边沿检测电路

边沿检测电路，包括上升沿、下降沿、双沿检测电路。在检测到所需要的边沿后产生一个高电平的脉冲。

  
  

   
   
   
   module
   
    edge_detect
(
 
   
   input
   
    clk,
 
   
   input
   
    rst_n,
 
   
   input
   
    data_in,
 
   
   output
   
    raising_edge_detect,
 
   
   output
   
    falling_edge_detect,
 
   
   output
   
    double_edge_detect
);


   
   reg
   
    data_in_d1;

   
   reg
   
    data_in_d2;


   
   always
   
    @ (
   
   posedge
   
    clk,
   
   negedge
   
    rst_n)

   
   begin
   
   
 
   
   if
   
   (
   
   !
   
   rst_n)
 
   
   begin
   
   
 data_in_d1 
   
   <=
   
    
   
   1
   
   '
   
   b0;
   
   

   
    data_in_d2 
   
   <=
   
    
   
   1
   
   '
   
   b0;
   
   

   
    
   
   end
   
    
 
   
   else
   
   
 
   
   begin
   
   
 data_in_d1 
   
   <=
   
    data_in;
 data_in_d2 
   
   <=
   
    data_in_d1;
 
   
   end
   
    

   
   end
   
    


   
   assign
   
    raising_edge_detect 
   
   =
   
    data_in_d1 
   
   &
   
    (
   
   ~
   
   data_in_d2);

   
   assign
   
    falling_edge_detect 
   
   =
   
    
   
   ~
   
   data_in_d1 
   
   &
   
    data_in_d2;

   
   assign
   
    double_edge_detect 
   
   =
   
    data_in_d1 
   
   ^
   
    data_in_d2;


   
   endmodule