Verilog (一) assignment

Verilog

  case-sensitive, all keywords are lowercase

 

1  continuous assignment  

assign  data_left  =  data_right;  // right drive left(net)

例 1)  mux

assign  data_out  =  select ? data_in1 : data_in0;

2  procedural assignment

1)  blocking ("=")

     execute sequential

2)  nonblocking ("<=")

     read (right)  -> schedule (left) ->  execute (<=)

例 2)  synchronizer

reg  [1:0]  data_sync;

always @ (posedge clk or posedge rst)
begin
  if (rst)
        data_sync  <=  2'b00;
  else
        data_sync  <= {data_sync[0], data_in};
end

assign  data_out  =  data_sync[1];

synchronizer

synchronizer