CompactPCI Serial has proven to be a beneficial technology upgrade for a number of embedded systems designers accustomed to working with the legacy CompactPCI platform. Not only does CompactPCI Serial bring modern serial interfaces and a ruggedized connector scheme into play, but it also provides significant cost advantages while adhering to many known design principles, lessening a developer’s need to learn a new and complex technology.
It’s no wonder CompactPCI systems have proliferated during the last few decades. They can be built using standard components and can run practically any operating system as well as thousands of application software packages without modification. Because of this, CompactPCI is a widely accepted — and utilized — technology platform in countless markets from telecommunications and computer telephony to industrial automation, real-time data acquisition and military systems.
When CompactPCI started failing to keep pace with current computing requirements, it seemed a shame to just toss aside a proven technology in favor of a different computing scheme. Instead, those computing needs were evaluated, the platform was modified and a solid, cost-effective, long-term solution was formed, positioning CompactPCI as a viable platform for applications well into the future. Thus, CompactPCI PlusIO and CompactPCI Serial were born.
A Trifecta of Computing Specs
Part of the quick adoption rate of CompactPCI Serial (PICMG CPCI-S.0) is due to its sister specification, CompactPCI PlusIO (PICMG 2.30), which enables the migration from legacy CompactPCI (PICMG 2.0) to serial-based systems, as time and money allow. CompactPCI PlusIO forms a link between the old and the new. This new family of specifications is a well-rounded set that incorporates the past, present and future needs of embedded computing systems using CompactPCI technologies (Figure 1).
From the beginning: As data requirements in embedded systems began to increase, CompactPCI systems were limited to a parallel bus design, yet system designers were being called on to provide greater bandwidth and higher data transfer rates among the input/output (I/O) resources. Older systems could not take advantage of the high-speed serial point-to-point communications needed to move all system information along effectively.
The challenge was developing a new standard that preserved the large number of installed CompactPCI-based systems as well as the knowledge base of designers already familiar with CompactPCI, while bringing systems in line with current data requirements. This was addressed by developing two separate standards, CompactPCI PlusIO and CompactPCI Serial, to move CompactPCI-based systems into the modern era.
Designed with a purpose: CompactPCI PlusIO was deliberately developed using the same 19" mechanics as legacy CompactPCI, while allowing for the integration of serial-based systems. This very calculated adaptation of the original specification addressed the challenges of maintaining existing systems, and therefore the time and money invested in those systems. It also preserved the reliability, robustness and maintenance-friendly attributes of the original CompactPCI.
While compatible with the interim CompactPCI PlusIO solution, CompactPCI Serial is geared towards completely new systems based solely on serial communications. But because of the link through the CompactPCI PlusIO structure, older systems can implement serial technologies on an as-needed basis — whether driven by functionality requirements or budgetary considerations.
The pivotal change in CompactPCI PlusIO that enables the legacy systems to work with serial-based ones is the use of an Ultra Hard Metric (UHM) connector with specific features to accommodate the performance demands of serial communications. While accommodating the high-speed signals increasingly required in today’s embedded systems, the new UHM connector still mates with the hard metric headers currently used in original CompactPCI system backplanes, enabling operation in legacy systems (Figure 2).
Because the original hard metric headers could not support high-speed differential signals like PCI Express or SATA, the UHM connector incorporates specific physical features to accommodate the needs of these higher data transfer speeds — up to 7 Gb/s — without crosstalk. The new connector includes individually shielded pins as well as 100 Ohm impedance suited for transmitting single-ended as well as differential signals.
The original CompactPCI standard called for a single 220-pin connector to provide all power, ground, 32-bit, and 64-bit PCI signals. That connector consisted of two halves — the lower half (110 pins) called J1, and the upper half (also 110 pins) called J2.
Backplanes use male (pin) connectors and plug-in boards use female (socket) connectors. User I/O pins were not defined by the PICMG 2.0 standard. In order to support serial communications interfaces, however, CompactPCI PlusIO does identify specific assignments for the J2 connector user pins that were reserved for 32-bit system slots in the original standard.
CompactPCI PlusIO uses these I/O signals to provide a variety of popular interface options to the backplane:
- 4 PCI Express x1 links
- 4 SATA
- 4 USB 2.0
- 2 Ethernet 1000Base-T
It can also support four PCI Express Type 2 peripheral boards.
CompactPCI Across the Board
As the technology platform has evolved, CompactPCI has not only maintained its foothold in the stable base of applications where it has always had a strong foundation, but has branched out into new industry segments requiring rugged, maintenance-free computing that is scalable and cost-effective. CompactPCI PlusIO and CompactPCI Serial were developed for much higher computing requirements, a trend that is on the path of continued growth for both existing markets and those yet to be developed.
Manufacturing: CompactPCI has its roots in the industrial sector, with many systems already installed and functioning for several years. Fluctuating production schedules and facility needs often factor into daily operations.
Manufacturing plants will typically need to accommodate varying computing requirements, making a modular 19" system that can go from CompactPCI to CompactPCI PlusIO and ultimately CompactPCI Serial ideal. From a station master system on the plant control level to redundant station master units, the enhancements to the CompactPCI technology can handle all the capabilities for efficient plant operation.
Transportation: The railway industry is another good example of an industry with strong ties to CompactPCI that has developed in scope and is finding new uses for CompactPCI-based technologies. Today’s railcars are expected to not only function efficiently and safely, but also provide passenger conveniences, such as telephony services, up-to-date travel information, and entertainment.
The same wireless networks running uploads and downloads from personal cell phones are exchanging train diagnosis data with the depot, getting route information and transmitting data from surveillance systems.
With the incorporation of a CompactPCI PlusIO component, an existing system based on CompactPCI can be upgraded to serial as needed — in other words, as travelers demand more data access during their trip, as the number of railcars sharing a track increases, etc. This flexibility enables technology upgrades without disrupting the continuity of the application where original CompactPCI hardware components are still performing acceptably.
Another aspect of train travel that requires flexible computing is the surveillance system, now an integral part of most railway operations. Not only are images captured and stored on a digital video recorder itself for security purposes, but information needs to be sent in real time between train and land-based systems for non-critical activities such as announcements, timetables, CCTV and location updates.
Mobile networks: A newer industry that has seen rapid development in the past few years is mobile networks. Testing the Quality of Service (QoS) globally for a single network means system configurations will differ depending on the location, leading to various computing requirements.
And because of the different growth patterns of mobile networks worldwide, scalability is an important consideration. Embedded systems based on CompactPCI are not only used for the preparation and execution of network tests, but also serve as a central database of those test cases and scenario libraries. Most of these systems need to be operated via a simple Web interface, as signal towers can be situated in remote and inaccessible locations.
Cinema: An important innovation in the film industry was the incorporation of a high-performance Intel mobile architecture into the video cameras used to shoot footage. Digital cinema camera systems were no longer limited to the dedicated hardware and now had the flexibility of software upgrades and the connectivity options available when using a general-purpose embedded processing platform.
Cameras based on embedded CompactPCI, CompactPCI PlusIO and CompactPCI Serial hardware can take advantage of the sufficient ruggedization, processing and graphics performance and IP connectivity benefits provided by the technology platform. Filmmakers can shoot film footage directly to disk at full HD (1920×1080) or greater cinema resolutions (2048×1152), changing the way movies are made.
This has also given filmmakers more flexibility in locations they can use to capture the footage they are after. Shooting movies under extreme conditions, like in deserts, can be a big challenge for recording equipment, but a rugged camera control unit based on COTS 3U CompactPCI and CompactPCI Serial will record reliably in those harsh operating conditions.
The low power consumption of this type of system will not only reduce heat from the camera — a concern to the cameraman whose ear is next to the unit for extended periods of time — but also will extend battery life for longer time in the field.
Not only are new application areas employing CompactPCI Serial systems, but with CompactPCI PlusIO’s ability to marry legacy systems with serial-based ones, traditional industries are migrating older, established systems to ones that offer the latest technology requirements (Figure 3).
In the Winner’s Circle
The path for CompactPCI-based systems is clear. Designers will long be able to develop systems that can build on the existing infrastructure that’s already in place while moving to newer, faster systems as the demands of the application shift. Modern serial technologies expertly combine with CompactPCI’s cost-effective robust structure for newer systems, making new inroads for this technology platform as well.
This article was written by Barbara Schmitz, CMO, MEN Mikro Elektronik (Nuremberg, Germany). For more information, Click Here