# next step after create Truth Table to make 7 segment LED counter by using Digital Works 95

#### Shen Joo

Joined May 23, 2018
12

I am a student.

After creating the truth table, I got stuck and I don't know what to do next to create a circuit that combines a separate circuit to form a complete circuit in the digital Works 95 software.

#### dl324

Joined Mar 30, 2015
13,820
Welcome to AAC!

Is the assignment to display your student ID number on a seven segment display?

#### WBahn

Joined Mar 31, 2012
26,398
View attachment 153009
I am a student.

After creating the truth table, I got stuck and I don't know what to do next to create a circuit that combines a separate circuit to form a complete circuit in the digital Works 95 software.
Just knowing that you "don't know what to do next to create a circuit that combines a separate circuit to form a complete circuit" doesn't give us much to go on.

What, exactly, is it you are trying to do?

What is your truth table for?

Remember, we are not mind readers.

#### dl324

Joined Mar 30, 2015
13,820
After creating the truth table, I got stuck and I don't know what to do next to create a circuit that combines a separate circuit to form a complete circuit in the digital Works 95 software.
While we're still waiting for clarification from you, I concur that your truth table and expressions make little sense.

How do you get abc+defg from the first row? Who is teaching you to write boolean expressions in this manner? What does this mean? You have seven segments you need to control, but your "statements" make no sense. How can abc+defg turn on segments a, b, and c?

#### Shen Joo

Joined May 23, 2018
12
Welcome to AAC!

Is the assignment to display your student ID number on a seven segment display?

The answer is yes, the seven segment display need to show the Student ID

and in the question need to using 3 sequencers or bit generators in the circuit as input.

#### Shen Joo

Joined May 23, 2018
12
Just knowing that you "don't know what to do next to create a circuit that combines a separate circuit to form a complete circuit" doesn't give us much to go on.

What, exactly, is it you are trying to do?

What is your truth table for?

Remember, we are not mind readers.

The Truth Table in xlsx.file

#### Attachments

• 8.2 KB Views: 42

#### dl324

Joined Mar 30, 2015
13,820
in the question need to using 3 sequencers or bit generators in the circuit as input.
How are you going to represent 8 with just 3 sequencers? Are you going to do something other than decode the actual numbers for display?

You seem to be having problems generating the truth table. Part of the table should be the counts from the sequencer (in the form of a 3 or 4 bit binary number). That's all I'm going to give away until I see more work from you.

#### Shen Joo

Joined May 23, 2018
12
How are you going to represent 8 with just 3 sequencers? Are you going to do something other than decode the actual numbers for display?

You seem to be having problems generating the truth table. Part of the table should be the counts from the sequencer (in the form of a 3 or 4 bit binary number). That's all I'm going to give away until I see more work from you.
The question say " You should use 3 sequence or bit generators in your circuit as input"

and honestly i now stuck in boolean expressions statement because it is too complicated...

So i am very sorry make things complicated.

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• 8.2 KB Views: 23

#### dl324

Joined Mar 30, 2015
13,820
The question say " You should use 3 sequence or bit generators in your circuit as input"
How many bits does it take to represent the number 8? Could it be that the question was written for the case where numbers were less than 8?

Since you're using Excel to create your table, you could use Excel formatting features to make the table more readable:

It would be more typical for the "ID Number" column to consist of multiple columns, with each representing the state of one of your bit sequencers. Does this hint help you?

#### WBahn

Joined Mar 31, 2012
26,398
Many members will not open a spreadsheet file because of security considerations, particularly when there is no reason to share a spreadsheet.

If you have three 1-bit sequence generators, then you can only get, at most, eight steps in the sequence. If your student ID is no longer than that, then you need to use the output of the sequence generators to dictate which segments are one and off at each step.

For instance, if the three bits tell you that you are at step 3, the because the digit in that spot is a 7 you know that the value of the signal driving the 'c' segment needs to be HI, while when you are at step 4 your digit is a 2 and the 'c' segment needs to be LO. Make a circuit that looks at ONLY the three bits of the sequencers and generates the right values for the 'c' segment.

What do you think you then need to do for the other segments?

#### dl324

Joined Mar 30, 2015
13,820
Many members will not open a spreadsheet file because of security considerations, particularly when there is no reason to share a spreadsheet.
Files with .xlsx extension don't contain macros. If a .xlsm extension is changed to .xlsx to try to fool someone into opening a file that contains macros, Excel will refuse to open it:

There could be ways to circumvent this protection, but I took a leap of faith.

When I tried renaming a file containing macros to .xlsx and then back to .xlsm, Excel gave this warning:

#### Shen Joo

Joined May 23, 2018
12
How many bits does it take to represent the number 8? Could it be that the question was written for the case where numbers were less than 8?

Since you're using Excel to create your table, you could use Excel formatting features to make the table more readable:
View attachment 153137

It would be more typical for the "ID Number" column to consist of multiple columns, with each representing the state of one of your bit sequencers. Does this hint help you?
I need to update something in the question

The 7 segment LED Counter need to display is : 18787725

I want to say sorry to you because after I read your reply, I found out that I had to add the year to the top of the student ID, such as "18" to reach 8 digits.

#### Shen Joo

Joined May 23, 2018
12
Files with .xlsx extension don't contain macros. If a .xlsm extension is changed to .xlsx to try to fool someone into opening a file that contains macros, Excel will refuse to open it:
View attachment 153138

There could be ways to circumvent this protection, but I took a leap of faith.

When I tried renaming a file containing macros to .xlsx and then back to .xlsm, Excel gave this warning:
View attachment 153140
Same file but i share using onedrive

#### dl324

Joined Mar 30, 2015
13,820
I need to update something in the question

The 7 segment LED Counter need to display is : 18787725

I want to say sorry to you because after I read your reply, I found out that I had to add the year to the top of the student ID, such as "18" to reach 8 digits.
That's been the requirement for students who have posted in the past regarding this question.

Now that you're up to 8 digits, are you still supposed to use 3 sequencers?

In your case, you only have 5 unique digits. But my recollection of past posts for this problem is that they used the sequencers to represent binary numbers. Since you only need to decode numbers in your ID, you wouldn't need 4 sequencers, but you wouldn't be decoding binary numbers.

Since there's more than one way to solve this problem, you should get clarification of what method you're supposed to use.

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#### dl324

Joined Mar 30, 2015
13,820
Same file but i share using onedrive
That's worse than posting the .xlsx file. We can't tell what the link points to and the preference is to post all files on this site; owing to it being archival in nature.

You can use a screen grabber to grab the relevant part of the spreadsheet, or you can print to PDF and attach PDF (or make a snapshot from a PDF viewer).

#### Shen Joo

Joined May 23, 2018
12
That's been the requirement for students who have posted in the past regarding this question.

Now that you're up to 8 digits, are you still supposed to use 3 sequencers?

In your case, you only have 5 unique digits. But my recollection of past posts for this problem is that they used the sequencers to represent binary numbers. Since you only need to decode numbers in your ID, you wouldn't need 4 sequencers, but you wouldn't be decoding binary numbers.

Since there's more than one way to solve this problem, you should get clarification of what method you're supposed to use.
The number need to show in the 7 Segment Counter is:17787725 (very latest and confirm no change anymore)
1. Yes, still need to using 3 sequencers.
2. In the question say:
-Build a circuit using only AND, OR, NOR , NAND and NOR logic gate to stimulate the counter.
-use 3 sequencers or bit generators in your circuit as input
- The numbers should change automatically without any user input.
that all the point write in the question paper...

#### dl324

Joined Mar 30, 2015
13,820

Step 1 says to use 3 sequencers. Step 2, first part says to use gates to simulate the counter.

Are you supposed to design a counter or use sequencers to emulate one?

Are you supposed to design a BCD to seven segment decoder for the numbers used in your ID plus year, or are you going to decode arbitrary numbers (e.g. 000 decodes to 1, 001 decodes to 8, etc)?

How do you plan to handle consecutive numbers that are the same?

#### Shen Joo

Joined May 23, 2018
12

Step 1 says to use 3 sequencers. Step 2, first part says to use gates to simulate the counter.

Are you supposed to design a counter or use sequencers to emulate one?

Are you supposed to design a BCD to seven segment decoder for the numbers used in your ID plus year, or are you going to decode arbitrary numbers (e.g. 000 decodes to 1, 001 decodes to 8, etc)?

How do you plan to handle consecutive numbers that are the same?
The question say:
The question mention that "Design a circuit to take a binary input and display a number on the counter (7 Segment LED in Digital Works)"
1. Build a circuit using only AND, OR, NOR , NAND and NOR logic gate to stimulate the counter and should use 3 sequencers in circuit as input.
2. draw circuit using Digital Works 95
3. The numbers should change automatically without any user input.

hint write on the question paper:
"First construct a separate circuit for each segment from the truth table you have constructed. The redraw the circuit to combine the separate to form one complete circuit."

In this question paper no mention "BCD" or "decode arbitrary numbers"

#### dl324

Joined Mar 30, 2015
13,820
The question mention that "Design a circuit to take a binary input and display a number on the counter (7 Segment LED in Digital Works)"
It's a poor choice of words to use "counter" in this sentence; the display doesn't count anything. It would have been more appropriate just say 7 segment display instead and get rid of the parenthetical.
1. Build a circuit using only AND, OR, NOR , NAND and NOR logic gate to stimulate the counter and should use 3 sequencers in circuit as input.
The fact that the question says to take "binary input" using only 3 sequencers is in conflict because it takes 4 bits to represent 8 as a binary number.
3. The numbers should change automatically without any user input.
How do you plan to handle the instances of "77"? Why did you change the year to 17?

When is this assignment due? You've been working on it for several days.

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#### WBahn

Joined Mar 31, 2012
26,398
The 3-bits from the sequencers form a binary input. No conflict there. They don't represent a number from the ID, they represent a number position in the ID. Simply add a column in the Truth Table for the value of the sequencer outputs and you have the input to your circuit.

The "77" issue is a probably a non-issue. If the counter advances at one digit per second, then it would simply display a '7' for two seconds.

The hint that was given in the assignment is exactly the recommendation I made previously -- figure out how to drive one of the segments and then do the others.

Also keep in mind that there is nothing (as far as I can tell) that says that the output from your bit sequencer has to go in binary order or that it can't repeat outputs. So you have the option to assign your 3-bit input values to the output values so as to minimize the decode logic. That may or may not be worth the effort.