flashwrite.vhd

适用于满足I2C协议的flash读/写操作程序

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

 ENTITY flashwrite IS
     generic (databyteshu: integer :=4);----需要保存数据字节数
     PORT (clkin : IN std_logic;
          dataram: in std_logic_vector(7 downto 0);
          clkout: buffer std_logic ;
          dataout: inout  std_logic;
          ramread: out std_logic;
          flashwrite:in std_logic;
          addrram: out integer range 0 to 9 );
 END  	flashwrite;                                
----------------------------------------------------------
ARCHITECTURE flashwrite OF flashwrite IS   
 
BEGIN   
------------产生相位差四分之一周期的时钟----------                                        
PROCESS(clkin,dataram)
      VARIABLE write: std_logic :='0'; 
      VARIABLE ramdatatemp: std_logic_vector(7 downto 0);  -----临时储存RAM数据
      VARIABLE temp1: INTEGER range 0 to 4:=0;-----产生flash周期及
                                           
      VARIABLE temp2: INTEGER :=0; -------整个计数
      VARIABLE temp_flashwrite:std_logic;
      VARIABLE temp4: INTEGER range 0 to 31:=0;  -----标记写到了哪个字节
      VARIABLE temp5: INTEGER range 0 to 1023;-------
      VARIABLE temp6: INTEGER range 0 to 15:=0;  ---------标志字节位
BEGIN 
---------------------------检验写信号-------------------------
         
-------------------------------------------------------------
ramdatatemp:=dataram;     

if rising_edge(clkin) then
	temp_flashwrite:=flashwrite;
end if;
       if(clkin'EVENT AND clkin='1') THEN
            temp1:=temp1+1;
            temp2:=temp2+1;

           if(flashwrite='1' and temp_flashwrite='0')then
             write:='1';
             temp2:=0;
             temp1:=0;
             temp4:=0;
             temp6:=0;

           end if;
           

             IF (temp1=1) THEN 
               clkout<= '1' and write;
                elsif (temp1=2)then
               clkout<= '1' and write;
                elsif (temp1=3)then
               clkout<='0';
                else 
                clkout<='0';
                temp1:=0;
             END IF;

           if temp2<117 then
             case temp2 is
                when 5 => dataout<= '1';
                 ramread<='0';   ------------开始状态锁闭ram
                when 14 => dataout<= '0'; ---------------------------------------------
-------------------------------------------------
                when 16 => dataout<= '1';-----------------------------------------------
  
                when 20 => dataout<= '0';
                when 24 => dataout<= '1';
                when 28 => dataout<= '0';  
----------------------------------------------------  
                when 32 => dataout<= '0'; 
                when 36 => dataout<= '0'; 
                when 40 => dataout<= '0'; 
-------------------------------------------------------------
                when 44 => dataout<= '0';   ---写命令 
                when 47 => dataout<= 'Z';
--------------------------地址字节(高位)----------------------------
                when 52 => dataout<= '0'; 
                when 56 => dataout<= '0'; 
                when 60 => dataout<= '0'; 
                when 64 => dataout<= '0'; 
                when 68 => dataout<= '0'; 
                when 72 => dataout<= '0'; 
                when 76 => dataout<= '0'; 
                when 80 => dataout<= '0'; 
                when 84 => dataout<= 'Z';
--------------------------地址字节(低位)----------------------------
                when 88 => dataout<= '0'; 
                when 92 => dataout<= '0'; 
                when 96 => dataout<= '0'; 
                when 100 => dataout<= '0'; 
                when 104 => dataout<= '0'; 
                when 108 => dataout<= '0'; 
                when 112 => dataout<= '0'; 
                when 116 => dataout<= '1'; 
                when 120 => dataout<= 'Z';
                        temp5:=124;  
               when others => null;  
             end case; 
          end if;
-----------------------------写入数据字节------------------------
                         if(temp2=116+temp4*36+4)then
                                dataout<= 'Z';
                         end if;
 
                         if(temp2=116+temp4*36+1)then
                           addrram<=temp4;
                           ramread<='1';
                           ramdatatemp:=dataram;
                         end if;
                        if(temp2=temp5)then
                          dataout<=ramdatatemp(temp6);------------------------------------------------------
                          temp6:=temp6+1;
                          temp5:=temp5+4;
                        end if;
                        if temp6>7 then
                           temp6:=0;
                           temp5:=116+temp4*36+44;
                           temp4:=temp4+1;
                            if temp4=databyteshu then
                                 temp4:=0;
                                 temp5:=124;   
                            end if;
                        end if;  

------------------------收最后一个ack信号-----------------------
         if  temp2=116+databyteshu*36+4 then
                dataout<='Z';
          end if; 
------------------------停止信号产生--------------
         if  temp2=116+databyteshu*36+8 then
                dataout<='0';
          end if; 
         if  temp2=116+databyteshu*36+10 then
               dataout<='1';
            ramread<='0';
         end if;  
-----------------------写结束后释放总线关闭时钟-----------------------
         if  temp2=116+databyteshu*36+12 then
               dataout<='Z';
            write:='0';-----------------此后时钟始终为零注意复用
         end if;  
---------------------------------------------------------------------   
      END IF;
     END PROCESS;

END flashwrite;