# design 7 segment

Discussion in 'Homework Help' started by G-207, Nov 27, 2009.

1. ### G-207 Thread Starter New Member

Nov 27, 2009
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0
I have to design a seven segment display which displays INDIA IS GREAT with certain delay (say 5 sec) between successive letter displays in continuously and decoding circuitry must be combinational circuit and OPTIMAL .Please help me in this matter or if u can provide me some support with circuit diagram........please

2. ### SgtWookie Expert

Jul 17, 2007
22,199
1,800
We can't do your homework for you. That would defeat the entire purpose of giving you the assignment to begin with.

First, you will need to figure out which segments need to be turned on in order to most effectively represent each letter in the phrase, "INDIA IS GREAT". You may have to use a mixture of UPPER CASE and lower case letters.

You should refer to a datasheet of a 7-segment display for reference purposes. Find one somewhere.

Note that each segment of a 7-segment display is normally referred to as a lower case letter, typically a, b, c, d, e, f, and g.

You will need to construct a truth table consisting of which segments need to be on and which need to be off for each letter.

Do that, and post your truth table.

3. ### mik3 Senior Member

Feb 4, 2008
4,846
69
After you make the truth table which shows which segments will light for each letter use an up counter and decode each output value of the counter to represent a letter to be displayed. For example, if the counter outputs 1 then the letter 'I' will appear on the display, when the counter increments to 2 the letter 'N' will appear and so on. If you increment the counter every 5 secs then all the letters will be displayed in sequence. On the counter's increment after the last letter reset the counter to start over. I think you got an idea now how to proceed.

4. ### G-207 Thread Starter New Member

Nov 27, 2009
8
0
yes sir i have made the truth table.....no what should i do??

5. ### G-207 Thread Starter New Member

Nov 27, 2009
8
0
i m giving u d truth table please tell me is it right and what i should do now

6. ### SgtWookie Expert

Jul 17, 2007
22,199
1,800
I don't see your truth table. You may have tried to attach it in a format that is not supported by the Board.

7. ### SgtWookie Expert

Jul 17, 2007
22,199
1,800
After you have posted your truth table, start converting it to Boolean statements.
For example, let's say you decided to use segments b and c to represent an "I".
So then, I = bc

8. ### G-207 Thread Starter New Member

Nov 27, 2009
8
0
sir can u lead me now if u r free

9. ### mik3 Senior Member

Feb 4, 2008
4,846
69
Where is the truth table?

10. ### G-207 Thread Starter New Member

Nov 27, 2009
8
0
sir i hav attached it in another window from your site please check it

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11. ### mik3 Senior Member

Feb 4, 2008
4,846
69
Now, you can use a decade counter which can count at least 12 input pulses before starting from the beginning. This is because you need 12 steps to display all your letters. The counter will be incremented every 5 secs. Thus you have to take each segment individually and find at which outputs of the counter it needs to light. Then OR these outputs for this particular segment. Do the same for all the segments.