--
-- Beep.vhd
--
-----------------------
-- A 30Hz beep with trigger signal timed for a 60Hz clock
-- Beep duration 0.10s
--coding by
--Chris Blasko, Kevin Lister, Tyler Brandon
--This will produce a 30Hz square wave, which will need
--amplification and probably an isolation capacitor.
--
--Total logic cells used:	102/1152   (  8%)
--

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity beep is
port(v_sync		: in std_logic;
	 collision	: in std_logic;		
	 --reset		: in std_logic;
  	 sound		: buffer std_logic);

end beep;

architecture behavioral of beep is

begin

counter :process(v_sync, collision) 
variable count	: integer;
variable done	: std_logic;

begin
	if rising_edge(v_sync) then --Note: v_sync acts like a 60 Hz clock
		--if reset = '0' then	--synchronous reset
		--	count := 0;
		--	done := '1'; --elsif
		if collision = '0' and done = '1' then	--If there is NO collision and the sound has
													--run its 0.10 second duration
			sound <='0';	--make all quiet (no noise)

		else --Collison detected (collision = 1) OR we haven't finished the beep (done = 0).

			done := '0';  --Let the program know we are producing sound
			count := count + 1;
			if count < 7 then  --produce sound for 0.10 seconds (6 / 60Hz)

				--Alternate between on and off (produces a 30Hz square wave)
				if sound = '1' then
					sound <= '0';
				else
					sound <= '1';
				end if;

			else --after 0.10 seconds
				done := '1';  --Tell the program we are done producing sound
				count := 0;	  --Reset the counter to zero
			end if;
			
		end if;  -- end if
	end if;--end if rising_edge( v_sync ) 

end process counter;

end behavioral;

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