rei2c.vhd

用VHDL编写的quartusii平台上的串行EEPROM配置读取的程序。

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

entity rei2c is
port(
	reset	: in std_logic;
	clk		: in std_logic;
	rd		: in std_logic;
	dout	: out std_logic_vector(7 downto 0);
	oe		: out std_logic;
	sda		: inout std_logic;
    scl		: out std_logic
	);
end rei2c;

architecture RTL of rei2c is
 
constant control1data	: std_logic_vector(7 downto 0):="10100000";--"1010","000"-A2A1A0,"0"-write
constant control2data	: std_logic_vector(7 downto 0):="10100001";--"1010","000"-A2A1A0,"1"-read
constant highaddress	: std_logic_vector(7 downto 0):="00000000";
constant lowaddress		: std_logic_vector(7 downto 0):="00000000";

signal datacount		: integer range 0 to 8;
signal data				: std_logic_vector(7 downto 0);
signal i2c_active		: std_logic;
signal i				: integer range 0 to 32767;
TYPE STATE_TYPE IS (initial1,start1,control1,highadd,lowadd,initial2,start2,control2,transfer,stop,quit); 
signal state			: STATE_TYPE;
signal count			: std_logic_vector(2 downto 0);

begin

process(reset,clk) --procduce scl
	begin
	if reset='0' then
		scl<='0';
	elsif  clk'event and clk='1' then			
        scl<=count(2);
	end if;
end process;

process(reset,clk) --produce sda
	begin
	if reset='0' then
		i2c_active<='0';
		sda<='1';
		count<="000";
		datacount<=0;
		state<=initial1;
		i<=0;
		dout<="00000000";
		oe<='0';
	elsif clk'event and clk='1' then
		if count(0)='0' then
			case state is
			
				when initial1 => 
					i2c_active<='0';
					if count(2 downto 1)="11" then
                   		sda<= '1';                       
                   		state<=start1;
                	end if;

				when start1 =>
                	if count(2 downto 1)="11" then
                   		sda <= '0'; 
						state <= control1; 
                	end if;
 
				when control1 =>
					if count(2 downto 1)="01" then
	                	if(datacount = 0) then sda <= control1data(7);
	                	elsif(datacount = 1)then sda <= control1data(6);
	                	elsif(datacount = 2) then sda <= control1data(5);
	                	elsif(datacount = 3) then sda <= control1data(4);
	                	elsif(datacount = 4) then sda <= control1data(3);
	                	elsif(datacount = 5) then sda <= control1data(2);
	                	elsif(datacount = 6) then sda <= control1data(1);
	                	elsif(datacount = 7) then sda <= control1data(0);
                		else sda<='0'; state<=highadd;
                		end if;

						if(datacount=8)then datacount<=0;
                    	else datacount<=datacount+1;
                    	end if;
		   			end if;
				
				when highadd =>
					if count(2 downto 1)="01" then
	                	if(datacount = 0) then sda <= highaddress(7);
	                	elsif(datacount = 1)then sda <= highaddress(6);
	                	elsif(datacount = 2) then sda <= highaddress(5);
	                	elsif(datacount = 3) then sda <= highaddress(4);
	                	elsif(datacount = 4) then sda <= highaddress(3);
	                	elsif(datacount = 5) then sda <= highaddress(2);
	                	elsif(datacount = 6) then sda <= highaddress(1);
	                	elsif(datacount = 7) then sda <= highaddress(0);
                		else sda<='0'; state<=lowadd;
                		end if;

						if(datacount=8)then datacount<=0;
                    	else datacount<=datacount+1;
                    	end if;
		   			end if;
		
				when lowadd =>
					if count(2 downto 1)="01" then
	                	if(datacount = 0) then sda <= lowaddress(7);
	                	elsif(datacount = 1)then sda <= lowaddress(6);
	                	elsif(datacount = 2) then sda <= lowaddress(5);
	                	elsif(datacount = 3) then sda <= lowaddress(4);
	                	elsif(datacount = 4) then sda <= lowaddress(3);
	                	elsif(datacount = 5) then sda <= lowaddress(2);
	                	elsif(datacount = 6) then sda <= lowaddress(1);
	                	elsif(datacount = 7) then sda <= lowaddress(0);
                		else sda<='0'; state<=initial2;
                		end if;

						if(datacount=8)then datacount<=0;
                    	else datacount<=datacount+1;
                    	end if;
		   			end if;
		
				when initial2 => 
					i2c_active<='0';
					if count="010" then                  		                       
                   		state<=start2;
						sda<= '1';
                	end if;

				when start2 =>
                	if count(2 downto 1)="11" then
                   		sda <= '0'; 
						state <= control2; 
                	end if;
				
				when control2 =>
					if count(2 downto 1)="01" then
	                	if(datacount = 0) then sda <= control2data(7);
	                	elsif(datacount = 1)then sda <= control2data(6);
	                	elsif(datacount = 2) then sda <= control2data(5);
	                	elsif(datacount = 3) then sda <= control2data(4);
	                	elsif(datacount = 4) then sda <= control2data(3);
	                	elsif(datacount = 5) then sda <= control2data(2);
	                	elsif(datacount = 6) then sda <= control2data(1);
	                	elsif(datacount = 7) then sda <= control2data(0);
                		else sda<='0'; state<=transfer;
                		end if;

						if(datacount=8)then datacount<=0;
                    	else datacount<=datacount+1;
                    	end if;
		   			end if;
		
				when transfer =>
				
					if rd='1' then
					
						if count(2 downto 1)="01" then
							if(datacount=8)then datacount<=0;
								if i=32767 then
									i<=0;
									state<=stop;
								else i<=i+1;
								end if;							
	                    	else datacount<=datacount+1;
	                    	end if;
						end if;
												
						if count="010" then
							if datacount<8 then
								sda<='Z';
							else sda<='0';
							end if;
						end if;
						
						if count="110" then
							if datacount>0 then
								data(8-datacount)<=sda;
	--						elsif datacount=0 then
	--							dout<=data;
							end if;
						end if;
						
						if count="010" then
							if datacount=8 then
								dout<=data;
								oe<='1';
							else oe<='0';
							end if;
						end if;
						
					end if;
           	
				when stop =>
					if count(2 downto 1)="11" then
						sda<='1';
					elsif count(2 downto 1) ="01" then       
						state <= quit; 
                	end if;	

				if count="010" then
					oe<='0';
				end if;
				
				when quit =>
					sda<='1';
					count<="000";
					i2c_active<='1';
					
				end case;
		end if;
						
		if i2c_active='0' then   
        	if count="111" then
            	count<=(others=>'0');
        	else count <=count+1;         
        	end if;
		else
            count<=(others=>'0');
		end if;

	end if;

end process;
	
end RTL;