Advanced Mezzanine Card

MicroTCA (also: MicroTCA ) stands for Micro Telecommunications Computing Architecture and is a standard adopted by PICMG modular standard that governs the structure of subracks and complete system integration. The MicroTCA specification defines the requirements for a system that operates directly on a PICMG AdvancedMC backplane. The specification describes general mechanical, electrical, thermal, and management concerning properties of a MicroTCA system that are necessary to support modules that are compatible with AdvancedMC standard.

MicroTCA is in addition to PICMG3.0 Advanced Telecommunications Computing Architecture ( AdvancedTCA ). While AdvancedTCA was designed for high capacity and high-performance applications, MicroTCA is focused on cost-sensitive, physically smaller applications with lower capacity, performance, and may be less stringent availability requirements. MicroTCA preserves many of the important philosophies of AdvancedTCA, including the basic connection topologies and management structures.

• 2.1 MicroTCA Pico
• 2.2 MicroTCA Cube
• 2.3 MicroTCA Shelf

• 4.1 Features
• 4.2 Management Controller

• 5.1 ports
• 5.2 clock networks 5.2.1 Non - redundant clock network
• 5.2.2 Redundant clock network
• 5.2.3 Change in the specification

• 5.5.1 FRU Information Device
• 5.5.2 Carrier Locator

• 6.1 AdvancedMC and MCH connectors
• 6.2 Power Connectors

Overview

History

MicroTCA was developed out of necessity to have a high-speed system platform available that meet both the high standards of the telecommunications industry as well as the less demanding requirements of the industry. For this, the Advanced Mezzanine Cards ( AMCs ), which were developed for the telecommunications platform AdvancedTCA, plugged directly into a backplane. This allows significant cost savings in the area of mechanics, electronics and management components can be achieved while taking full advantage of the high data rates, redundancy and modularity are utilized.

Market positioning

In the telecommunications sector, MicroTCA positioned by some limitations in both the number of modules as well as in the topology in the medium bandwidth range. MicroTCA systems with low-bandwidth can be used as a workgroup router or wireless base stations, while systems can be used with high-bandwidth, for example, as a DSL Access Points ( DSLAMs ).

Modularity

MicroTCA allows a number of options relating to modularity. The systems can be designed in many different levels of complexity. The advantage of a modular design of the systems is the easy interchangeability of components, which is thanks to the extensive management possible even during operation. For example, are replaced by the replacement of the corresponding fan tray failed fan, without the system must be shut down. This contributes to a smooth operation and high reliability of the systems. This is essential especially for telecom applications since these systems must be constantly available.

Components

A MicroTCA system includes several different components, which can be plugged into the system. Firstly, up to twelve AMCs can be integrated in the system. Furthermore, up to four power modules designed for redundant operation, be integrated. Moreover, in a system of one or two cooling units ( fan units ) can be integrated. All removable components are called " Field Replaceable Units " ( FRUs).

System concepts

MicroTCA Pico

The MicroTCA specification allows several concepts for the realization of a system. The smallest unit that corresponds to the MicroTCA standard, MicroTCA is the Pico. The Pico is usually a subassembly of a larger application. The external dimensions are not prescribed and are usually not larger than the rack itself, the applications, which require mostly based on a Pico little power, so usually only a few slots available in the system.

MicroTCA Cube

Another design, which is defined by the MicroTCA specification, the MicroTCA cube. This has approximately the shape of a cube (English " Cube "). The predetermined depth of the card cage of the cube has a side length of approximately 200 mm. A MicroTCA Cube is similar to a Pico usually only a part of a larger assembly. In contrast to Pico the cube but is often larger than the card cage itself. The Cube has additional space for MCH and PMs that are plugged in certain circumstances, and in modular construction. CUs are often already integrated in the cube, allowing it to be used as a stand-alone system. These cubes are particularly common as test systems for map developers or system integrators.

MicroTCA Shelf

The biggest and most common system is the so-called MicroTCA Shelf. This is a basic system with a width of usual in this market segment 19 inches. This card can be integrated with an overall width of 84 HP. The shelf usually includes two MCH, two Power Modules and two cooling units. Here, the cooling units are mounted above or below the card cage, MCH and Power Modules are located in the card cage. The most common size of the pluggable modules ( AdvancedMC, MCH and Power Modules ) have the size, " Single Module, Full Size ". This means a height of approximately 75 mm and a width of 6 modules. Thus remain through the integration of two MCHs and two Power Modules 60 TE left, which can be used for the AMCs. This eight " full-size " modules ( 6 modules ) and four "Compact Size" modules ( 3 modules ) can be integrated, with two side- located "Compact Size" slots can also be used for a " full size" AdvancedMC.

Cooling

Cooling in a MicroTCA system is very important since the power density in the system is very high. A module ( AdvancedMC, MCH or Power Module) with the size of "Double Module, Full Size " can generate up to 80 watts of heat. This can produce up to 14 times 80 watts = 1120 watts of waste heat a shelf.

Management

The management in a MicroTCA system is very extensive. There is a central management entity in the system, the MicroTCA Carrier Hub (MCH ). This is connected via a star-shaped IPMI bus with all AMCs and a redundant IPMI bus with the remaining components. The MCH activated and deactivated all components and their ports.

Features

The management of the MicroTCA system is very extensive by the Protocol IPMI and supports numerous features. Through this bus, temperatures are queried in the system and on the modules, checked fan speeds and adjusted. But above all is the hot-swap an important feature to enable a smooth exchange of components during operation. A result, the rest of the system are minimized, thereby applications and services are constantly available. Furthermore, the management also supports the electronic keying (E - Keying). This is a feature that allows you to query the compatibility of the modules before starting up and, depending on the thereupon fully, partly or not at all to activate the module. For example, modules, the operating voltages and power are not compatible with the system turned off. Modules, their protocols are not compatible on certain ports with switching capabilities of the MCH can enable, but not enable the affected ports.

Management Controller

Each module that is integrated into a MicroTCA system, and can be replaced, must have a management controller. The AMCs must have a "Module Management Controller " (MMC ), Power Modules, Cooling Units and application-specific modules must have an "Enhanced Module Management Controller" ( EMMC ). The purpose of this Management Controller, communication with the management controller of the MCH, the " MicroTCA Carrier Management Controller " ( MCMC ) is called. This communication is necessary in order to support hot -swap and the E- Keying.

Compounds

The backplane is one of the most important components in the MicroTCA system. It includes all the connections between the components. These include the high-speed serial ports, the clock networks, the management connections and the voltage supply.

Ports

In order to realize the required high bandwidth, the AMCs on the high-speed ports are connected. These consist of two differential pairs, which allow a quick transfer of the order of several Gbit / s. The signaling is done via Low Voltage Differential Signaling. About the ports are the logs PCI Express, Serial Rapid IO, (10 ) transmit Gigabit Ethernet or Serial Attached SCSI. Each AdvancedMC can use up to 21 ports (port to port). The MicroTCA standard specifies merely the first twelve ports. The rest can be used custom events or for outputting signals on the back side of the system.

Clock networks

MicroTCA defines three clock networks ( Clock 1, Clock 2 and Clock 3). The compounds are different depending on whether the system is equipped with a redundant MCH or not. The frequency of Clock 1 and Clock 2 is according to requirement 8 kHz, 1.544 MHz, 2.048 MHz or 19.44 MHz. 3 has a clock frequency of 100 MHz, and can be carried out as a spread spectrum clock in order to save costs.

Non - redundant clock network

If only one MCH is integrated in the system, the clock network is designed non- redundant. This single point-to -point connections between each of the clock terminals of AMCs and the MCH is carried out. For this, the MCH has 36 clock terminals, three clock terminals for each AdvancedMC.

Redundant clock network

In the redundant clock network, the first stroke of each AdvancedMC is connected to the first clock of the first MCH. The third cycle of the AMCs is connected to the first clock of the second MCH (redundancy in case of failure of the first MCH ). The second cycle of the AMCs is connected to the second clock of the two MCH. This is possible that the final network is adjusted so that each participant despite branching provides a degree of 100 ohms. By connecting an MCH Clock 1 Clock 3 to the AMCs can here be transmitted no PCI Express, because the corresponding clock network is not available.

Change in the specification

On 15 November 2006, Revision 2.0 of the specification AdvancedMC.0 ( Base Specification) has been released. In this specification, the clock terminals and their names have been revised. There are added two additional clock networks, which are used instead of port. ( Newly added ) The names have been changed so that the clock networks now TCLKA ( Clock 1 ) TCLKB (clock 2) FCLKA (clock 3) TCLKC ( newly added ) and TCLKD hot. The letter 'T' before CLK ( clock = ) stands for " Telecom ", ' F' stands for " Fabric". It is expected that the MicroTCA specification adapts to the changes.

Supply voltages

In conventional bus systems, are " power planes ", that complete copper layers, which are connected to the supply voltages, integrated into the backplane. These copper layers are used for a simple way to offer to bind all slots and components using vias to the supply voltages. Furthermore, the use of complete copper layers has the advantage that the copper layers constitute electrical shielding, whereby the impedance of the conductor tracks between the layers is uniform and easy to customize. In a MicroTCA system "Power Planes" can not be used, as for monitoring the compatibility of the components, the inserted E- keying is used. To support the e- keying all the power supplies of the inserted modules must be separately switched on and off. In the system, two different voltage levels are available. This is for a " Power Management ", which provides the management controller of the components with 3.3 V, which is responsible for controlling the E- keying. Further " payload power " is used to supply the actual payload of the module. This 12 V must be converted locally to the required voltage level. Through this separate power supplies, each component has two supply networks which must be separated from the other components.

Management connections

For the comprehensive management in a MicroTCA system, numerous compounds must be present. These are primarily the IPMI bus, whose hardware and data transmission corresponds to the I ² C bus. This means that each IPMI bus from a data (" Serial Data ", SDA) and a clock line ( "Serial Clock", SCL) is. Each AMC is connected to both a separate MCH radially IPMI connection. This twelve local IPMI connections (IPMI -L) are required. Furthermore, the Power Modules and Cooling Units and any given application-specific modules are linked via two redundant IPMI connections. These two compounds are called IPMI IPMI A and -B and together IPMI -0. Due to the possible connection of the application-specific modules to the IPMI 0 the number of existing components here is not limited. Therefore IPMI 0 can not be as IPMI L compounds radially guided but is arranged in a serial bus topology. Furthermore, the contacts are present on the modules that are needed for the recognition and activation. On the one hand, these are the Present pins PS0 # and PS1 # # and an ENABLE pin. The PS0 # pin indicates to the engine that it is fully plugged in, while PS1 # PMs signals the presence of the module. The PM then activates the ENABLE # pin and Power Management for this component. Further enable # is used to perform a reset of the management controller. The Power Module itself has no PS0 # PS1 # # and ENABLE pins, but has only one PS_PM pin. This pin has the same function as the PS0 pin # and displays the Power Module that it is fully plugged in and thus can activate.

Information modules

FRU Information Device

The FRU Information Device used to store system-specific data. These are absolutely necessary to support functions such as e - keying. It is stored information such as performance of the Power Module, consumption of the other modules, slot arrangement, port connections and activation cycles. By the port connections, the communication partner can be identified, and thus the activation of the driver can be controlled. For each MCH a FRU information device is provided, which is connected through a local bus with the I ² C MCH.

Carrier Locator

The Carrier Locator serve to locate the system in a larger assembly. To this end, an I ² C IO expander is connected to DIP switches. This makes it possible via the I ² C bus interrogate the number of the system. Locator carrier is connected via the same I ² C bus to the MCH as the FRU information device.

Connectors

AdvancedMC and MCH connectors

The MicroTCA connector that connects the backplane with the modules was determined by the existing AMCs. These were integrated into AdvancedTCA systems via a " Carrier Card " in the system. The AMCs have "Card Edge " contacts, ie gold contacts that are located directly on the PCB. Thus, the PCB edge is directly plugged into the mating connector. Since the AdvancedMC is inserted parallel to the Carrier Card, but perpendicular to the backplane, a new, compatible connectors must be developed for MicroTCA. The connector 170 has contacts 85 on both sides respectively of the printed circuit board. There are three types of MicroTCA connectors available on the market. There is a SMT connector that is soldered to the surface of the circuit board. Further, there is a compression mount connector which is only screwed on. In this case, a connection is made to the circuit board by the spring contacts of the plug. The third connector is a Einpressstecker.

For the uniformity of the MCH is placed over the same connector on the backplane. However, the MCH requires a plurality of contacts that can not be performed over one of these plugs. Therefore, up to four of these connectors mounted directly next to each other on the backplane to perform all connections to a MCHs on the backplane.

Power Connectors

The connector for the power modules requires one hand, high-current contacts for the supply of the modules in the system and on the other hand signal contacts for the management functions. For this purpose, a separate connector has been developed which has a high current contacts 24 and signal contacts 72.