4-bit binary

dl324

Joined Mar 30, 2015
18,339
Not really, i've talked with a couple of people I know in the same course as me and they didn't have any clue either
Presumably you've been taught how to make truth tables and use Kmaps. Have you learned about the double dabble algorithm?

That's fine because 7447 won't do what you want.
I missed the part where you wanted to display 0-15, not 0-F. That can be done with a truth table of 4 variables with 9 outputs. I would have done it with a binary to BCD converter, but that would take a couple dozen gates in addition to the logic it would take to implement a BCD to seven segment decoder.

Are you breadboarding or just simulating?

EDIT: solution with a 2-digit display or a hexadecimal display.
1726149898994.png
There was a ROM based commercial binary to hexadecimal decoder (MC14495). I implemented the one I used with logic gates.

EDIT 2:
The 4 bit binary to 2 seven segment display decoder took me about 60 gates (with no attempt to reuse expressions).
 
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Thread Starter

chrisvicor

Joined Sep 11, 2024
9
Presumably you've been taught how to make truth tables and use Kmaps. Have you learned about the double dabble algorithm?


I missed the part where you wanted to display 0-15, not 0-F. That can be done with a truth table of 4 variables with 9 outputs. I would have done it with a binary to BCD converter, but that would take a couple dozen gates in addition to the logic it would take to implement a BCD to seven segment decoder.

Are you breadboarding or just simulating?

EDIT: solution with a 2-digit display or a hexadecimal display.
View attachment 331477
There was a ROM based commercial binary to hexadecimal decoder (MC14495). I implemented the one I used with logic gates.

EDIT 2:
The 4 bit binary to 2 seven segment display decoder took me about 60 gates (with no attempt to reuse expressions).
I am breadboarding. I will read on the double dabble algorithm right now.
 

dl324

Joined Mar 30, 2015
18,339
I am breadboarding.
Since you're having difficulties, it would be better for you to post your work so we can save you some hassle if your work has errors.
I will read on the double dabble algorithm right now.
If you haven't already heard about double dabble in your coursework, it's unlikely that you're expected to use it.

If you were working on a more general-purpose solution (e.g. an 8-bit binary counter to 3 BCD digits), double dabble would be helpful. Look up tables are the easiest way to do the conversion. For fun, I made a 13+ bit binary to 4-digit BCD converter using a 27C4002 256Kbx16 EPROM.

EDIT: corrected EPROM size.
 
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WBahn

Joined Mar 31, 2012
32,883
I am breadboarding. I will read on the double dabble algorithm right now.
While I always recommend learning more about anything that comes along (so, by all means, look into and understand what the algorithm is and how it works), it is overkill for the problem at hand.

Focus on the ten's display first. Which segments do you need to ever light up for this task (or turn off, depending on if you want to display '7' or '07')? What is the logic that will make just that happen? It's pretty trivial. Don't make things harder than they are.
 
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