Using Logic Systems

[GreenGiant]

Even though I have only been working with electronics for the last 5 years or so I still feel like an old fart when saying this but, I very much like to us Logic systems when I can. Yes I know that I can use a microcontroller for everything that logic can do, but I really enjoy figuring out how to implement logic systems rather than fall back on Micros.

Does anyone else follow this belief I guess you could call it?

Maybe Im just crazy but I like using flip flops, timers, ANDs, ORs, NORs, etc

I guess my goal for this thread is just to debate logic and/or appreciate it

So which do you prefer?
How do you go about designing a logic system? (formula/input+outputs/etc)

What are some of your favorite logic systems you've dealt with/designed?

Green

 

[BobK]

Well, since you said it was a debate, I guess I will take the other side

I have been toying with electonics since my teen years, but I never really go into it until I discovered PICs a few years ago. Perhaps that has something to do with the fact that I am a software professional (I have made a living writing compilers for almost 40 years now). To me, that fact that I can do really complex things with mostly software has enabled me to tackle things I never would have considered otherwise. The only reason I see to using logic chips now is if the speed needs to be higher than you can achieve with a microcontroller, but I am doubtful that I could design and build things at those kind of speeds anyway.

Edit: by the way, where in MA, GG?

Bob

 

[GreenGiant]

Well, since you said it was a debate, I guess I will take the other side

I didn't necessarily mean for it to be nothing but a debate

I have been toying with electonics since my teen years, but I never really go into it until I discovered PICs a few years ago. Perhaps that has something to do with the fact that I am a software professional (I have made a living writing compilers for almost 40 years now). To me, that fact that I can do really complex things with mostly software has enabled me to tackle things I never would have considered otherwise. The only reason I see to using logic chips now is if the speed needs to be higher than you can achieve with a microcontroller, but I am doubtful that I could design and build things at those kind of speeds anyway.

See I started out with the hardware side of things, and logic just makes sense to me, plus with a lot of things its a lot cheaper. Like a friend wanted me to design a little setup for his car where if he pressed a momentary switch something would turn on, press it again something else would turn on, and press it a third time and everything would be off. Yes a micro could do that, but its so small and simple that I just took some flip flops, a couple AND/OR gates (and I think and XOR) and BAM it worked. Took me about an hour/hour and a half to design and build that

Edit: by the way, where in MA, GG?

Bob

I am currently working in Waltham MA, and live not too far from there

 

[BobK]

Yes a micro could do that, but its so small and simple that I just took some flip flops, a couple AND/OR gates (and I think and XOR) and BAM it worked. Took me about an hour/hour and a half to design and build that

But, excluding the power supply and components needed to interface to the devices controlled, the uController solution would require 3 parts: An 8-pin micro, a decoupling capacitor, and the switch. Then it would need maybe 30 lines of C.

Then when your friend says, wow, this is great, but can you make it turn everything off if I haven't touched a button or 1 hour? What do you do? I just reprogram the micro, no hardware necessary.

Bob

 

[CocaCola]

plus with a lot of things its a lot cheaper.

Excluding the development tools what used to be a gap in cost is simply not there anymore, even in small designs and certainly not in large ones...

You can get small micros for pennies now... In your example (as Bob pointed out) an 8 (or even 6) pin micro will do the job and can be had for about 50 cents...

I'm not against logic chips, but the fact is micros are a lot more veritable... They are a simple one chip solution to many things...

 

[gorgon]

Even though I have only been working with electronics for the last 5 years or so I still feel like an old fart when saying this but, I very much like to us Logic systems when I can. Yes I know that I can use a microcontroller for everything that logic can do, but I really enjoy figuring out how to implement logic systems rather than fall back on Micros.

Does anyone else follow this belief I guess you could call it?

Maybe Im just crazy but I like using flip flops, timers, ANDs, ORs, NORs, etc

I guess my goal for this thread is just to debate logic and/or appreciate it

So which do you prefer?
How do you go about designing a logic system? (formula/input+outputs/etc)

What are some of your favorite logic systems you've dealt with/designed?

Green

Being a much older fart in electronics, I started with it almost before the IC was public known, and microprocessors more or less a bright light in the future. During my first job I started designing special interfaces for the equipment I serviced, with logic. And after that I did many big designs in logic, but also microprocessor designs. The first micro I designed with was one of the first cmos micros, the CDP1802.

Designing with logic today is more or less for fun, and I like to use the 74hc series.

But even today you need to make some glue logic when programmable logic is too expencive.

That said, I have an even more crazy design in mind, when I get the time. I would very much like to design a desk top calculator with transistors only, no ICs at all! I've got an old design with logic from a 30+ years old magazine, and want to use that as a template for the pure transistor design. I've just started to design the logic on paper and I've no idea of how many transistors I'll use on the way.

This is a far cry from the newest Freescale ARM micros I use designing at work. But I hope it'll be fun on the way. Isn't that what it's all about?

TOK

 

[GreenGiant]

Excluding the development tools what used to be a gap in cost is simply not there anymore, even in small designs and certainly not in large ones...

You can get small micros for pennies now... In your example (as Bob pointed out) an 8 (or even 6) pin micro will do the job and can be had for about 50 cents...

I'm not against logic chips, but the fact is micros are a lot more veritable... They are a simple one chip solution to many things...

That may be true, but I dont have enough experience at this point to use just a generic micro, so I was referring to using an Arduino, in which case purchasing and using logic can be cheaper if its a small setup.

Plus micros seem like cheating sometimes, when you can build it with logic it looks cooler most of the time too

 

[CocaCola]

Plus micros seem like cheating sometimes, when you can build it with logic it looks cooler most of the time too

And I'm sure a previous generation felt that using ICs of any kind was cheating, when you could use them groovy tubes And I think most will agree the tubes do look better

It's not cheating it's simply embracing the new technology...

 

[GreenGiant]

And I'm sure a previous generation felt that using ICs of any kind was cheating, when you could use them groovy tubes And I think most will agree the tubes do look better

It's not cheating it's simply embracing the new technology...

They do look a lot cooler, but they are hard to find nowadays haha

I lov fooling around with my Arduino's and building stuff with it, I just like the challenge of not using a micro sometimes

 

[CocaCola]

I understand, and you point about the Arduino is exactly why I suggest people really consider not getting fixated on them and learning how to do the micros the traditional way... It just opens up so many more options, and you are not out a substantial investment with each new design...

 

[Raven Luni]

Its the challenge of solving problems with the simplest of building blocks - thats where the fun is. I've been programming computers since I was 6 years old and one disturbing pattern I've noticed is that the fundamental knowledge is disappearing. Everyone is relying on proprietary scripts to perform highly abstract tasks. It is so much the norm now that if I was to apply for another job (outwith my field), I'd be laughed at.

I wouldnt say that electronics is necessarily going the same way as there will always be a need for simple circuits and discrete components, BUT when computers become involved ie. microcontrollers, then you are into the realm of software. How many PIC users can program in machine code / assembler? How many can only use the higher level tools like C and other languages? And how many rely purely on copying whats available on the web?

Its not only that the tools we have access to are becoming over-simplified, its that big business is taking advantage of this, creating 'vendor lock-in' scenarios, anti-tampering measures, DRM etc. In essence, hoarding knowledge (and therefore power). Again I'm speaking of software, but this stuff is actually being implemented at the IC level - particularly between intel and microsoft. If they get their way, the CPU itself will nolonger be something one can control, but something with a hidden layer of operation only able to run 'approved' software.

Basic electronics is relatively immune from all this........for now.........

 

[GreenGiant]

Its the challenge of solving problems with the simplest of building blocks - thats where the fun is. I've been programming computers since I was 6 years old and one disturbing pattern I've noticed is that the fundamental knowledge is disappearing.

I totally agree

Basic electronics is relatively immune from all this........for now.........

I think that there will be a lot of time before things change, I mean there is only so much difference you can make, you cant avoid using (inadvertently mind you) the basic building blocks. For almost every circumstance a function can be broken down into the basic ANDs/OR's/NORs etc

 

[BobK]

I hear you. Fortunately I work in compilers, so I am still at the machine instruction level. But I could not get a job as an application programmer nowadays. You have to have 3 years experience with the XYZ framework running on top of the PQR platform communicating in the FGH protocol using the latest version of the JKL language.

I long for the days when I could program on DOS knowing the entire set of commonly used system calls in my head. And I swear that DOS on a 386 was more responsive than any WinDoze system today.

So to me, for fun, microcontrollers are the answer, I can have control from the first instruction executed.

Bob

 

[Raven Luni]

Maybe not the material itself, but one very prominent and unfortunate truth is that the more people that have access to knowledge, the greater the potential it has to be misused. Given the level of paranoia in governments these days, I wouldnt be surprised if the likes of google made it harder and harder to find such knowledge.

We have reached the peak of what was a revolution in terms of available knowledge and empowerment of the individual. It wont last, and things can only go downhill from here.

 

[CocaCola]

Its the challenge of solving problems with the simplest of building blocks - thats where the fun is

And there is lies the imaginary line in the sand... Logic chips are not the building blocks they are integrated circuits just like micros, if you are going to use any integrated circuit you are really being hypocritical and just moving the line in the sand a little to the left or right...

Now if you are building the gates with discretes, I applaud you, knock your socks off, but it's simply not practical for most modern day designs...

 

[Raven Luni]

I've built many a gate with transistors because using logic ICs would be wasteful and leave unused gates

 

[GreenGiant]

And there is lies the imaginary line in the sand... Logic chips are not the building blocks they are integrated circuits just like micros, if you are going to use any integrated circuit you are really being hypocritical and just moving the line in the sand a little to the left or right...

Now if you are building the gates with discretes, I applaud you, knock your socks off, but it's simply not practical for most modern day designs...

That is an applaudable feat, but for that there is not a HUGE difference, I mean yes for some of the more complicated (XOR/XNOR) you have some level of difficulty in building them (for 2 inputs you have like 10 or so components

In my original post I was talking about the actual logic of it not going as basic as possible, though I would love to at some point build a simple counter or something with as basic components as possible

any ideas of a circuit that would be complicated and fun to build?

 

[CocaCola]

any ideas of a circuit that would be complicated and fun to build?

I have always though a basic arithmetic calculator would be fun to build from discretes... Maybe when I'm retired and have lots of time, but probably not as I don't have the patience...

This looks fun though...

http://www.transistorclock.com/

I'd probably go with the Nixe tube version to even add more coolness... Same guy...

http://tube-clock.com/

 

[BobK]

I have always though a basic arithmetic calculator would be fun to build from discretes... Maybe when I'm retired and have lots of time, but probably not as I don't have the patience...

I thought at one time that I might want to build a simple 4-bit micro out of transistors. But now I have upped the ante. My fun retirement project now is to design and build a 32-bit CPU using programmable logic, then develop the compiler and OS for it. I figure it might keep me busy for a couple of weeks

Bob

 

[GreenGiant]

I have always though a basic arithmetic calculator would be fun to build from discretes... Maybe when I'm retired and have lots of time, but probably not as I don't have the patience...

This looks fun though...

http://www.transistorclock.com/

I'd probably go with the Nixe tube version to even add more coolness... Same guy...

http://tube-clock.com/

I would love to build something like either of those