MicroTCA Carrier Hub

from Wikipedia, the free encyclopedia

MicroTCA Carrier Hub (also: MCH ) is a key component in a MicroTCA system. MicroTCA, AMC and MCH are an open and modular standard adopted by the PICMG . These specifications define the system requirements so that PICMG AdvancedMCs can be operated directly on a backplane . Mechanical, electrical, thermal and management-related properties of a MicroTCA system are described so that the plug-in cards are compatible with the AdvancedMC standard.

overview

history

Based on the MicroTCA standard, high-speed system platforms can be set up that meet both the high demands of the telecommunications sector and the less demanding needs of industry. For this purpose, the Advanced Mezzanine Cards (AdvancedMCs), which were originally developed for the AdvancedTCA telecommunications platform, were plugged directly onto a backplane. The functions of the separate system management card, the switch card and the AMC carrier card of the ATCA standard were combined in the MicroTCA standard on a single card, the MCH, for reasons of cost and space.

management

The management in a MicroTCA system is very extensive and independent of the operating systems used and the status of the inserted AMC cards. The central management instance in a MicroTCA system is the MicroTCA Carrier Hub (MCH). This is connected to all AdvancedMCs via a star-shaped IPMI bus and to the intelligent cooling unit and the intelligent power modules via a redundant IPMI bus. The MCH activates and deactivates all components and their ports via the intelligent power module .

Features

The management of the MicroTCA system is very extensive thanks to the IPMI protocol and supports numerous features. Temperatures and other sensors in the system and on the modules are queried via this bus, and fan speeds are checked and readjusted. In addition, hot swap is supported to enable the components to be exchanged smoothly during operation. Instead of using leading pins or key pins, this is implemented electronically (electronic keying (e-keying)). Before the AMC module is supplied with 12-volt voltage, only a small, separate controller (Module Management Controller) located on the card is supplied with 3 V and the standardized parameters are queried. If the AMC module is compatible, the 12 volt supply voltage is switched through to this AMC slot.

Management controller

Every module that is integrated into a MicroTCA system and that is interchangeable must have a management controller. The AdvancedMCs must have a "Module Management Controller" (MMC), the Power Modules, Cooling Units and application-specific modules must have an "Enhanced Module Management Controller" (EMMC). The task of these management controllers is to communicate with the MCH's management controller, which is called the “MicroTCA Carrier Management Controller” (MCMC). This communication is necessary to support hot-swap and e-keying.

links

The backplane represents the backbone of the MicroTCA system. It contains all connections between the components. This includes the serial high-speed ports, the clock networks, the management connections and the power supply. Since the high-speed ports are designed as differential lines in the backplane, the topology is only defined by plugging in the AMC modules and the MCH. S-ATA , SRIO , GbE , 10 Gbe (XAUI) or PCI-Express can be specified with the same backplane by simply exchanging the AMC modules and the MCH.

Clock networks

MicroTCA defines three clock networks (Clock 1, Clock 2 and Clock 3). The connections differ depending on whether the system is equipped with a redundant MCH or not. The frequency of Clock 1 and Clock 2 is 8 kHz, 1.544 MHz, 2.048 MHz or 19.44 MHz, depending on the requirements. Clock 3 has a frequency of 100 MHz and can be implemented as a spread spectrum clock to save costs.

Non-redundant clock network

If only one MCH is integrated in the system, the clock network is designed to be non-redundant. Here, individual point-to-point connections are established between all clock connections of the AdvancedMCs and the MCH. The MCH has 36 clock connections for this purpose, three clock connections for each AdvancedMC.

Redundant clock network

In the redundant clock network, the first clock of each AdvancedMC is connected to the first clock of the first MCH. The third cycle of the AdvancedMCs is connected to the first cycle of the second MCH (redundancy if the first MCH fails). The second cycle of the AdvancedMCs is connected to the second cycle of the two MCHs. This is made possible by the fact that the termination network is adapted in such a way that each participant sees a termination of 100 ohms despite branching. By connecting clock 1 of an MCH to clock 3 of the AdvancedMCs, no PCI Express can be transmitted here because the corresponding clock network is not available.

Change of specification

On November 15, 2006, Revision 2.0 of the AMC.0 specification (Base Specification) was published. The clock connections and their designations have been revised in this specification. Two more clock networks have been added that are used in place of port [16]. The names have been changed so that the clock networks are now called TCLKA (Clock 1), TCLKB (Clock 2), FCLKA (Clock 3), TCLKC (new addition) and TCLKD (new addition). The letter 'T' in front of CLK (= Clock) stands for "Telecom", 'F' stands for "Fabric". It is expected that the MicroTCA specification will adapt to the changes.

Management connections

Numerous connections must be available for extensive management in a MicroTCA system. These are primarily the IPMI buses, the hardware and data transmission of which corresponds to the I²C bus. This means that every IPMI bus consists of a data line ("Serial Data", SDA) and a clock line ("Serial Clock", SCL). Each AdvancedMC is connected radially to the two MCHs via a separate IPMI connection. This means that twelve local IPMI connections (IPMI-L) are required. Furthermore, the Power Modules and Cooling Units and any application-specific modules that may be present are connected via two redundant IPMI connections. These two connections are called IPMI-A and IPMI-B and together make up IPMI-0. As the application-specific modules can be connected to the IPMI-0, the number of components available here is not limited. This is why IPMI-0 cannot be routed radially like the IPMI-L connections, but is arranged in a serial bus topology.

In addition, there are contacts on the modules that are necessary for detection and activation. On the one hand, there are the present pins PS0 # and PS1 # and an ENABLE # pin. The PS0 # pin indicates to the module that it is completely plugged in, while PS1 # signals the presence of the module to the PMs. The PM then activates the ENABLE # pin and management power for this component. ENABLE # is also used to reset the management controller. The Power Module itself has no PS0 #, PS1 # and ENABLE # pins, but only has one PS_PM pin. This pin has the same function as the PS0 # pin and indicates to the Power Module that it is fully inserted and can therefore be activated.

AdvancedMC / MCH connectors

The MicroTCA connector that connects the backplane with the modules was determined by the already existing AdvancedMCs. These were integrated into the system in AdvancedTCA systems via a "carrier card". The AdvancedMCs have "Card Edge" contacts, ie gold contacts that are located directly on the circuit board. Thus, the edge of the circuit board is plugged directly into the mating connector. Since the AdvancedMC is plugged in parallel to the carrier card but vertically on the backplane, a new, compatible connector has to be developed for MicroTCA. The connector has 170 contacts, 85 on either side of the circuit board.

There are three types of MicroTCA connectors available on the market. There is an SMT connector that is soldered to the surface of the circuit board. There is also a compression mount connector that is simply screwed on. A connection to the circuit board is established via the spring contacts of the plug. The third connector is a press-fit connector .

To ensure uniformity, the MCH is plugged into the backplane using the same connector. However, the MCH requires a large number of contacts that cannot be routed via one of these connectors. For this reason, up to four of these connectors are attached directly next to each other on the backplane in order to route all connections of an MCH to the backplane.

Web links