Page 275 - Embedded Microprocessor Systems Real World Design

Development Cost

Embedded systems based on a PC platform require no costly board design/
fabricatioddebug cycles. PC tools usually are used for software development, elim-
inating the need to purchase emulators. As product development cycles get shorter,
there is an incentive to buy proven, off-the-shelf components. Another factor
driving the use of purchased hardware is increasing clock speeds. As CPU speeds
pass a GHz, it is increasingly difficult for every company that needs a processor
board to create its own designs. The tools are prohibitively expensive, partly because
extensive simulation is required to ensure a good design.

Specialization
Some embedded designs still can be accomplished using processors with clock rates
in the low MHz range. However, as clock rates go up and development costs follow,
more companies concentrate their efforts on the hardware and software that makes
their products unique. Off-the-shelf CPUs, Ethernet boards, and similar compo-
nents are treated as commodity parts, which they are. This is buying the “jellybean”
parts of the design, leaving the company’s engineers free to do the unique things.
Since all modern, high-speed CPU boards essentially are the same, you pick a CPU,
pick a chipset that supports it, and wire it accordingly. Why assign an engineer to
spend three months developing a board that looks and works like a hundred other
nearly identical designs?

Mass Storage
Disk drives, interface boards, and driver software are standard parts of the PC plat-
form. Some systems need mass storage to capture data; for example, a system that
keeps a log of instrument readings from a fluid pipeline. If the system takes a
reading every second, the storage requirements can add up quickly. Other appli-
cations where mass storage could be a requirement include storing bitmapped
images and store-and-forward interface systems. And some real-time operating
systems (RTOSs) are designed to operate with mass storage.

Standard Software
You need not learn the interface to an RTOS with a PGbased system, as DOS, OS/2,
Linux, and Windows NT are already available. Off-the-shelf software is available for
communications, graphics display, and many other applications. New features,
depending on what they are, may be bought instead of designed. If your applica-
tion needs some kind of database, you can buy a database package instead of writ-
ing one.

256 Embedded Microprocessor Systems