--過(guò)流保護(hù)程序
--電路將反饋電流轉(zhuǎn)換為[-5--+5]范
--通過(guò)減法電路將之轉(zhuǎn)換為[0--10]
--最后，通過(guò)分壓電路將之轉(zhuǎn)換為[0--5]
--作為ADC0809的輸入信號(hào)
--中點(diǎn)為2.5v

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity overcur_ctrl is
 port(c0809in:in std_logic_vector(7 downto 0);
      posin :in std_logic_vector(7 downto 0); 
      en:out std_logic;
      ctrl_out:out std_logic_vector(7 downto 0));
end entity;

architecture one of overcur_ctrl is
 begin
   process(c0809in,posin)
    begin
        if c0809in>="01001101"  and c0809in<="10110100"then   --77~180 
              ctrl_out<=posin;en<='1';     --en為PWM波使能信號(hào)
        else  en<='1'; ctrl_out<=posin-"00101111";
        end if;
   end process;
end one;