliers available, only those actually used in this system are presented - to show the diverse system flavors which can be created with today's off-the shelf products. Running the application The NT operating system, straight from the NT CDROM, is installed on the EIDE drive and boots the system on power-up. Startup programs also boot the VME controller, check for network connections and confirm communications with the real-time source. The customer supplied programs, developed in the Windows® environment, make calls to a simple, message passing API to communicate with the VME peripherals through Alta's programmable VME controller. Other controllers can be used - for example, DEC's VME Alpha products or VME-hosted PC's. AlphaPowered CompactPCI Alta's SBC/P164™ Alpha Single Board Computer provides the highest computation capability available in the CompactPCI market and represents an exceptional computing solution. With up to 1 GByte of DIMM memory, there is adequate memory for most applications and at 500 MHz, it's performance is similar to Digital's highly respected workstations. Unlike many of the low-cost Alpha workstations, the SBC/P164's 21172 chipset provides a 256-bit path to memory and an unconstrained memory path from the 32/64-bit PCI bus. The architecture heavily favors PCI transfers at the same time as intensive computation. Heat? The 500 MHz Alpha (38 Watts) is cooled by a fan embedded in a heatsink. The combination of fan and heatsink means that most CompactPCI or VME chassis will have little trouble keeping it cool. The scaleable nature of clustered computing with Alpha processors relies on the high communications bandwidth available through peripherals on the CompactPCI bus. Using high speed communications between processors, the computation can be "farmed out" to multiple processors. In addition to built-in Fast Ethernet (10/100 Mbit), two other communications technologies are available from Alta. Gigabit Ethernet (PacketEngines -- www.packetengines.com) provides up to 50 Mbytes/second of switched TCP/IP communications and Myrinet™ PMC modules (Myricom Inc. - www.myri.com) provide 75-125 Mbytes of raw data between the processors. With such communications capabilities, farms with hundreds of processors have been constructed by large supercomputing users. Alta provides a 2-slot backplane (3 physical slots) which supports an entire processing "node"- up to 6 processors in a 19" chassis - to enhance the computation of an existing system. Off-the-shelf backplanes with up to seven peripheral slots are also available from most vendors. The result? A new product! Alta's success in packaging Celerity's Access256 board with an AlphaPowered CompactPCI system created a new product: AltaAccess.™ This integrated product provides the base for an entire range of build-it-yourself VME + CompactPCI systems. AltaAccess includes CompactPCI Alpha and VME controller, with options for all of the other components. Its like having the newest electronic Tinkertoys® which can be used to make structures of every size and function. The newest toys just happen to use CompactPCI. Glen Lowry (ski@altatech.com) is the president and co-founder of Alta Technology. Build it yourself! What does it take to build this system? Although Alta now sells the system, already integrated with optional components, here's what is needed for a "make-it-yourself" solution. The components are listed with references to the manufacturer's home page. CompactPCI Backplane SBC/P164™ Alpha Single Board Computer (Alta Technology "Alta" -- www.altatech.com) This 64-bit, 6U CompactPCI board provides all of the functionality you would expect of an SBC - keyboard, mouse, dual serial port, parallel port, floppy and dual EIDE ribbon cable connectors (plus a front panel connector), plus a PMC connector on the board. The 500 MHz Alpha processor provides enough processing power for many applications and supports clustered computing (with multiple Alpha's) as well. The board can be shipped with either NT or Linux operating system installed. Combination I/O card (Alta's CPCI/HD-NET-PMC™) This 6U card includes the 10/100 Ethernet interface, a 4.2 GByte EIDE drive (larger sizes are available), and a PMC slot that can be used for any of the peripherals. The Ethernet interface connects the entire system to an outside network. SVGA PMC Graphics module (Alta) The TGA chip on this module is the same one supported on most DEC workstations. Other graphics modules are available from Alta and other suppliers, with the 3Dlabs® Permedia®2 and GLINT® chipsets being among the most interesting. Dual PMC carrier (Alta's CPCI/PMC-XP™) CompactPCI expansion is often implemented on PMC modules, plugged onto carrier cards such as this one. With two PMC slots per card, expansion can usually be handled in a standard (7 peripheral slot) configuration. HAI/PMC2™ Host Adapter Interface (Alta) This PMC module supplies the connection to the MVPA VME controller. It's 20 Mbit/sec link and low latency (around 1 microsecond) provides the "slow speed" connection for controlling the VME side of the system. The reset and reboot functions from the HAI/PMC2 allow the Alpha to reboot the entire VME side and download different programs on the fly. FPDP/CPCI™ Front Panel Data Port (FPDP) interface (Alta) Many existing signal processing and data acquisition applications can utilize an FPDP interface to quickly move data into the CompactPCI environment. This 6U card supports FPDP rates of over 75 Mbytes/Second. Multiple cards can be used to achieve marginally faster (up to 125 Mbytes/Sec) speed on a 32-bit bus. A PCI version of this card can be used in a workstation. UltraSCSI PMC Module (Alta) For applications where large amounts of storage are required, the UltraSCSI PMC module can be used to add large SCSI disks or RAIDs. GPIB PMC Module (National Instruments -- www.daq.com) This module can be used to interface with most GPIB (IEEE-488) devices. For this application, scopes, voltmeters, and other analytical equipment were "hung" off the GPIB. The user code on the Alpha communicates through a standard API from National Instruments. VME BACKPLANE MVPA™ VME Controller (Alta's HSI/MVPA™ - www.altatech.com) This VME slot-zero bus master provided an inexpensive and easy-to-use alternative to a second SBC, Disk and monitor. Because it can be booted from the Alpha (with drivers and run-time libraries supplied by Alta) the embedded processor can be program-med for a variety of tasks and reloaded on the fly. Additional 20 Mbit link communications over copper or optical fiber permit it to be daisy chained to remote chassis controlled by other MVPA cards. Access256™ (Celerity Systems, Inc. -- www.csidaq.com) The Access256(TM) VME/VXI motherboards from Celerity Systems, Inc. provide flexible high speed memory control for data recording, storage, and playback at rates up to 160 Mbytes a second. Daughtercards attach to the motherboard for a range of input and output formats and configurations. Ultrafast 8/10/12-bit analog I/O, serial and 8/16/32-bit parallel digital I/O, and digital tuners are included in Celerity Systems' daughtercard offering. Alta's solution provided the customer with the multi-channel Analog signal which was converted to digital, framed, and sent out the FPDP daughtercard module. SCRAMNet+® 6U VME card (Systran --www.sys-tran.com) This 150-megabit/second fiber optic card is part of a communication system designed for use in real-time computer systems. SCRAMNet+ is optimized for the high-speed transfer of small packets of data among computers when low-latency data transmission is required. SCRAMNet is ideally suited for applications including: simulation, telemetry, robotics, data acquisition, instrumentation and control, and virtual reality. Chassis and Backplanes There are many suppliers of chassis for both Compact-PCI and VME. Alta has used chassis from Elma, Shroff, Zero, and others. A ruggedized rackmounted chassis from American Ruggedized Enclosures, Inc. can provide extra cooling in a field-deployable chassis. The most important issues are generally cooling and power (of course!) At least 200 Linear Feet per Minute (LFM) of air flow must be supplied to each of the slots (some suppliers are now specifying up to 400 LFM). The 3.3V power necessary for the CPCI backplane (and the Alpha) is built-in by each of these suppliers.