Vending machine

Student name : Rand F. Al-Aqrabawi Dr. Abaza M. GH.

History

• Vending machine became popular during the industrial revolution .

• The first modern coin-operated vending machines were introduced in England in the early 1880s .

• The first vending machine in the U.S. was built in 1888 by the Thomas Adams Gum Company.

• In 1897 games has been added to these machine .

• In December 1970, Ussery Industries of Dallas, Texas at its Dallas convention displayed its "talking" vending machine, the Venda Talker.

What is the vending machine

• Electronic machine used to disperse a product to a consumer after a certain amount of money has been put into the machine.

• Vending machines are commonly used to disperse beverages and snack items, but in recent years companies have introduced vending machines that disperse other items, even including electronic items such as digital cameras or iPods.

Simple vending machine

The vending machine delivers an item after it has received 15 cents in coins.

The machine has a single coin slot that accepts nickels and dimes, one coin at a time.

A mechanical sensor indicates whether a dime or a nickel has been inserted into the coin slot.

The controller's output causes a single item to be released down a chute to the customer.

Block diagram

N

D open Reset

CLK

Vending machine FSM

coin sensor

Gum release

mechanism

assume that N is asserted for one clock period when a nickel is inserted into the coin slot and that D is asserted when a dime has been deposited.

Furthermore, we'll postulate that it is enough if the machine asserts Open for one clock period to release an item after 15 cents (or more) has been deposited since the last reset.

Abstract representations

• Three nickels in sequence: N, N, N• Two nickels followed by a dime: N, N, D• A nickel followed by a dime: N, D• A dime followed by a nickel: D, N• Two dimes in sequence: D, D

State diagram

s1

s0

s3

s7

s2

s6

s8

s4 s5

reset

ND

N

D

ND

ND

The machine will pass through the states S0, S1, S3, S7 if the input sequence is three nickels.

in state S0 if neither input N or D is asserted, we assume the machine remains in state S0 (the

specification allows us to assume that N and D are never asserted at the same time).

Also, we include the output Open only in states in which it is asserted. Open is implicitly unasserted in any other state.

State Minimization

This nine-state description isn't the "best" possible. For one thing, since states S4, S5, S6,S7 and S8 have identical behavior, they can be combined into a single state.

To reduce the number of states even further, we can think of each state as representing the amount of money received so far. For example, it shouldn't matter whether the state representing 10 cents was reached through two nickels or one dime.

0

5

10

15

reset

N

N

N

D

D

State table

Minimized symbolic state transition

FSM IMPLEMENTATION

Vending machine kinds

There are so many types of vending machines available from different vending machine manufacturers and suppliers.

Some machines need electricity to vend the products, while some others use mechanical motion to vend.

They come in several sizes, shapes, colors, and prices. Vending machines are found mostly in shopping malls, waiting areas, bowling alleys, businesses, and schools.

Commonly vending machines

• Soda vending machine• Gumball vending machine• Snack vending machine• Food and toy vending machine • Coffee vending machine• Cigarette vending machines• Pop corn vending machine

Gumball vending machine

Coffee vending machine

Cigarette vending machine

Toys vending machine

Cold drinks vending machine

Snack vending machine

Designing coffee vending machine

Present state Input Next state Output

QA QB N D DA DB C0 0 0 0 0 0 0

0 0 0 1 1 0 0

0 0 1 0 0 1 0

0 0 1 1 X X 0

0 1 0 0 0 1 0

0 1 0 1 1 1 0

0 1 1 0 1 0 0

0 1 1 1 X X 0

1 0 0 0 1 0 0

1 0 0 1 1 1 0

1 0 1 0 1 1 0

1 0 1 1 X X 0

1 1 0 0 1 1 1

1 1 0 1 1 1 1

1 1 1 0 1 1 1

1 1 1 1 X X 1

DA 00 01 11 10

00 1 1

01 1 1 1 1

11 X X X X

10 1 1 1

C 00 01 11 10

00 1

01 1

11 1

10 1

DB 00 01 11 10

00 1 1

01 1 1 1

11 X X X X

10 1 1 1

QA QB QA AB

QA QB

ND

ND

ND

Flip-flop Inputs Equations and System Output Equation and it’s conversion to NAND Gates:

• DA = QA + D + NQB = (QA + D + NQB)” = (QA’D’(NQB)’)’

• DB = NQB’ + NQA + DQA + N’QB = (NQB’ + NQA + DQA + N’QB)” = ((NQB’)’(NQA)’(DQA)’(N’QB)’)’

• C’ = (QAQB)’ = ((QAQB)’)” = (QA’QB’)’

Logic circuit diagram using NAND gates and two Flip Flops

References

• http://EzineArticles.com/352816 ^• "Old World, High Tech".

Smithsonian Magazine. • http://en.wikipedia.org/wiki/Vending_machin

e• http://www.ecgf.uakron.edu/grover/web/ee2

63/labs/ASimpleVendingMachine.pdf• :

http://www.businessdictionary.com/definition/vending-machine.html#ixzz2XoOXrsBt