原创 【转】cpld与PC机通讯vhdl代码

--功能:实现cpld与pc机通讯
--原理:模拟232的发送时序每次发送10bits,一个开始位,八个数据位,一个停止位.
--波特率:9600bps
--环境:cpld器件:epm7128stc100-10,外部1m 时钟,pc机端:串口调试助手.
--操作:从串口调试助手中发送一个byte.cpld接收到信号再返回到串口调试助手.
--本程序仅供学习,不得用与商业.
--作者:sagestar　

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
--USE IEEE.STD_LOGIC_ARITH.ALL;

ENTITY cpld232 IS
PORT(
        clk:        in std_logic;
        rx:         in std_logic;
        tx:         out std_logic;
        rtx_control: in std_logic
    );
END cpld232;

ARCHITECTURE cpld OF cpld232 IS
    signal Rx_Buffer: std_logic_vector(7 downto 0);
    signal Tx_Buffer: std_logic_vector(7 downto 0);
    BEGIN
                    --receive subprogrammer
    PROCESS(clk,rx)
    variable Baud_Number1:integer range 0 to 100;
    variable Rx_start: std_logic_vector(7 downto 0);
    variable Rx_Over:std_logic;
    variable Rx_Complete:std_logic;                               
    BEGIN
        if clk'event and clk='0' then
            if rx='0'and Rx_Start="00000000"and Rx_Over='0'and Rx_Complete='0' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    --Rx_Buffer(0) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(0):='1';
                end if;
            elsif Rx_Start(0)='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    Rx_Buffer(0) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(0):='0';
                    Rx_Start(1):='1';
                end if;
            elsif Rx_Start(1)='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    Rx_Buffer(1) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(1):='0';
                    Rx_Start(2):='1';
                end if;
            elsif Rx_Start(2)='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    Rx_Buffer(2) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(2):='0';
                    Rx_Start(3):='1';
                end if;
            elsif Rx_Start(3)='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    Rx_Buffer(3) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(3):='0';
                    Rx_Start(4):='1';
                end if;
            elsif Rx_Start(4)='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    Rx_Buffer(4) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(4):='0';
                    Rx_Start(5):='1';
                end if;
            elsif Rx_Start(5)='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    Rx_Buffer(5) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(5):='0';
                    Rx_Start(6):='1';
                end if;
            elsif Rx_Start(6)='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    Rx_Buffer(6) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(6):='0';
                    Rx_Start(7):='1';
                end if;
            elsif Rx_Start(7)='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    Rx_Buffer(7) <= rx;
                    Baud_Number1:=0;
                    Rx_Start(7):='0';
                    Rx_Over:='1';
                end if;
            elsif Rx_Over='1' then
                Baud_Number1:=Baud_Number1+1;
                if Baud_Number1=100 then
                    if rx='1'then
                        Baud_Number1:=0;
                        Rx_Over:='0';
                        Rx_Complete:='1';
                    end if;
                end if;
            elsif Rx_Complete='1' then
                Tx_Buffer<=Rx_Buffer;
                Rx_Complete:='0';
            else
                Rx_Start:="00000000";
                Rx_Over:='0';
                Rx_Complete:='0';
            end if;
        end if;
    END PROCESS;
                    --send subprogrammer
    PROCESS(clk)                                          
    variable Baud_Number:integer range 0 to 200000;
    variable Tx_start: std_logic_vector(7 downto 0);
    variable Tx_Over:std_logic;
    variable Tx_Complete:std_logic;
    BEGIN
        if clk'event and clk='0' then
            if rtx_control='1' then
                if Tx_Start="00000000"and Tx_Over='0'and Tx_Complete='0'then
                    --Baud_Number:=Baud_Number+1;
                    --if Baud_Number=100 then
                        tx <= '0';
                        --Baud_Number:=0;
                        Tx_Start(0):='1';
                    --end if;
                elsif Tx_Start(0)='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<=Tx_Buffer(0);
                        --  tx<='1';
                        Baud_Number:=0;
                        Tx_Start(0):='0';
                        Tx_Start(1):='1';
                    end if;
                elsif Tx_Start(1)='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<=Tx_Buffer(1);
                        --tx<='1';
                        Baud_Number:=0;
                        Tx_Start(1):='0';
                        Tx_Start(2):='1';
                    end if;
                elsif Tx_Start(2)='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<=Tx_Buffer(2);
                        --tx<='0';
                        Baud_Number:=0;
                        Tx_Start(2):='0';
                        Tx_Start(3):='1';
                    end if;
                elsif Tx_Start(3)='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<=Tx_Buffer(3);
                        --tx<='1';
                        Baud_Number:=0;
                        Tx_Start(3):='0';
                        Tx_Start(4):='1';
                    end if;
                elsif Tx_Start(4)='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<=Tx_Buffer(4);
                        --tx<='1';
                        Baud_Number:=0;
                        Tx_Start(4):='0';
                        Tx_Start(5):='1';
                    end if;
                elsif Tx_Start(5)='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<=Tx_Buffer(5);
                        --tx<='0';
                        Baud_Number:=0;
                        Tx_Start(5):='0';
                        Tx_Start(6):='1';
                    end if;
                elsif Tx_Start(6)='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<=Tx_Buffer(6);
                        --tx<='0';
                        Baud_Number:=0;
                        Tx_Start(6):='0';
                        Tx_Start(7):='1';
                    end if;
                elsif Tx_Start(7)='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<=Tx_Buffer(7);
                        --tx<='1';
                        Baud_Number:=0;
                        Tx_Start(7):='0';
                        Tx_Over:='1';
                    end if;
                elsif Tx_Over='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=104 then
                        tx<='1';
                        Baud_Number:=0;
                        Tx_Over:='0';
                        Tx_Complete:='1';
                    end if;
                elsif Tx_Complete='1' then
                    Baud_Number:=Baud_Number+1;
                    if Baud_Number=200000 then
                        Baud_Number:=0;
                        Tx_Complete:='0';
                    end if;
                else
                    Tx_Start:="00000000";
                    Tx_Over:='0';
                    Tx_Complete:='0';
                end if;
            end if;
        end if;
    END PROCESS;
END cpld;