Page 288 - Embedded Microprocessor Systems Real World Design

The PC in this application is not capable of controlling the system at the lowest
timing level, but it does act as a real time controller with hard real-time deadlines.
These include receiving and processing the images in a timely manner and keeping
up with the rate of data coming out of the FIFO. The operating system is not deter-
ministic in that the time to check and read the data from the microcontroller is
predictable. However, due to the speed of the CPU and the addition of the inter-
face FIFO, the system is deterministic because it will always be fast enough. In this
sense, it is truly real time.
In this design, the PC was chosen for the image-processing function for the
following reasons:
Standard operating system and drivers allow use of the standard Ctt develop-
ment system as well as easy interface to Ethernet, video, disk, and so on.
Any PC can be used by loading the right drivers-application software is
independent of hardware implementation.
Easy upgrade to faster CPU/more memory/bigger disk, and so on. No changes
to application or operating system are required.
Standard printer port for interface to microcontroller board makes this interface
universal.
The image interface boards required a standard PCI bus.
Chapter 11 will examine some advanced microprocessor concepts.

Industry-Standard Embedded Platfwms 269