------------------------------------------------------------------------------------ Company: -- Engineer: -- -- Create Date:    14:21:14 11/17/2008 -- Design Name: -- Module Name:    scan4digit - Behavioral -- Project Name: -- Target Devices: -- Tool versions: -- Description: ---- Dependencies: ---- Revision: -- Revision 0.01 - File Created-- Additional Comments: ------------------------------------------------------------------------------------library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity Scan4Digit is
Port ( Digit0 : in std_logic_vector (6 downto 0);
Digit1 : in std_logic_vector(6 downto 0);
Digit2 : in std_logic_vector(6 downto 0);
Digit3 : in std_logic_vector(6 downto 0);
Clock : in std_logic;
An : out std_logic_vector(3 downto 0);
Ca : out std_logic;
Cb : out std_logic;
Cc : out std_logic;
Cd : out std_logic;
Ce : out std_logic;
Cf : out std_logic;
Cg : out std_logic;
Dp : out std_logic);

end Scan4Digit;
architecture Scan4Digit_Arch of Scan4Digit is
signal iCount16: std_logic_vector (15 downto 0) := (others=>'0');
signal iDigitOut: std_logic_vector (6 downto 0);
begin
-- Generate the scan clock 50MHz/2**16 (763Hz)
process(Clock)
begin
if Clock'event and Clock='1' then
	iCount16 <= iCount16 + '1';
end if;
end process;
--Send four digits to four 7-segment display using scan mode
with iCount16 (15 downto 14) select
iDigitOut <= Digit0 when "00", -- Connect Digit0 to the 7-segment display
				Digit1 when "01", -- Connect Digit1 to the 7-segment display
				Digit2 when "10", -- Connect Digit2 to the 7-segment display
				Digit3 when "11", -- Connect Digit3 to the 7-segment display
				Digit0 when others;
				
with iCount16 (15 downto 14) select
	An <= "1110" when "00", -- with AN0 low only
			"1101" when "01", -- with AN1 low only
			"1011" when "10", -- with AN2 low only
			"0111" when "11", -- with AN3 low only
			"1110" when others;
			
Ca <= iDigitOut(6);
Cb <= iDigitOut(5);
Cc <= iDigitOut(4);
Cd <= iDigitOut(3);
Ce <= iDigitOut(2);
Cf <= iDigitOut(1);
Cg <= iDigitOut(0);
Dp <= '1';
end Scan4Digit_Arch;