i2c_controller.vhd

Pacman 4 DE1-FPGA-Board

LIBRARY ieee;
USE ieee.std_logic_1164.all;
USE ieee.numeric_std.all;

ENTITY I2C_Controller IS 
	port
	(
	CLOCK 		: in STD_LOGIC;
	I2C_SCLK	: out STD_LOGIC;					--I2C CLOCK
 	I2C_SDAT	: inout STD_LOGIC;					--I2C DATA
	I2C_DATA	: in STD_LOGIC_VECTOR(23 downto 0);	--DATA:[SLAVE_ADDR,SUB_ADDR,DATA]
	GO			: in STD_LOGIC;      				--GO transfor
	ENDE 		: out STD_LOGIC;     				--END transfor 
	ACK			: out STD_LOGIC;      				--ACK
	RESET		: in STD_LOGIC--;
	);
END I2C_Controller;

ARCHITECTURE I2C OF I2C_Controller IS

SIGNAL SD_COUNTER 	: UNSIGNED(5 DOWNTO 0);
SIGNAL SCLK			: STD_LOGIC;
SIGNAL SDO			: STD_LOGIC;
SIGNAL ACK1			: STD_LOGIC;
SIGNAL ACK2			: STD_LOGIC;
SIGNAL ACK3			: STD_LOGIC;
SIGNAL SD			: STD_LOGIC_VECTOR(23 downto 0);


BEGIN
I2C_SCLK <= ((SCLK)or(not CLOCK))when((SD_COUNTER >= 4)and(SD_COUNTER <=30))else SCLK;
I2C_SDAT <= 'Z' when SDO='1' else '0';
ACK		 <= ACK1 or ACK2 or ACK3;

	process(CLOCK,RESET)
	begin
	if(RESET = '0')then	
		SD_COUNTER<="111111";
		SCLK<='1';
		SDO<='1';
		ACK1<='0';
		ACK2<='0';
		ACK3<='0'; 
		ENDE<='1';	
	elsif(rising_edge(CLOCK))then
		if (GO='0')then
			SD_COUNTER<="000000";
		else 
			if(SD_COUNTER < "111111")then SD_COUNTER<=SD_COUNTER+1; end if;
		end if;
		---
		case(SD_COUNTER)is
		when "000000" => ACK1<='0'; ACK2<='0'; ACK3<='0'; ENDE<='0'; SDO<='1'; SCLK<='1';
		--start
		when "000001" => SD<=I2C_DATA; SDO<='0';
		when "000010" => SCLK<='0';
		--SLAVE ADDR
		when "000011" => SDO<=SD(23);
		when "000100" => SDO<=SD(22);
		when "000101" => SDO<=SD(21);
		when "000110" => SDO<=SD(20);
		when "000111" => SDO<=SD(19);
		when "001000" => SDO<=SD(18);
		when "001001" => SDO<=SD(17);
		when "001010" => SDO<=SD(16);
		when "001011" => SDO<='1';--ACK
		--SUB ADDR
		when "001100" => SDO<=SD(15);  ACK1<=I2C_SDAT;
		when "001101" => SDO<=SD(14);
		when "001110" => SDO<=SD(13);
		when "001111" => SDO<=SD(12);
		when "010000" => SDO<=SD(11);
		when "010001" => SDO<=SD(10);
		when "010010" => SDO<=SD(09);
		when "010011" => SDO<=SD(08);
		when "010100" => SDO<='1';--ACK
		--DATA
		when "010101" => SDO<=SD(07);  ACK2<=I2C_SDAT;
		when "010110" => SDO<=SD(06);
		when "010111" => SDO<=SD(05);
		when "011000" => SDO<=SD(04);
		when "011001" => SDO<=SD(03);
		when "011010" => SDO<=SD(02);
		when "011011" => SDO<=SD(01);
		when "011100" => SDO<=SD(00);
		when "011101" => SDO<='1';--ACK
		--stop
		when "011110" => SDO<='0'; SCLK<='0'; ACK3<=I2C_SDAT;
		when "011111" => SCLK<='1';
		when "111111" => SDO<='1'; ENDE<='1';
		when others => NULL;
		end case;
		---		
	end if;	
	end process;
	
END I2C;