# 7-Segment display with flip flop

Discussion in 'Homework Help' started by Darknight7, May 22, 2012.

1. ### Darknight7 Thread Starter New Member

May 21, 2012
20
0
Here is the question we need help to design the circuit If you help us we will be pleased:

Design a circuit which display the letters A through J on a seven-segment
indicators. The circuit has three inputs X2-X1-X0 which represents the last
3 bits of the ASCII code for the letter to be displayed. For example, if
X2X1X0 = 000, A will be displayed. The letters should be displayed in
the following form:

A-b-C-d-E-F-g-H

Try to minimize the number of gates required. The circuits which implement
only using NOR gates and inverters.

How should we design the circuit by using pspice or multimedia logic programme. We have been researching for flip flop however we do not know how to connect them with eachother

2. ### MrChips Moderator

Oct 2, 2009
12,636
3,455
Why do you need a flip-flop?
Your instructions say to use NOR and NOT gates.
This is a 4-bit to 7-bit encoder. Draw the truth-table first.

3. ### Darknight7 Thread Starter New Member

May 21, 2012
20
0
Thank you. We need flip flop because; the given information is that "Design a 3 bit binary counter which works the frequency at 1 Hz. Thus, your
counter will count once per second. You can use T, D or J-K flip-flop considering
synchronous or asynchronous design"
Therefore we need it; we also draw a trurth table;
I will upload it. A few minutes later...

4. ### Darknight7 Thread Starter New Member

May 21, 2012
20
0
here is the truth table..

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5. ### MrChips Moderator

Oct 2, 2009
12,636
3,455
What happened to the letters I and J?

6. ### Darknight7 Thread Starter New Member

May 21, 2012
20
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Because we will use 3 bit binary counter therefore we won't take them..so have you got any idea we designed a circuit by using multimedia logic programme however our outputs are wrong only "g" and "b" is true. but we could not design a JK flip flop in the programme not yet. I think we need the circuit diagram of the project. Becasue our four design is wrong. We have been trying to develop the diagram.

7. ### Qwazzerman New Member

May 8, 2012
10
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Another layout for the g would be a capital letter, which would differentiate g from 9.

Of course, that might not be a concern...

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8. ### Darknight7 Thread Starter New Member

May 21, 2012
20
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Any other advices because we have a few problems to design the circuit....We need really help.

9. ### MrChips Moderator

Oct 2, 2009
12,636
3,455
From the truth table the next step is to write out the boolean expression for each LED segment.

10. ### absf Senior Member

Dec 29, 2010
1,493
374
The 3 bit binary counter part is easy. Just refer to the datasheet of 74LS93.

Allen

11. ### absf Senior Member

Dec 29, 2010
1,493
374
I am a beginner in Boolean Algebra. This is an exercise for me to use Truth table, Demorgan and boolean algebra to generate a schematics. For the "G" pattern I used Qwazzerman's suggestion.

I am not sure they are in the simplest term or not.. The pulses are coming from a 4510 Up/Down counter. I will do the logic gates version later..

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12. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
This is homework, as far as I can tell, so I have moved it to the Homework forum.

Mr. Chips has give you some good advice. At this point you need to write the Boolean expression for each segment, all seven of them, and simplify.

ABSF: it is very poor form to give the answer directly, better to show the OP how to solve for themselves.