# Verilog Vending Machine State Detailed Specification

## Timing Requirements

$1.$ All state transitions must occur on posedge clock

$2.$ Coin processing must occur on negedge clock and trigger only once

$3.$ Reset functionality is asynchronous and must be processed immediately

$4.$ Statements must be implemented using Case statements

$5.$ vending$\_$machine inputs include clk$,3$bits drinkchoose, $6$bits money, cancel; output has $6$bits change

$6.$ Implement the vending machine simulation using the finite state machine method shown in the diagram

## S$0$: Initial State $($Coin Input State$)$

$-**$Functional Requirements:$**$

$1.$ Display current total amount inserted

$2.$ Accept coins $(1,5,10,50$ NTD$)$

$3.$ Only one coin can be inserted at a time

$4.$ Must update and display total amount in real$-$time

$5.$ Transition to S$1$ state when input amount reaches minimum beverage price $(10$ NTD$)$

$6.$ Return all inserted money when cancel button $($reset$)$ is pressed

$7.$ Process coin insertion on negedge clock

## S$1$: Selection State $($Available Beverage Display State$)$

$-**$Functional Requirements:$**$

$1.$ Display available beverages based on inserted amount:

$-10$ NTD: Display Tea

$-15$ NTD: Display Tea, Coke

$-20$ NTD: Display Tea, Coke, Coffee

$-25$ NTD: Display Tea, Coke, Coffee, Milk

$2.$ Allow continued coin insertion to increase amount

$3.$ Wait for customer beverage selection $($drink$\_$choose input$)$

$4.$ Upon beverage selection, check if amount is sufficient:

$-$ Sufficient: Transition to S$2$ state

$-$ Insufficient: Remain in current state

$5.$ If cancel button is pressed, transition to S$0$ state and return all money

## S$2$: Dispensing State $($Output State$)$

$-**$Functional Requirements:$**$

$1.$ Output selected beverage name

$2.$ Calculate change amount

$3.$ Automatically transition to S$3$ state upon completion

$4.$ Do not accept new coins or selections in this state

$5.$ If cancel button is pressed, transition to S$0$ state and return all money

## S$3$: Checkout State $($Change Return State$)$

$-**$Functional Requirements:$**$

$1.$ Calculate and display change amount $($inserted amount $-$ beverage price$)$

$2.$ Output change amount $(6-$bit change output$)$

$3.$ Automatically transition back to S$0$ state upon completion

$4.$ Do not accept new coins or selections in this state

$5.$ If cancel button is pressed, transition to S$0$ state and return all money

## Reset Functionality $($Applicable to All States$)$

$-**$Functional Requirements:$**$

$1.$ When reset $($cancel button$)$ is pressed in any state:

$-$ Immediately stop current operation

$-$ Return all inserted money

$-$ Clear all state records

$-$ Return to S$0$ initial state

$2.$ Ensure all counters and registers are cleared during reset

$3.$ Display returned amount

## Deliverable

One main.v file