Vending Machine (verilog)

Submitted By: Wajahat Ali Butt 107 Hashir Badar 113 Muhammad Fahad Shabbir 127 Muhammad Safeer 134

DESIGN SPECIFICATIONS We have designed this machine for three products. The user will first select one of the three products. The machine will tell him the price of the product. Then he will enter money. If the amount of money entered is equal to the price of the product then product will be issued. But if the amount of money entered is greater than the price then product will be issued as well as change will be returned. The return of change as well as the issue of product is indicated by LED. The product selected as well as its price is displayed on 7 segment LED display. The product is selected as well as money is entered through switches. There is a reset button to reset the machine to idle state. The 1st product has Rs.1 , 2nd product has Rs.2 fare and 3rd product has Rs.3. The three products are represented in binary no. as 001,010,100 respectively. The user is allowed to enter Rs. 1, Rs.2, or Rs.3 coin which are represented in binary as 0 or 1.

STATE DIAGRAM `

Free state

Produc t_A_St ate

Produc t_B_St ate

Chang e State

Produc t_C_St ate

VERILOG CODING

`timescale 1ns / 1ps /////////////////////////////////////////////////////////// /////////////////////// // Company: // Engineer: // // Create Date: 00:10:36 07/11/2008 // Design Name: // Module Name: vend // Project Name: // Target Devices: // Tool versions: // Description: // // Dependencies: // // Revision: // Revision 0.01 - File Created // Additional Comments: // /////////////////////////////////////////////////////////// /////////////////////// module vend( //Inputs clk, reset, RS1, RS3, RS2, product,

// // // // //

internal clock (50 reset variable Rupees 1 coin (dip Rupees 3 coin (dip Rupees 2 coin (dip

//Outputs // 2nd SEVEN Segment LED_a2, LED_b2,

MHz) switch) switch) switch)

//

LED_c2, LED_d2, LED_e2, LED_f2, LED_g2, 1 st SEVEN Segment LED_a1, LED_b1, LED_c1, LED_d1, LED_e1, LED_f1, LED_g1,

); //********************************************************* ******************* // ASSIGNING each variable as input or input clk; input reset; input RS1; input RS2; input RS3; input[2:0] product;

//

output output output output output output output

LED_a2; LED_b2; LED_c2; LED_d2; LED_e2; LED_f2; LED_g2;

output output output output output output output

LED_a1; LED_b1; LED_c1; LED_d1; LED_e1; LED_f1; LED_g1;

output LED_timer;

output.

// declaring output as reg reg reg reg reg reg reg reg

LED_a2; LED_b2; LED_c2; LED_d2; LED_e2; LED_f2; LED_g2;

reg reg reg reg reg reg reg

LED_a1; LED_b1; LED_c1; LED_d1; LED_e1; LED_f1; LED_g1;

reg reg reg reg

[3:0]t_money; [3:0]r_money; [3:0]first_digit; [3:0]second_digit;

reg temp1; for toggling reg temp2; reg temp3;

// temporary reg variables

reg [1:0]pres_state, next_state; parameter FREE_STATE= 3'd0, PRODUCT_A_STATE=3'd1, PRODUCT_B_STATE = 3'd2, PRODUCT_C_STATE= 3'd3, CHANGE_STATE = 3'd4; //********************************************************* ******************* always@(posedge clk or negedge reset) begin if (reset == 0) pres_state <= FREE_STATE; else pres_state <= next_state; end

//********************************************************* ******************* always@ (posedge clk) begin case(pres_state) FREE_STATE: begin case(product) 3'b001: next_state<=PRODUCT_A_STATE; 3'b010: next_state<=PRODUCT_B_STATE; 3'b100: next_state<=PRODUCT_C_STATE; default: next_state <= FREE_STATE; endcase end

next_state<=PRODUCT_A_STATE: begin if(t_money<3) next_state <=PRODUCT_A_STATE; else if(t_money >=3 ) next_state <= CHANGE_STATE; end

next_state<=PRODUCT_B_STATE: begin

if(t_money<4) next_state <=PRODUCT_B_STATE; else if(t_money >=4) next_state <= CHANGE_STATE; end

next_state<=PRODUCT_C_STATE: begin if(t_money<5) next_state <=PRODUCT_C_STATE; else if(t_money >=5) next_state <= CHANGE_STATE; end

CHANGE_STATE: begin next_state <= CHANGE_STATE; end endcase end //********************************************************* ******************* always@ (posedge clk) begin case(pres_state) FREE_STATE: begin if (reset == 0) begin temp3 <= 0; temp2 <= 0; temp1 <= 0; if(product==3'b000) r_money <= 0; else if(product==3'b001)

r_money <= 3; else if(product==3'b010) r_money <= 4; else if(product==3'b100) r_money <= 5; first_digit <= 4'd0; second_digit <= 4'd0; end end PRODUCT_A_STATE: begin if(RS1 == !temp1) begin temp1 <= !temp1; t_money <= t_money + 1; r_money <= r_money - 1; end else if(RS2 == !temp2) begin temp2 <= !temp2; t_money <= t_money + 2; r_money <= r_money - 2; end else if(RS3 == !temp3) begin temp3 <= !temp3; t_money <= t_money + 3; r_money <= r_money - 3; end second_digit <=r_money; end

PRODUCT_B_STATE: begin if(RS1 == !temp1) begin temp1 <= !temp1; t_money <= t_money + 1; r_money <= r_money - 1; end else if(RS2 == !temp2) begin temp2 <= !temp2; t_money <= t_money + 2; r_money <= r_money - 2; end else if(RS3 == !temp3) begin temp3 <= !temp3; t_money <= t_money + 3; r_money <= r_money - 3; end second_digit <=r_money; end

PRODUCT_C_STATE: begin if(RS1 == !temp1) begin temp1 <= !temp1; t_money <= t_money + 1; r_money <= r_money - 1;

end else if(RS2 == !temp2) begin temp2 <= !temp2; t_money <= t_money + 2; r_money <= r_money - 2; end else if(RS3 == !temp3) begin temp3 <= !temp3; t_money <= t_money + 3; r_money <= r_money - 3; end second_digit <=r_money;

end

CHANGE_STATE: begin first_digit<=12; second_digit<=0 end

;

endcase end //********************************************************* ******************* //display on 7segments always @(first_digit) begin case(first_digit) 4'b0000 : begin LED_a1 <= 1'b0; // for displaying nothing at seven - segment LED_b1 <= 1'b0;

LED_c1 LED_d1 LED_e1 LED_f1 LED_g1 end

<= <= <= <= <=

1'b0; 1'b0; 1'b0; 1'b0; 1'b0;

4'b1100 : begin LED_a1 <= 1'b1; // display C at seven - segment LED_b1 LED_c1 LED_d1 LED_e1 LED_f1 LED_g1

<= <= <= <= <= <=

1'b0; 1'b0; 1'b1; 1'b1; 1'b1; 1'b0;

end default : begin LED_a1 <= LED_a1; // maintain output LEDs LED_b1 LED_c1 LED_d1 LED_e1 LED_f1 LED_g1 end

<= <= <= <= <= <=

LED_b1; LED_c1; LED_d1; LED_e1; LED_f1; LED_g1;

endcase end //********************************************************* ******************* always @(second_digit) begin case(second_digit) 4'b0000 : begin LED_a2 <= 1'b1; // 0 display at seven segment LED_b2 LED_c2 LED_d2 LED_e2

<= <= <= <=

1'b1; 1'b1; 1'b1; 1'b1;

LED_f2 <= 1'b1; LED_g2 <= 1'b0; end 4'b0001 : begin LED_a2 <= 1'b0; // 1 display at seven segment LED_b2 LED_c2 LED_d2 LED_e2 LED_f2 LED_g2 end

<= <= <= <= <= <=

1'b1; 1'b1; 1'b0; 1'b0; 1'b0; 1'b0;

4'b0010 : begin LED_a2 <= 1'b1; // 2 display at seven segment LED_b2 LED_c2 LED_d2 LED_e2 LED_f2 LED_g2 end

<= <= <= <= <= <=

1'b1; 1'b0; 1'b1; 1'b1; 1'b0; 1'b1;

4'b0011 : begin LED_a2 <= 1'b1; // 3 display at seven segment LED_b2 LED_c2 LED_d2 LED_e2 LED_f2 LED_g2 end

<= <= <= <= <= <=

1'b1; 1'b1; 1'b1; 1'b0; 1'b0; 1'b1;

4'b0100 : begin LED_a2 <= 1'b0; // 4 display at seven segment LED_b2 <= 1'b1; LED_c2 <= 1'b1; LED_d2 <= 1'b0;

LED_e2 <= 1'b0; LED_f2 <= 1'b1; LED_g2 <= 1'b1; end 4'b0101 : begin LED_a2 <= 1'b1; // 5 display at seven segment LED_b2 LED_c2 LED_d2 LED_e2 LED_f2 LED_g2 end

<= <= <= <= <= <=

1'b0; 1'b1; 1'b1; 1'b0; 1'b1; 1'b1;

default : begin LED_a2 <= LED_a2; // maintain output LEDs LED_b2 LED_c2 LED_d2 LED_e2 LED_f2 LED_g2 end endcase end endmodule

<= <= <= <= <= <=

LED_b2; LED_c2; LED_d2; LED_e2; LED_f2; LED_g2;