Cortex Technical R&D Ltd.


Digital Signal Processor based Binary Frame Grabber & Image Processor

The UltraGrab binary frame grabber and image processor PC-board has been primarily designed for real-time industrial applications. It is based on the Analog Devices*s ADSP-2111 Digital Signal Processor (DSP) running at 13 MHz. The board has 32Kx16 bits of external data RAM for storing images and processing data. Like the majority of industrial vision systems, this board works on binary (1 bit/pixel) images. The maximum image size is 656*576 pixels, the limit set by standard PAL video cameras. The board is also applicable for NTSC standard, in which case the resolution is somewhat lower.


The most interesting feature of the board is that there is almost no extra digital hardware for image acquisition and display, but these functions are realized on the DSP itself using its on- chip serial ports. This solution not only results a fairly compact and low-cost board, but also a very flexible system, since image size, format, timing etc. are completely under software control. For example, it is possible to have multiple windows on the image and grab images to the windows independently. To help making vision systems even more compact, the board also includes 2+2 bits of optocoupled inputs and outputs, which can be directly connected to most industrial controllers. One of the inputs can be associated with a DSP interrupt, thus even very strict synchronisation requirements can also be met.

Communication towards the PC host is done via the DSP*s Host Interface Port (HIP). Communication is initiated by the PC, but for alerting the host the DSP can take control over one of the PC interrupt lines. If greater information throughput is required, the host can also have direct access to the DSP external data memory.

For creating vision systems with the UltraGrab board, two different software approaches can be taken. In the first scheme the UltraGrab is a stand-alone measurement system, where the PC only provides power, initialisation and optional registration or supervision of the measurements. This is ideal for the more simple applications, or when several DSP boards are plugged in a single PC. For complex systems, however, it is getting clumsy to program all the measuement control into the DSP. In this case, the DSP program only includes the lower- level, computationally demanding measurement routines, while these routines are invoked and parametrized by a higher level program run by the host. In this case, DSP programming can be minimized or completely omitted.

As a product, the DSP board is shipped with the following software environment:

There are several systems so far based on the UltraGrab board, including a system for qualifying glass tubes at a plant of General Electric Lighting Company at Vác, Hungary, which has 4 UltraGrab boards running parallel. Another system used for testing automobile dashboard instruments is a good example for a single board system.

(C) 1999. Cortex Ltd.