Notes

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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
entity JK is
PORT ( J,K,CLOCK,R : IN STD_LOGIC;
Q : INOUT STD_LOGIC);
end JK;
architecture Behavioral of JK is
begin
PROCESS (CLOCK,R)
BEGIN
IF (R='1') THEN
Q<='0';
ELSIF (CLOCK'EVENT AND CLOCK='1') THEN
IF (J='0' AND K='0') THEN
Q<=Q;
ELSIF (J='0' AND K='1') THEN
Q<='0';
ELSIF (J='1' AND K='0') THEN
Q<='1';
ELSIF (J='1' AND K='1') THEN
Q<=NOT Q;
END IF;
END IF;
END PROCESS;
end Behavioral;
-----------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity VENDING is
PORT ( COIN,WATER,BEER,CLOCK,R : IN STD_LOGIC;
SEND_W,SEND_B,CHANGE : OUT STD_LOGIC);
end VENDING;
architecture Behavioral of VENDING is
COMPONENT JK is
PORT ( J,K,CLOCK,R : IN STD_LOGIC;
Q : INOUT STD_LOGIC);
end COMPONENT;
SIGNAL Q1,Q2,Q3,Q4,RESET,CCOIN,FULL : STD_LOGIC;
begin
CCOIN <= CLOCK AND COIN; -- when you put coin, coin process with clock signal
RESET <= R OR ((NOT CLOCK) AND ((Q4 AND BEER) OR (Q4 AND WATER) OR (Q3 AND WATER) OR (Q2 AND WATER))); -- External reset or reset of item sending
JK_25 : JK PORT MAP ('1','0',CCOIN,RESET,Q1); -- 1 quarter cent
JK_50 : JK PORT MAP (Q1,NOT Q1,CCOIN,RESET,Q2); -- 2 quarter cent
JK_75 : JK PORT MAP (Q2,NOT Q2,CCOIN,RESET,Q3); -- 3 quarter cent
JK_100 : JK PORT MAP (Q3,NOT Q3,CCOIN,RESET,Q4); -- 4 quarter cent
JK_CHANGE : JK PORT MAP (Q4,NOT Q4,CCOIN,RESET,FULL); -- Full signal after 4 quarter cent
CHANGE <= (Q4 AND BEER) OR (Q4 AND WATER) OR (Q3 AND WATER) OR (Q2 AND WATER) OR (FULL AND COIN); -- give 5th quarter cent back or change delivery
SEND_W <= (Q4 AND WATER) OR (Q3 AND WATER) OR (Q2 AND WATER) OR (Q1 AND WATER); -- activate water sending
SEND_B <= (Q4 AND BEER) OR (Q3 AND BEER); -- activate beer sending
end Behavioral;