Babary,

Good question!

If it were a mission-critical application, I'd favor discrete over microprocessor because you don't want to get sued over a software bug creating injuries. As you say, a discrete design also hands over all future system control to the customer. They don't need you again or at least they think they dn't.

If you want to put in a micro, its very easy to make the case for it. I usually tell the customer about the flexibility and the design's potential to "extend the reach" of the product. The flexibility of the micro means that the customer has a product more ready to adapt to changes in his market, at the sometimes significant cost of future code modifications.

Few businessmen have the luxury of knowing precisely their market requirements and this "elbow room" in the design can be a good feature for the customer.

Usually you can tell the sophistication of your customer when you mention using a microprocessor. If they immediately bring up discussions of source code and ownership issues, then they know more about the process - I consider this more positive than negative.

And to be perfectly honest, if someone has a design that doesn't require a microprocessor, they're wasting their money hiring me to do it.

-Jay C. Box