# Minimize logic expression for each segment in 7 segment LED

#### vick5821

Jan 22, 2012
700
Hey guys, currently I am working on to find the minimize logic expression to lights up each individual segment in 7 segment LED

For segment a : B +D + A(bar) C(bar) + AC
For segment b : C(bar) + D + A(bar)B(bar) +AB

So far correct ? Can anyone provide me for the the next few logic ? want to compare my answer.

Thank you

#### War_Spigot

Feb 20, 2012
43
Looking at the datasheet for a 7 segment decoder would help. They usually have logic diagrams. From that you could write the equations for each segment and then try to simplify it.

#### vick5821

Jan 22, 2012
700
Looking at the datasheet for a 7 segment decoder would help. They usually have logic diagrams. From that you could write the equations for each segment and then try to simplify it.

yea..I wrote the equations, now I wanna compare the final answer

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,179
The homeworks section doesn't work like that.

You provide the answer and we can tell you (hopefully) whether it is correct or not. And if not guide you along to find the right answer.

Harald

#### vick5821

Jan 22, 2012
700
This is my final answer. Correct me if I am wrong

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,179
For reason of little time I checked only sheet one for segment a. It looks entirely correct to me.

There is a second approach: Look at the KV diagram for segment a again. You evaluated, correctly, the situations where a=1 (or a=x) to arrive at an equation with 4 terms. What happens if you look at the same diagram but this time watch out for a=0? The equation will have only 2 terms, at the cost of each single term being more complex. From the equation for a=0 you get a=1 by negating the complete equation.
Note: this is only a hint for an additional solution and shall in no way imply that the solution you found by yourself is not well evaluated.

Harald

#### Laplace

Apr 4, 2010
1,252
Here is an example of using a spreadsheet (O Calc) as a logic simulator. The conditional formatting effects do not seem to carry through if you open the .ods file in Microsoft Excel. Segment 'd' seems to have a problem for the BCD value 0110.

#### Attachments

• Seven-Segment.ods.zip
7.5 KB · Views: 523

#### vick5821

Jan 22, 2012
700
Here is an example of using a spreadsheet (O Calc) as a logic simulator. The conditional formatting effects do not seem to carry through if you open the .ods file in Microsoft Excel. Segment 'd' seems to have a problem for the BCD value 0110.

How to use that file ?? @@@

Moderator
Jan 21, 2010
25,505

#### vick5821

Jan 22, 2012
700
How about other segment ? Is it done correctly ?

#### Luke Vassallo

Dec 10, 2014
33
I would suggest, that you simulate your circuit, it's important to do this especially if you are building your circuit. First you know I its behaving correctly and secondly it will help you troubleshoot errors when a certain part of your circuit isn't working.

I would suggest icircuit - very basic and working wonderfully with logic circuits or multisim.

Hope this helps. Be sure to fully annotate your diagrams!

#### Ratch

Mar 10, 2013
1,098
Hey guys, currently I am working on to find the minimize logic expression to lights up each individual segment in 7 segment LED

For segment a : B +D + A(bar) C(bar) + AC
For segment b : C(bar) + D + A(bar)B(bar) +AB

So far correct ? Can anyone provide me for the the next few logic ? want to compare my answer.

Thank you
You can try a program I wrote to check logic calculations. Expand the zip file into a temporary file and read the documentation. Take your K-map answer and plug it in. My program will give you the minterms. If the minterms match what you used on your K-map, then your reduction is correct. My program assumes that your logic variable "A" is the highest order variable, whereas you assume that "A" is the lowest order variable. Therefore, you have to transpose A-->D, B-->C, C-->B, D-->A . I checked the first two calculations you made and they appear correct.

Ratch

#### Attachments

• BOOLIT.zip
4.7 KB · Views: 216

Replies
5
Views
1K
Replies
10
Views
725
A
Replies
3
Views
1K
Nico Coesel
N
J
Replies
27
Views
3K
Jack Zeal
J
B
Replies
13
Views
1K
N. Thornton
N