Vending-Machine/vending_machine.v at main · Kyoko108/Vending-Machine · GitHub

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`timescale 1ns/1ps

module vending_machine(
    input clk,
    input rst,
    input coin5,
    input coin10,
    output reg dispense,
    output reg change
);

parameter S0  = 3'b000;
parameter S5  = 3'b001;
parameter S10 = 3'b010;
parameter S15 = 3'b011;
parameter S20 = 3'b100;

reg [2:0] state;
reg [2:0] next_state;

// State Register
always @(posedge clk or posedge rst)
begin
    if (rst)
        state <= S0;
    else
        state <= next_state;
end

// Next-State Logic
always @(*)
begin
    case(state)

        S0:
        begin
            if (coin5)
                next_state = S5;
            else if (coin10)
                next_state = S10;
            else
                next_state = S0;
        end

        S5:
        begin
            if (coin5)
                next_state = S10;
            else if (coin10)
                next_state = S15;
            else
                next_state = S5;
        end

        S10:
        begin
            if (coin5)
                next_state = S15;
            else if (coin10)
                next_state = S20;
            else
                next_state = S10;
        end

        S15:
            next_state = S0;

        default:
            next_state = S0;

    endcase
end

// Output Logic
always @(*)
begin
    dispense = 0;
    change   = 0;

    case(state)

        S15:
        begin
            dispense = 1;
            change   = 0;
            /*if (coin10)
                change = 1;*/
        end

        S20:
        begin
            dispense = 1;
            change   = 1;
        end
    endcase
end

endmodule