Anyone here know VHDL?

[plutomed]

[plutomed]

If there is anyone...

 

Errors:

ERROR:Xst:528 - Multisource in Unit <Calc> on signal <row<3>>; this signal is connected to multiple drivers.

ERROR:Xst:528 - Multisource in Unit <Calc> on signal <row<2>>; this signal is connected to multiple drivers.

ERROR:Xst:528 - Multisource in Unit <Calc> on signal <row<1>>; this signal is connected to multiple drivers.

ERROR:Xst:528 - Multisource in Unit <Calc> on signal <row<0>>; this signal is connected to multiple drivers.

 

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

entity Calc is
    Port ( KeyCode : out  STD_LOGIC_VECTOR (3 downto 0);
           row : out  STD_LOGIC_VECTOR (3 downto 0);
           col : in  STD_LOGIC_VECTOR (3 downto 0);
           CLK : out  STD_LOGIC);
end Calc;

architecture SendKeyCode of Calc is

begin
	row 		<= 	"0111";

	KeyCode 	<= 	"0000" when col="0111" else
						"0001" when col="1011" else
						"0010" when col="1101" else
						"0011" when col="1110" else
						"ZZZZ";

	row 		<= 	"1011";

	KeyCode 	<=		"0100" when col="0111" else
						"0101" when col="1011" else
						"0110" when col="1101" else
						"0111" when col="1110" else
						"ZZZZ";

	row 		<= 	"1101";

	KeyCode 	<=		"1000" when col="0111" else
						"1001" when col="1011" else
						"1010" when col="1101" else
						"1011" when col="1110" else
						"ZZZZ";

	row 		<= 	"1110";

	KeyCode 	<=		"1100" when col="0111" else
						"1101" when col="1011" else
						"1110" when col="1101" else
						"1111" when col="1110" else
						"ZZZZ";

	CLK		<=		'0' when col="1111" else '1';


end SendKeyCode;

 

As I am just learning. Is there anyone who could tell me where I have gone wrong?

 

Thanx in advance, Dan.