1. Vending Machine
Final Report
Project Members:
 Hassan Saeed (Group leader) (5718)
 Taimoor Tahir (4628)
 Syed Ali Zargham (4625)
 Yahya Ahmad
Submitted to:
Sir. Nasir Mehmood

2. Scope of the project:
The project basically aims on construction of a vending machine such that when the inputs are
given in the BCD format the desired output is displayed via a 14 segment display. The project
though is a simple one but it contains all the workings necessary for a commercial level
wending machine if used for a commercial purpose.
Design Step and Procedure followed:
 Firstly, the problem was studied in detail.
 Then we decided the outputs we want to give and decided how many inputs might
require.
 We took the first input of the item that the user want from the vending machine (5
items).
 Then the input of the user is displayed by the 7 segment display.
 Any other selected input out of the 5 inputs an error message is displayed through a 14
segment display.
 Now, the second part of the input taking for the vending machine was money input.
 The user is allowed to enter two digit BCD number.
 These are also displayed by 7 segment display.
 Now, in the next step the price of items are matched with the item number.
 In case of mismatch of prices an error is displayed on the 14 segment display.
 If the price matches then it checks weather the item is present or not.
 If item is present then O sign is displayed on the IC.
 If items are finished then E output is displayed.
 Amount of items are stored in an up down IC. Which is different for each item.
 An item is decreased as the input pulse came to the IC.
 In this vending a new intervention was made that if the time difference of the insertion
of the input and money is more than 10s then it displays an error T.
 For this purpose a flip flop is used with another IC. Which produces a pulse that remains
high for 10s.

3. Circuitry:
List of different items used by us is given below:
 Resistors (110k, 210k, 10k)
 Capacitors (1n, 1m)
 NOT gate
 AND gates (2, 4 input)
 OR gates (2,3,4 input)
 XOR gates
 NAND gates
 XNOR gates
 555 timer IC
 D flip flop
 74190 (up/down decade counter)
 Bread Board
 7 segment displays
 14 segment displays
 7 segment decoders
 Logic states
 Wires
Given Below is the snap shot of our project which we have built on Proteus. From this picture
all the elements used along with their usage are visible.

4. Block Diagram:
Block Diagram of the circuit is shown below:

5. Explanation:
We started our work to get the following outputs:
When the user press the correct item number and money required for the item within 10s
along with the availability of the item. Then he/she gets output, shown by O.
If the item number and the money mismatch, in case inputs are given in 10s then M output is
shown, But if item tank is empty then output is shown by E.
In case of delay of more than 10s T output is shown.
If input item is wrong I output is displayed.
Also we have to take only the input of the item and money from the user while the items
should be added by the owner of the Vending machine.
These are the basis around which we have started our work and made different logic diagram
and tables along with mental visualization to proceed to our objective.
The state diagram of our flip flop is shown below:
Given below is the state diagram of our up/down decade counter IC. Which decreases the items
in the container one by one. As the amount of money and item number are matched if the
difference in the time of provision of inputs is less than 10s.

6. While our D flip flop is only used to store the previous value of the input. Which is done by the
help of the pulse generated as the input is given.
The state table or the truth table of our program is very difficult to show here as the number of
combination of the possibilities is too high. So, it is explained in terms of words in the above
lines. However the circuit can be simplified and can be constructed by building the truth tables
of the small portions. As, the truth table to show our first output from the inputs.
BCD input(item) Output
0000 N
0001 1
0010 2
0011 3
0100 4
0101 5
0111 N
1000 N
1001 N
In this way we proceed to our work. Till the end to display different symbols like O (When we
get the item), M (When we have a mismatch in money and item number), I (When the inputs
are wrong) and T (When is not entered until 10s).
Results and Achievements:
The project although quite lengthy. Firstly, it was not quite easy to design the circuit we have to
take a lot of things in our mind but we were successful in performing that task step by step. It
has been arranged in the best of manners and the outputs displayed are as desired. Though, we
did face problem in the collection of hardware because some of the ICs were not available in
the market, also patching the circuit was a hectic and time consuming task but worked hard to
get through these problems and find some alternatives to solve them at our best.

7. Recommended Future Work:
The project although built as well as we could but it might can further be improved. The circuit
can be made cheaper. Students in the future can also add the input of adding number of items
in the machine as this circuit is limited to adding specific number of items.
Conclusion:
At the end we conclude our work by saying that nothing is impossible in this word although
some things seems so. By the dint of hard work and constant effort a person can perform any
task. Also, the help of others is a great gift. That is why our teacher has divided us in the form of
groups not individuals.