Embedded World was the setting for PICMG Europe – along with its members and MEN Mikro Elektronik – to officially release the new bus standard, CompactPCI Serial.
Set up 15 years ago, PICMG Europe was established to support usage across the European market and today has approximately 350 member companies. And, according to the group´s chairman Eelco van der Wal, the official launch of the new standard will 'pave the way for the future'.
The independent basic standard supplements the parallel CompactPCI 2.0, but there are crucial updates. For one, it has a faster serial data transfer. And, as it has been built on the mechanics of CompactPCI, it remains compatible to IEC1101, so migration is made simpler and users can keep existing 19in systems. A new rugged connector from Airmax has been added. With a signal density of up to 184 pin pairs (on 3U), it can achieve fast serial point to point connections, higher signal density and a higher transmission frequency of 12Gbit/s.
The AirMax connector was originally developed for use in rugged environments. There are versions of the male connector - the connector on the plug in board - with only two walls, which can be mounted side by side without any clearance, and where the pins are enclosed by four walls. An additional model has been developed especially for CompactPCI Serial; a male connector with three walls. In total, it uses three male connector types and three female connector types from AirMax' range.
"A connector with four walls and six pin rows is always used on the assembly," van der Wal said. "This is complemented by several side by side mountable types with two walls and eight rows. A 3U board is completed by a connector with three walls and eight rows. In this fashion a protected male connector with a cross wall in the middle is built."
MEN Mikro Elektronik's G20 single board computer is based on the compact PCISerial specification.
This cross wall has been designed to support the stability of the plugged in board and prevents the possibility of a CompactPCI Serial board accidentally being plugged into a conventional CompactPCI slot and distorting pins. "The standard supports both 3U and 6U," explained Manfred Schmitz from MEN Mikro Elektronik. "This allows the implementation of hybrid backplanes."
Schmitz explained the need for the new update. "The new Serial platform overcomes the I/O speed limitations of CompactPCI's parallel bus interface, but by using common mechanics. CompactPCI Serial is based on a simple, complete star topology equally for PCI Express – and optionally,
Serial Rapid IO, SRIO – SATA, SAS and USB. The system slot supports up to eight of these peripheral slots. No bridges or switches are needed for a system with up to nine slots." In principle, stated Schmitz, all the peripheral slots are identical. "Only one is connected via an extra wide PCI Express link, the Fat Pipe," he said." This slot can be used for a high end graphics extension, for example."
Cost effective computing
When CompactPCI was established in 1999, it was designed as a standard for building cost effective and reliable industrial computers. Two years later, an update created the basis for CompactPCI 2.0 Core Specification. This defined the form factors, the parallel bus, the connectors and pin layout for power consumption, cooling and topologies.
Additions to the Core specification were set up to satisfy more demanding industrial requirements, such as hot swap, multicomputing, rear I/O of mezzanine cards or conduction cooling. But there were limitations. Within a CompactPCI system, serial point to point connections could be achieved via user defined pins on a J2 connector.
Schroff's subrack system takes advantage of the CompactPCI serial high speed serial bus topology.
However, the downside was this led to a growing incompatibility of assemblies from different manufacturers. As a result, two new PICMG standards – CompactPCI PlusIO (PICMG 2.30) and CompactPCI Serial (PICMG CPCI-S.0) – were set up to define the common integration of serial high speed signals into a modular 19in environment.
Compared to CompactPCI, the male and female connectors of PlusIO were exchanged, with the male connector located on the plug in board and the female connector on the backplane, as in VMEbus systems. This was implemented to reduce the chance of crimping or distorting pins on the backplane, and, even if a pin was damaged, it was much easier to replace a plug in board than a backplane or a complete system.
According to Alexander Buralev from Fastwel, the requirement set out for the development of the new standard was to cover a broad spectrum of all kind of applications across industrial markets – while keeping costs under control. "As a result," he said, "CompactPCI Serial can be used from simple industrial pcs to clustered, redundant high end systems, from harsh environments to safety critical, supporting Ethernet, USB, SATA and PCI Express in parallel."
In previous versions, the standard focused purely on core telecom applications. "Systems such as CompactPCI and Advanced TCA are ideal for office applications," Buralev asserted. "But Serial is focused on filed applications." The new architecture is moving to serial high speed interconnects.
A configuration of one system slot and up to eight peripheral slots doesn't need switches and bridges. Keeping the proven 19in mechanics of the IEC 1101 as well as hot plug, the standard introduces a new rugged connector with a signal density of up to 184 pin pairs (on 3U) and transmission frequencies of 12Gbit/s.
CompactPCI Serial basics
The system slot supports eight PCI Express links (six x4 lanes, two x8 lanes), eight SATA/SAS, 8 USB 2.0/3.0 and eight Ethernet interfaces, plus signals for general system management (including reset, IPMB, hot plug and geographical addressing). It is supplied with 12V (60W per 3U, 120W per 6U slot).
Each peripheral slot offers a PCI Express link, one SATA/SAS and one USB 2.0/3.0 interface. Each slot can support up to eight Ethernet interfaces to build a full mesh. All interfaces are accessible at the same time. It is supplied with 12V (60W per 3U, 120W per 6U slot).
The pin assignment of the system and the peripheral slot is congruent. This way it is possible to plug a system slot board into each peripheral slot to support symmetrical multiprocessing.
The star topology is equal for PCI Express, SATA/SAS and USB. All peripheral slots are identical except two that are connected via PCI Express links x8 lanes. Ethernet is wired as a full mesh. Transmission is based on the proven standards for copper connections up to 10GbaseT to allow configuration of redundant, safety critical systems.
