VHDL Vending Machine
Project source code
For the source code for this project, please refer to the following github repository VHDL Vending Machine
Synopsis
This is a VHDL project to implement a Vending Machine. The purpose of the project is to employ RTL design to implement a simple vending machine. This project demonstrates the importance of RTL design in solving hardware design problems. It employes two subsystems; a Controls subsystem and a Datapath subsystem. Each handles a specefic set of tasks to achieve the end goal. The two subsystems work in conjunction by exchanging internal inputs/outputs to output the final results.
Motivation
This projects was developed for a VLSI -Very Large Scale Integration- class. To show the capabilities of VHDL and Hardware Design in designing systems and solving problems. The purpose of this implementation is to employ RTL design as the main mechanism of the machine. In addition, to utilize an FPGA rather than a conventional Microprocessor/Single board computer to process data and execute commands.
Installation
This project was developed using Altera Quartus II Web Edition. Simply clone the repo into your local directory and import the project.
Tests
For simulations and tests, please refer to the README file in the project -Link above-.
Contributors
This project was developed with the help of Abdul-Sattar Aboukarr
Detailed Description
For simplicity, the vending machine has two choices of items -This can easily be expanded to many more-. The cost of each item must be predefined by the user -Can be either hardcoded, or variable during simulation-.
Upon simulations, Users must select their choice of items by setting the variable C either to 0 or 1. Then, users must feed the vending machine with values which represents coins, the machine will add up the inserted coins (a coin check will happen every clock cycle) until total adds up to equal or greater than the price that corrosponds with the users choice. After that, the vending machine will dispense the item and give back the change that the costumer owes. The process then is restarted and the machine is ready to accept new values and a new choice. At any point in time if an item has not been dispensed yet, costumers can reset and get their money back.
This implementation consists of two main components; a Control Subsystem and a Data Subsystem. The Control subsystems is a simple state machine which handles the different states of the vending machine. It controls the Enable and Reset flags of the various registers along with dispensing the items.
As for the Data subsystem, it executes the mathmatical operations of the system. It recieves the value of the coin from the Control subsystem and adds it to an accumulator. It also outputs the total and the change amounts to the user. The Data subsystem contains all the registers of the vending machine, along with the adder and the comparitor. It also feeds the values of the comparitor to the Control subsystem as an internal signal which in turn uses it to change the states.