# multiplexer circuit design

Discussion in 'Homework Help' started by carlabelen, Jun 28, 2011.

1. ### carlabelen Thread Starter New Member

Jun 28, 2011
5
0
This project is like a robot controller. When the user pressed go, the robot will go. Or press forward or back, the robot will do what is said. In this project, we will use push buttons as the inputs and LED's as the output or the output movement of the so-called robot.

There is 7 inputs.
1. Go
2. Stop
3. Forward
4. Back
5. Left
6. Right
7. Kick

It has 5 LED outputs: (the output will be 1 or the led will light if these buttons were pushed)
1. Go
2. Fwd
3. Left
4. Right
5. Kick

(the output will be 0 for the opposite the led will not light if these buttons were pushed)
1. stop
2. back
3. no Left
4. no Right
5. no Kick

Can go together (2 led's can light at the same time if push together).
1. Forward and right
2. forward and left
3. back and left
4. back and right
5. forward and kick

Can't go together (no led will light if pushed together)
1. forward and back
2. left and right
3. back and kick

I want to ask what is the simplest way to do this using multiplexer? I'm thinking of using multiple 2-to-1 multiplexer. Thank you!

2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
293
This is a bit confusing. Are you actually designing a controller for your robot, or a controller for a simulated robot?

In either case, do you have a concept of how the buttons will actually do the controlling? Have you got as far as a block diagram and flow chart?

3. ### Georacer Moderator

Nov 25, 2009
5,177
1,285
I think the functions to look for here are the "Can't go together" restrictions. The forward LED should be checked with the Forward input and the Back input for example.
The kick LED with Kick input and Back input and so on.
You don't need a MUX for a 2 input function just gates.

Is the system allowed to do Forward-Left-Kick or other more complex actions or are the constraints just the 3 that you mentioned?

I would include the Stop and Go actions through filtering the outputs through a latch, controlled by those signals.

4. ### carlabelen Thread Starter New Member

Jun 28, 2011
5
0
We're just doing a simulated robot. Our professor just want us to show that once we pressed the push button, the 5 LED output will light up correctly based on the given conditions. For now, I don't have flow chart or block diagram. I'll get back to that later. I tried to make a truth table for this, but it ended up complicated because of several inputs.

5. ### carlabelen Thread Starter New Member

Jun 28, 2011
5
0
I also think of using just gates for this one, but since it has several combinations and inputs, it will make the circuit complicated. The system doesn't allowed to do 3 movements at a time.

6. ### Georacer Moderator

Nov 25, 2009
5,177
1,285
Since only two actions are allowed at once, you could build a bus arbiter-like circuit. Monitor the inputs and allow a new input to come out of the "black box" only if one or less inputs are currently conducted.

I imagine that will require one adder and a comparator for each input.
AAC has a couple of threads on summing single bits of data.

7. ### MrCarlos Active Member

Jan 2, 2010
400
136
Hello carlabelen

How are you doing with your project "multiplexer circuit design" today?
Fortunately, each movement of the robot's name starts with a different letter.

Note that the names of the LED's are full and the names of the buttons only have the initial letter of the name. Also note that the meaning of nS and nG is: not Stop and not Go.
The sign "=", read it as IF.

This is all you mention in your statement:
Go = (G AND nS.)
Stop = (S AND nG.)
1- Forward And Right = (G AND F AND R.)
2- Forward And Left = G AND F AND L.)
3- Back And Left = G AND B AND L.)
4- Back And Right = G AND B AND R.)
5- Forward And Kick = G AND F AND K.)

It's Also Is Possible ?... Or Not ?
(G AND F)
(G AND B)

Not Allowed:
1- (G AND F AND B.)
2- (G AND L AND R.)
3- (G AND B AND K.)
////////////////////////////////////////////

I'm assuming the Go Button (G) is to turn on the robot.
The Go LED must be ON for all of the following cases:

FWD LED should turn on for these cases:
(Forward AND Right) OR (Forward AND Left) OR (Forward AND Kick)

Left LED should turn on for these cases:
(Forward AND Left) OR (Back AND Left).

Right LED Should turn on for these cases:
(Forward AND Right) OR (Back AND Right).

Kick LED should turn on for these cases:
(Forward AND Kick).

Note the "AND" and "OR"... Are logic gates. It's that easy.

regards
PS: if you still want to do with multiplexers I can help you too.

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8. ### carlabelen Thread Starter New Member

Jun 28, 2011
5
0
I just read this now. As of now, I'm still not doing this project since I also have my thesis to work on. And my professor still requires state diagram which make it more complicated. I look at the design you uploaded. Thank you very much. I think this will help me a lot And yes, forward or just back is possible but still the GO button it still at default

9. ### carlabelen Thread Starter New Member

Jun 28, 2011
5
0
The go and forward is possible but not go and back In your circuit, we'll just make the first or gate as 4 input or

10. ### MrCarlos Active Member

Jan 2, 2010
400
136
Hello carlabelen

One suggestion to not make it too long this subject:
As several people say, comment or give suggestions is better to say:
Hello (Here enter the alias of the person to whom you are sending the message).
do not attach my post in yours.
Otherwise the messages will become very large.

"And still my professor Which Requires state diagram make it more complicated. I look at the design you uploaded. Thank you very much."
You can do easily the state diagram Based on the design that I uploaded.

and, as you say, it is possible to go forward but not go backwards, we should modify the design I sent.

But always remember, AND, NAND, OR, NOR, NOT. Etc. Are all keywords for the logic circuit design.
Let me tell you, for example:
The alarm will sound if (> 60 ° C) + ((> 45 ° C & <60 ° C) & (Smoke & Gas)) + (<45 ° C & Smoke & Gas).
& = AND gate
+ = OR gate.
“If” take as sign “=”.
you see ...? All the logic circuit can be defined by that statement.

A basic tool for the development of logic circuits is called Boole-Deusto. which can be found on the web. through Google.com.
Try to find and install it on your PC.
You can also develop the state diagram by means of this software tool.

regards

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