THE MAGAZINE FOR COMPUTER APPLICATIONS
Circuit Cellar Online offers articles illustrating creative solutions
and unique applications through complete projects, practical
tutorials, and useful design techniques.

VIM: A POWERFUL NEW MEZZANINE

by Rodger Hosking

Start ý Design Rationale ý VIM Streaming Parallel Bus ý Serial Ports ý Power Supply ý Single-Slot VIM-Based Systems ý Sources and PDF

POWER SUPPLY

Power supply lines from the motherboard include +5 VDC and ý12 VDC for powering the module. The number of pins for each supply and the maximum current for the module are shown in Table 4. A total maximum power dissipation of 15 W is recommended.

MECHANICAL ASPECTS OF VIM

Pin-and-socket-style connectors were selected for the baseboard/module interconnect. These compact 160-pin four-row connectors occupy a minimal board footprint of 2.1 ý 0.25 inches and feature both male and female connectors in surface-mount versions, conserving valuable inner-layer PCB real estate.

VIM was first implemented on the Model 4290 Quad ýC6201 DSP processor, a standard 6U VMEbus board. Each of the four processors features its own private VIM interface, allowing simultaneous full-bandwidth transfers in and out of each processor. The four VIM connectors were arranged in a single line parallel to the front panel as shown in Figure 2.

Figure 2ýOn the VIM processor board, each of the four processors features its own private VIM interface which allows simultaneous full-bandwidth transfers in and out of each processor.

A fifth connector, of the same style as the four processor VIM connectors, is installed near the rear of the board just in front of the P2 backplane connector. This 200-pin interconnect includes a shared global bus as well as the 64 user-defined pins of the VME P2 connector to support mezzanine board connections to RACEway. This fifth connector is not part of the VIM specification and can be specific to the needs of a particular baseboard.

So far, several different mezzanine module form factors have been defined for the quad ýC6x DSP boards using the VIM specification. These meet the various needs of a wide range of applications, but the first and most popular is the VIM-2 format shown in Figure 3.

Figure 3ýThe VIM-2 Module attaches to two of the four processor nodes and allows for two completely independent interfaces to each DSP.

The VIM-2 module has a front panel, which becomes part of the front panel of the DSP board, nesting in the same slot as the DSP board. It attaches to two of the four processor nodes and allows two completely independent interfaces to each DSP through interface circuitry to front panel I/O functions.

Photo 1 shows two VIM-2 modules being attached to the processor baseboard.

Photo 1ýVIM modules attach directly to the processor board through the I/O connectors. Shown here are two Model 6223 Comm Port Adapter VIM-2 modules in the process of being plugged into a Model 4291 Quad ýC6701 processor board, as viewed from the rear of the board. Two different modules may be used to provide more I/O functions.

Photo 2 shows the final assembly with two VIM-2 modules attached to the baseboard. Note that the complete assembly occupies only one VMEbus slot!

Photo 2ýThe two VIM-2 modules are now fully inserted into the I/O connectors of the Model 4291 Quad ýC6701 processor board. Shown here is the completed assembly as viewed from the front. The front panels of the two modules have become part of the front panel of the 4291 processor board.

The VIM-2 format is especially useful because it allows two different types of VIM interfaces to be combined on the same DSP board, perhaps supporting an input function with one module and an output function with the other. Other VIM form factors include the VIM-4, which provides connectivity from all front-panel connectors to all four DSPs as shown in Figure 4.

Figure 4ýThe VIM-4 module provides connectivity from all front-panel connectors to all four DSPs on the processor board.

PREVIOUS • NEXT