mc8051_siu_rtl.vhd

mc8051源码

                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0101") =>  	-- D5
                if s_m2_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0110") =>  	-- D6
                if s_m2_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0111") =>  	-- D7
                if s_m2_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("1000") =>  	-- D8
                if s_m2_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("1001") =>  	-- D9
                if s_m2_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("1010") =>  	-- D10, set done bit
                if s_m2_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  s_tran_done           <= '1';
                  v_txstep              := "10";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when others =>  		-- D0
                -- commence transmission if conditions are met
                s_txdm0 <= '1';
                if s_m2_shift_en = '1' then
                  if s_trans = '1' then
                    s_tran_sh(10)         <= '1';
                    s_tran_sh(9)          <= s_tb8;
                    s_tran_sh(8 downto 1) <= unsigned(sbuf_i);
                    s_tran_sh(0)          <= '0';
                    v_txstep              := "01";
                    s_tran_done           <= '0';
                    s_txdm0               <= '0';
                  end if;
                end if;
            end case;
-------------------------------------------------------------------------------
-- MODE 3
-------------------------------------------------------------------------------
          when ("11") =>
            rxd_o <= '0';
            rxdwr_o <= '0';
            case s_tran_state is
              when ("0001") =>  	-- D1
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0010") =>  	-- D2
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0011") =>  	-- D3
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0100") =>  	-- D4
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0101") =>  	-- D5
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0110") =>  	-- D6
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("0111") =>  	-- D7
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("1000") =>  	-- D8
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("1001") =>  	-- D9
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  v_txstep              := "01";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when ("1010") =>  	-- D10, set done bit
                if s_m13_shift_en = '1' then
                  s_tran_sh(10)         <= '1';
                  s_tran_sh(9 downto 0) <= s_tran_sh(10 downto 1);
                  s_tran_done           <= '1';
                  v_txstep              := "10";
                  s_txdm0               <= s_tran_sh(1);
                end if;
              when others =>  		-- D0
                -- commence transmission if conditions are met
                s_txdm0 <= '1';
                if s_m13_shift_en = '1' then
                  if s_trans = '1' then
                    s_tran_sh(10)         <= '1';
                    s_tran_sh(9)          <= s_tb8;
                    s_tran_sh(8 downto 1) <= unsigned(sbuf_i);
                    s_tran_sh(0)          <= '0';
                    s_tran_done           <= '0';
                    v_txstep              := "01";
                    s_txdm0               <= '0';
                  end if;
                end if;
            end case;
-------------------------------------------------------------------------------
          when others =>
            null;
        end case;

        case v_txstep is
          when "01" =>
            s_tran_state <= s_tran_state + conv_unsigned(1, 1);
          when "10" =>
            s_tran_state <= conv_unsigned(0, 4);
          when others =>
            null;
        end case;
        
      end if;
    end if;
  end process p_transmit;

-------------------------------------------------------------------------------
--**************************** RECEIVE ****************************************
-- This is the finit state machine for the receive shift register
-------------------------------------------------------------------------------
      
  p_receive: process (clk,
                      reset)
    
    variable v_rxstep : std_logic_vector(1 downto 0);
    
    begin

      if reset = '1' then
        s_recv_state <= conv_unsigned(0,4);
        s_recv_sh <= conv_unsigned(0,8);
        s_recv_buf <= conv_unsigned(0,8);
        s_recv_done <= '0';
        s_rb8 <= '0';
      else
        if clk'event and clk = '1' then

-------------------------------------------------------------------------------
-- MODE 0
-------------------------------------------------------------------------------
	  v_rxstep := "00";
          case s_mode is
          when ("00") =>
            case s_recv_state is
            when ("0000") =>            -- D0
              -- commence reception if conditions are met
              if s_ren = '1' and s_ri = '0' then
                if s_m0_shift_en = '1' then
                  v_rxstep := "01";
                  s_recv_done <= '0';
                end if;
              end if;
            when ("0001") =>            -- D1
              if s_m0_shift_en = '1' then
                s_recv_sh(7) <= rxd_i;
		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "01";
              end if;
            when ("0010") =>            -- D2
              if s_m0_shift_en = '1' then
                s_recv_sh(7) <= rxd_i;
		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "01";
              end if;
            when ("0011") =>            -- D3
              if s_m0_shift_en = '1' then
                s_recv_sh(7) <= rxd_i;
		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "01";
              end if;
            when ("0100") =>            -- D4
              if s_m0_shift_en = '1' then
                s_recv_sh(7) <= rxd_i;
		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "01";
              end if;
            when ("0101") =>            -- D5
              if s_m0_shift_en = '1' then
                s_recv_sh(7) <= rxd_i;
		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "01";
              end if;
            when ("0110") =>            -- D6
              if s_m0_shift_en = '1' then
                s_recv_sh(7) <= rxd_i;
		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "01";
              end if;
            when ("0111") =>            -- D6
              if s_m0_shift_en = '1' then
                s_recv_sh(7) <= rxd_i;
		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "01";
              end if;
            when ("1000") =>            -- D7, set bits and store data
              if s_m0_shift_en = '1' then
                s_recv_sh(7) <= rxd_i;
		s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                s_recv_done <= '1';
                s_recv_buf(7) <= rxd_i;
		s_recv_buf(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "10";
              end if;
            when others =>            
                v_rxstep := "10";
            end case;

-------------------------------------------------------------------------------
-- MODE 1
-------------------------------------------------------------------------------
          when ("01") =>
            case s_recv_state is
            when ("0000") =>            -- synchronise reception
              if s_ren = '1' and s_detect = '1' then
                v_rxstep := "01";
                s_recv_sh <= conv_unsigned(0,8);
                s_recv_done <= '0';
              end if;
            when ("0001") =>            -- D0 = START BIT
              if s_detect = '0' then
                if s_rxd_val = '0' then
                  if s_m13_shift_en = '1' then
                    s_recv_sh(7) <= s_rxd_val;
		    s_recv_sh(6 downto 0) <= s_recv_sh(7 downto 1);
                v_rxstep := "01";
                  end if;
                else                    -- reject false start bits
                  if s_m13_shift_en = '1' then
                v_rxstep := "10";                    
                  end if;