Sudhanshu Srivastava {B. Tech. Electronics & Communication Engineering} V.B.S. Purvanchal University, Jaunpur, U.P.

1. Minor Presentation on
Vending Machine Controller
Using VHDL
Er. Vishal Yadav

2. What is VHDL ????
 In VHDL “V” stands for Very High Speed
Integrated Circuit and “HDL” stands for Hardware
Description Language.
 It is the Hardware Description Language that can be
used in electronic design automation to describe digital
and mixed-signal systems such as field-programmable
gate arrays and integrated circuits.

3. Main Part of VHDL
 There are Three main part of VHDL:{1} Library ,
{2} Entity Declaration ,
{3} Architecture Body .
 Library:- {syntax}
use ieee std_logic_arith. all
use ieee std_logic_unsigned. all

4. (continued)…….
• Entity Declaration:- All designs are expressed in terms of
entities. An entity is the most basic building block in a
design.
 Syntax:entity entity_name is
port (port1 , port2 : port- type data-type;
port n : port type data type) ;
end entity_name ;
 Port Type:- (1)- in
(2)- out
(3)- inout
(4)- buffer

5. (continued)…….
• Architecture Body:- All entities that can be
simulated have an architecture description.
The architecture describes the behaviour of the entity.
A single entity can have multiple architectures.
 Syntax:architecture arch_name of entity_name is
begin
concurrent_statement ;
end arch_name ;

6. Some Other VHDL Terms







Configuration
Package
Driver
Bus
Attribute
Generic
Process

7. Modelling
 Architecture body can be model in
following modelling –
 Data Flow Modelling
 Behavioural Modelling
Basic Modelling
 Structural Modelling
 Mixed Modelling

8. Data Flow Modelling
• In this modelling the functionality of
the object occur due to “Concurrent Statements”
such as –
 Direct statement,
 When Else statement,
 With Signal select statement,
 Unaffected statement.

9. Behavioural Modelling
• In this modelling the functionality of the sequence is
defined using “Sequential statement”.
 Syntax:entity declaration;
architecture arch_name of entity_name is
begin
[process_label:] process (sensitive_list)
begin
sequential statements;
end process [process_label];
end arch_name;

10. Structural Modelling
 In this modelling an entry is modelled as
a set of interconnected components.
 In the Architecture Declaration part “Component
Declaration” and in the Architecture Body “Component
Instantiation” statements are used.
 We have used Structural Modelling in programming of
“VENDING MACHINE CONTROLLER”.

11. (continued……)
 Syntax:---Component Declaration part--architecture arch_name of entity-name is
component component_name is
port (port_declaration);
end component;
---Component Instantiation part--begin
component_label: component name port map;
end arch_name;

12. History of VMC
 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.

13. What is the Vending Machine??
 Electronic machine used to dispense a product to
a consumer after a prescribed
amount of money has been put into the machine.
 Vending machines are commonly used to
dispense beverages and snack items, but in
recent years companies have introduced vending
machines that dispense other items, even
including electronic items such as digital cameras
or iPods.

14. Simple Vending Machine
 The vending machine delivers an item after it has
received prescribed amount of money in coins.
 The machine have coins slot that accepts one coin at a
time.
 A mechanical sensor indicates whether prescribed no. of
coins has been inserted into the coin slot.
 The controller's output causes a single item to be
released down a item(e.g. cold drink) to the customer.
 And surplus money returned back to consumer.

15. Functional View of VMC

16. Basic Feature of VMC
• The basic feature of Vending Machine Controller
is governed by three main aspects
1. Controller,
2. Cold Storage,
3. Money Changer.
Every blocks are made by “Structural Modelling”
separately and after this every blocks are port mapped to
each other by “VHDL Coding”

17. Block Diagram of VMC

18. State Diagram Representation

19. 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 .

20. Gumball Vending Machine

21. Coffee Vending Machine

22. Cigarette Vending Machine

23. Toys Vending Machine

24. Cold Drinks Vending Machine

25. Snack Vending Machine

26. Advantage and Disadvantage
 The greatest benefit of these vending machines is that
they are very versatile and convenient. When you find
yourself in the middle of closed shops, with a hungry
stomach, a vending machine can really come in handy.
 When you talk about vending machines, costly items
always come with it, making this one of its major
disadvantages. Compared to items being sold in other
stores, those items that are on vending machines are
way on the high-priced spectrum.