SW for digital circuits

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

Reply to
Newberry
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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

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

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.

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John Larkin         Highland Technology, Inc 
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Reply to
John Larkin

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

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

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.

Reply to
gnuarm.deletethisbit

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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.

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.

Reply to
gnuarm.deletethisbit

My protos usually include optics and lasers and stuff, not just logic.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

What's your point?

Rick C.

Reply to
gnuarm.deletethisbit

You can't use a synthesis tool to 'prototype' mixed-technology systems.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

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.

Reply to
gnuarm.deletethisbit

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.

Reply to
George Herold

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:

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Reply to
bitrex

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.

Reply to
bitrex

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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

Reply to
Richard Jones

And having read the whole thread I see someone else mentioned this site too so consider my earlier reply a +1 :-)

Reply to
Richard Jones

;)

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

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

I just need to visualize Boolean functions.

Reply to
Newberry

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