How to design a circuit to compare two selected numbers without using memory components (Please...)

[Sabrina]

Hi, I came here cause I heard from my friend that here can help me, since there are many experts.. Thanks a lot in advance..

I have to solder it and make it work, but since I don't even know how to design this circuit, I am dying...
If anyone can design this circuit, please help me... I am so desperate ..

<The goal is to Implement a circuit to compare two selected numbers without using memory components such as RAM or ROM.>

[Operation Sequence]

1. Start: Press the Start button to begin. When this button is pressed, the M LED displays 0, and the A and B LEDs remain off. If the "Start" button is pressed during operation, it returns to this state.
2. Increment M LED Number: Each time the "Input" button is pressed, the M LED number increases. (After 9, it returns to 0). At this point, the A and B LEDs remain off.
3. Move to Desired Number A: When the desired number is displayed on the M LED, press "Select". The number on the M LED moves to the A LED, and the M LED displays 0 again. If you want to input 0, you can press the "Select" button immediately.
4. Increment M LED Number Again: Press the "Input" button again, and the M LED number starts increasing as in step 2. There is no change in the number displayed on the A LED, and the B LED remains off.
5. Move to Desired Number B: When the desired number is entered on the M LED, press "Select". Then, the number on the M LED moves to the B LED, and the M LED turns off (not displaying 0). The A LED should still display the previously selected number. After this point, pressing "Input" should not change the M LED. To display a number on the M LED again, press the "Start" button to restart.
6. Check Result by Pressing the Result Button: Press the "Result" button to illuminate the LEDs according to the table below. The numbers on the A and B LEDs should remain the same, and the M LED should remain off. Result S1 S0 A=B 1(on) 1 A>B 1 0(off) A<B 0 1 If the "Result" button is pressed before A and B numbers are input, the LEDs should all be off: 0 0 0
7. Restart: To restart, press "Start". This returns to the state described in step 1.

 

[alec_t]

Welcome to ETO!
This is a Homework Help forum, not a homework-done-for-you one. Post your best effort at doing this assignment and we can give guidance where necessary.

 

[Papabravo]

Addition and subtraction are combinatorial circuits which do not require any memory. They are also trivial circuits.

 

[Sabrina]

alright.. I'll try my best and come back thanks

 

[danadak]

Can you use processors ? Can you code, or does this have to be
a logic gate level design ?

Odd that you cant use memory because you are being asked to do a state
machine design, which requires memory.

Back in the day, in TTL logic, there were comparators, ALUs, adders, flops
(because you are asking for a state machine)....

Regards, Dana.

 

[Sabrina]

Hi Dana, thanks for the comments I think I have to design with basic logic gates, but I think I am possible to use flip-flop or latches

nt use memory because you are being asked to do a state
machine design, which requires memory.

Back in the day, in TTL logic, there were comparators, ALUs, adders, flops
(because you are asking for a state machine)....

 

[danadak]

Do you have choice of where you get parts and what type ? Are you at the
point of working with FPGA and its tools, or any logic simulator ? Are you
give a board to work with....?

Start at the beginning.

1. Start: Press the Start button to begin. When this button is pressed, the M LED displays 0, and the A and B LEDs remain off. If the "Start" button is pressed during operation, it returns to this state.
2. Increment M LED Number: Each time the "Input" button is pressed, the M LED number increases. (After 9, it returns to 0). At this point, the A and B LEDs remain off.

So you need a "input" button, and a counter that counts 0 - 9 whenever you press the input button.
And you need to interface counter to a decoder to drive 7 segment LED display digit.

And you need a "start" button, when pressed, resets counter.

You have to press buttons and they bounce. So debounce them first and then apply to F-F's, counters.
Google "debounce buttons" for methods and why you need to do this.

Break this down into basic pieces, like above, and get each to work.

Steps 3 on you need to choose what is displayed on LED, so something has to hold
LED value, and a method of choosing where it gets its input for display what are those
2 logic elements called ? You mentioned latch earlier, whats the 2'ond one ? In simplest
terms if you had two bits, each one considered a different bit, how would you select one
to pass on to other logic versus the other....? Thern expand design to manage how many
bits have to be handled.


Regards, Dana.

 

[Papabravo]

Hi Dana, thanks for the comments I think I have to design with basic logic gates, but I think I am possible to use flip-flop or latches

Why would you need flip-flops or latches for a combinatorial circuit? At least for the element that compares two numbers by doing a subtraction. The rest of the sequencing can benefit from flip-flops.

 

[danadak]

Why would you need flip-flops or latches for a combinatorial circuit? At least for the element that compares two numbers by doing a subtraction. The rest of the sequencing can benefit from flip-flops.

Its not purely combinational, post #1 shows number must be held, then transferred and source reset on demand.
So a latch is required to hold the number from the counter. And a state machine sequence, unless sync parts
are used, to reset source.

Unless I am miss reading something here....

Regards, Dana.