Advanced Telecommunications Computing Architecture[1] (ATCA or AdvancedTCA) is the largest specification effort in the history of the PCI Industrial Computer Manufacturers Group (PICMG), with more than 100 companies participating. Known as AdvancedTCA, the official specification designation PICMG 3.x (see below) was ratified by the PICMG organization in December 2002.[2] AdvancedTCA is targeted primarily to requirements for "carrier grade" communications equipment, but has recently expanded its reach into more ruggedized applications geared toward the military/aerospace industries as well.[3] This series of specifications incorporates the latest trends in high speed interconnect technologies, next-generation processors, and improved Reliability, Availability and Serviceability (RAS).
The PCI Industrial Computer Manufacturers Group (PICMG) is a consortium of over 150 companies. Founded in 1994, the group was originally formed to adapt PCI technology for use in high-performance telecommunications, military, and industrial computing applications, but its work has now grown to include newer technologies. PICMG is distinct from the similarly named and adjacently-focused PCI Special Interest Group (PCI-SIG).
In telecommunication, a "carrier grade" or "carrier class" refers to a system, or a hardware or software component that is extremely reliable, well tested and proven in its capabilities. Carrier grade systems are tested and engineered to meet or exceed "five nines" high availability standards, and provide very fast fault recovery through redundancy.
An AdvancedTCA board (blade) is 280mm deep and 322mm high. The boards have a metal front panel and a metal cover on the bottom of the printed circuit board to limit electromagnetic interference and to limit the spread of fire. The locking injector-ejector handle (lever) actuates a microswitch to let the Intelligent Platform Management Controller (IPMC) know that an operator wants to remove a board, or that the board has just been installed, thus activating the hot-swap procedure. AdvancedTCA boards support the use of PCI Mezzanine Card (PMC) or Advanced Mezzanine Card (AMC) expansion mezzanines.
A printed circuit board (PCB) mechanically supports and electrically connects electronic components or electrical components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. Components are generally soldered onto the PCB to both electrically connect and mechanically fasten them to it.
Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data. Both man-made and natural sources generate changing electrical currents and voltages that can cause EMI: ignition systems, cellular network of mobile phones, lightning, solar flares, and auroras. EMI frequently affects AM radios. It can also affect mobile phones, FM radios, and televisions, as well as observations for radio astronomy and atmospheric science.
A PCI Mezzanine Card or PMC is a printed circuit board assembly manufactured to the IEEE P1386.1 standard. This standard combines the electrical characteristics of the PCI bus with the mechanical dimensions of the Common Mezzanine Card or CMC format.
The shelf supports RTMs (Rear Transition Modules). RTMs plug into the back of the shelf in slot locations that match the front boards. The RTM and the front board are interconnected through a Zone-3 connector. The Zone-3 connector is not defined by the AdvancedTCA specification.
Each shelf slot is 30.48mm wide. This allows for 14-board chassis to be installed in a 19-inch rack-mountable system and 16 boards in an ETSI rack-mountable system. A typical 14-slot system is 12 or 13 rack units high. The large AdvancedTCA shelves are targeted to the telecommunication market so the airflow goes in the front of the shelf, across the boards from bottom to top, and out the rear of the shelf. Smaller shelves that are used in enterprise applications typically have horizontal air flow.
A rack unit is a unit of measure defined as 13⁄4 inches (44.45 mm). It is most frequently used as a measurement of the overall height of 19-inch and 23-inch rack frames, as well as the height of equipment that mounts in these frames, whereby the height of the frame or equipment is expressed as multiples of rack units. For example, a typical full-size rack cage is 42U high, while equipment is typically 1U, 2U, 3U, or 4U high.
Telecommunication is the transmission of signs, signals, messages, words, writings, images and sounds or information of any nature by wire, radio, optical or other electromagnetic systems. Telecommunication occurs when the exchange of information between communication participants includes the use of technology. It is transmitted through a transmission media, such as over physical media, for example, over electrical cable, or via electromagnetic radiation through space such as radio or light. Such transmission paths are often divided into communication channels which afford the advantages of multiplexing. Since the Latin term communicatio is considered the social process of information exchange, the term telecommunications is often used in its plural form because it involves many different technologies.
The small-medium AdvancedTCA shelves are targeted to the telecommunication market; for the lab research operation, some shelves have an open cover in order to make testing easier.
Backplane architecture
The AdvancedTCA backplane provides point-to-point connections between the boards and does not use a data bus. The backplane definition is divided into three sections; Zone-1, Zone-2, and Zone-3. The connectors in Zone-1 provide redundant −48VDC power and Shelf Management signals to the boards. The connectors in Zone-2 provide the connections to the Base Interface and Fabric Interface. All Fabric connections use point-to-point 100 Ω differential signals. Zone-2 is called "Fabric Agnostic" which means that any Fabric that can use 100 Ω differential signals can be used with an AdvancedTCA backplane.[4]
The connectors in Zone-3 are user defined and are usually used to connect a front board to a Rear Transition Module. The Zone-3 area can also hold a special backplane to interconnect boards with signals that are not defined in the AdvancedTCA specification.
The AdvancedTCA Fabric specification uses Logical Slots to describe the interconnections. The Fabric Switch Boards go in Logical Slots 1 and 2. The chassis manufacturer is free to decide the relationship between Logical and Physical Slots in a chassis. The chassis Field Replaceable Units (FRU) data includes an Address Table that describes the relationship between the Logical and Physical slots.
The Shelf Managers communicate with each board and FRU in the chassis with IPMI (Intelligent Platform Management Interface) protocols running on redundant I²C buses on the Zone-1 connectors.
The Intelligent Platform Management Interface (IPMI) is a set of computer interface specifications for an autonomous computer subsystem that provides management and monitoring capabilities independently of the host system's CPU, firmware and operating system. IPMI defines a set of interfaces used by system administrators for out-of-band management of computer systems and monitoring of their operation. For example, IPMI provides a way to manage a computer that may be powered off or otherwise unresponsive by using a network connection to the hardware rather than to an operating system or login shell. Another use case may be installing a custom operating system remotely. Without IPMI, installing a custom operating system may require an administrator to be physically present near the computer, insert a DVD or a USB flash drive containing the OS installer and complete the installation process using a monitor and a keyboard. Using IPMI, an administrator can mount an ISO image, simulate an installer DVD, and perform the installation remotely.
I²C, pronounced I-squared-C, is a synchronous, multi-master, multi-slave, packet switched, single-ended, serial computer bus invented in 1982 by Philips Semiconductor. It is widely used for attaching lower-speed peripheral ICs to processors and microcontrollers in short-distance, intra-board communication. Alternatively I²C is spelled I2C or IIC.
The Base Interface is the primary Fabric on the Zone-2 connectors and allocates 4 differential pairs per Base Channel. It is wired as a Dual-Star with redundant fabric hub slots at the core. It is commonly used for out of band management, firmware uploading, OS boot, etc.
The Fabric Interface on the backplane supports many different Fabrics and can be wired as a Dual-Star, Dual-Dual-Star, Mesh, Replicated-Mesh or other architectures. It allocates 8 differential pairs per Fabric Channel and each Channel can be divided into four 2-pair Ports. The Fabric Interface is typically used to move data between the boards and the outside network.
The Synchronization Clock Interface routes MLVDS (Multipoint Low-voltage differential signaling) clock signals over multiple 130 Ω buses. The clocks are typically used to synchronize telecom interfaces.
Update Channel Interface is a set of 10 differential signal pairs that interconnect two slots. Which slots are interconnected depends on the particular backplane design. These are signals commonly used to interconnect two hub boards, or redundant processor boards.
Fabrics
The Base Interface can only be 10BASE-T, 100BASE-TX, or 1000BASE-T Ethernet. Since all boards and hubs are required to support one of these interfaces there is always a network connection to the boards.
The Fabric is commonly SerDes Gigabit Ethernet, but can also be Fibre Channel, XAUI 10-Gigabit Ethernet, InfiniBand, PCI Express, or Serial RapidIO. Any Fabric that can use the point-to-point 100 Ω differential signals can be used with an AdvancedTCA backplane.
AdvancedTCA blades can be Processors, Switches, AMC carriers, etc. A typical shelf will contain one or more switch blades and several processor blades.
When they are first inserted into the shelf the onboard IPMC is powered from the redundant −48V on the backplane. The IPMC sends an IPMI event message to the Shelf Manager to let it know that it has been installed. The Shelf Manager reads information from the blade and determines if there is enough power available. If there is, the Shelf Manager sends a command to the IPMC to power-up the payload part of the blade. The Shelf Manager also determines what fabric ports are supported by the blade. It then looks at the fabric interconnect information for the backplane to find out what fabric ports are on the other end of the fabric connections. If the fabric ports on both ends of the backplane wires match then it sends an IPMI command to both blades to enable the matching ports.
Once the blade is powered-up and connected to the fabrics the Shelf Manager listens for event messages from the sensors on the blade. If a temperature sensor reports that it is too warm then the Shelf Manager will increase the speed of the fans.
The FRU data in the board contains descriptive information like the manufacturer, model number, serial number, manufacturing date, revision, etc. This information can be read remotely to perform an inventory of the blades in a shelf.
Shelf Management
AdvancedTCA Shelf manager
The Shelf Manager monitors and controls the boards (blades) and FRU in the shelf. If any sensor reports a problem the Shelf Manager can take action or report the problem to a System Manager. This action could be something simple like making the fans go faster, or more drastic such as powering off a board. Each board and FRU contains inventory information (FRU Data) that can be retrieved by the Shelf Manager. The FRU data is used by the Shelf Manager to determine if there is enough power available for a board or FRU and if the Fabric ports that interconnect boards are compatible. The FRU data can also reveal the manufacturer, manufacturing date, model number, serial number, and asset tag.
Each blade, intelligent FRU, and Shelf Manager contains an Intelligent Platform Management Controller (IPMC). The Shelf Manager communicates with the boards and intelligent FRUs with IPMI protocols running on redundant I²C buses. IPMI protocols include packet checksums to ensure that data transmission is reliable. It is also possible to have non-intelligent FRUs managed by an intelligent FRUs. These are called Managed FRUs and have the same capabilities as an intelligent FRU.
The interconnection between the Shelf Manager and the boards is a redundant pair of Intelligent Platform Management Buses (IPMBs). The IPMB architecture can be a pair of buses (Bused IPMB) or a pair of radial connections (Radial IPMB). Radial IPMB implementations usually include the capability to isolate individual IPMB connections to improve reliability in the event of an IPMC failure.
Two new working groups have been started to adapt ATCA to the specific requirements of physics research.
WG1: Physics xTCA I/O, Timing and Synchronization Working Group
WG1 will define rear I/O for AMC modules and a new component called the μRTM. Additions will be made to the μTCA Shelf specification to accommodate the μRTM and to the ATCA specification to accommodate AMC Rear I/O for an ATCA carrier RTM. Signal lines be identified for use as clocks, gates, and triggers that are commonly used in Physics data acquisition systems.
WG2: Physics xTCA Software Architectures and Protocols Working Group
WG2 will define a common set of software architectures and supporting infrastructure to facilitate inter-operability and portability of both hardware and software modules among the various applications developed for the Physics xTCA platform and that will minimize the development effort and time required to construct experiments and systems using that platform.
A working group was formed to extend ATCA to non-telecom markets.
PICMG 3.7 ATCA Extensions for Applications Outside the Telecom Central Office
The goals of this new working group are to define enhanced features to support double-wide boards; add enhancements to support 600W single-slot boards and 800W double-slot boards; add support for double-sided shelves with full sized boards plugged into both the front and rear of the shelf; and add support for 10Gbs signaling on the Base Interface.
PICMG specifications
3.0 is the "base" or "core" specification. The AdvancedTCA definition alone defines a Fabric agnostic chassis backplane that can be used with any of the Fabrics defined in the following specifications:
AdvancedMC - expansion cards for AdvancedTCA; also can be used standalone in MicroTCA systems.
AXIe - A new modular instrumentation standard formally launched in November 2009, based on the ATCA standard.
Related Research Articles
A backplane is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbone to connect several printed circuit boards together to make up a complete computer system. Backplanes commonly use a printed circuit board, but wire-wrapped backplanes have also been used in minicomputers and high-reliability applications.
PCI Express, officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards. It is the common motherboard interface for personal computers' graphics cards, hard drives, SSDs, Wi-Fi and Ethernet hardware connections. PCIe has numerous improvements over the older standards, including higher maximum system bus throughput, lower I/O pin count and smaller physical footprint, better performance scaling for bus devices, a more detailed error detection and reporting mechanism, and native hot-swap functionality. More recent revisions of the PCIe standard provide hardware support for I/O virtualization.
A single-board computer (SBC) is a complete computer built on a single circuit board, with microprocessor(s), memory, input/output (I/O) and other features required of a functional computer. Single-board computers were made as demonstration or development systems, for educational systems, or for use as embedded computer controllers. Many types of home computers or portable computers integrate all their functions onto a single printed circuit board.
CompactPCI is a computer bus interconnect for industrial computers, combining a Eurocard-type connector and PCI signaling and protocols. Boards are standardized to 3U or 6U sizes, and are typically interconnected via a passive backplane. The connector pin assignments are standardized by the PICMG US and PICMG Europe organizations. The connectors and the electrical rules allow for eight boards in a PCI segment. Multiple bus segments are allowed with bridges.
A blade server is a stripped-down server computer with a modular design optimized to minimize the use of physical space and energy. Blade servers have many components removed to save space, minimize power consumption and other considerations, while still having all the functional components to be considered a computer. Unlike a rack-mount server, a blade server needs a blade enclosure, which can hold multiple blade servers, providing services such as power, cooling, networking, various interconnects and management. Together, blades and the blade enclosure form a blade system. Different blade providers have differing principles regarding what to include in the blade itself, and in the blade system as a whole.
The Service Availability Forum is a consortium that develops, publishes, educates on and promotes open specifications for carrier-grade and mission-critical systems. Formed in 2001, it promotes development and deployment of commercial off-the-shelf (COTS) technology.
Open Platform Management Architecture (OPMA) is an open, royalty free standard for connecting a modular, platform hardware management subsystem to a computer motherboard. Platform hardware management generally refers to the remote monitoring of platform hardware variables such as fan speed, voltages, CPU and enclosure temperatures along with a wide range of other sensors. It also implies the ability to remotely control the power state of the platform and to reset the system back into an operational state should it "hang". A significant advantage of OPMA over previous generation management subsystem attachment methods is that OPMA does not consume a PCI socket. OPMA cards are also smaller and lower cost than their PCI predecessors.
Advanced Mezzanine Cards are printed circuit boards (PCBs) that follow a specification of the PCI Industrial Computers Manufacturers Group (PICMG), with more than 100 companies participating.
Communications servers are open, standards-based computing systems that operate as a carrier-grade common platform for a wide range of communications applications and allow equipment providers to add value at many levels of the system architecture.
VPX technology was presented at Bus&Board (VITA) in 2004. VPX, formally known as VITA 46, is an ANSI standard that provides VMEbus-based systems with support for switched fabrics over a new high speed connector. Defined by the VITA working group, it has been designed specifically with defense applications in mind, with an enhanced module standard that enables applications and platforms with superior performance. VPX retains VME's existing 6U and 3U Eurocard form factors, supporting existing PCI Mezzanine Card (PMC) and XMC mezzanines, and maintaining the maximum possible compatibility with VMEbus.
The Hardware Platform Interface (HPI) is an open specification that defines an application programming interface (API) for platform management of computer systems. The API supports tasks including reading temperature or voltage sensors built into a processor, configuring hardware registers, accessing system inventory information like model numbers and serial numbers, and performing more complex activities, such as upgrading system firmware or diagnosing system failures.
CompactPCI Serial is an industrial standard for modular computer systems. It is based on the established PICMG 2.0 CompactPCI standard, which uses the parallel PCI bus for communication among a system's card components. In contrast to this, CompactPCI Serial uses only serial point-to-point connections. CompactPCI Serial was officially adopted by the PCI Industrial Computer Manufacturers Group PICMG as PICMG CPCI-S.0 CompactPCI Serial in March 2011. Its mechanical concept is based on the proven standards of IEEE 1101-1-1998 and IEEE 1101-10-1996. CompactPCI Serial includes different connectors that permit very high data rates. The new technology standard succeeding parallel CompactPCI comprises another specification called PICMG 2.30 CompactPCI PlusIO. This is why CompactPCI Serial and CompactPCI PlusIO as a whole were also called CompactPCI Plus. PICMG's first working title of CompactPCI Serial was CPLUS.0. CompactPCI Serial backplanes and chassis are developed by Schroff, Elmа, and Pixus Technologies companies, as for the CompactPCI Serial board level electronics – they are developed by MEN Mikro Elektronik, Fastwel, EKF, Emerson Embedded Computing, ADLINK, and Kontron.
PICMG 1.3 is a PICMG specification which is commonly referred to as SHB Express. SHB Express is a modernization of PICMG 1.0 single board computer specification. SHB Express, or System Host Board – Express, uses the same physical form factor as PICMG 1.0 boards. The board-to-backplane interfaces are PCI Express instead of PCI and ISA, although the use of PCI remains as an option.
PICMG 2.9 is a specification by PICMG that defines an implementation of a system management bus in a CompactPCI system. This system management bus uses an I2C hardware layer, and is based on the Intelligent Platform Management Interface (IPMI) and Intelligent Platform Management Bus (IPMB) specifications.
PICMG 2.12 is a specification by PICMG that defines vendor-independent software interfaces for supporting control of the software and hardware connection processes. The specification was updated in May 2002 to add Windows and Linux updates, Redundant System Slot (RSS) API, Switched PCI-PCI bridging support, Hardware- and O/S-independent models of network-connected intelligent nodes, Standards-based management of HS- and RSS-capable CompactPCI platforms and IDSEL to global address (GA) mapping.
HPM.1 is Hardware Platform Management IPM Controller Firmware Upgrade Specification of PICMG. This specification describes firmware upgrade procedure into PICMG IPM Controllers, as specified in the specifications AdvancedTCA, AdvancedMC and MicroTCA specifications. An Upgrade Agent upgrades firmware via any IPMI interfaces .The specification also describes format of upgrade image. The upgrade image can contain one or more than one component's firmware. The upgrade agent upgrades the component's firmware one by one. The IPM controller can have more than one component. The firmware upgrade procedure contains three stages. In preparation stage Upgrade Agent gets target capabilities and all component properties. Then it compares this information with Upgrade image. If there is a mismatch, Upgrade Agent abandons the firmware upgrade. Otherwise it moves into Upgrade stage. In Upgrade stage upgrade agent sends all components firmware one by one. After successfully receiving the firmware, IPM controller waits for activation. In Activation stage Upgrade Agent activates newly uploaded firmware. If self-test is supported by IPM controller, then it is invoked. If self-test fails, IPM controller automatically rolls back to previous firmware. If IPM controller does not support automatic roll back, operator or Upgrade Agent has to initiate the manual roll back.
MicroTCA is an open standard embedded computing specification created by PICMG. First ratified in 2006, the specification utilizes the existing Advanced Mezzanine Card (AMCs) in a hot-swappable backplane format. It features MicroTCA Carrier Hubs (MCHs) which provide IPMI-based shelf management and switching functionality to the system. MicroTCA systems provide up to 99.9999% uptime in a smaller form factor than 3U and 6U Eurocard systems. A typical mid-sized 4HP AMC is 73.8mm x 18.96mm x 181.5mm. There are also compact-sized AMCs at 3HP wide (13.88mm) and full-sized at 6HP wide (28.95mm). Double modules have also been created, extending the height of the modules from 73.8mm to 148.8mm. The architecture was originally designed for telecom applications, but MicroTCA has gained significant popularity in other applications including military/aerospace, railway, high-energy physics, and more.
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