VME bus:

VMEbus (Versa Module Europa bus) is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. It is physically based on Eurocard sizes, mechanicals and connectors (DIN 41612), but uses its own signalling system, which Eurocard does not define. It was first developed in 1981 and continues to see widespread use today.

Development tools

When developing and/or troubleshooting the VME bus, examination of hardware signals can be very important. Logic analyzers and bus analyzers are tools which collect, analyze, decode, store signals so people can view the high-speed waveforms at their leisure.

Time to change to MicroTCA(µTCA)

Today ATCA is being used in various highend applications that include the core network, semiconductor fabrication and military/aerospace. The research and test markets have also used ATCA for applications involving experimentation as well. Generally speaking applications in the standard embedded computing market  find ATCA as platform that exceeds their requirements for cost, power consumption and size.
The Micro Telecommunications Computing Architecture(MicroTCA) is an embedded, scalable, architecutre which offers flexibility to build robust systems. MicroTCA was designed as a complimentary system to the Advanced Telecommunication Computing Architecture (ATCA). specifications were first released in 2006 by the PCI Industrial Computer Manufacturers Group (PICMG®) to establish an open standard for the MicroTCA systems. The Primary goal of the PICMG specifications was to allow re-use of the existing concepts of an ATCA system in small scale applications.

MicroTCA was designed using the Advanced Mezzanine Card (AMC) form factor for applications that required low startup cost, smaller physical size, lower capacity and less tringent  equirements compared to an ATCA system.

MicroTCA system architecture

A typical MicroTCA system will have one or more shelves, Each shelf can support up to 16 carriers and each carriers can have up to 12 AMCs modules. A Carrier Manager, Shelf Manager, Power Module and Cooling Units are also present for each shelf as shown in following figure. An optional System Manager provides easy to use graphical interface for the system administrators and also for easy management of complex systems.

Advantage of MicroTCA

To summarize the advantages of a MicroTCA system are:

 Fully managed platforms by definition, supporting fully redundant systems for high availability applications
 Modular Open System Architecture (MOSA) provides low entry cost and rapid marker entry
 Strong interoperability and multiple fabric support
 Scalable, high speed data processing and connectivity
 Vast ecosystem based on hundreds of AMCs
 Flexible design options to meet custom application requirements
 Flexible chassis options to meet demanding environments and SWaP optimized solutions

Building a Typical MicroTCA System

To build a MicroTCA system is a complex process based on the requirement of the end user application, but the following steps give a brief overview of the considerations that are required when deciding to build a typical system.

1. Select one or more AMC based on the requirements of the end user application. The AMC(s) are selected considering the following factors:

 I/O Requirements – consider what types of input and outputs are required such as Ethernet, RF, Optical, Serial, etc. Your application may require a combination of inputs and outputs, so select the AMC that can handle the required I/Os.

 Processing Requirements – Some applications require high data processing and for this, a suitable Processor AMC (PrAMC) may be required. When using a processor AMC consider the speed and type of processing required and choose an AMC that can meet your requirements.

 Graphics – Some applications may require visual processing and output rendering, in such cases a Graphics AMC may be useful.

 Storage – If your application processes large amount of data and requires data storage facilities, storage AMC can be used.

 Field Programming – For applications that require field programming, FPGA based AMCs are useful, they provide flexibility and allow more customization of the user application.

2. Select a chassis: Once the required AMCs are selected, select a suitable chassis that is compatible with the AMCs. Consider the following when selecting a chassis:

 Number of AMCs required
 AMC compatibility
 Redundancy support
 Power supply requirements
 Telco alarm requirements
 Chassis coating requirements
 Environmental requirements based on the application use (ruggedized or not)
 Chassis dimensions, depending on how it will be integrated with the rest of the system

3. Select an appropriate MCH, consider if you require redundant MCH configuration and some chassis have integrated MCH.

4. Select a Power Module to meet your system requirements and more than one Power Module is required for high availability and high payload power applications.

5. Select a cooling unit to that is compatible with the chassis and provides the required cooling mechanism (back to front, bottom to top or side to side).

6. Optional JTAG switch modules can be used for debugging and diagnosing prototype designs.

7. Optional System Manager software is used to configure and manage the entire system along with other application software.

Please note that the above steps are high level overview of the selecting a MicroTCA system, once the system is designed, they must be configured to meet the application requirements. The configuration and implementation of the modules are not scope of this post.


News Reporter
Dr. Lu