Help me modify my FSM (Verilog code)

[MRFGUY]

I just try to study FSM.

I just wrote a FSM by using verilog. My plan is selling ticket with 15. user are allowed to add 5 or 10. whenever it reach to 15 ticket will come out and back to start state. If it reach to 20, ticket and change 5 and return to start state . It seem ok at this moment. (but let me know what should I change in my program)

But I also want to show in two 7 seg disp. like how much user need to add more to get a ticket. At this point I am not sure how to add.

Should I assume 7 seg into two condition (present led and next led).

I've attached my program here.

Thanks


`timescale 1ns / 1ps
////////////////////////////////////////////////////////////////////////////////
// Company:
// Engineer:
//
// Create Date: 16:15:08 08/29/05
// Design Name:
// Module Name: sell_ticket
// Project Name:
// Target Device:
// Tool versions:
// Description: Selling ticket with 15. If user add 15 only ticket will come out.
// If user add 20 the machine chnage 5 and ticket will come out.
//
// Dependencies:
//
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
//
////////////////////////////////////////////////////////////////////////////////
module sell_ticket(a, b, reset, clk, t, c);

input a, b, reset, clk; //a is 5$ input and b is 10 $ input

output t, c; // c is coin change and t is ticket

reg t, c;
reg [2:0] state, next_state;

parameter zero=3'b000;
parameter five=3'b001;
parameter ten=3'b010;
parameter fifteen=3'b011;
parameter twenty=3'b100;


always @(posedge clk)
begin
if (reset)
state<=zero;
else
state <= next_state;
end

always @(a,b,state)
begin
case (state)

zero: case({b,a})
2'b00 : next_state= zero;
2'b01 : next_state= five;
default : next_state = ten;
endcase

five: case({b,a})
2'b00 : next_state= five;
2'b01 : next_state= ten;
default : next_state = fifteen;
endcase

ten: case({b,a})
2'b00 : next_state= ten;
2'b01 : next_state= fifteen;
default : next_state = twenty;
endcase

default :next_state = zero;
endcase //state state case end
end //always end


always@(state)
begin
case(state)
fifteen : {t,c}= 2'b10;
twenty : {t,c} = 2'b11;
default : {t,c} = 2'b00;
endcase
end

endmodule

 

[nand_gates]

Re: How to modify my FSM

Here I added 7-seg display to ur code....

`timescale 1ns / 1ps
module sell_ticket(a, b, reset, clk, t, c, seven_seg_led_0, seven_seg_led_1);
   
   input a, b, reset, clk; //a is 5$ input and b is 10 $ input
   
   output      t, c; // c is coin change and t is ticket
   output [6:0] seven_seg_led_0, seven_seg_led_1;
   
   reg         t, c;
   reg [6:0]   seven_seg_led_0, seven_seg_led_1;
   reg [2:0]   state, next_state;
   
   parameter   zero    = 3'b000;
   parameter   five    = 3'b001;
   parameter   ten     = 3'b010;
   parameter   fifteen = 3'b011;
   parameter   twenty  = 3'b100;
   
   
   always @(posedge clk)
      if (reset)
        state <= zero;
      else
        state <= next_state;

   
   always @(a or b or state) begin
      next_state = state;
      case (state)
        zero: case({b,a})
                2'b00 : next_state   = zero;
                2'b01 : next_state   = five;
                default : next_state = ten;
              endcase
        
        five: case({b,a})
                2'b00 : next_state   = five;
                2'b01 : next_state   = ten;
                default : next_state = fifteen;
              endcase
        
        ten: case({b,a})
               2'b00 : next_state   = ten;
               2'b01 : next_state   = fifteen;
               default : next_state = twenty;
             endcase 
        fifteen : next_state = zero;  
        twenty  : next_state = zero; 
      endcase //state state case end
   end //always end
   

   always@(state) begin
      case(state)
        zero    : begin
           {t,c} = 2'b00;     //abcdefg
           seven_seg_led_1 = 7'b0110000; // display 15
           seven_seg_led_0 = 7'b1011011;
        end
        five    : begin
           {t,c} = 2'b00;     // abcdefg
           seven_seg_led_1 = 7'b0110000; // display 10
           seven_seg_led_0 = 7'b0000000;
        end
        ten     : begin
           {t,c} = 2'b00;     //abcdefg
           seven_seg_led_1 = 7'b0000000; // display 05
           seven_seg_led_0 = 7'b1011011;
        end
        fifteen : begin
           {t,c} = 2'b10;     //abcdefg
           seven_seg_led_1 = 7'b0000000; // display 00
           seven_seg_led_0 = 7'b0000000;
        end
        twenty  : begin
           {t,c} = 2'b11;     //abcdefg
           seven_seg_led_1 = 7'b0000001; // display -5
           seven_seg_led_0 = 7'b1011011;
        end
        default : begin
           {t,c} = 2'b00;
           seven_seg_led_1 = 7'b0000000; // display 00
           seven_seg_led_0 = 7'b0000000;
        end
      endcase
   end
endmodule

 

[MRFGUY]

Re: How to modify my FSM

Thanks nand_gates for your help.

If I want to wait sometime at state fifteen or twenty for other activites , lets say to give out tickets and change coins, how can we add.

thanks