DESIGN VIEW is the summary of the complete DESIGN SOLUTION contributed article, which begins on Page 2.
Cost is king in many embedded-system designs. To reduce costs, designers will typically call upon a single microprocessor to run the whole show, figuring that fewer parts mean lower cost. But splitting up the task among multiple processors can often simplify a design and speed its arrival to the market, more than compensating for the added cost.
However, attention must be paid to your design's characteristics to find the right solution. Keep in mind that adding a satellite processor affects system cost both positively and negatively, so the overall impact needs to be evaluated. Multiprocessing just may turn out to be the lower-cost option.
Using a satellite can lower the performance needs of the main processor, allowing for a less expensive version. It can also simplify wiring, and most importantly, it will ease development and debugging of the design. Tradeoffs must be considered, though. First, there's the cost of the additional processor. A larger potential penalty is the cost of development tools for the additional processor when it differs from the main processor.
However, smart design teams will pick a satellite processor that meets the needs of many multiprocessor designs. Thus, tool cost can be spread over many designs, lowering the overall impact. It also allows for volume purchasing of parts, yielding discounts greater than a single product run.
An actual design can illustrate best when to use multiprocessing. In this article, a state-of-the-art vending machine, which requires lots of control, is used as an example. Discussion surrounds the vending-machine controller (VMC), choosing the right serial bus for your application among the popular serial buses out there, and achieving overall simplicity in the design.
Full article begins on Page 2