Interfacing requirements for nonstandard applications are constantly evolving, and the 4MEG VIDEO Model 12 has been engineered to adapt. The Model 12 features three new connectors that allow easy interfacing to a wide range of imaging devices.
Evolved From the 4MEG VIDEO Model 10
The award-winning design of the Model 10, a design that was first introduced 5 years ago, has been successfully interfaced to a wide range of imaging systems. Some of the more challenging applications have required removal of resistors, addition of jumper wires, installation of connectors, and removal of ICs. A goal for the design of the Model 12 was to eliminate the need for most of these hardware modifications and to allow easier development of new interfaces.
Programmable I/O Signals
The Model 12 provides a more flexible DB25 connection. Only 8 of the connector's 25 pins are wired directly to the Model 12 motherboard (Video In, Green, Red, Blue Out, and grounds for each). These are the signals required for standard RS-170 ! CCIR input, with either grey level or RGB video output. The remaining pins are wired to CON6 (a 40-pin connector) which accepts a small printed circuit board (a "module") dedicated to meeting specific I/O requirements. The circuitry on the module defines the remaining 17 pins, and as a result, the interfacing characteristics of the Model 12 can be easily changed. The need to modify Model 12 motherboard circuitry to accommodate various non-standard cameras has been significantly reduced.
The default configuration for the Model 12 includes a module called the "Analog Module." The Analog Module provides the same VO drive, trigger, and pixel clock interface signals as the 4MEG VIDEO Model 10. An improvement over the Model 10 is the addition of a high speed comparator for the pixel clock instead of a TTL input. EPIX engineers can design modules for cameras with signal requirements not supported by current designs.
The Look Up Table (LUT) connector provides the potential for real time image processing prior to writing data to image memory. The data out of the LUT connector is registered data from the analog to digital converter. Data received back into the LUT connector is clocked into a register. Other signals available at the LUT connector include an inverted pixel clock, a horizontal load signal, +5 volt power, and a ground for each.
One application for this connector is the attachment of an input look up table board. An input look up table can re-assign or bias data values. Other uses include bit packing or real time arithmetic operations prior to data storage.
V-8 Connector Provides Digital Interfacing
Three options are available:
Digital Camera Interfacing
The Model 12 allows software to switch between analog and digital input without removing the A-D converter as was required on the Model 10. Digital data is transferred to the Model 12 by connecting a ribbon cable between a TTL level digital source and the V-8 connector. Since many digital cameras output RS-422 differential pair signals, this source is usually an interface board that converts the camera's RS-422 output to single ended TTL levels.
Multiple Model 12s
Moving data through the PC bus limits transfer rates to about two megabytes per second. Interconnecting multiple boards with their V-8 connectors avoids the PC bus, and allows image transfer at pixel clock rates (up to 50 MHz). This image transfer capability allows multiple board arrangements which can significantly increase the performance of a Model 12 imaging system.
Up to eight Model 12s can be used in a single PC. Eight 64 megabyte boards provide 512 megabytes of image memory. Use of more than one Model 12 in a computer also requires setting different base VO addresses for each board. A jumper that allows selection between two base I/O addresses is provided, with additional addresses available by changing an I/O decoder.
Single Monitor Display
The use of a single monitor for display of images and software menus sacrifices the convenience of simultaneous image and menu display on two separate monitors. This option allows switching between a full-screen display of software menus and a full 640x480 view of a captured image.
The single monitor display option, interfaced to the V-8 connector, requires a VGA board which provides horizontal and vertical drive as well as pixel clock output signals needed to drive the Model 12 with the VGA's video timing while accepting data from the Model 12. Image display is provided as 7 bits (128 grey levels) at 60 fps non-interlaced. The 8th bit is reserved for cursor display.
(Note: 4MIP provides a VGA display option under Obscure Menus. This alternative provides single monitor display by transferring images through the [slower] PC bus to the VGA adapter.)
The 4MEG VIDEO Model 12 features three new connectors that provide enhanced interfacing flexibility. CON6 allows development of interface modules dedicated to specific I/O requirements, the LUT connector allows image processing before storage in image memory, and the V-8 connector provides convenient digital interfacing. Continue to read EPIX Vision to see how EPIX engineers use these resources to develop exciting new products.
EPIX Vision - January 1994 Newsletter