Add I2C to RAM

src/cpu16.vhd

@@ -44,20 +44,25 @@ architecture Implementation of Cpu16 is
   signal ImmediateValue      : std_logic_vector(15 downto 0) := (others => '0');
   signal PcEnable            : std_logic                     := '0';
   signal Jump                : std_logic                     := '0';
+  signal I2CClient           : std_logic_vector(15 downto 0) := (others => '0');
+  signal I2CServer           : std_logic_vector(15 downto 0) := (others => '0');
 begin
 
   -- Include Entities
   Ramblock : entity work.Ram(Behavioral)
     port map(
-      Clk         => Clk,
+      Clk          => Clk,
-      AddrA       => RamAddrA,
+      AddrA        => RamAddrA,
-      AddrB       => RamAddrB,
+      AddrB        => RamAddrB,
-      WriteEnable => RamWriteEnable,
+      WriteEnable  => RamWriteEnable,
-      DataIn      => RamDataWrite,
+      DataIn       => RamDataWrite,
-      ReadA       => RamReadA,
+      ReadA        => RamReadA,
-      ReadB       => RamReadB,
+      ReadB        => RamReadB,
-      DirectIn    => Switches,
+      DirectIn     => Switches,
-      DirectOut   => LED
+      DirectOut    => LED,
+      I2CClientIn  => I2CClient,
+      I2CClientOut => I2CClient,
+      I2CServerOut => I2CServer
       );
 
   Alu : entity work.Alu(Implementation)

src/ram.vhd

@@ -8,15 +8,18 @@ use IEEE.numeric_std.all;
 
 entity Ram is
   port(
-    Clk         : in  std_logic;
+    Clk          : in  std_logic;
-    AddrA       : in  std_logic_vector(15 downto 0);
+    AddrA        : in  std_logic_vector(15 downto 0);
-    AddrB       : in  std_logic_vector(15 downto 0);
+    AddrB        : in  std_logic_vector(15 downto 0);
-    WriteEnable : in  std_logic;
+    WriteEnable  : in  std_logic;
-    DataIn      : in  std_logic_vector(15 downto 0);
+    DataIn       : in  std_logic_vector(15 downto 0);
-    ReadA       : out std_logic_vector(15 downto 0);
+    ReadA        : out std_logic_vector(15 downto 0);
-    ReadB       : out std_logic_vector(15 downto 0);
+    ReadB        : out std_logic_vector(15 downto 0);
-    DirectIn    : in  std_logic_vector(15 downto 0);
+    DirectIn     : in  std_logic_vector(15 downto 0);
-    DirectOut   : out std_logic_vector(15 downto 0)
+    DirectOut    : out std_logic_vector(15 downto 0);
+    I2CClientIn  : in  std_logic_vector(15 downto 0);
+    I2CClientOut : out std_logic_vector(15 downto 0);
+    I2CServerOut : out std_logic_vector(15 downto 0)
     );
 end Ram;
 
@@ -37,6 +40,9 @@ architecture Behavioral of Ram is
 
   signal BoardInput  : std_logic_vector(15 downto 0) := (others => '0');
   signal BoardOutput : std_logic_vector(15 downto 0) := (others => '0');
+
+  signal I2CClient : std_logic_vector(15 downto 0) := (others => '0');
+  signal I2CServer : std_logic_vector(15 downto 0) := (others => '0');
 begin
 
   block1 : entity work.Ram_Block(Memory)
@@ -71,6 +77,7 @@ begin
     if rising_edge(clk) then
       -- must be treated as register 
       BoardInput <= DirectIn;
+      I2CClient  <= I2CClientIn;
 
       -- handle Directin
       if unsigned(AddrA) = 1 then
@@ -99,9 +106,60 @@ begin
         BoardOutput <= DataIn;
       end if;
 
+      -- handle I2CClient
+      if unsigned(AddrA) = 3 then
+        ReadA <= I2CClient;
+      else
+        case AddrA(15) is
+          when '1' =>
+            ReadA <= SReadA2;
+          when others => ReadA <= SReadA1;
+        end case;
+      end if;
+
+      if unsigned(AddrB) = 3 then
+        ReadB <= I2CClient;
+      else
+        case AddrB(15) is
+          when '1' =>
+            ReadB <= SReadB2;
+
+          when others => ReadB <= SReadB1;
+        end case;
+      end if;
+
+      -- handle I2CClient
+      if unsigned(AddrB) = 3 and WriteEnable = '1' then
+        I2CClient <= DataIn;
+      end if;
+
+      -- handle I2CServer
+      if unsigned(AddrA) = 4 then
+        ReadA <= I2CServer;
+      else
+        case AddrA(15) is
+          when '1' =>
+            ReadA <= SReadA2;
+          when others => ReadA <= SReadA1;
+        end case;
+      end if;
+
+      if unsigned(AddrB) = 4 then
+        ReadB <= I2CServer;
+      else
+        case AddrB(15) is
+          when '1' =>
+            ReadB <= SReadB2;
+
+          when others => ReadB <= SReadB1;
+        end case;
+      end if;
+
     end if;
   end process DirectIO;
 
-  DirectOut <= BoardOutput;
+  DirectOut    <= BoardOutput;
+  I2CClientOut <= I2CClient;
+  I2CServerOut <= I2CServer;
 
 end Behavioral;