cpld与8051的总线接口vhdl设计源码

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;
entity cpldbus51 is
port (            
  Clk: in STD_LOGIC;                     --Clock    16MHZ  
  Clr: in STD_LOGIC;         --Clear   high
  P0: inout STD_LOGIC_VECTOR (7 downto 0);   --8052 Port 0
  P2: in STD_LOGIC_VECTOR (7 downto 0);    --8052 Port 2
  ALE: in STD_LOGIC;                         --8052 ALE
--  PSEN: in STD_LOGIC;         --8052'Psen
--  INT0ut  STD_LOGIC;                       --8052 INT0
  Wr: in STD_LOGIC;         --8052'Wr
  Rd: in STD_LOGIC;         --8052'Rd
---------------------------
  Pinaut STD_LOGIC;                     ---output
-----------------------
  nCS8255: out STD_LOGIC;           --select 8255
  RamBank: out STD_LOGIC_VECTOR (1 downto 0);--Ram68128a bank switch   A15 A16
  nCsFlashRam: out STD_LOGIC;       --select Flash Rom   CE
  FlashRomBank: out STD_LOGIC_VECTOR (2 downto 0) --Flash Rom switch  A14 A15 A16

);
end cpldbus51;

architecture cpldbus51 of cpldbus51 is           
------------------------------------------------------------------------------
signal Addr: std_logic_vector(15 downto 0);  --16bit address
signal ALE_Sample:STD_LOGIC;
signal RamBankReg: STD_LOGIC_VECTOR (1 downto 0);--Ram bank switch reg, 4 banks, 4*32K=128k bytes
signal FlashRomBankReg: STD_LOGIC_VECTOR (2 downto 0);--Flash Rom bank switch reg, 8 banks, 8*16K=128k bytes
--Rd Sample
signal RdSample:std_logic; --for Rd Sample
--WR Sample
signal WrSample0:std_logic; --Wr for Sample
signal WrSample1:std_logic;
signal WrSample2:std_logic;
signal WrSample3:std_logic;
signal WrSample4:std_logic;
signal WrSample5:std_logic;
--Wr Sample output
signal Wr_en:std_logic;
--Clr Sample
signal ClrSample0:std_logic; -- for Clr Sample
signal ClrSample1:std_logic;
signal ClrSample2:std_logic;
signal ClrSample3:std_logic;
signal ClrSample4:std_logic;
signal ClrSample5:std_logic;
signal ClrSample6:std_logic;
signal ClrSample7:std_logic;
signal ClrSample8:std_logic;
signal ClrSample9:std_logic;
--Clr Sample output
signal Clr_en:std_logic;
------------------------------------------------------------------------------
--output Reg
signal PinaReg:std_logic;
begin  
--------------------------------------------
--Sample Clr signal  
ClrSample_p:process(Clk)
begin
if Clk'event and Clk='1' then
  ClrSample0<=Clr;
  ClrSample1<=ClrSample0;
  ClrSample2<=ClrSample1;
  ClrSample3<=ClrSample2;
  ClrSample4<=ClrSample3;
  ClrSample5<=ClrSample4;
  ClrSample6<=ClrSample5;
  ClrSample7<=ClrSample6;
  ClrSample8<=ClrSample7;
  ClrSample9<=ClrSample8;
end if;
end process;      
---------------------------------------
--Clr Enable Signal
Clr_en_p:process(Clk)
begin   
if Clk'event and Clk='1' then
  if      ClrSample0='1' and ClrSample1='1'
   and ClrSample2='1' and ClrSample3='1'
   and ClrSample4='1' and ClrSample5='1'
   and ClrSample6='1' and ClrSample7='1'
   and ClrSample8='1' and ClrSample9='1' then
   Clr_en<='1';
  else
   Clr_en<='0';
  end if;
end if;
end process;      
------------------------------------------------
--sample ALE signal
ALE_p:process(Clk)
begin
  if Clk'event and Clk='1' then
   if Clr_en='1' then
    ALE_Sample<='0';
   else
    ALE_Sample<=ALE;
   end if;
  end if;
end process;
-------------------------------------------------      
--Address Latch
Address_p:process(Clk)
begin
  if Clk'event and Clk='1' then
   if Clr_en='1' then
     Addr<="0000000000000000";
   elsif ALE_Sample='1' then
    Addr<=P2&0;
   end if;
  end if;
end process;            
-------------------------------------
--Sample Wr
WrSample_p:process(Clk)
begin
if Clk'event and Clk='1' then
  if Clr_en='1' then
   WrSample0<='1';
   WrSample1<='1';
   WrSample2<='1';
   WrSample3<='1';
   WrSample4<='1';
   WrSample5<='1';
  else
   WrSample0<=Wr;
   WrSample1<=WrSample0;
   WrSample2<=WrSample1;
   WrSample3<=WrSample2;
   WrSample4<=WrSample3;
   WrSample5<=WrSample4;
  end if;
end if;
end process;
---------------------------------------
--internal Wr enable signal
WrEn_p:process(WrSample0,WrSample1,WrSample2,WrSample3,WrSample4,WrSample5)
begin
if (WrSample0='0' and  WrSample1='0'
  and WrSample2='0' and WrSample3='0'
  and WrSample4='1'and WrSample5='1')then
  Wr_en<='1';
else
  Wr_en<='0';
end if;
end process;      
----------------------------------------
--Rd Sample
RdSample_p:process(Clk)
begin
if Clk'event and Clk='1' then
  if Clr_en='1' then
   RdSample<='1';
  else
   RdSample<=Rd;
  end if;
end if;
end process;

-----------------------------------
--Flash Rom Chip select signal
CS_Flash_p:process(Addr)
begin
if Addr(15 downto 14)="10" then            --Address:8000h--BFFFh
     nCsFlashRam<='0';
else
  nCsFlashRam<='1';
end if;
end process;
-----------------------------------
-- 8255 Chip select signal
cs8255_p:process(Addr)
begin
  if Addr(15 downto 2)="11000000000000" then  --C000h--C003h
   nCS8255<='0';
  else
   nCS8255<='1';
  end if;
end process;      
-----------------------------------
-----------------------------------
-- Ram Bank Switch Reg
Ram_bank_p:process(Clk)
begin      
if Clk'event and Clk='1' then
  if Clr_en='1' then
      RamBankReg<="00";  
  elsif Addr="1100000000000100" and Wr_en='1' then    --Address:C004h
         RamBankReg<=P0(1 downto 0);
  end if;
end if;
end process;
RamBank<=RamBankReg;      
----------------------------------
----------------------------------
--Flash Rom Switch Reg
Flash_bank_p:process(Clk)
begin      
if Clk'event and Clk='1' then
  if Clr_en='1' then
   FlashRomBankReg<="000";
  elsif Addr="1100000000000101"  and Wr_en='1' then      --Address:C005h
   FlashRomBankReg<=P0(2 downto 0);
  end if;
end if;
end process;
FlashRomBank<=FlashRomBankReg;   
--------------------------------
--------------------------------
--Rd process
-- now just two in-builde register
Rd_p:process(RdSample,Addr,RamBankReg,FlashRomBankReg)
begin
if    Addr="1100000000000100"  and RdSample='0' then    --C004h
     P0<="000000"&RamBankReg;
elsif Addr="1100000000000101"  and RdSample='0' then    --C005h
  P0<="00000"&FlashRomBankReg;
else
  P0<="ZZZZZZZZ";
end if;
end process;   
-------------------------------   
Pina_p:process(Clk)
begin
if Clk'event and Clk='1' then
  if Clr_en='1' then
   PinaReg<='0';
  elsif Addr="1100000000000110"  and Wr_en='1' then      --C006h
   PinaReg<=P0(0);
  end if;
end if;
end process;   
Pina<=PinaReg;   
end cpldbus51;

                        

顶~~~~~~~~~~~~~~