Question

I need the VHDL code for this pls.

Figure 1 Design a soda machine controller that can dispense two kinds of soda. If S1 Sel is selected, soda1 2. is dispensed, if S2Sel is selected then soda2 is dispensed. Each soda costs 75 cents and your machine accepts quarters only. The coin sensor has three outputs to detect first coin, second coin and the third coin. Once the soda is dispensed, the controller must be reset to be able to detect the coins again. The black-box view of the system is given here. The FPGA board push button are used to simulate the reset button and the coin sensor. DIP switches are used to simulate S1Sel and S2Sel. Since these push buttons have a pull-up resistor, they read 1 when they are not pressed. When you press them they will read in a zero. A coin in is simulated by pressing the push button, therefore when the coin is inserted, cin 0. Use LEDS to simulate | = S1out and S2out. Download the VHDL code into board and examine its functionality to practice. S1Sel S2Sel cinl Coin Sensor Soda Machine cin2 Controller S1out cin3 S2out

Answer 1

library ieee;
use ieee.std_logic_1164.all;

entity soda_controller is

   port (   clock :   in std_logic;
       cin1 :   in std_logic;
       cin2 :    in std_logic;
       cin3 :   in std_logic;
       S1Sel:    in std_logic;
       S2Sel:   in std_logic;
       S1out:   out std_logic;
       S2out:   out std_logic
   );

end soda_controller;

architecture arch of soda_controller is

type state is (idle, coin1, coin2, releaseS1, releaseS2);

signal present_state, next_state : state;

begin

   process (clock)

   begin
       if rising_edge (clock) then
           present_state <= next_state;
       end if;
  
   end process;

   process (present_state, cin1, cin2, cin3, S1Sel, S2Sel)

   begin
       case (present_state) is

           when idle=>   if (cin1 = '0') then
                       next_state <= coin1;
                   else
                       next_state <= idle;
                   end if;

           when coin1=>   if (cin2 = '0') then
                       next_state <= coin2;
                   else
                       next_state <= coin1;
                   end if;

           when coin2=>   if (cin3 = '0') then
                       if (S1Sel = '0') then
                           next_state <= releaseS1;
                       elsif (S2Sel = '0') then
                           next_state <= releaseS2;
                       else
                           next_state <= coin2;
                       end if;
                   else
                       next_state <= coin2;                      
                   end if;

           when releaseS1=>   next_state <= idle;

           when releaseS2=>   next_state <= idle;

           when others=>   next_state <= idle;

       end case;

   end process;

   S1out <= '1' when (present_state = releaseS1) else '0';

   S2out <= '1' when (present_state = releaseS2) else '0';

end arch;

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