SW for digital circuits

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Hi, is there any SW such that you give it a Boolean formula and it draws  
a circuit diagram?

Re: SW for digital circuits
On 05/16/2018 11:38 AM, Newberry wrote:
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Not exactly.  You can write VHDL, Verilog, or System C, and there's
software to implement that in an FPGA or CPLD.

Not too much logic is done by wiring gates together on a board anymore.

It's pretty fun to play with SSI and MSI chips--I use them very often in
protos and proof-of-concept systems--but implementing anything of any
size gets unwieldy.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: SW for digital circuits
On Wed, 16 May 2018 13:19:45 -0400, Phil Hobbs

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Fast stuff still, but in small quantities. Sometimes it makes sense to
wrap some gates and flops around the edges of an FPGA. FPGAs can have
a lot of jitter and delay-temperature effects, and their actual prop
delays are poorly defined. People still sell ECL!

I've never been a fan of Boolean equations or Karnaugh maps, mainly
because I generally have to work with whatever logic chips are
available, preferably in stock. And often some logic paths have
different speed constraints compared to others.


--  

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement  

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Re: SW for digital circuits
On 05/16/18 13:47, John Larkin wrote:
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Karnaugh maps are occasionally useful--I remember my second-year physics  
lab had some simple logic synthesis in it (4 inputs iirc), so the TA got  
me to teach everybody how to do Karnaugh maps.  Sure sped up the process.

A lot of what I use MSI for is stuff like simple sequencers (often with  
a 74HC4017 one-of-ten counter) or frequency synthesis.  A couple of  
years ago I implemented the signal processing for an acousto-optically  
scanned laser microscope using a bunch of counters and Mini-Circuits  
parts in die-cast aluminum boxes.  Worked great.

Resynchronizing jittery stuff is also super useful, as you say.

Cheers

Phil Hobbs


--  
Dr Philip C D Hobbs
Principal Consultant
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Re: SW for digital circuits
On 05/16/2018 01:47 PM, John Larkin wrote:
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K maps can be useful because they allow straightforward identification  
of potential race conditions; even fairly simple boolean expressions  
when implemented with async/hairball logic can have races/glitch hazards  
intrinsic to the topology even ignoring particulars of the  
implementation/logic family/temperature etc.

Re: SW for digital circuits
On Wednesday, May 16, 2018 at 1:19:57 PM UTC-4, Phil Hobbs wrote:
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s

The ham community does.  They like low tech assembly methods and DIP packag
es, so use a lot of TTL still.  I recently saw a post by a rather experienc
ed ham who was testing a LFSR noise generator made of 4 bit shift register  
TTL chips.  He couldn't figure out why it was producing energy at half the  
intervals expected.  Turns out he was clocking the register faster than it  
was spec'd for and essentially was running it at half the rate he expected.
  

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Far to slow and clunky for prototyping even small designs like LFSRs.  I mu
ch prefer a simulation verified by an automated test bench.  Once you get u
sed to writing these they get to be pretty easy.  While reading about the h
am's problem I realized it would be feasible to construct an LFSR noise gen
erator with an output in the GHz and a repetition rate in the mHz using a l
ow cost FPGA.  

Rick C.

Re: SW for digital circuits
On 05/16/2018 04:59 PM, snipped-for-privacy@gmail.com wrote:
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My protos usually include optics and lasers and stuff, not just logic.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: SW for digital circuits
On Wednesday, May 16, 2018 at 5:13:29 PM UTC-4, Phil Hobbs wrote:
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What's your point?  

Rick C.  

Re: SW for digital circuits
On 05/16/2018 05:22 PM, snipped-for-privacy@gmail.com wrote:
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You can't use a synthesis tool to 'prototype' mixed-technology systems.

Cheers

Phil Hobbs


--  
Dr Philip C D Hobbs
Principal Consultant
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Re: SW for digital circuits
On Wednesday, May 16, 2018 at 5:26:30 PM UTC-4, Phil Hobbs wrote:
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That's true, you can't use a synthesis tool to simulate digital technology either.  I have used a "digital" simulator to simulate mixed signal systems.  After all, the analog portion is just math and simulators typically support floating point arithmetic.  

When you come down to it, you are only limited by your imagination.  :)  

Rick C.  

Re: SW for digital circuits
On Wednesday, May 16, 2018 at 5:13:29 PM UTC-4, Phil Hobbs wrote:
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I cut this metal tube today, stuck a laser diode (run low current as  
a LED) and my spad at the other end, worked OK, but then flopping around.
so I wrapped some bus wire around the tube (18 awg I think)  
and soldered that onto the proto board.  Nice and solid...  
and all of a sudden my spad (photodiode) is taking off at zero volts  
bias.  I have a simple opamp current source feeding the laser diode.
(floating load)
When the case, touched the tube, soldered to ground... it was a laser  
at the current limit of the opamp.  (fortunately less than max for LD. :)
I sat there looking at it for at least a minute. Shaking wires and such.

George H.  
  
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Re: SW for digital circuits
On 05/16/18 19:43, George Herold wrote:
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;)

In building new instruments, I spend a surprising amount of time  
staring at perfectly functioning equipment figuring out what it's doing,  
because it's never exactly what I expect.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: SW for digital circuits
On Wednesday, May 16, 2018 at 11:38:50 AM UTC-4, Newberry wrote:
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In a way, yes.  When designing FPGAs, the synthesis tool will translate your formulas into a design which it then is capable of drawing.  Not sure where you are going with this so I can't say if this will be what you want.  

Rick C.  

Re: SW for digital circuits
snipped-for-privacy@gmail.com wrote:
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I just need to visualize Boolean functions.

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Re: SW for digital circuits
On 05/16/2018 11:38 AM, Newberry wrote:
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If you do a search for "online quine mccluskey solver" it will pull up a  
number of applets that will let you enter truth tables and will generate  
a Karnaugh map and minterm/maxterm canonical forms, straightforward  
enough to translate to a logic circuit implementation.

This one does up to 7/8 variables for QM and K map, respectively:

http://www.32x8.com/



Re: SW for digital circuits
On 16/05/2018 16:38, Newberry wrote:
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http://www.32x8.com/var4.html
This site allows you to define the logic by truth table or K map and it  
will output an ASCII logic diagram if you wish

Re: SW for digital circuits
On 17/05/2018 10:08, Richard Jones wrote:
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And having read the whole thread I see someone else mentioned this site  
too so consider my earlier reply a +1 :-)

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