# Vending Machine

Discussion in 'The Projects Forum' started by smith5753, Apr 23, 2010.

1. ### smith5753 Thread Starter New Member

Apr 22, 2010
4
0
Hello Everyone. I checked all the recent posts pertaining to the vending machine problem, but didnt quite find anything to help me.

I do not have a good professor for digital logic and I have fallen behind in the class. I feel lost with this project.

You are to design a synchronous sequential controller for a simple vending machine. Your controller should operate in the following manner:

1 Wait until money is entered. As long as money is available, an input signal M=1 and a 7bit unsigned number, F=F6F5....F0, representing the amount entered in cents is available as input. The number F is continually updated as money is entered. If the user cancels the transaction before making a choice M=0.

2 Wait until the user chooses an item to purchase. When choice is made another input signal C=1, but only for one clock period. During this clock period another 7-bit unsigned binary number, P=P6P5.P0, representing the item price.

3 If F>=P then set the output to dispense the item, D=1, and compute the amount of change to dispense, (F-P). Your controller must wait until M=0 to return to initial state.

4 If F<P then set the insufficient funds output R=1. As long as money remains available, recheck F and P whenever a choice is made, C=1. Note that an insufficient funds warning the user must re-choose the item.

5 If the user cancels a transaction, i.e., M=0 before a valid choice is made, then return to the initial state and set the cancel transaction output X=1.

6 You need not worry about an item being out of stock.

7 Give the state diagram and table; circuit design; include K-maps, PLA tables, mux tables etc.
Any input would be greatly appreciated! Thank you!

2. ### R!f@@ AAC Fanatic!

Apr 2, 2009
8,523
715
That is quite an assignment.
What are the type of logic u want. CMOS, TTL or PIC's

3. ### retched AAC Fanatic!

Dec 5, 2009
5,201
312
Where are you running into trouble?
What do you feel you "get" completely?

4. ### awwende Active Member

Feb 17, 2009
39
0
I have some friends working on this project too. where do you go to school? and what problem are you having?

5. ### smith5753 Thread Starter New Member

Apr 22, 2010
4
0
Im honestly having trouble with where to start. I sort of understand how the circuit is supposed to behave. User inserts money which is F. F is updated every time change is inserted. Then you need to take F and compare it to price P and decide if they need more money, or if they should get change back. Im not sure how to show the money being inserted and then how to compare it to the price.

I don't know the answer to the type of logic question. Im in digital logic 202 class if that helps at all

6. ### smith5753 Thread Starter New Member

Apr 22, 2010
4
0
and I go to UAH in Huntsville AL

7. ### smith5753 Thread Starter New Member

Apr 22, 2010
4
0
If anyone can come up with a solution for this by wednesday 4/28 ill pay you for it. my email is smith5753@gmail.com if interested. Im running out of time and I hav not gotten anywhere with this project.

8. ### t06afre AAC Fanatic!

May 11, 2009
5,939
1,222
Ah, the end of the semester, and school projects are due. But if you pay somebody you will not have any money to test your vending machine
I will also ad that offering someone payment to do your school work. Say very much about you ass a person. No further comment

9. ### retched AAC Fanatic!

Dec 5, 2009
5,201
312
Oh, jeez. Wait a minute t06afre...

smith5753? How much you got? kidding..dont answer that...

Okokok.. You've got 4 days... thats 96 hours (if you dont sleep)