multi_baudrate_generator.vhd

波特率发生器,用于uart源码的开发,可以用于非标准波特率

-- 库声明
library IEEE;
use IEEE.STD_LOGIC_1164.all;
use WORK.UART_PACKAGE.ALL;

-- 实体声明
entity multi_baudrate_generator is
	-- 类属参数声明
 --	generic (
 --	FULL_PULSE_COUNT : BD_COUNT := BD9600_FPC;
 --	RISE_PULSE_COUNT : BD_COUNT := BD9600_HPC );
	-- 端口声明
	port (
	clk : in std_logic;
	reset_n : in std_logic;
	ce : in std_logic;
        bcr: in std_logic_vector(3 downto 0);
        bcrs_n: in std_logic;
	bg_out : out std_logic);
---	indicator : out std_logic );
	
end multi_baudrate_generator;

--}} End of automatically maintained section
-- 结构体
architecture multi_baudrate_generator of multi_baudrate_generator is
signal bcr_s:std_logic_vector(3 downto 0);
signal FULL_PULSE_COUNT:BD_COUNT;
signal RISE_PULSE_COUNT:BD_COUNT;
begin
  bcr_latch_proc:process(reset_n,bcrs_n,bcr_s)
    begin
        if(reset_n='0') then
           bcr_s<="0101";
        elsif(bcrs_n='0') then
           bcr_s<=bcr;

        end if;
    end process bcr_latch_proc;
  baudrate_set_proc:process(bcr_s)  -----波特率设定
   begin 
      
         case bcr_s is
      when "0000" =>
          FULL_PULSE_COUNT<=28409;
          RISE_PULSE_COUNT<=14205;
      
      when "0001" =>
          FULL_PULSE_COUNT<=10417;
          RISE_PULSE_COUNT<=5208;
      when "0010" =>
          FULL_PULSE_COUNT<=2604;
          RISE_PULSE_COUNT<=1302;
      when "0011" =>
          FULL_PULSE_COUNT<=1302;
          RISE_PULSE_COUNT<=651;
      when "0100" =>
          FULL_PULSE_COUNT<=651;
          RISE_PULSE_COUNT<=326;
      when "0101" =>
          FULL_PULSE_COUNT<=326;
          RISE_PULSE_COUNT<=163;
      when "0110" =>
          FULL_PULSE_COUNT<=163;
          RISE_PULSE_COUNT<=81;
      when "0111" =>
          FULL_PULSE_COUNT<=81;
          RISE_PULSE_COUNT<=41;
      when "1000" =>
          FULL_PULSE_COUNT<=54;
          RISE_PULSE_COUNT<=27;
      when "1001" =>
          FULL_PULSE_COUNT<=27;
          RISE_PULSE_COUNT<=14;
      when "1010" =>
          FULL_PULSE_COUNT<=14;
          RISE_PULSE_COUNT<=7;
      when "1011" =>
          FULL_PULSE_COUNT<=7;
          RISE_PULSE_COUNT<=3;
      when "1100" =>
          FULL_PULSE_COUNT<=3;
          RISE_PULSE_COUNT<=2;
      when others =>
     end case;  
   end process baudrate_set_proc;
	-- enter your statements here --
	-- 主过程
	-- main process
	main : process( clk, reset_n )
	variable clk_count : BD_COUNT; 
	begin
		-- 判断复位信号
		if reset_n = '0' then
			bg_out <= '0';
		---	indicator <= '0';
			clk_count := 0;
		-- 在时钟信号的上升沿动作
		elsif rising_edge(clk) then
			-- 判断使能信号
			if ce = '1' then
				-- 经过了RISE_PULSE_COUNT个计数，数脉冲上升
				if clk_count = RISE_PULSE_COUNT-1 then		-- pulse rise
					bg_out <= '1';
					clk_count := clk_count+1;
				-- 经过了FULL_PULSE_COUNT个计数，数脉冲下降
				elsif clk_count = FULL_PULSE_COUNT-1 then	-- indicator output and pulse fall
					-- 输出提示信号，使其为高
   ----					indicator <= '1';
					bg_out <= '0';
					-- 重置计数器计数为0
					clk_count := 0;
				-- 恢复提示信号为低
				elsif clk_count = 0 then
------					indicator <= '0';
					clk_count := clk_count+1;
				else
					clk_count := clk_count+1;
				end if;
			end if;
		end if;
	end process;

end multi_baudrate_generator;