Using a Karnaugh map I need to

I think it was Don Lancaster, before he abandoned electronic design for surplus baronage, who decided K-mapping was a waste of time because gates were cheap.

Don apparently didn't profit much from this idea, but some one did. Ironically, his name was.....Gates!

IIRC, Don was an APPLICATIONS engineer at Motorola, NOT a DESIGNER ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

Whoa, Jim, it's not only IC designers who may be electronic design engineers! I'm an electronic design engineer who doesn't design ICs. Furthermore, many applications engineers are fully-educated skillful electronic designers, for example Bob Pease and Jim Williams, just to mention two familiar ones. It's fair to say Don Lancaster is an electronic designer, even though he doesn't design ICs. What he did at Motorola, I can't say, but many a clueless customer calls up and expects (and often gets, if they're big enough) free design work, designs that incorporate ICs, rather than design them from scratch. This is an issue Jim Williams describes in his app notes, telling of an anxious boss who wants to see the customer's design finished.

It's also a good exercise for IC houses, because it's a good way to learn of new IC requirements (e.g., an efficient piezo-transformer driver for laptop screen lighting), that may bring in the big bucks.

I wants to convert my old hot tub controller, wich is currently using relays, to more reliable TTL gates (solid state) and opto-isolators. Design and build a logic circuit thatl will replace the control function of the relay controller. The all solid-state circuitry would have to operate the following functions:

Switch Input #1-Main Power Switch Input #2-Underwater Light Switch Input #3-Circulator Pump Switch Input #4-Jet Pump Switch Input #5-Heat Demand Signal (thermostat)

Nothing may operate until switch #1 is activated (main power).

The light swithch (#2)may then be switched on or off independently after the main power switch is on. However, they may not operate at the same time. If one has been previously turned on, the other will not operate. The first motor function to occure will have priority.

If switch #5 (heat demand) is activated, water must be moving through the system, therefore if the water is stagnant, the circulator must start automatically. If the circulator or jet pump is already running when the heat demand is activated, no other function needs to take place. Please reply via usenet. My header is a spam trap

Do your own homework

Back in the '60's Analog chip designs were done around an application requirement. Then the applications (aka publications) group wrote it up all "purty" and nice... 'cept they often made mistakes. Some of the PLL notes are truly hilarious.

...Jim Thompson

Guess ;-)

...Jim Thompson

If there are any '60's vintage Motorola ANALOG parts you'd like to know more about just ask.

...Jim Thompson

So if the light switch (#2) is turned on before Main power (#1) is applied, then the system will not respond to switch #1? This is perhaps a tactical hot tub?

It got so bad that we designers were spending so much time proofing data sheets that we went back to doing them ourselves.

...Jim Thompson

I've never used a K-map. They always seemed silly to me; I like logic that has intermediate terms that mean something.

Besides, you can do most logic by inspection.

And besides, FPGA compilers reduce the logic for you.

Take the current example: the correct solution to the problem isn't a K-map, it a statement that the proposed logic is stupid.

John

Ah, so his motive was to *sell* gates, rather than *use* them. I never met anyone (outside a sales, perhaps) who believed that more packages were better.

Ok,then which one of you two guys left the essential info out of the data sheet then?

martin

dammit, too many thens

martin

This is readily achieved by using main power to power the other logic circuitry. Must be a homework problem.

What is the antecedent to "they?" It is not clear to me at all. Did the professor post the assignment on-line? If so, it would be nice to include a URL to the assignment.

Is this supposed to be a state machine or do you just want combinatorial logic? You might ask your professor if the problem doesn't state anything about it.

--Mac

Aah, the great "Open Loop" system. Wonder if Harold Black is turning in his grave?

martin

Not everyone has an FPGA compiler laying around. I can still do K-maps by hand, but I usually use...

KarnaughMap Version 4.4.5 by Russell Sasamori, which can handle up to

BTW, gates aren't cheap, they consume _significant_ power at high speeds, and some of us fret over that ;-)

...Jim Thompson

Most of the logic we do these days is inside FPGAs, and most of that, by cell count, is data paths. And the logic is LUT-based, so pure K-map reduction isn't necessarily optimum. Logic in 22V10-type chips has its own constraints, like sum-of-products, so that's not classicly K-mappable either. And we usually tune for speed, not minimum number of gates.

Professors like K-maps because they're rigid, easy to teach and easy to test on.

The sum-of-products thing is a nice way to clearly document what's really going on. One-hot state machines are nice, too. Neither is a "classic" technique, where minimizing gates was the goal.

John

In my situation I'm building my own gates and flops from transistors. But usually trivial stuff ancillary to analog functions.

...Jim Thompson