startadmode.vhd

是关于对数据采集卡的基于PC104总线的读写程序

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
--  Entity Declaration

ENTITY StartAdMode IS
	-- {{ALTERA_IO_BEGIN}} DO NOT REMOVE THIS LINE!
	PORT
	(
		SelectBit : IN STD_LOGIC;
		InternalChl : IN STD_LOGIC;
		StartAD : IN STD_LOGIC;
		nReset : IN STD_LOGIC;
		Clk : IN STD_LOGIC;
		OUT_ST : IN STD_LOGIC;
		Convst : OUT STD_LOGIC
	);
	-- {{ALTERA_IO_END}} DO NOT REMOVE THIS LINE!
	
END StartAdMode;


--  Architecture Body

ARCHITECTURE StartAdMode_architecture OF StartAdMode IS
	SIGNAL ExternalChl: STD_LOGIC;
	SIGNAL Flag: STD_LOGIC;
	SIGNAL qn:STD_LOGIC_VECTOR(9 DOWNTO 0);
BEGIN
	ExternalChl<='1' WHEN(OUT_ST='1')ELSE 
				 '0' WHEN(nReset='0')ELSE
			     ExternalChl;
	Flag<=InternalChl WHEN(SelectBit='0')ELSE ExternalChl;
	
	PROCESS(nReset,Clk)
	BEGIN
	IF(nReset='0')THEN
		qn<="1111100110";
	ELSIF(Clk'EVENT AND Clk='1')THEN
		IF(Flag='1'AND StartAD='1')THEN
			IF(qn="1111100111")THEN
				qn<="0000000000";
			ELSE 
				qn<=qn+'1';
			END IF;
		END IF;
	END IF;
	END PROCESS;
	Convst<=(qn(9) OR qn(8) OR qn(7) OR qn(6) OR qn(5) OR qn(4) OR qn(3));	
END StartAdMode_architecture;