| Author |
Message |
DarkPath
Guest
|
 Posted:
Sun Oct 23, 2005 11:08 pm Post subject:
Using a Karnaugh map I need to |
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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
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A. Gum
Guest
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| Posted:
Mon Oct 24, 2005 12:14 am Post subject:
Re: Using a Karnaugh map I need to |
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DarkPath wrote:
| Quote: | 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 |
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Tim Wescott
Guest
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| Posted:
Mon Oct 24, 2005 12:23 am Post subject:
Re: Using a Karnaugh map I need to |
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DarkPath wrote:
| Quote: | I wants to convert my old hot tub controller, wich is currently using
relays, to more reliable TTL gates (solid state) and opto-isolators.
|
Well, that's a worthy goal, indeed.
| Quote: | Design and build a logic circuit that will replace the control function
of the relay controller.
|
How cleverly you make this sound like a homework problem.
| Quote: | 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.
|
Why? That sounds like a dumb feature, but a good one to add complexity
to a homework problem. I'd want the underwater lights to be completely
independent of the heat/circulation control, and possibly even the main
power.
| Quote: | The first motor function to occur will have priority.
|
Once again a dumb-sounding feature. Wouldn't it be nicer to have the
jet pump be on user demand, and the circulator only go on if the
heater's running but not the jet pump?
| Quote: |
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
|
* You don't need to use a Karnaugh map to do this unless you want
to -- unless it's a homework problem. Simply reverse engineering
the relay logic, or using solid-state relays may be better.
* What's the make and model of your hot-tub controller?
* Here's what you do:
* Figure out how many internal states you have.
* List all your inputs and "starting" internal states in
columns on the left of your page
* List all your outputs and "ending" internal states in
columns on the right of your page
* Since you're dealing with an asynchronous system, append
two columns for each state with the necessary 'S' and 'R'
signals for your favorite S-R flip-flops.
* Enumerate all possible inputs and internal states. Use gray
code, it'll make generating the maps easier.
* For each output, 'S' and 'R' signal make a Karnaugh map.
If you don't know how just refer to your textbook or do
a web search.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
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Winfield Hill
Guest
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| Posted:
Mon Oct 24, 2005 12:35 am Post subject:
Re: Using a Karnaugh map I need to |
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Jim Thompson wrote...
| Quote: |
Bret Ludwig wrote:
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.
[snip]
IIRC, Don was an APPLICATIONS engineer at Motorola, NOT a DESIGNER ;-)
|
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.
--
Thanks,
- Win |
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Jim Thompson
Guest
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| Posted:
Mon Oct 24, 2005 12:35 am Post subject:
Re: Using a Karnaugh map I need to |
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On 23 Oct 2005 13:53:54 -0700, Winfield Hill
<Winfield_member@newsguy.com> wrote:
| Quote: | Jim Thompson wrote...
Bret Ludwig wrote:
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.
[snip]
IIRC, Don was an APPLICATIONS engineer at Motorola, NOT a DESIGNER ;-)
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.
|
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
--
| 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 |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
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Jim Thompson
Guest
|
| Posted:
Mon Oct 24, 2005 12:35 am Post subject:
Re: Using a Karnaugh map I need to |
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On Sun, 23 Oct 2005 14:35:12 -0700, Jim Thompson
<thegreatone@example.com> wrote:
| Quote: | On 23 Oct 2005 13:53:54 -0700, Winfield Hill
Winfield_member@newsguy.com> wrote:
Jim Thompson wrote...
Bret Ludwig wrote:
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.
[snip]
IIRC, Don was an APPLICATIONS engineer at Motorola, NOT a DESIGNER ;-)
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.
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
|
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
--
| 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 |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
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Bret Ludwig
Guest
|
| Posted:
Mon Oct 24, 2005 12:35 am Post subject:
Re: Using a Karnaugh map I need to |
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|
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! |
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Jim Thompson
Guest
|
| Posted:
Mon Oct 24, 2005 12:35 am Post subject:
Re: Using a Karnaugh map I need to |
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On 23 Oct 2005 12:46:06 -0700, "Bret Ludwig" <bretldwig@yahoo.com>
wrote:
| Quote: | 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.
[snip] |
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 |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
|
| Back to top |
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John Larkin
Guest
|
| Posted:
Mon Oct 24, 2005 6:02 am Post subject:
Re: Using a Karnaugh map I need to |
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|
On 23 Oct 2005 12:46:06 -0700, "Bret Ludwig" <bretldwig@yahoo.com>
wrote:
| Quote: | 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.
|
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 |
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keith
Guest
|
| Posted:
Mon Oct 24, 2005 6:35 am Post subject:
Re: Using a Karnaugh map I need to |
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On Sun, 23 Oct 2005 13:01:18 -0700, Jim Thompson wrote:
| Quote: | On 23 Oct 2005 12:46:06 -0700, "Bret Ludwig" <bretldwig@yahoo.com
wrote:
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.
[snip]
IIRC, Don was an APPLICATIONS engineer at Motorola, NOT a DESIGNER ;-)
|
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.
--
Keith |
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Mac
Guest
|
| Posted:
Mon Oct 24, 2005 8:30 am Post subject:
Re: Using a Karnaugh map I need to |
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|
On Sun, 23 Oct 2005 14:08:00 -0400, DarkPath wrote:
| Quote: | 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).
|
This is readily achieved by using main power to power the other logic
circuitry. Must be a homework problem.
| Quote: | 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.
|
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.
| Quote: | 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
|
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 |
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Jim Thompson
Guest
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| Posted:
Mon Oct 24, 2005 4:35 pm Post subject:
Re: Using a Karnaugh map I need to |
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On Sun, 23 Oct 2005 18:02:13 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
| Quote: | On 23 Oct 2005 12:46:06 -0700, "Bret Ludwig" <bretldwig@yahoo.com
wrote:
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.
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
|
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
5 variables.
BTW, gates aren't cheap, they consume _significant_ power at high
speeds, and some of us fret over that ;-)
...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 |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
|
| Back to top |
|
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Jim Thompson
Guest
|
| Posted:
Mon Oct 24, 2005 4:35 pm Post subject:
Re: Using a Karnaugh map I need to |
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|
On Mon, 24 Oct 2005 08:28:26 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
| Quote: | On Mon, 24 Oct 2005 07:46:52 -0700, Jim Thompson
thegreatone@example.com> wrote:
On Sun, 23 Oct 2005 18:02:13 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
On 23 Oct 2005 12:46:06 -0700, "Bret Ludwig" <bretldwig@yahoo.com
wrote:
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.
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
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
5 variables.
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
--
| 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 |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
|
| Back to top |
|
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John Larkin
Guest
|
| Posted:
Mon Oct 24, 2005 4:35 pm Post subject:
Re: Using a Karnaugh map I need to |
|
|
On Mon, 24 Oct 2005 07:46:52 -0700, Jim Thompson
<thegreatone@example.com> wrote:
| Quote: | On Sun, 23 Oct 2005 18:02:13 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
On 23 Oct 2005 12:46:06 -0700, "Bret Ludwig" <bretldwig@yahoo.com
wrote:
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.
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
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
5 variables.
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 |
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Keith Williams
Guest
|
| Posted:
Mon Oct 24, 2005 4:35 pm Post subject:
Re: Using a Karnaugh map I need to |
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|
In article <luupl1tmgnpsff5q7hfoashb6rpiaj6cgm@4ax.com>,
jjlarkin@highNOTlandTHIStechnologyPART.com says...
| Quote: | 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.
|
Curious, why do you like one-hots? I agree that they're generally
preferable with FPGA state machines but explicitly coding them
seems to go against the grain. I always use enumerated types for
state variables and either let the software decide on the encoding
or override it (if software chooses poorly) with an attribute.
--
Keith |
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