------------------------------------------------------------------------
-- hw3a.vhd -- Demonstrate basic functions
------------------------------------------------------------------------
-- Author: Don Bouldin, Univ. of Tennessee, 9/19/05
------------------------------------------------------------------------
-- This module tests basic functions and I/O on the Spartan3 board.
------------------------------------------------------------------------

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity hw3a is
Port (
clock_50MHz : in std_logic;

btn0: in std_logic;


swt : in std_logic_vector(7 downto 0);
-- swt(7) = most  significant sliding switch; OFF = LOW; ON = HIGH
-- swt(0) = least significant sliding switch; OFF = LOW; ON = HIGH


led : out std_logic_vector(7 downto 0);
-- led(7) = most significant  led is ON when active HIGH
-- led(0) = least significant led is ON when active HIGH


seg : out std_logic_vector(7 downto 0);
-- segment lights when active LOW
-- seg(0) = seg-a
-- seg(1) = seg-b
-- seg(2) = seg-c
-- seg(3) = seg-d
-- seg(4) = seg-e
-- seg(5) = seg-f
-- seg(6) = seg-g
-- seg(7) = dp


dig : out std_logic_vector(3 downto 0)
-- dig(3) = most  significant digit is displayed when active LOW
-- dig(0) = least significant digit is displayed when active LOW

);
end hw3a;

architecture Behavioral of hw3a is
 
SIGNAL reset_pb_flag, pb_flag, clock_10hz: std_logic;

SIGNAL initialize : STD_LOGIC;

SIGNAL seg_3 : std_logic_vector(7 downto 0);
SIGNAL seg_2 : std_logic_vector(7 downto 0);
SIGNAL seg_1 : std_logic_vector(7 downto 0);
SIGNAL seg_0 : std_logic_vector(7 downto 0);

COMPONENT hierarch
	PORT(
      clock_50Mhz, btn0, reset_pb_flag: IN STD_LOGIC;
      pb_flag, clock_10Hz : OUT STD_LOGIC
		);
END COMPONENT;

-- Use Port Map to connect signals between components in the hiearchy

BEGIN

hw3a : hierarch PORT MAP (clock_50Mhz => clock_50Mhz,
			      btn0 =>  btn0,
                  reset_pb_flag => reset_pb_flag,
				  pb_flag => pb_flag,
				  clock_10hz => clock_10hz
					    );

-- begin loop
PROCESS
BEGIN

			-- initialize will be initialized to '0' at power up
    IF initialize = '0' THEN
			-- This code resets the critical signals once at power up


led(7 downto 0) <= "00000000";

seg_3(7 downto 0) <= "11111111";
seg_2(7 downto 0) <= "11111111";
seg_1(7 downto 0) <= "11111111";
seg_0(7 downto 0) <= "11111111";
WAIT UNTIL clock_10hz'EVENT and clock_10hz = '1';

--reset push button flag after wait

reset_pb_flag <= '0';

ELSE
	initialize <= '1';

WAIT UNTIL clock_10hz'EVENT and clock_10hz = '1';

--reset push button flag after wait

reset_pb_flag <= '0';

-- display each of the four digits for 0.1 second each forever

seg(7 downto 0) <= seg_0(7 downto 0) ;
dig <= "1110"   ;                     --digit(0) is ON
--now wait for 0.1 second
WAIT UNTIL clock_10hz'EVENT and clock_10hz = '1';

seg(7 downto 0) <= seg_1(7 downto 0) ;
dig(3 downto 0) <= "1101"   ;                      --digit(1) is ON
--now wait for 0.1 second
		WAIT UNTIL clock_10hz'EVENT and clock_10hz = '1';

seg(7 downto 0) <= seg_2(7 downto 0);
dig(3 downto 0) <= "1011"   ;                      --digit(2) is ON
--now wait for 0.1 second
		WAIT UNTIL clock_10hz'EVENT and clock_10hz = '1';	

seg(7 downto 0) <= seg_3(7 downto 0);
dig(3 downto 0) <= "0111"    ;                     --digit(3) is ON

-- repeat display until USER sets sliding switches and then presses btn0

-- if btn0_pressed has NOT occurred then skip to repeat this loop,
-- else copy the switch settings and update the display

  IF pb_flag = '1' THEN 
				
-- copy the sliding switch settings to the leds
led(7 downto 0) <= swt(7 downto 0);

-- copy the sliding switch settings to the internal digit segments
seg_3(7 downto 0) <= not (swt(7 downto 0)) ;
seg_2(7 downto 0) <= not (swt(7 downto 0)) ;
seg_1(7 downto 0) <= not (swt(7 downto 0)) ;
seg_0(7 downto 0) <= not (swt(7 downto 0)) ;

reset_pb_flag <= '1';

ELSE
END IF;

END IF;

-- repeat loop
END PROCESS;
			  			    
END Behavioral;