rs232_receive.txt

关于EDA编程的一些程序

module rs232_receive(clk,rxd,dout,into);
input clk,rxd;
output into;
output[7:0] dout;

reg bt_cp,cy_cp,into;
reg[3:0] rxd_st;                        //the staute of receiving
reg[2:0] cy_st;                         //1/8 time using  
reg[9:0] bt;                            //the speed of every bit to rs232
reg[7:0] dout;

always @(posedge clk)
begin
  bt=(bt!=71)?bt+1:0;                   //edit speed  19200 bit/s
  bt_cp=(bt==71)?1:0;  
end

always @(posedge bt_cp)
begin
  if((rxd==1)&&(rxd_st==0)) cy_st=0;
  else cy_st=cy_st+1;
  cy_cp=(cy_st==4)?1:0;                      //the forth clect point
end

always @(posedge cy_cp)
begin
  case(rxd_st)
  0:begin rxd_st=(rxd==0)?1:0;into=1;end
  1:begin rxd_st=2;dout[0]=rxd;end
  2:begin rxd_st=3;dout[1]=rxd;end
  3:begin rxd_st=4;dout[2]=rxd;end
  4:begin rxd_st=5;dout[3]=rxd;end
  5:begin rxd_st=6;dout[4]=rxd;end
  6:begin rxd_st=7;dout[5]=rxd;end
  7:begin rxd_st=8;dout[6]=rxd;end
  8:begin rxd_st=0;dout[7]=rxd;into=0;end
  default:rxd_st=0;
  endcase
end

endmodule